| two types of virus-related particles are found during transmissible gastroenteritis virus morphogenesis. | the intracellular assembly of the transmissible gastroenteritis coronavirus (tgev) was studied in infected swine testis (st) cells at different postinfection times by using ultrathin sections of conventionally embedded infected cells, freeze-substitution, and methods for detecting viral proteins and rna at the electron microscopy level. this ultrastructural analysis was focused on the identification of the different viral components that assemble in infected cells, in particular the spherical, p ... | 1998 | 9557690 |
| transmissible gastroenteritis coronavirus induces programmed cell death in infected cells through a caspase-dependent pathway. | in this report, we show that apoptosis (or programmed cell death) is induced in different cell lines infected with a coronavirus, the porcine transmissible gastroenteritis virus (tgev). kinetic analysis of internucleosomal dna cleavage by agarose gel electrophoresis and flow cytometry or cytometric monitoring of the mitochondrial transmembrane potential showed that, for st cells infected with tgev, the first overt signs of apoptosis appeared from 10 to 12 h postinfection on. they preceded morpho ... | 1998 | 9573259 |
| antiviral effect of trimeric 2',5'-oligoadenylic acid and some of its analogues. | the antiviral effect of 2',5'-trioligoadenylate (2',5'-a3) and some of its analogues was studied using several model cell culture systems and viruses: mice l929 fibroblast cells inoculated with vaccine virus, testicular piglet cells inoculated with aueszki disease virus (strain buk-628), and the same culture inoculated with a reference strain of transmissible gastroenteritis virus, strain purdue-115. our results suggest that both 2',5'-trioligoadenylate and its analogues are promising antiviral ... | 1998 | 9579338 |
| screening of a small set of random peptides: a new strategy to identify synthetic peptides that mimic epitopes. | small diversity libraries, composed of 4550 synthetic dodecapeptides and 8000 synthetic tripeptides, have been used to identify sequences homologous to small linear and non-linear parts of epitopes. here we report that synthetic peptides identified through alignment of dodecapeptides and tripeptides derived from these small libraries have, in direct elisa and/or competitive elisa, activities similar to that of peptides covering the native epitope and similar to that of peptides derived from larg ... | 1997 | 9587871 |
| characterization of determinants involved in the feline infectious peritonitis virus receptor function of feline aminopeptidase n. | feline aminopeptidase n (fapn) is a major cell surface receptor for feline infectious peritonitis virus (fipv), transmissible gastroenteritis virus (tgev), human coronavirus 229e (hcv 229e) and canine coronavirus (ccv). by using chimeric molecules assembled from porcine, human and feline apn we have analysed the determinants involved in the coronavirus receptor function of fapn. our results show that amino acids 670-840 of fapn are critically involved in its fipv and tgev receptor function where ... | 1998 | 9634079 |
| field isolates of transmissible gastroenteritis virus differ at the molecular level from the miller and purdue virulent and attenuated strains and from porcine respiratory coronaviruses. | the diversity in selected regions of the transmissible gastroenteritis virus (tgev) and porcine respiratory coronavirus (prcv) genomes was analyzed among known tgev and prcv strains and field isolates. the n-terminal half of the spike (s) glycoprotein gene and open reading frames (orf) 3, 3-1 and 4 were amplified by reverse transcriptase reaction and polymerase chain reaction (rt/pcr), and analyzed using restriction fragment length polymorphism (rflp) patterns of the amplified dna. reference tge ... | 1998 | 9637293 |
| differences in virus receptor for type i and type ii feline infectious peritonitis virus. | feline infectious peritonitis viruses (fipvs) are classified into type i and type ii serogroups. here, we report that feline aminopeptidase n (apn), a cell-surface metalloprotease on the intestinal, lung and kidney epithelial cells, is a receptor for type ii fipv but not for type i fipv. a monoclonal antibody (mab) r-g-4, which blocks infection of felis catus whole fetus (fcwf-4) cells by type ii fipv, was obtained by immunizing mice with fcwf-4 cells which are highly susceptible to fipv. this m ... | 1998 | 9645192 |
| nucleotide sequence of the inter-structural gene region of feline infectious peritonitis virus. | the sequence of the region located between the s and m glycoprotein genes of the 79-1146 strain of feline infectious peritonitis virus (fipv) is presented. the inter-structural gene region encodes 3 open reading frames (orfs), termed orfs 3a, 3b and 4, with nucleotide sequences conforming to the minimum conserved transcription signal upstream of each. an additional orf, 3x, partially overlaps the 3' end of orf 3a. the fipv interstructural gene region is identical in length when compared to the i ... | 1998 | 9654687 |
| discrimination between transmissible gastroenteritis virus isolates. | twenty tgev isolates were compared by sequencing a 393-414 nucleotide stretch near the 5' end of the s gene, after amplification by rt-pcr. this part of the s gene is known to show considerable variation between porcine, canine and feline coronaviruses and is completely deleted from porcine respiratory coronaviruses. the discrimination achieved by nucleotide sequence analysis was compared with that obtained by monoclonal antibody typing. the viruses could be split into several clusters, and rece ... | 1997 | 9672630 |
| prior infection of nursery-age pigs with porcine reproductive and respiratory syndrome virus does not affect the outcome of transmissible gastroenteritis virus challenge. | thirty-six specific-pathogen-free pigs were weaned at 2 weeks of age and separated into 4 treatment groups (a-d, 9 pigs/group). treatment groups b and d were infected with porcine reproductive and respiratory syndrome virus (prrsv), whereas groups a and c remained uninfected. two weeks later, 1 pig from each group was necropsied to assess gross lung involvement, and then the remaining group d prrsv-infected pigs and the group c uninfected pigs were challenged at 4 weeks of age with transmissible ... | 1998 | 9683070 |
| immune response of sows vaccinated with attenuated transmissible gastroenteritis virus (tgev) and recombinant tgev spike protein vaccines and protection of their suckling pigs against virulent tgev challenge exposure. | to compare recombinant transmissible gastroenteritis virus (tgev) spike protein, (sp) r2-2, with attenuated live virus (alv) vaccine in sows during late pregnancy. | 1998 | 9706204 |
| interferon-alpha response to swine arterivirus (poav), the porcine reproductive and respiratory syndrome virus. | we studied the interferon-alpha (ifn-alpha) system in relation to the porcine arterivirus (poav), porcine reproductive and respiratory syndrome virus (prrsv). recombinant porcine ifn-alpha inhibited the growth of this virus in alveolar macrophage cultures. when pigs were challenged intranasally with poav, their serum contained ifn-alpha in relatively low concentrations on the second day after challenge and up to 5 days at the latest. most animals had no ifn-alpha in their lung secretions, even t ... | 1998 | 9712364 |
