Publications

TitleAbstractYear
Filter
PMID
Filter
pathogenicity and immunogenicity of a mutagen-attenuated rift valley fever virus immunogen in pregnant ewes.a mutagenized clone of rift valley fever virus (rvfv; mv p12) used in inoculation of 3 pregnant ewes was immunogenic, nonpathogenic, and nonabortogenic. in contrast, inoculation of a matched group of 3 pregnant ewes with parent rvfv induced clinical disease and abortions. ewes given mv p12 delivered healthy lambs that had rvfv antibody titers of less than 1:10 at birth, increasing to greater than or equal to 1:80 after ingestion of colostrum. ewes inoculated with parent rvfv developed marked vir ...19873631685
characterization of attenuated strains of rift valley fever virus.the wild-type zh501 strain of rift valley fever (rvf) virus and two small-plaque strains (t1 and t46) derived from it were characterized by plaque size, pathogenicity for hamsters and ability to replicate in vero cells. additionally, a mutagenized, attenuated, large-plaque, vaccine-candidate strain of rvf virus (zh548-m12) was also studied. infections with either the zh501 or t46 strain were uniformly fatal to hamsters. in contrast, nearly all hamsters infected with either the t1 or zh548-m12 st ...19883356978
ranking of prophylactic efficacy of poly(iclc) against rift valley fever virus infection in mice by incremental relative risk of death.the prophylactic efficacy of poly(iclc) (stabilized, synthetic, double-stranded polyriboinosinic-polyribocytidylic acid) against rift valley fever virus infection in swiss-webster mice was dependent on the treatment schedule. the treatment schedule was optimized by ranking the results of various treatments by the cox proportional-hazard model based on the incremental relative risk of death. with this ranking procedure, the schedule of choice was three doses of 20 micrograms each given 5 days apa ...19873631943
reduced survival of adult culex pipiens infected with rift valley fever virus.the effect of rift valley fever (rvf) viral infection on the survival of female culex pipiens was examined. in 3 experiments in which mosquitoes ingested rvf virus, there was a 44% decrease in survival to days 14-16 for transmitting vs. nontransmitting mosquitoes, and a 48% decrease in survival for individuals with disseminated vs. nondisseminated infections. these results were corroborated by other experiments in which survival of mosquitoes intrathoracically inoculated with rvf virus was compa ...19873661832
enhanced therapeutic efficacy of poly(iclc) and ribavirin combinations against rift valley fever virus infection in mice.the therapeutic efficacy of polyriboinosinic-polyribocytidylic acid stabilized with poly-l-lysine and carboxymethyl cellulose [poly(iclc)] given alone or in combination with ribavirin was evaluated in swiss webster mice infected with rift valley fever virus. four or more 20-micrograms doses of poly(iclc) given at various intervals beginning 24 h after infection protected all mice against death. on the other hand, a treatment regimen consisting of only three doses of poly(iclc) given 24 h postinf ...19873662477
vector competence of senegalese aedes fowleri (diptera: culicidae) for rift valley fever virus. 19883404545
rift valley fever in egypt 1986. surveillance of sheep flocks grazing in the northeast nile delta.from october 1985 through november 1986, 1714 presumably unvaccinated sheep in 13 nomadic flocks located in four provinces in dakahliya governorate, in the northeast nile delta, were ear tagged and monitored for acquisition of rift valley fever virus (rvfv) antibodies. sheep were bled at approximately 3 month intervals and sera were tested for haemagglutination inhibition (hi) antibodies to rvfv. hi reactors were tested for rvfv specific igm antibody by enzyme-linked immunosorbent assay (elisa) ...19883404565
evaluation of a new rift valley fever vaccine: safety and immunogenicity trials.a formalin-inactivated rift valley fever vaccine prepared in primary monkey kidney cells has been used to protect laboratory workers from disease since 1967. a similar but improved vaccine was prepared in 1978-1979 using well characterized diploid fetal rhesus lung cells. in initial clinical trials reported here, the new vaccine elicited high levels of plaque neutralizing antibodies and caused only minimal local reactions at the injection site. significant variability was observed in the geometr ...19863532605
reduced recovery of rift valley fever virus associated with assay of mosquito (diptera: culicidae) larval pools. 19863735349
isolation of rift valley fever virus from cattle abortions in tanzania. 19854060243
rift valley fever surveillance in mobile sheep flocks in the nile delta.rift valley fever (rvf) surveillance was carried out in the nile delta by monitoring mobile and stationary sheep flocks for antibodies to rvf virus. sheep are known to be susceptible to rvf virus infection and experienced severe morbidity in 1977 and 1978 when rvf was epidemic in egypt. four hundred six sheep in 32 flocks were surveyed during 1984. twenty-four sheep from 7 flocks had antibodies to rvf virus detected by hemagglutination inhibition and plaque reduction neutralization tests. antibo ...19863766852