| optimization of phosphorus localization by eftem of nucleic acid containing structures. | energy filtered transmission electron microscopy (eftem) has been used to study nucleic acids localization in unstained thin sections of virus-infected cells. for this purpose, phosphorus maps (p-maps) have been obtained by applying the n-windows egerton model for background subtraction from data acquired by a non-dedicated tem jeol 1200exii equipped with a post-column peels gatan 666-9000 and a gatan image filter (gif-100). to prevent possible errors in the evaluation of elemental maps and thus ... | 1998 | 9744088 |
| coronavirus pseudoparticles formed with recombinant m and e proteins induce alpha interferon synthesis by leukocytes. | transmissible gastroenteritis virus (tgev), an enteric coronavirus of swine, is a potent inducer of alpha interferon (ifn-alpha) both in vivo and in vitro. incubation of peripheral blood mononuclear cells with noninfectious viral material such as inactivated virions or fixed, infected cells leads to early and strong ifn-alpha synthesis. previous studies have shown that antibodies against the virus membrane glycoprotein m blocked the ifn induction and that two viruses with a mutated protein exhib ... | 1998 | 9765403 |
| specific cytotoxic lymphocyte response in swine against structural proteins of transmissible gastro-enteritis virus: a study using lymphoblastoid cell line and recombinant vaccinia virus. | to determine the specificity, if any, of cellular cytotoxicity against transmissible gastro-enteritis virus (tgev) infected cells, we developed a test using b lymphoblasts from a mhc histocompatible (d/d haplotype) cell line (l14), as stimulating and target cells. these cells were previously infected with recombinant vaccinia virus including different tgev structural genes, either the spike (vs), membrane (vm) or nucleoprotein gene (vn). lymphocytes from a tgev immunized (d/d) swine developed a ... | 1998 | 9779559 |
| obtention of porcine aminopeptidase-n transgenic mice and analysis of their susceptibility to transmissible gastroenteritis virus. | to obtain a laboratory animal model for transmissible gastroenteritis virus (tgev) infection, transgenic mice (tg) were produced by introducing two porcine aminopeptidase-n (apn) cdna-derived constructs into the mouse genome. in the first construct, the apn cdna was fused in 5' with the 1 kb upstream region of the apn gene and in 3' with the sv40 small intron and polyadenylation site. in the second construct, the 5' end of the apn cdna was replaced by the corresponding domain of the apn gene com ... | 1998 | 9782264 |
| molecular analysis of the coronavirus-receptor function of aminopeptidase n. | aminopeptidase n (apn) is a major cell surface for coronaviruses of the serogroup i. by using chimeric apn proteins assembled from human, porcine and feline apn we have identified determinants which are critically involved in the coronavirus-apn interaction. our results indicate that human coronavirus 229e (hcv 229e) is distinct from the other serogroup i coronaviruses in that determinants located within the n-terminal parts of the human and feline apn proteins mediate the infection of hcv 229e, ... | 1998 | 9782265 |
| feline aminopeptidase n is a receptor for all group i coronaviruses. | human coronavirus hcv-229e and porcine transmissible gastroenteritis virus (tgev), both members of coronavirus group i, use aminopeptidase n (apn) as their cellular receptors. these viruses show marked species specificity in receptor utilization as they can only use apn of their respective species to initiate virus infection. feline and canine coronaviruses are also group i coronaviruses. to determine whether feline apn could serve as a receptor for feline coronaviruses (fcovs), we cloned the cd ... | 1998 | 9782266 |
| the spike protein of transmissible gastroenteritis coronavirus controls the tropism of pseudorecombinant virions engineered using synthetic minigenomes. | the minimum sequence required for the replication and packaging of transmissible gastroenteritis virus (tgev)-derived minigenomes has been determined. to this end, cdnas encoding defective rnas have been cloned and used to express heterologous spike proteins, to determine the influence of the peplomer protein in the control of tgev tropism. a tgev defective interfering rna of 9.7 kb (di-c) was isolated, and a cdna complementary to di-c rna was cloned under the control of t7 promoter. in vitro tr ... | 1998 | 9782282 |
| progress towards the construction of a transmissible gastroenteritis coronavirus self-replicating rna using a two-layer expression system. | three transmissible gastroenteritis coronavirus (tgev) defective interfering rnas of 21, 10.6 and 9.7 kb (di-a, di-b and di-c, respectively) were isolated. dilution experiments showed that the largest di rna, di-a, is a self-replicating rna (replicon), and thus codes for a functional rna polymerase and all the necessary replication signals. in order to engineer a cdna encoding the rna replicon a strategy based on the cloning of di-c cdna, followed by the insertion of the sequences required to co ... | 1998 | 9782299 |
| structure and intracellular assembly of the transmissible gastroenteritis coronavirus. | coronaviruses have been described as pleomorphic, round particles with a helical nucleocapsid as the unique internal structure under the virion envelope. our studies on the organization of the transmissible gastroenteritis coronavirus (tgev) have shown that the structure of these viruses is more complex. different electron microscopy techniques, including cryomicroscopy of vitrified viruses, revealed the existence of an internal core, most probably icosahedral, in tgev virions. disruption of the ... | 1998 | 9782301 |
| interferon alpha inducing property of coronavirus particles and pseudoparticles. | previous work in our laboratory have provided evidence that the membrane glycoprotein m of tgev is centrally involved in efficient induction of alpha interferon (ifn-alpha) synthesis by non-immune peripheral blood mononuclear cells incubated with fixed, tgev-infected cells or inactivated virions. here we report recent completion of studies initiated to get a better understanding of the nature of the interferogenic determinant(s). transfected cells expressing tgev m together with the minor struct ... | 1998 | 9782306 |
| pathogenesis of coronavirus-induced infections. review of pathological and immunological aspects. | coronaviruses and arteriviruses infect multiple species of mammals, including humans, causing diseases that range from encephalitis to enteritis. several of these viruses infect domestic animals and cause significant morbidity and mortality, leading to major economic losses. in this category are included such pathogens as transmissible gastroenteritis virus, porcine respiratory and reproductive virus and infectious bronchitis virus. the feline coronaviruses (fecv) generally do not cause infectio ... | 1998 | 9782322 |
| is the sialic acid binding activity of the s protein involved in the enteropathogenicity of transmissible gastroenteritis virus? | transmissible gastroenteritis virus (tgev) is able to recognize sialic acid on sialo-glycoconjugates. analysis of mutants indicated that single point mutations in the s protein (around amino acids 145-155) of tgev may result both in the loss of the sialic acid binding activity and in a drastic reduction of the enteropathogenicity. from this observation we conclude that the sialic acid binding activity is involved in the enteropathogenicity of tgev. on the basis of our recent results we propose t ... | 1998 | 9782329 |
| isolation of hemagglutination-defective mutants for the analysis of the sialic acid binding activity of transmissible gastroenteritis virus. | the surface protein s of transmissible gastroenteritis virus (tgev) has a sialic acid binding activity that enables the virus to agglutinate erythrocytes. a protocol is described that has been successfully applied to the isolation of hemgglutination-defective mutants. the potential of these mutants for the characterization of the sialic acid-binding site and the function of the binding activity is discussed. | 1998 | 9782330 |
| transmissible gastroenteritis coronavirus carrier sow. | a sow infected with virulent transmissible gastroenteritis virus (tgev) shed virulent virus in her feces for 18 months. the virus was isolated from rectal swabs beginning 2 days postexposure (pe) and continued at irregular intervals. virus shedding was detected on 24 separate occasions. the titer of the virus shed ranged from < 1 x 10(2) pfu/ml to 7.2 x 10(3) pfu/ml, while the duration of the shedding ranged from 1 to 5 consecutive days. inoculation of 3-day-old piglets with tgev isolated from t ... | 1998 | 9782340 |
| interference of coronavirus infection by expression of igg or iga virus neutralizing antibodies. | mouse immunoglobulin gene fragments encoding the variable modules of the heavy (vh) and light (vl) chains of a transmissible gastroenteritis coronavirus (tgev) neutralizing monoclonal antibody (mab) have been cloned and sequenced. the selected mab recognizes a highly conserved viral epitope and does not lead to the selection of neutralization escape mutants. chimeric immunoglobulin genes with the variable modules from the murine mab and constant modules of human gamma 1 and kappa chains were con ... | 1998 | 9782343 |
| lactogenic immunity in transgenic mice producing recombinant antibodies neutralizing coronavirus. | protection against coronavirus infections can be provided by the oral administration of virus neutralizing antibodies. to provide lactogenic immunity, eighteen lines of transgenic mice secreting a recombinant igg1 monoclonal antibody (rigg1) and ten lines of transgenic mice secreting recombinant iga monoclonal antibodies (riga) neutralizing transmissible gastroenteritis coronavirus (tgev) into the milk were generated. genes encoding the light and heavy chains of monoclonal antibody (mab) 6a.c3 w ... | 1998 | 9782344 |
| natural killer cell frequency and function in pigs selectively bred for high or low antibody and cell-mediated immune response: response to vaccination with modified live transmissible gastroenteritis virus. | porcine nk cells are small to medium lymphocytes which are lytic for tumours and virally infected cells when co-cultured for long periods ( approximately 16 h). the frequency and function of nk cells were examined in generation 8 of pigs genetically selected for high (h), low (l), and control (c) antibody (ab) and cell-mediated immune response (cmir). the nk phenotype was identified using a pan-species nk-specific murine monoclonal antibody (5c6) and both binding and lysis of the nk target, k562 ... | 1998 | 9789121 |
| expression of immunogenic glycoprotein s polypeptides from transmissible gastroenteritis coronavirus in transgenic plants. | the use of transgenic plants as vaccine production systems was described recently. we report on the immunological response elicited by two recombinant versions of the glycoprotein s from the swine-transmissible gastroenteritis coronavirus (tgev) expressed in transgenic plants. arabidoposis plants were genetically transformed with cdnas constructs encoding either the n-terminal domain (amino acid residues 1-750) or the full-length glycoprotein s of tgev, responsible for the neutralizing antibody ... | 1998 | 9791026 |
| diarrhoea in nursing piglets associated with coccidiosis: prevalence, microscopic lesions and coexisting microorganisms. | a retrospective study was made of natural infections with isospora suis in nursing piglets, recorded from april 1994 to may 1997, to determine the prevalence, microscopical lesions and other microorganisms associated with coccidiosis. one hundred and five (17.3 per cent) of the 605 nursing piglets submitted from 304 pig farms were diagnosed positive for coccidiosis. the affected piglets were from seven to 20 days old, with a mean age of 11.1 days. coccidiosis occurred in each year but the incide ... | 1998 | 9807791 |
| absence of porcine interferon alpha secreting cells in severe combined immunodeficiency (scid) mice inoculated with porcine leukocytes. | a low frequency leukocyte subpopulation, referred to as natural interferon producing cells (nipc) is able to produce high amounts of interferon alpha (ifn-alpha) following contact with noninfectious viral structures. in order to examine the possible leukocytic nature and bone marrow origin of nipc, severe combined immunodeficiency (scid) mice were reconstituted with porcine leukocyte populations, including bone marrow cells. at different times after reconstitution, enriched cd4 and cd45 positive ... | 1998 | 9851013 |
| polymeric display of immunogenic epitopes from herpes simplex virus and transmissible gastroenteritis virus surface proteins on an enteroadherent fimbria. | the strong immunogenicity of bacterial fimbriae results from their polymeric and proteinaceous nature, and the protective role of these immunogens in experimental or commercial vaccines is associated with their capacity to induce antiadhesive antibodies. fimbria-mediated intestinal colonization by enteropathogens typically leads to similar antibody responses. the possibility of taking advantage of these properties was investigated by determining whether enteroadhesive fimbriae, like the 987p fim ... | 1999 | 9874660 |
| replication and packaging of transmissible gastroenteritis coronavirus-derived synthetic minigenomes. | the sequences involved in the replication and packaging of transmissible gastroenteritis virus (tgev) rna have been studied. the structure of a tgev defective interfering rna of 9.7 kb (di-c) was described previously (a. mendez, c. smerdou, a. izeta, f. gebauer, and l. enjuanes, virology 217: 495-507, 1996), and a cdna with the information to encode di-c rna was cloned under the control of the t7 promoter. the molecularly cloned di-c rna was replicated in trans upon transfection of helper virus- ... | 1999 | 9882359 |
| enteric viral infections of pigs and strategies for induction of mucosal immunity. | | 1999 | 9890034 |
| transmissible gastroenteritis virus induced apoptosis in swine testes cell cultures. | transmissible gastroenteritis virus (tgev) is a coronavirus which causes severe gastroenteritis and atrophy of intestinal villous epithelial cells in piglets. however, the mechanism of cell death caused by tgev is not known. in this study, we report that tgev induces cell death by apoptosis. tgev-induced apoptosis was demonstrated by agarose gel electrophoresis, electron microscopy, and terminal deoxytransferase digoxigenin-dutp nick end labeling (tunel). double labeling experiment confirmed the ... | 1998 | 9930203 |