effect of extrinsic incubation temperature on the ability of aedes taeniorhynchus and culex pipiens to transmit rift valley fever virus.studies were conducted to examine the effects of extrinsic incubation (ei) temperature on the vector competence of egyptian culex pipiens and north american aedes taeniorhynchus for rift valley fever (rvf) virus. following per os exposure, infection rates in ae. taeniorhynchus remained relatively constant at 55%, 56%, and 59% for mosquitoes held at ei temperatures of 13, 26, and 33 degrees c, respectively. in contrast, significantly fewer cx. pipiens became infected when held at 13 degrees c (38 ...19853834803
detection of rift valley fever viral activity in kenya by satellite remote sensing imagery.data from the advanced very high resolution radiometer on board the national oceanic and atmospheric administration's polar-orbiting meteorological satellites have been used to infer ecological parameters associated with rift valley fever (rvf) viral activity in kenya. an indicator of potential viral activity was produced from satellite data for two different ecological regions in kenya, where rvf is enzootic. the correlation between the satellite-derived green vegetation index and the ecologica ...19873823909
comparison of techniques for demonstrating antibodies to rift valley fever virus.nine serological techniques were compared by monitoring the response to infection with rift valley fever (rvf) virus in three sheep. antibodies were monitored daily for the first 14 days after infection, then weekly and later fortnightly up to week 24. the earliest antibody response was detected in one sheep on day 3 by a plaque reduction neutralization test, and by day 6 antibodies were demonstrable in all three sheep by haemagglutination-inhibition, reversed passive haemagglutination-inhibitio ...19863537118
comparative pathogenicity and antigenic cross-reactivity of rift valley fever and other african phleboviruses in sheep.homologous and heterologous haemagglutination-inhibition (hai), complement-fixation (cf), immunodiffusion (id) and mouse neutralization tests were performed with the lunyo (lun) and a zimbabwean strain of rift valley fever (rvf) virus, the prototype and a south african strain of arumowot (amt) virus and prototype strains of gordil (gor), saint-floris (saf) and gabek forest (gf) viruses, using immune mouse ascitic fluids prepared against these viruses. reactions of identity occurred in all tests ...19863537119
enzyme-linked immunosorbent assay for detection of antibodies to rift valley fever virus in ovine and bovine sera.an enzyme-linked immunosorbent assay (elisa) was developed for the rapid detection of antibodies to rift valley fever virus (rvfv) in ovine and bovine sera. conditions to reduce nonspecific reactions were optimized. the elisa results correlated with those of a plaque-reduction neutralization test, revealing 100% specificity and 90.7% sensitivity. in sera from sheep and cattle inoculated against rvfv, the hemagglutination-inhibition test in combination with the elisa provided a better indication ...19873631700
[recent data on hemorrhagic fevers in west africa].among the viruses which can provoke human haemorrhagic fevers, the congo-crimean haemorrhagic fever and rift valley fever viruses have been discovered relatively recently in west africa. two human cases of severe haemorrhagic fever have been connected with congo-chf, in mauritania and burkina-faso. the epidemiological enquiry performed in mauritania, consequent to the appearance of the first case, has demonstrated that the patient had been contaminated by contact with camels. twelve strains of c ...19853836774
rainfall and epizootic rift valley fever.epizootic rift valley fever (rvf) has occurred in kenya four times over the last 30 years. widespread, frequent, and persistent rainfall has been a feature of these epizootic periods. a composite statistic, based upon measurements of these rainfall characteristics, is positive during periods of epizootic rift valley fever. the heavy rainfall raises the level of the water table in certain areas, flooding the grassland depressions (dambos) that are the habitat of the immature forms of certain grou ...19853879206
long term existence of rift valley fever virus in immune mice. 19734805358
enhanced mosquito blood-finding success on parasitemic hosts: evidence for vector-parasite mutualism.the generalized hematopathology frequently found in animals infected with vector-borne pathogens may maximize transmission by enhancing the ability of vectors to locate blood in infected hosts. we tested this idea of mutualism between parasite and vector by comparing duration of probing of mosquitoes feeding on noninfected and on malaria-(plasmodium chabaudi) or arbovirus-(rift valley fever virus) infected animals. we found that median duration of probing (blood location) on infected rodents was ...19853865192