| one-tube fluorogenic reverse transcription-polymerase chain reaction for the quantitation of feline coronaviruses. | a one-tube reverse transcription-polymerase chain reaction (rt-pcr) for absolute feline coronavirus (fcov) quantitation was developed. the assay is based on the 5' nuclease activity of the thermus flavus (tfl) polymerase and a fluorogenic probe which generates fluorescence when it is cleaved. the fluorogenic probe, also called taqman(tm) probe (perkin elmer, foster city, usa), is an oligonucleotide designed to bind between the two pcr primers to the target cdna and is labeled with a reporter and ... | 1999 | 10029323 |
| the major product of porcine transmissible gastroenteritis coronavirus gene 3b is an integral membrane glycoprotein of 31 kda. | the open reading frame potentially encoding a polypeptide of 27.7 kda and located as the second of three orfs (gene 3b) between the s and m genes in the genome of the purdue strain of porcine transmissible gastroenteritis coronavirus (tgev) was cloned and expressed in vitro to examine properties of the protein. gene 3b has a postulated role in pathogenesis, but its truncated form in some laboratory-passaged strains of tgev has led to the suggestion that it is not essential for virus replication. ... | 1999 | 10087235 |
| evaluation of the baculovirus-expressed s glycoprotein of transmissible gastroenteritis virus (tgev) as antigen in a competition elisa to differentiate porcine respiratory coronavirus from tgev antibodies in pigs. | the spike (s) glycoprotein of the miller strain of transmissible gastroenteritis virus (tgev) was recently cloned and expressed in baculovirus. the recombinant s protein was used as the coating antigen in a competition (blocking) enzyme-linked immunosorbent assay (elisa) in combination with monoclonal antibodies to the s protein epitope a (conserved on tgev and porcine respiratory coronavirus [prcv]) or epitope d (present on tgev only) to differentiate prcv- from tgev-induced antibodies. one set ... | 1999 | 10353350 |
| characterisation of a recent virulent transmissible gastroenteritis virus from britain with a deleted orf 3a. | analyses of transmissible gastroenteritis virus (tgev) and porcine respiratory coronavirus (prcv) isolates have suggested that tropism and pathogenicity are influenced by the spike protein and orf 3. in general, enteric viruses (tgev) have been shown to contain intact spike and orf 3 genes, whilst respiratory isolates (prcv) have major deletions within both regions. virulence has been correlated to a functional orf 3. here, sequence analysis of a recent isolate of virulent tgev, revealed a varia ... | 1999 | 10365166 |
| development of a nested pcr assay for the detection of canine coronavirus. | a diagnostic test for canine coronavirus (ccv) infection based on a nested polymerase chain reaction (n-pcr) assay was developed and tested using the following coronavirus strains: ccv (usda strain), ccv (45/93, field strain), feline infectious peritonitis virus (fipv, field strain), transmissible gastroenteritis virus (tgev, purdue strain), bovine coronavirus (bcv, 9wbl-77 strain), infectious bronchitis virus (ibv, m-41 strain) and fecal samples of dogs with ccv enteritis. a 230-bp segment of t ... | 1999 | 10403671 |
| targeted recombination demonstrates that the spike gene of transmissible gastroenteritis coronavirus is a determinant of its enteric tropism and virulence. | targeted recombination within the s (spike) gene of transmissible gastroenteritis coronavirus (tgev) was promoted by passage of helper respiratory virus isolates in cells transfected with a tgev-derived defective minigenome carrying the s gene from an enteric isolate. the minigenome was efficiently replicated in trans and packaged by the helper virus, leading to the formation of true recombinant and pseudorecombinant viruses containing the s proteins of both enteric and respiratory tgev strains ... | 1999 | 10438851 |
| a novel internal open reading frame product expressed from a polycistronic mrna of porcine epidemic diarrhoea virus may not contribute to virus attenuation. | cell-culture-adapted (ca) porcine epidemic diarrhoea virus (pedv) contains three internal open reading frames (i orf) within the nucleocapsid protein gene and lacks the downstream counterpart of porcine transmissible gastroenteritis virus orf7 or feline infectious peritonitis virus orf6a. to confirm whether such features also exist in wild-type (wt) pedv, the 3' 1800 nucleotides of its genome were sequenced and were found to be identical to those of ca virus. the coding potential of i-1 orf was ... | 1999 | 10466791 |
| the s gene of canine coronavirus, strain ucd-1, is more closely related to the s gene of transmissible gastroenteritis virus than to that of feline infectious peritonitis virus. | to gain insight into the genetic relationships among six canine coronavirus (ccv) strains, the variable region of the spike (s) protein gene was sequenced. the ccv strains were: two atcc reference strains, the insavc-1 vaccine strain, the national veterinary services laboratories (ames, ia) challenge strain, and two california field isolates (ucd-1 and ucd-2) from the 1970s. all six strains, downstream of the nucleocapsid (n) protein gene, had sufficient size for an orf 7b, and thus, none were t ... | 1999 | 10475084 |
| design and construction of african swine fever virus chimeras incorporating foreign viral epitopes. | in the present work we have studied the feasibility of introducing foreign epitopes into the african swine fever virus (asfv) particle by genetic manipulation of the virus. for this purpose, we developed specific transfer vectors containing the gene encoding for the highly antigenic structural asfv protein p54 in which foreign sequences were introduced. dna sequences encoding continuous linear epitopes, the antigenic site a from foot-and-mouth disease virus (fmdv) vp1 protein and the da3 antigen ... | 1999 | 10481737 |
| structural maturation of the transmissible gastroenteritis coronavirus. | during the life cycle of the transmissible gastroenteritis coronavirus (tgev), two types of virus-related particles are detected in infected swine testis cells: large annular viruses and small dense viruses. we have studied the relationships between these two types of particles. immunoelectron microscopy showed that they are closely related, since both large and small particles reacted equally with polyclonal and monoclonal antibodies specific for tgev proteins. monensin, a drug that selectively ... | 1999 | 10482542 |
| active immunity and t-cell populations in pigs intraperitoneally inoculated with baculovirus-expressed transmissible gastroenteritis virus structural proteins. | the intraperitoneal inoculation of pigs with baculovirus-expressed transmissible gastroenteritis virus (tgev) structural proteins (s, n, m) in conjunction with thermolabile escherichia coli mutant toxin (lt-r192g) in incomplete freund's adjuvant (ifa) was tested in an attempt to elicit active immunity to tgev in gut-associated lymphoid tissues (galt). four groups of 63 (1-5-week-old) suckling, tgev-seronegative pigs were used to assess the efficacy of the recombinant protein vaccine (group 3) in ... | 1999 | 10507362 |