heat- and acid-labile virus-inhibiting factor or interferon induced by rift valley fever virus in mice. 19715003260
rift valley fever in kenya: the presence of antibody to the virus in camels (camelus dromedarius).five hundred and seventy-one camel sera collected after an epizootic of rift valley fever were examined for antibody to the virus. clinical disease had not been observed in cattle and sheep in the ecosystems shared with the camels. positive sera with high titres of serum neutralizing antibody were found in 22% of camels at one of the seven sampling sites.19853989285
investigations following initial recognition of crimean-congo haemorrhagic fever in south africa and the diagnosis of 2 further cases.sera from 124 cattle herds were tested, and antibodies to crimean-congo haemorrhagic fever (cchf) were found in 93 herds. the prevalence of antibodies was high in the interior of the country, in excess of 90% in some herds, but was less than 4% in cattle along the coast from cape town to east london. only 17 out of 1109 (1,5%) human residents of 55 farms had antibodies to cchf, while none of 164 veterinary research workers or 98 veterinarians engaged in farm animal practice had them. specimens f ...19853933132
a rift valley fever vaccine trial: 2. serological response to booster doses with a comparison of intradermal versus subcutaneous injection.a booster dose of a formalin-inactivated, cell culture-propagated rift valley fever vaccine (tsi-gsd-200) was administered without significant reactogenicity to 60 volunteers 18 months after they received a three dose primary series. blood was drawn for serological testing prior to boosting and 10, 49, and 180 days thereafter. neutralizing antibody response was prompt, being maximum on day 10 and considerably higher than the peak titres obtained on day 42 after the initial series. a marked decli ...19854036270
enhanced efficacy of liposome-encapsulated ribavirin against rift valley fever virus infection in mice.administration of liposome-encapsulated ribavirin to mice led to ribavirin concentrations in the liver, the primary site of rift valley fever virus proliferation, that were fivefold greater than those attained with the same doses of free ribavirin. liposomal ribavirin given at a dose of either 25 or 50 mg of drug per kg of body weight protected mice against a rapidly lethal high-titer challenge with rift valley fever virus, whereas similar doses of free drug or empty liposomes had no detectable ...19854026264
rift valley fever virus vaccine trial: study of neutralizing antibody response in humans.the serological response to immunization with a formalin inactivated rift valley fever (rvf) vaccine was studied in 963 swedish un soldiers serving in the sinai peninsula. antibody titres were determined with a plaque reduction neutralization test (prnt). attempts were made to give all soldiers three injections (1 ml s.c. days 0, 7-10 and 28-30) but 128 soldiers received only two injections. in a group of 51 fully vaccinated individuals, repeated blood samples were collected. fifty of the vaccin ...19854036271
experimental infection and protection of lambs with a minute plaque variant of rift valley fever virus.the injection of a single dose containing 5 x 10(3) plaque forming units (pfu) of a minute plaque variant of rift valley fever virus (rvfv) into two susceptible lambs resulted in no detectable viremia, pyrexia or clinical signs of disease. immunization with the minute plaque variant induced neutralizing antibody as early as seven days postinoculation; however, no complement fixing antibodies were detected. lambs immunized in this manner were protected when challenged with an infectious dose cont ...19863706629
rift valley fever: a sero-epidemiological survey among pregnant women in mozambique.rift valley fever (rvf) causes abortion in sheep and cattle. however, the teratogenic and abortogenic potential of rvf in humans is not known. sera from a total of 1163 pregnant women in mozambique were tested for rvf virus antibodies by elisa and 28 (2%) were found to be positive. mothers experiencing fetal death or miscarriage (155) had the same rvf virus antibody prevalence as those with normal deliveries. analysis of maternity histories showed some indication of increased fetal wastage among ...19873678406
growth of rift valley fever virus in human diploid (wi-38) cells. 19695766737
mutagen-directed attenuation of rift valley fever virus as a method for vaccine development.serial mutagenesis with 5-fluorouracil has been employed to derive an attenuated strain of rift valley fever virus for use as a live virus vaccine.19854045430
rift valley fever. 2. attempts to transmit virus with seven species of mosquito. 19734148061