| sequence analysis of the turkey coronavirus nucleocapsid protein gene and 3' untranslated region identifies the virus as a close relative of infectious bronchitis virus. | the 3' end of the turkey coronavirus (tcv) genome (1740 bases) including the nucleocapsid (n) gene and 3' untranslated region (utr) were sequenced and compared with published sequences of other avian and mammalian coronaviruses. the deduced sequence of the tcv n protein was determined to be 409 amino acids with a molecular mass of approximately 45 kda. the tcv n protein was identical in size and had greater than 90% amino acid identity with published n protein sequences of infectious bronchitis ... | 1999 | 10581391 |
| selection for high immune response: an alternative approach to animal health maintenance? | to test the hypothesis that variation in ability to respond immunologically correlates with health, yorkshire pigs were bred for high (hir) and low (lir) antibody (ab) and cell-mediated immune response (cmi). selection was based on standardized measures of ab (secondary response to hen egg white lysozyme, serum igg concentration) and cmi (cutaneous delayed-type hypersenstivity to purified protein derivative of tuberculin after immunization with bacillus calmette-guérin and in vitro lymphocyte re ... | 1999 | 10614513 |
| horizontal transmissible protection against myxomatosis and rabbit hemorrhagic disease by using a recombinant myxoma virus. | we have developed a new strategy for immunization of wild rabbit populations against myxomatosis and rabbit hemorrhagic disease (rhd) that uses recombinant viruses based on a naturally attenuated field strain of myxoma virus (mv). the recombinant viruses expressed the rhdv major capsid protein (vp60) including a linear epitope tag from the transmissible gastroenteritis virus (tgev) nucleoprotein. following inoculation, the recombinant viruses induced specific antibody responses against mv, rhdv, ... | 2000 | 10627521 |
| characterization of the sialic acid binding activity of transmissible gastroenteritis coronavirus by analysis of haemagglutination-deficient mutants. | transmissible gastroenteritis coronavirus (tgev) agglutinates erythrocytes of several species by virtue of sialic acid binding activity of the surface protein s. we have isolated and characterized five haemagglutination-defective (had) mutants. in contrast to the parental virus, the mutants were unable to bind to porcine submandibulary mucin, a substrate rich in sialic acid. each of the mutants was found to contain a single point mutation in the s protein (cys155phe, met195val, arg196ser, asp208 ... | 2000 | 10644848 |
| interference with virus and bacteria replication by the tissue specific expression of antibodies and interfering molecules. | historically, protection against virus infections has relied on the use of vaccines, but the induction of an immune response requires several days and in certain situations, like in newborn animals that may be infected at birth and die in a few days, there is not sufficient time to elicit a protective immune response. immediate protection in new born could be provided either by vectors that express virus-interfering molecules in a tissue specific form, or by the production of animals expressing ... | 1999 | 10659342 |
| immunogenicity of porcine transmissible gastroenteritis virus spike protein expressed in plants. | transgenic plants expressing recombinant proteins from pathogenic microorganisms provide an inexpensive edible vaccine for induction of local immunity. three transgenic plant lines were generated expressing the spike (s) protein of transmissible gastroenteritis virus (tgev), a protein crucial for establishing mucosal immunity. all three of them were driven by a strong plant promoter. one construct contained the 3.7 kb 5' end of the native s gene sequence. in the second construct part of the s ge ... | 2000 | 10706964 |
| downstream ribosomal entry for translation of coronavirus tgev gene 3b. | gene 3b (orf 3b) in porcine transmissible gastroenteritis coronavirus (tgev) encodes a putative nonstructural polypeptide of 27.7 kda with unknown function that during translation in vitro is capable of becoming a glycosylated integral membrane protein of 31 kda. in the virulent miller strain of tgev, orf 3b is 5'-terminal on mrna 3-1 and is presumably translated following 5' cap-dependent ribosomal entry. for three other strains of tgev, the virulent british fs772/70 and taiwanese tfi and aviru ... | 2000 | 10725209 |
| characterization of the stunting syndrome agent: relatedness to known viruses. | an enteric disease of young turkeys, referred to as stunting syndrome (ss), causes reduced growth and impaired feed efficiency. a recently isolated virus, stunting syndrome agent, (ssa) has been found to be the etiologic agent of ss. the objective of the present study was to determine relatedness of the ssa with other viral agents. serologic (viral neutralization and enzyme-linked immunosorbent assay [elisa]) assays and a reverse transcriptase-polymerase chain reaction (rt-pcr) were used. the an ... | 2000 | 10737643 |
| the viral nucleocapsid protein of transmissible gastroenteritis coronavirus (tgev) is cleaved by caspase-6 and -7 during tgev-induced apoptosis. | the transmissible gastroenteritis coronavirus (tgev), like many other viruses, exerts much of its cytopathic effect through the induction of apoptosis of its host cell. apoptosis is coordinated by a family of cysteine proteases, called caspases, that are activated during apoptosis and participate in dismantling the cell by cleaving key structural and regulatory proteins. we have explored the caspase activation events that are initiated upon infection of the human rectal tumor cell line hrt18 wit ... | 2000 | 10756009 |
| engineering the largest rna virus genome as an infectious bacterial artificial chromosome. | the construction of cdna clones encoding large-size rna molecules of biological interest, like coronavirus genomes, which are among the largest mature rna molecules known to biology, has been hampered by the instability of those cdnas in bacteria. herein, we show that the application of two strategies, cloning of the cdnas into a bacterial artificial chromosome and nuclear expression of rnas that are typically produced within the cytoplasm, is useful for the engineering of large rna molecules. a ... | 2000 | 10805807 |
| mucosal and systemic immune responses to chimeric fimbriae expressed by salmonella enterica serovar typhimurium vaccine strains. | recombinant live oral vaccines expressing pathogen-derived antigens offer a unique set of attractive properties. among these are the simplicity of administration, the capacity to induce mucosal and systemic immunity, and the advantage of permitting genetic manipulation for optimal antigen presentation. in this study, the benefit of having a heterologous antigen expressed on the surface of a live vector rather than intracellularly was evaluated. accordingly, the immune response of mice immunized ... | 2000 | 10816454 |
| detection and differentiation of porcine epidemic diarrhoea virus and transmissible gastroenteritis virus in clinical samples by multiplex rt-pcr. | a multiplex reverse-transcriptase-pcr (rt-pcr) procedure was developed for the simultaneous detection of porcine epidemic diarrhoea virus (pedv) and transmissible gastroenteritis virus (tgev) in preweaning pigs with diarrhoea. the membrane gene of pedv and the nucleocapsid gene of tgev were chosen as targets. the pcr products of pedv and tgev had molecular sizes of 412 and 612 base pairs, respectively. primers from pedv did not react with any tgev tested and vice versa. in addition, the primers ... | 2000 | 10872784 |