a possible route for the introduction of rift valley fever virus into egypt during 1977.rift valley fever (rvf), which was enzootic in sudan in 1976 and epidemic in egypt in 1977-78, may have been introduced into egypt from sudan via sheep transported along lake nasser. a hypothesis is presented which describes sheep transport from holding areas in north-central sudan, where rvf was epizootic, to live animal markets in southern egypt. travel time from north-central sudan to the aswan area was less than 5 days, approximating the incubation period of rvf virus in sheep. reintroductio ...19863795324
fluorescent and neutralizing antibody response to infection by rift valley fever virus. 19734588885
rift valley fever. 3. viraemia in cattle and sheep. 4. the susceptibility of mice and hamsters in relation to transmission of virus by mosquitoes. 19734149110
the pathogenicity of rift valley fever virus for the baboon. 19724558832
selection of avirulent variants of rift valley fever virus. 19744465474
induction of virus-inhibiting factor or interferon in mice by strains with different virulence of rift valley fever virus. 19724632205
immunofluorescent cell-counting assay of rift valley fever virus. 19694893388
messenger rna of the m segment rna of rift valley fever virus.the putative messenger rna (mrna) of the m segment rna of the phlebovirus rift valley fever virus (rvfv) has been characterized using s1 nuclease mapping and oligonucleotide primer extension procedures. these experiments revealed that the 3' end of the mrna lacks approximately 112 nucleotides of the m genomic rna sequences, and that the 5' end of the mrna possesses all of the sequences present at the 3' end of the m rna but is further extended beyond the end of the genome by some 12-14 nucleotid ...19863962188
prevalence of hepatitis virus and some arbovirus infections in kavango, northern swa/namibia.a survey of the frequency of hepatitis b markers in 258 subjects from kavango, northern south west africa/namibia, was undertaken during february - may 1983. the hepatitis b surface antigen and hepatitis b e antigen carrier rates were 13,6% and 2,7% respectively. only 1,9% of the subjects were negative for all the markers tested, indicating that infection had been present at some stage in 98,1% of the sample. no known transmission method of the virus seems to fit this high exposure rate. the pos ...19853983734
enzyme-linked immunosorbent assay for detection of rift valley fever virus antigen in mosquitoes.an enzyme-linked immunosorbent assay (elisa) was used to measure the quantity of rift valley fever (rvf) viral antigen in infected egyptian culex pipiens. infectivity, as measured by plaque assay, was significantly correlated with viral antigen, as measured by the elisa, in all groups of mosquitoes regardless of the time interval after the infectious blood meal. the proportion of noninfectious viral antigen in these groups increased with time. when individual mosquitoes were assayed the plaque a ...19853985279
detection of rift valley fever virus by the fluorescent antibody technique in organs of experimentally infected animals. 19704926635
culex pipiens (diptera: culicidae) morbidity and mortality associated with rift valley fever virus infection. 19854009630
relationship between plaque assay and the mouse assay for titrating rift valley fever virus. 19705457747
the clinical aspects of rift valley fever virus in household pets. 3. pathologic changes in the dog and cat. 19705460685
the clinical aspects of rift valley fever virus in household pets. ii. susceptibility of the cat. 19705460684
electron microscopic studies on bhk 21 cells infected with rift valley fever virus. 19685729635
concentration of rift valley fever and chikungunya viruses by precipitation.simple and efficient methods for concentrating rift valley fever (rvf) virus and chikungunya (chik) virus are described. ammonium sulfate, potassium sulfate, or alcohol was used as a precipitating agent and the precipitate was resuspended to volumes suitable for further processing and purification. the methods permitted concentration of live rvf virus and chik virus about 100-fold with negligible losses of virus. rvf virus retained a high level of infectivity with potassium aluminum sulfate and ...19705494763
rdb--a new product of plant origin for cell culture dispersion.rdb is a crude preparation extracted from a plant source. it is a very potent agent for dispersion of monolayer cell cultures as well as for the preparation of primary cell suspensions. it was found to be most effective in dispersing a wide range of animal and mosquito cells and dissociating neuronal and muscular tissue for primary cell cultures. rdb was also found to be useful for preparation of primary culture for chick embryo fibroblasts. after treatment with rdb cell viability was found to b ...19854043538
evaluation of factors related to growth of rift valley fever virus in suspended cell cultures.the effect of several controlled variables on the peak titer and fold increase of rift valley fever virus grown in suspension culture on two variants of earle's l cell, l-dr and l-ma clone 1-1, was studied. no significant amount of cell-associated virus was found at 24 hr, indicating a release of virus soon after its formation. mild sonic treatment of the virus produced in serum-free medium increased the infective titer about 10x. this difference was not observed with virus produced in medium su ...19695814993
interacting factors that influence long-term storage of live pasteurella tularensis vaccine and rift valley fever virus.studies were conducted on the interaction of various parameters which affect the storage stability and growth potential of liquid cultures of pasteurella tularensis live vaccine strain (lvs) and rift valley fever virus van wyk strain (rvfv). storage variables studied with lvs included four storage temperatures (4, -20, -65, -175 c), single and multiple freeze-thaw cycles, two freezing and two thawing rates (slow and fast), various inoculum levels (1, 3, 5, and 10%) for the determination of growt ...19695780399
stability of rift valley fever virus at 4 c. 19676029841
effect of virus input multiplicity and tissue cell concentration on growth of rift valley fever virus.the effects of virus input multiplicity and of tissue cell concentration upon the growth of rift valley fever virus in l cells (earle) were determined. the titers obtained in suspension cultures with cells obtained from two separate laboratories were significantly different. with both monolayer culture and suspension culture systems, a virus input multiplicity of 2.5 resulted in the greatest proliferation of virus. optimal viral yields were obtained in suspension cultures containing 4 x 10(5) ti ...19676035052
experimental infection of cattle with pantropic rift valley fever virus. 19676064502
vector studies on rift valley fever virus in south africa. 19806105722
biological characteristics of plaque variants of rift valley fever virus. 19676070948
serological relation between rift valley fever virus and viruses of phlebotomus fever serogroup. 19806103252
[hematophagous diptera arbovirus vectors in africa (author's transl)].the authors, in a first part, show the general arthropods-viruses-vertebrates relationships and specially the different conditions of virus maintenance in the selvatic foci. then they succinctly give the main characteristics of the vectors bioecology useful for understanding the epidemiology of arbovirus diseases of man and domestic animals. thus diptera vectors of o'nyong-nyong and chikungunya fevers, yellow fever, dengue fever, wesselsbron, sindbis, and west nile viruses, rift valley fever, sa ...19816116145
possible vectors of rift valley fever in kenya. 19806111141
susceptibility of dogs and cats to rift valley fever by inhalation or ingestion of virus. 19725016294
ultrafiltration as a method for concentrating rift valley fever virus grown in tissue culture.filtration by means of a diaflo ultrafilter was used to concentrate three 1,000-ml lots and one 3,000-ml lot of tissue culture-grown rift valley fever virus. quantitation of both infectivity and total protein was achieved. water treatment with continued ultrafiltration of the virus concentrate provided a final virus product approximately 99.25% free of low-molecular-weight materials originally present in the growth medium.19715103483
[brain teratology as a result of transplacental virus infection in ruminants].various viruses relating to congenital brain teratology in ruminants are discussed. these include: bluetongue which may be responsible for porencephaly and hydranencephaly; akabane disease, rift valley fever (mouse brain attenuated virus) and wesselsbron disease (wild-type and mouse brain attenuated viruses) which can give rise to porencephaly, hydranencephaly, micrencephaly and cerebellar hypoplasia, and bovine viral diarrhoea-mucosal disease which results only in cerebellar hypoplasia. certain ...19806267276
the clinical aspects of rift valley fever virus in household pets. i. susceptibility of the dog. 19705410787
mechanical transmission of rift valley fever virus by hematophagous diptera.experimental studies were conducted to determine if hematophagous diptera were capable of mechanical transmission of rift valley fever (rvf) virus to laboratory animals. all species tested (glossina morsitans, aedes aegypti, aedes taeniorhynchus, culex pipiens, stomoxys calcitrans, lutzomyia longipalpis, and culicoides variipennis) mechanically transmitted the virus to hamsters. mechanical transmission rates for g. morsitans ranged from 0-100%, with the probability of mechanical transmission pos ...19853970308
[rift valley fever]. 19846145273
increased mosquito feeding on rift valley fever virus-infected lambs.experiments were conducted to determine whether or not mosquitoes exhibited an increase in feeding on rift valley fever (rvf) virus-infected lambs as compared to uninfected ones. overall, when given a choice between a viremic lamb, or its uninfected twin, 65% (1,264/1,943) of the engorged female culex pipiens obtained blood from the viremic lamb. this excess of feedings on viremic lambs was demonstrated regardless of the age of the lambs, or the time period between inoculation of the lambs and e ...19846150656
studies on the antigenic relationship among phleboviruses. 19826174048