| transmissible gastroenteritis virus induces apoptosis in swine testicular cell lines but not in intestinal enterocytes. | evidence of apoptosis caused by infection with the purdue strain of transmissible gastroenteritis virus (tgev) was sought in vitro (in infected swine testicular [st] cells) and in vivo (in the intestinal tissues of infected piglets). the methods used were (1) dna electrophoresis for detection of dna fragmentation, and (2) terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-fluorescein nick and labelling (tunel). dna "laddering" was detected in tgev-infected st cells only. nu ... | 2000 | 10906258 |
| development of a reverse transcription-nested polymerase chain reaction assay for differential diagnosis of transmissible gastroenteritis virus and porcine respiratory coronavirus from feces and nasal swabs of infected pigs. | transmissible gastroenteritis virus (tgev), a coronavirus, replicates in intestinal enterocytes and causes diarrhea in young pigs. porcine respiratory coronavirus (prcv), a spike (s) gene natural deletion mutant of tgev, has a respiratory tissue tropism and causes mild or subclinical respiratory infections. conventional antigen-based diagnostic tests fail to differentiate tgev and prcv, and a blocking elisa test to serologically differentiate tgev/prcv-infected pigs is conducted on convalescent ... | 2000 | 10907874 |
| molecular characterization and pathogenesis of transmissible gastroenteritis coronavirus (tgev) and porcine respiratory coronavirus (prcv) field isolates co-circulating in a swine herd. | tgev replicates in intestinal enterocytes and causes diarrhea in young pigs. prcv, a spike (s) gene deletion mutant of tgev with an altered respiratory tissue tropism, causes mild or subclinical respiratory infections. comparisons of tgev and prcv strains suggest that tropism and pathogenicity are influenced by the s gene and orf3, respectively. recently, outbreaks of tge of reduced virulence were reported in the field. we investigated a similar suspect tgev outbreak of reduced virulence in nurs ... | 2000 | 10948987 |
| seroprevalence of porcine respiratory coronavirus in selected korean pigs. | a total of 446 serum samples from 88 herds in korea were examined for antibody to porcine respiratory coronavirus (prcv) using blocking enzyme-linked immunosorbent assay (elisa). all serum samples were collected from 24- to 26-week-old finishing pigs between december 1998 and june 1999. by elisa, 237 out of 446 sera tested (53.1%) and 54 out of 88 sampled herds (61.3%) were positive against prcv. of 446 sera from 88 herd tested, 185 (41.5%) serum samples from 22 (25%) herds were seronegative aga ... | 2000 | 10960715 |
| comparison of serologic testing and slaughter evaluation for assessing the effects of subclinical infection on growth in pigs. | to compare serologic testing with slaughter evaluation in assessing effects of subclinical infection on average daily weight gain (adg) in pigs. | 2000 | 10997163 |
| strategy for systematic assembly of large rna and dna genomes: transmissible gastroenteritis virus model. | a systematic method was developed to assemble functional full-length genomes of large rna and dna viruses. coronaviruses contain the largest single-stranded positive-polarity rna genome in nature. the approximately 30-kb genome, coupled with regions of genomic instability, has hindered the development of a full-length infectious cdna construct. we have assembled a full-length infectious construct of transmissible gastroenteritis virus (tgev), an important pathogen in swine. using a novel approac ... | 2000 | 11044104 |
| prevalence of porcine epidemic diarrhoea virus and transmissible gastroenteritis virus infection in korean pigs. | | 2000 | 11110482 |
| construction and characterization of recombinant porcine adenovirus serotype 5 expressing the transmissible gastroenteritis virus spike gene. | five recombinant porcine adenoviruses of serotype 5 (padv-5) carrying the full-length or the 5' 2.2 kb half of the transmissible gastroenteritis virus (tgev) spike (s) gene were generated by homologous recombination in e. coli strain bj5183 cells and subsequent transfection of swine testicle cells. the foreign genes were inserted into the e3 region of padv-5. one recombinant virus had no deletion in the e3 region, whereas a 1.2 kb fragment was removed from the e3 region in the remainder of the r ... | 2001 | 11125171 |
| sialic acid binding activity of transmissible gastroenteritis coronavirus affects sedimentation behavior of virions and solubilized glycoproteins. | the sedimentation behavior of transmissible gastroenteritis coronavirus (tgev) was analyzed. upon sucrose gradient centrifugation, the major virus band was found at a density of 1.20 to 1.22 g/cm(3). this high density was observed only when tgev with a functional sialic acid binding activity was analyzed. mutants of tgev that lacked sialic acid binding activity due to a point mutation in the sialic acid binding site of the s protein were mainly recovered at a lower-density position on the sucros ... | 2001 | 11134297 |
| the membrane m protein carboxy terminus binds to transmissible gastroenteritis coronavirus core and contributes to core stability. | the architecture of transmissible gastroenteritis coronavirus includes three different structural levels, the envelope, an internal core, and the nucleocapsid that is released when the core is disrupted. starting from purified virions, core structures have been reproducibly isolated as independent entities. the cores were stabilized at basic ph and by the presence of divalent cations, with mg(2+) ions more effectively contributing to core stability. core structures showed high resistance to diff ... | 2001 | 11152504 |
| an investigation of the etiology of a mild diarrhea observed in a group of grower/finisher pigs. | an investigation into a mild diarrhea in a group of grower/finisher pigs was carried out in order to determine the etiology. a tiamulin injection and a carbadox-medicated ration were given to pens of pigs in a 2 x 2 factorial experimental design. pens of pigs were assessed a score, based on the consistency of the feces in the pen, each week. the clinical investigation looked for the intestinal pathogens brachyspira pilosicoli, b. hyodysenteriae, lawsonia intracellularis, salmonella spp., yersini ... | 2001 | 11195519 |
| efficacy of a transmissible gastroenteritis coronavirus with an altered orf-3 gene. | serial passage of virulent transmissible gastroenteritis virus through cell culture reduced its virulence in 3-day-old piglets. intramuscular inoculation of pregnant gilts with 2 doses of this modified-live virus elicited a level of lactogenic immunity that protected their nursing piglets against a lethal dose of challenge virus. sequence analysis of a 637-bp fragment of the spike gene containing most of the aminopeptidase receptor and the 4 major antigenic sites from the original and the serial ... | 2001 | 11227191 |