in-vivo activity of antivirals against exotic rna viral infections.infection of humans by viruses belonging to the families of toga-, bunya-, and arenaviridae constitutes a major health problem worldwide and certain of the viruses have the potential to cause widespread epidemics. in the search for effective chemotherapy against these viruses several hundred nucleoside and nucleotide analogues have been screened for antiviral activity. of the compounds tested, ribavirin, has been shown in laboratory animal models to have significant inhibitory effects against ri ...19846208183
rift valley fever. 19836359835
antiviral efficacy of pyrazofurin against selected rna viruses.the antibiotic pyrazofurin, 3-(beta-d-ribofuranosyl)-4-hydroxypyrazole-5-carboxamide, markedly inhibited the in vitro replication of a number of rna viruses including rift valley fever (rvf), venezuelan equine encephalomyelitis (vee), sandfly, pichinde, lassa and lcm virus. plaque formation was reduced by 80% or more with 2-10 micrograms/ml of pyrazofurin while 2 micrograms/ml reduced by 1000-fold the yield of lassa and lcm virus in a yield reduction assay. in vivo, pyrazofurin failed to protect ...19826299188
characterization of eight new phlebotomus fever serogroup arboviruses (bunyaviridae: phlebovirus) from the amazon region of brazil.eight new members of the phlebotomus fever arbovirus serogroup (family bunyaviridae; genus phlebovirus) from the amazon region of brazil are described. one serotype was recovered from a febrile patient, three from small wild animals and four from sand flies. a small serum survey carried out with the human isolate, alenquer virus, suggests that it rarely infects man. complement-fixation and plaque reduction neutralization tests were done, comparing the eight new viruses with other members of the ...19836312820
zinga virus: a strain of rift valley fever virus. 19836403821
antibodies against haemorrhagic fever viruses in kenya populations.human sera from lodwar (77 sera), nzoia (841 sera), masinga (251 sera), laisamis (174 sera) and the malindi/kilifi area (556 sera) in kenya were tested by indirect immunofluorescence for antibodies against marburg, ebola (zaire and sudan strains), congo haemorrhagic fever, rift valley fever and lassa viruses. antibodies against ebola virus, particularly the zaire strain, were detected in all regions and were, over-all, more abundant than antibodies against the other antigens. ebola and marburg a ...19836419422
detection of rift valley fever virus antigen by enzyme-linked immunosorbent assay.a double-antibody (sandwich) enzyme-linked immunosorbent assay (elisa) was adapted to detect rift valley fever virus antigen. antibodies were purified from hyperimmune mouse and rabbit sera by affinity chromatography, using cnbr-activated sepharose 4b coupled to a beta-propiolactone-inactivated sucrose-acetone-extracted suckling mouse liver antigen. in the assay, antigen was captured by mouse antibody adsorbed to polystyrene plates and then detected by reacting sequentially with rabbit anti-rift ...19836409920
enhanced arboviral transmission by mosquitoes that concurrently ingested microfilariae.infection, dissemination, and transmission of an arbovirus in mosquitoes are enhanced by concurrent ingestion of microfilariae. ingestion of rift valley fever virus alone infected only 64 percent of female aedes taeniorhynchus. of these, only 5 percent of refeeding mosquitoes actually transmitted virus. in contrast, ingestion of the same amount of virus from concurrently microfilaremic (brugia malayi) gerbils resulted in 88 percent infection and 31 percent transmission. enhanced transmission of ...19846474165
recombinant dna technology for the preparation of subunit vaccines.recombinant dna technology appears to be on the verge of producing safe and effective protein vaccines for animal and human diseases. the procedure is applicable to most viruses because their isolated surface proteins generally possess immunogenic activity. strategies used for the preparation and cloning of the appropriate genes depend on the characteristics of the viral genomes: whether dna or rna; their size, strandedness, and segmentation; and whether messenger rna are monocistronic or polyci ...19826129235
active and passive immunization against rift valley fever virus infection in syrian hamsters.the protection by active and passive immunization of golden syrian hamsters challenged with rift valley fever (rvf) virus intraperitoneally was studied. six groups of 10 hamsters were inoculated with different amounts of immune serum while five groups were actively immunized with different doses of a formalin-inactivated rvf vaccine. one day after passive and three weeks after active immunization all hamsters were challenged with 5000 plaque-forming units of rvf virus. plaque reduction neutraliz ...19846507105
monoclonal antibodies to identify zinga virus as rift valley fever virus. 19836131312
the effect of laboratory colonization on the vector-pathogen interactions of egyptian culex pipiens and rift valley fever virus.field and laboratory findings implicated culex pipiens as a vector of rift valley fever (rvf) virus during the 1977-1978 epizootics/epidemics in egypt. this study evaluated changes in infection and transmission rates, and viral titers in f1 through f16 generation cx. pipiens mosquitoes orally infected with rvf virus. infection and transmission rates of rvf virus by this species changed significantly during the colonization process. however, the ultimate viral titers of either the transmitting or ...19836625070
rift valley fever and its epidemiology in egypt: a review. 19836577119
synergistic antiviral effects of ribavirin and the c-nucleoside analogs tiazofurin and selenazofurin against togaviruses, bunyaviruses, and arenaviruses.binary combinations of the n-nucleoside ribavirin (1-beta-d-ribofuranosyl-1,2,4-triazole-3-carboxamide) and the c-nucleoside analog selenazofurin (2-beta-d-ribofuranosylselenazole-4-carboxamide) or tiazofurin (2-beta-d-ribofuranosylthiazole-4-carboxamide) were tested in vitro for activity against venezuelan equine encephalomyelitis, japanese encephalitis, yellow fever, rift valley fever, korean hemorrhagic fever, and pichinde viruses. the 50% effective dose for each compound alone or in a series ...19846151377
isolation of crimean-congo haemorrhagic fever and rift valley fever viruses in upper volta. 19846144896
[recent research progress on interferon]. 19826180965
[use of veterinary vaccines for preventing and combatting rift valley fever: memorandum of a who/fao meeting]. 19836603918
clinical and pathological studies in adult sheep and goats experimentally infected with wesselsbron disease virus.the clinical symptoms and pathology in 33 adult sheep and 31 adult goats experimentally infected with wesselsbron disease virus are described. there was moderate to severe hyperthermia in most animals, but no other clinical signs of disease or deaths were recorded. eleven sheep and 6 goats were sacrificed for pathological studies at various stages during the febrile response. the macroscopic and microscopic lesions in these cases are described. microscopic studies revealed that the liver was con ...19826289220
broad-spectrum antiviral activity of 2-beta-d-ribofuranosylselenazole-4-carboxamide, a new antiviral agent.the relative in vitro antiviral activities of three related nucleoside carboxamides, ribavirin (1-beta-d-ribofuranosyl-1,2,4-triazole-3-carboxamide), tiazofurin (2-beta-d-ribofuranosylthiazole-4-carboxamide), and selenazole (2-beta-d-ribofuranosylselenazole-4-carboxamide), were studied against selected dna and rna viruses. although the activity of selenazole against different viruses varied, it was significantly more potent than ribavirin and tiazofurin against all tested representatives of the ...19836615611
viral haemorrhagic fever surveillance in kenya, 1980-1981.following two cases of marburg virus disease in kenya in 1980, viral haemorrhagic fever surveillance was undertaken in western kenya. over a 21-month period investigations, including virus isolation attempts, patient and contact serology, visits to areas where suspected cases occurred, interviewing family members and neighbours of suspected cases and following up any additional illnesses in these areas, were carried out. during the study two cases were found that were likely to have been ebola h ...19836684336
replication of rift valley fever virus in the sand fly lutzomyia longipalpis.rift valley fever virus was shown to replicate in lutzomyia longipalpis after intrathoracic inoculation. viral titers peaked at approximately 4 days postinoculation [mean titer = 10(4.0) plaque forming units (pfu)] and remained relatively constant through day 7. a minimum of 6 of 326 sand flies transmitted virus by bite to susceptible hamsters after 5-9 days of extrinsic incubation. viral titers of sand flies exposed per os declined steadily through day 9. none of 378 flies that had ingested app ...19846711746
protein synthesis in rift valley fever virus-infected cells.rift valley fever virus-induced protein synthesis was examined by polyacrylamide gel electrophoresis and fluorography. five virus-induced polypeptides were detected, the nucleocapsid protein n, the nucleus-associated nonstructural protein ns1, the glycoproteins g1 and g2, and a protein of molecular weight 80k. the n, g1, g2, and 80k proteins were present in virion preparations. sequential studies showed that ns1 accumulated in the nucleus as soon as it was formed and readily associated with nucl ...19846710870
[rift valley fever and zinga virus: a pathogenic arbovirus in man and animal new for madagascar].virus zinga strains have been isolated from several pools of mosquitoes collected in perinet area, 130 km far from tananarive, at the institut pasteur of madagascar in 1980. although this virus is pathogenic for man, it seemed to give only a mild illness and did not appear to constitute a problem of public health. but today it is seen in quite a different way; since the who center for arbovirus reference and research of new haven has shown the serologic identity between virus zinga and an anothe ...19846534285