| in situ hybridization for the detection of transmissible gastroenteritis virus in pigs and comparison with other methods. | archived formalin-fixed, paraffin-embedded tissues from 25 pigs naturally infected with transmissible gastroenteritis virus (tgev) were examined by in situ hybridization for tgev nucleic acid using a nonradioactive digoxigenin-labeled cdna probe that targeted the nucleocapsid sequence of tgev strains. the results of in situ hybridization for the detection of tgev were compared with virus isolation (vi), a fluorescent antibody test (fat), and transmission electron microscopy (tem). vi, fat, and t ... | 2001 | 11227192 |
| interferon-alpha-producing cells are localized in gut-associated lymphoid tissues in transmissible gastroenteritis virus (tgev) infected piglets. | transmissible gastroenteritis virus (tgev) infection of piglets results in a very rapid and massive release of ifn-alpha in serum and secretions. the objective of this work was to characterize the ifn-alpha-producing cells (ipc) in tissues of tgev-infected piglets. caesarean-derived colostrum-deprived piglets were infected orally with the tgev virulent miller strain and ipc were characterized in situ by immunohistochemistry, using a rabbit anti-pig ifn-alpha antiserum. ipc were almost exclusivel ... | 2001 | 11254179 |
| plant-based vaccines: unique advantages. | numerous studies have shown that viral epitopes and subunits of bacterial toxins can be expressed and correctly processed in transgenic plants. the recombinant proteins induce immune responses and have several benefits over current vaccine technologies, including increased safety, economy, stability, versatility and efficacy. antigens expressed in corn are particularly advantageous since the seed can be produced in vast quantities and shipped over long distances at ambient temperature, potential ... | 2001 | 11257418 |
| enhanced immune responses to viral epitopes by combining macrophage-inducible expression with multimeric display on a salmonella vector. | in this study, the immunogenicity of chimeric 987p fimbriae on a salmonella vaccine strain was improved by optimizing fimbrial expression. the constitutive teta promoter and the in vivo activated nirb and pagc promoters were evaluated for their use to express two epitopes of the transmissible gastroenteritis virus (tgev) spike protein carried by fimbriae which were displayed on a salmonella vaccine strain. constructs with the pagc promoter were shown to drive increased expression of chimeric 987 ... | 2001 | 11282213 |
| comparison of the sialic acid binding activity of transmissible gastroenteritis coronavirus and e. coli k99. | transmissible gastroenteritis coronavirus (tgev) and escherichia coli k99 are both enteropathogenic for pigs with infections being most severe in neonate animals. for both microorganisms, a sialic acid binding activity has been shown to be an essential pathogenicity factor. here we demonstrate with haemagglutination and haemagglutination-inhibition assays that tgev and e. coli k99 differ in their sialic acid binding activities with respect to the type and amount of sialic acid residues required ... | 2001 | 11311429 |
| feline and canine coronaviruses are released from the basolateral side of polarized epithelial llc-pk1 cells expressing the recombinant feline aminopeptidase-n cdna. | in this study feline (fecv and fipv) and canine (ccov) coronavirus entry into and release from polarized porcine epithelial llc-pk1 cells, stably expressing the recombinant feline aminopeptidase-n cdna, were investigated. virus entry appeared to occur preferentially through the apical membrane, similar to the entry of the related porcine coronavirus transmissible gastroenteritis virus (tgev) into these cells. however, whereas tgev is released apically, feline and canine coronaviruses were found ... | 2001 | 11402864 |
| partial passive protection with two monoclonal antibodies and frequency of feeding of hyperimmune anti-transmissible gastroenteritis virus (tgev) serum for protection of three-day-old piglets from a tgev challenge infection. | passive protection experiments were conducted to determine the frequency and amounts of hyperimmune antiserum needed to block a transmissible gastroenteritis virus (tgev) challenge infection and to identify monoclonal antibodies that are partially protective against tgev. hyperimmune antiserum or monoclonal antibodies were added to milk at each feeding or at selected feedings when the amount of antiserum was reduced. three-day-old piglets were challenged with virulent virus that had been preincu ... | 2001 | 11478599 |
| localization to the nucleolus is a common feature of coronavirus nucleoproteins, and the protein may disrupt host cell division. | the subcellular localization of transmissible gastroenteritis virus (tgev) and mouse hepatitis virus (mhv) (group i and group ii coronaviruses, respectively) nucleoproteins (n proteins) were examined by confocal microscopy. the proteins were shown to localize either to the cytoplasm alone or to the cytoplasm and a structure in the nucleus. this feature was confirmed to be the nucleolus by using specific antibodies to nucleolin, a major component of the nucleolus, and by confocal microscopy to im ... | 2001 | 11533198 |
| complete genome sequence of transmissible gastroenteritis coronavirus pur46-mad clone and evolution of the purdue virus cluster. | the complete sequence (28580 nt) of the pur46-mad clone of the purdue cluster of transmissible gastroenteritis coronavirus (tgev) has been determined and compared with members of this cluster and other coronaviruses. the computing distances among their s gene sequences resulted in the grouping of these coronaviruses into four clusters, one of them exclusively formed by the purdue viruses. three new potential sequence motifs with homology to the alpha-subunit of the polymerase-associated nucleoca ... | 2001 | 11556396 |
| molecular determinants of species specificity in the coronavirus receptor aminopeptidase n (cd13): influence of n-linked glycosylation. | aminopeptidase n (apn), a 150-kda metalloprotease also called cd13, serves as a receptor for serologically related coronaviruses of humans (human coronavirus 229e [hcov-229e]), pigs, and cats. these virus-receptor interactions can be highly species specific; for example, the human coronavirus can use human apn (hapn) but not porcine apn (papn) as its cellular receptor, and porcine coronaviruses can use papn but not hapn. substitution of papn amino acids 283 to 290 into hapn for the corresponding ... | 2001 | 11559807 |
| dna mediated immunization with encoding the nucleoprotein gene of porcine transmissible gastroenteritis virus. | the immune response to a naked plasmid dna encoding the nucleoprotein (n protein) of porcine transmissible gastroenteritis virus (tgev) was investigated in this study. a complementary dna of the entire n gene was amplified by rt-pcr, and inserted into a mammalian expression vector (pcdna3.1) to construct a recombinant plasmid (pcdna/n). to evaluate the immunogenicity of the construct, balb/c mice were intramuscularly immunized with different doses (50, 100 and 200 microg/mouse) of pcdna/n twice ... | 2001 | 11597750 |
| micro-indirect immunofluorescent antibody test for the detection of antibody to transmissible gastroenteritis virus. | | 2001 | 11702938 |
| organization of two transmissible gastroenteritis coronavirus membrane protein topologies within the virion and core. | the difference in membrane (m) protein compositions between the transmissible gastroenteritis coronavirus (tgev) virion and the core has been studied. the tgev m protein adopts two topologies in the virus envelope, a nexo-cendo topology (with the amino terminus exposed to the virus surface and the carboxy terminus inside the virus particle) and a nexo-cexo topology (with both the amino and carboxy termini exposed to the virion surface). the existence of a population of m molecules adopting a nex ... | 2001 | 11711614 |
| differential detection of transmissible gastroenteritis virus and porcine epidemic diarrhea virus by duplex rt-pcr. | transmissible gastroenteritis (tge) and porcine epidemic diarrhea (ped) are highly contagious enteric diseases of piglets. the clinical signs of these diseases are very similar and include watery, yellowish diarrhea. thus, the effective differential detection of tge virus and ped virus is required. in the present study, a duplex reverse transcription-polymerase chain reaction (rt-pcr) was established for the differential detection of tge and ped viruses. the primers were designed for the s gene ... | 2001 | 11724144 |
| completion of the porcine epidemic diarrhoea coronavirus (pedv) genome sequence. | the sequence of the replicase gene of porcine epidemic diarrhoea virus (pedv) has been determined. this completes the sequence of the entire genome of strain cv777, which was found to be 28,033 nucleotides (nt) in length (excluding the poly a-tail). a cloning strategy, which involves primers based on conserved regions in the predicted orf1 products from other coronaviruses whose genome sequence has been determined, was used to amplify the equivalent, but as yet unknown, sequence of pedv. primary ... | 2001 | 11724265 |
| a serodiagnostic elisa using recombinant antigen of swine transmissible gastroenteritis virus nucleoprotein. | a serodiagnostic elisa utilizing the recombinant nucleoprotein (rn protein) of transmissible gastroenteritis virus (tgev) was developed, and evaluated by examining a panel of 141 virus neutralization (vn) positive and 101 negative sera. the rn protein-based elisa (rnelisa) appeared to be highly sensitive and specific (98.6% and 98.0%, respectively) when it was compared to the vn test. the result was similar to that of an elisa based on purified viral antigens with showing good correlation (r=0.8 ... | 2001 | 11767065 |
| transcription regulatory sequences and mrna expression levels in the coronavirus transmissible gastroenteritis virus. | the transcription regulatory sequences (trss) of the coronavirus transmissible gastroenteritis virus (tgev) have been characterized by using a helper virus-dependent expression system based on coronavirus-derived minigenomes to study the synthesis of subgenomic mrnas. the trss are located at the 5' end of tgev genes and include a highly conserved core sequence (cs), 5'-cuaaac-3', that is essential for mediating a 100- to 1,000-fold increase in mrna synthesis when it is located in the appropriate ... | 2002 | 11773405 |
| heterologous gene expression from transmissible gastroenteritis virus replicon particles. | we have recently isolated a transmissible gastroenteritis virus (tgev) infectious construct designated tgev 1000 (b. yount, k. m. curtis, and r. s. baric, j. virol. 74:10600-10611, 2000). using this construct, a recombinant tgev was constructed that replaced open reading frame (orf) 3a with a heterologous gene encoding green fluorescent protein (gfp). following transfection of baby hamster kidney (bhk) cells, a recombinant tgev (tgev-gfp2) was isolated that replicated efficiently and expressed g ... | 2002 | 11773416 |
| are intestinal mucins involved in the pathogenicity of transmissible gastroenteritis coronavirus? | | 2001 | 11774472 |
| a strategy for the generation of an infectious transmissible gastroenteritis coronavirus from cloned cdna. | | 2001 | 11774479 |
| expression of transcriptional units using transmissible gastroenteritis coronavirus derived minigenomes and full-length cdna clones. | | 2001 | 11774506 |
| a simple strategy to assemble infectious rna and dna clones. | | 2001 | 11774510 |
| cloning of a transmissible gastroenteritis coronavirus full-length cdna. | | 2001 | 11774519 |
| the membrane m protein of the transmissible gastroenteritis coronavirus binds to the internal core through the carboxy-terminus. | | 2001 | 11774530 |
| antigenic and genomic relatedness of turkey-origin coronaviruses, bovine coronaviruses, and infectious bronchitis virus of chickens. | in earlier studies in our laboratory, we found that bovine coronavirus (bcv) was pathogenic for 1-day-old turkey poults. this finding prompted us to study the antigenic and genomic relatedness of turkey origin coronaviruses (tocvs) to bcv. a one-step reverse transcription (rt)-polymerase chain reaction (pcr) targeting a 730-base pair fragment of the nucleocapsid (n) gene of bcv and a nested pcr targeting a 407-base pair fragment of the n gene were used in an attempt to detect tocv from north car ... | 2001 | 11785902 |
| experimental infection of piglets with transmissible gastroenteritis virus: a comparison of three strains (korean, purdue and miller). | eighty-four colostrum-deprived piglets aged 1 day were inoculated with either a korean strain of transmissible gastroenteritis virus (tgev) or one of two american strains (purdue and miller). the purpose was to compare, by morphometric analysis and in-situ hybridization, the korean strain with the two american strains in respect of pathogenicity and viral distribution over a period of 72 h. the progression of infection in pigs infected with the korean strain was much slower than that in pigs inf ... | 2002 | 11814319 |
| in vitro and in vivo expression of foreign genes by transmissible gastroenteritis coronavirus-derived minigenomes. | a helper-dependent expression system based on transmissible gastroenteritis coronavirus (tgev) has been developed using a minigenome of 3.9 kb (m39). expression of the reporter gene beta-glucuronidase (gus) (2-8 microg per 10(6) cells) and the porcine respiratory and reproductive syndrome virus (prrsv) orf5 (1-2 microg per 10(6) cells) has been shown using a tgev-derived minigenome. gus expression levels increased about eightfold with the m.o.i. and were maintained for more than eight passages i ... | 2002 | 11842252 |
| conservation of substrate specificities among coronavirus main proteases. | the key enzyme in coronavirus replicase polyprotein processing is the coronavirus main protease, 3cl(pro). the substrate specificities of five coronavirus main proteases, including the prototypic enzymes from the coronavirus groups i, ii and iii, were characterized. recombinant main proteases of human coronavirus (hcov), transmissible gastroenteritis virus (tgev), feline infectious peritonitis virus, avian infectious bronchitis virus and mouse hepatitis virus (mhv) were tested in peptide-based t ... | 2002 | 11842254 |
| stabilization of a full-length infectious cdna clone of transmissible gastroenteritis coronavirus by insertion of an intron. | the stable propagation of a full-length transmissible gastroenteritis coronavirus (tgev) cdna in escherichia coli cells as a bacterial artificial chromosome has been considerably improved by the insertion of an intron to disrupt a toxic region identified in the viral genome. the viral rna was expressed in the cell nucleus under the control of the cytomegalovirus promoter and the intron was efficiently removed during translocation of this rna to the cytoplasm. the insertion in two different posit ... | 2002 | 11932433 |