a serological survey for rift valley fever antibody in food animals in kaduna and sokoto states of nigeria.a total of 1106 serum samples from cattle, sheep, goats and camels were collected from kaduna and sokoto states of nigeria. these were tested for the presence of antibody to rift valley fever virus by the agar gel immunodiffusion method. the antibody prevalence rates were 2.85% in cattle, 6.67% in sheep, 0.98% in goats and 3.13% in camels.19826820360
reversed passive hemagglutination and inhibition with rift valley fever and crimean-congo hemorrhagic fever viruses.reversed passive hemagglutination (rpha) tests were performed by coating glutaraldehyde-fixed and tannic acid-treated sheep erthrocytes with antibodies to rift valley fever (rvf) and crimean-congo hemorrhagic fever (cchf) viruses. cells coated with crude antibody, in the form of mouse immune ascitic fluid, reacted with high specificity and sensitivity in rpha tests with live or inactivated virus antigens. in inhibition (rphi) tests, rvf antibody titers in human and sheep sera were similar to tho ...19836407347
marburg, ebola and rift valley fever virus antibodies in east african primates.sera from 464 primates held at four institutes in kenya were tested by indirect immunofluorescence for the presence of antibodies against marburg, ebola, congo haemorrhagic fever, rift valley fever and lassa viruses. four of 136 vervet monkeys were positive for marburg virus antibodies and three of 184 baboons had antibodies against ebola virus. one baboon was positive for marburg virus antibodies. two vervet monkeys, three baboons and one grivet monkey (of 56 tested) had antibodies against rift ...19826810518
weather, host and vector--their interplay in the spread of insect-borne animal virus diseases.the spread of insect-borne animal virus diseases is influenced by a number of factors. hosts migrate, move or are conveyed over long distances: vectors are carried on the wind for varying distances in search of hosts and breeding sites; weather and climate affect hosts and vectors through temperature, moisture and wind. as parasites of host and vector, viruses are carried by animals, birds and insects, and their spread can be correlated with the migration of hosts and the carriage of vectors on ...19806131919
serological evidence of endemic zinga virus and rift valley fever virus in central african republic. 19836134127
preliminary survey of domestic animals of the sudan for precipitating antibodies to rift valley fever virus.in a preliminary seroepidemiological survey a total of 780 serum samples derived from various domestic animals of the sudan were examined for rift valley fever (rvf) virus precipitating antibodies. the incidence was approximately 34.3% in sheep, 33.2% in cattle, 22% in goats, 7.9% in camels and 4% in donkeys. the findings indicated that rvf is mainly prevalent in the rich savanna areas of the south as well as the irrigated areas close to the nile in the north. circumstantial evidence suggests th ...19846512261
reduced pathogenicity associated with a small plaque variant of the egyptian strain of rift valley fever virus (zh501).variants of rift valley fever virus producing plaques in cer cells of four different sizes are described. a plaque-forming unit (pfu) variant forming minute plaques was isolated and purified. virus derived from this variant was not pathogenic to adult swiss albino mice by the intraperitoneal (i.p.) route and was less pathogenic than the parent strain (zh501) to adult sprague dawley rats by i.p. route, but produced typical severe liver necrosis in adult syrian hamsters with intranuclear and intra ...19826926765
a comparison of indirect immunofluorescence and electron microscopy for the diagnosis of some haemorrhagic viruses in cell cultures.yellow fever, dengue (types 1, 2 and 4), chikungunya, rift valley fever, ebola, marburg, and lassa viruses were inoculated into susceptible cell cultures and daily investigated by indirect immunofluorescence (ifa) and electron microscopy (em) with a view to achieve an early detection-identification of these agents. compared to the other cell lines tested (vero, bhk-21 and aedes albopictus), cv-1 cells were found to be more sensitive. viral antigens were detected by ifa from a few hours post inoc ...19817024293
the use of veterinary vaccines for prevention and control of rift valley fever: memorandum from a who/fao meeting.this memorandum considers the use of veterinary vaccines for the prevention of rift valley fever (rvf) and for its control during outbreaks. veterinary vaccines are the first line of defence against rvf. existing live and inactivated vaccines have been used extensively in africa but further development of both is warranted. the live virus vaccine may cause abortion and its potential for reversion to virulence has not been adequately investigated. it should be used only in enzootic and epizootic ...19836602663
rift valley fever: an emerging human and animal problem. 19827102093
Displaying items 201 - 300 of 1560