origin of 1997-98 rift valley fever outbreak in east africa. 19989843109
the carboxy-terminal acidic domain of rift valley fever virus nss protein is essential for the formation of filamentous structures but not for the nuclear localization of the protein.the ambisense s segment of rift valley fever (rvf) virus (a phlebovirus in the bunyaviridae family) codes for two proteins: the viral complementary-sense rna for the n nucleoprotein and the genomic-sense rna for the nonstructural protein nss. except for the fact that the nss protein is phosphorylated and forms filamentous structures in the nuclei of infected cells (r. swanepoel and n. k. blackburn, j. gen. virol. 34:557-561, 1977), its role is poorly understood, especially since the replication ...199910233964
could bats act as reservoir hosts for rift valley fever virus?the inter-epizootic reservoir host of rift valley fever virus (rvfv) remains unknown, although the namaqua rock rat, aethomys namaquensis, as well as bats have been implicated. bats can be asymptomatically infected with rabies, as well as several arboviruses; the possibility that they can act as host for rvfv therefore exists. to examine this possibility, 350 different samples (brain, liver, salivary glands and brown fat) obtained from 150 bats (comprising seven species) were tested for rvfv ant ...199910396763
climate and satellite indicators to forecast rift valley fever epidemics in kenya.all known rift valley fever virus outbreaks in east africa from 1950 to may 1998, and probably earlier, followed periods of abnormally high rainfall. analysis of this record and pacific and indian ocean sea surface temperature anomalies, coupled with satellite normalized difference vegetation index data, shows that prediction of rift valley fever outbreaks may be made up to 5 months in advance of outbreaks in east africa. concurrent near-real-time monitoring with satellite normalized difference ...199910411500
genetic reassortment of rift valley fever virus in nature.rift valley fever virus (rvfv), a phlebovirus of the bunyaviridae family, is an arthropod-borne virus which emerges periodically throughout africa, emphasizing that it poses a major threat for animal and human populations. to assess the genetic variability of rvfv, several isolates from diverse localities of africa were investigated by means of reverse transcription-pcr followed by direct sequencing of a region of the small (s), medium (m), and large (l) genomic segments. phylogenetic analysis s ...199910482570
rift valley fever surveillance in the lower senegal river basin: update 10 years after the epidemic.after the rift valley fever (rvf) epidemic of 1987 in the senegal river basin, rvf surveillance based on serosurveys has been conducted for 10 years. serum samples were obtained from 1336 persons and from sheep and goats in selected areas, and these were tested for igg/igm rvf antibodies by elisa. after a period of regular decrease in rvf prevalence in domestic animals until 1993, an epizootic was observed in all herds in 1994-95 with increases in igm levels and abortions. during the same period ...199910499082
immunogenicity of an inactivated rift valley fever vaccine in humans: a 12-year experience.rift valley fever (rvf) virus causes serious and fatal disease in animals and man. to protect personnel who work with rvf virus in the laboratory, or troops who may be exposed to this virus, the us army successfully developed an improved version of inactivated rvf vaccine, tsi-gsd-200. from early 1986 to late 1997, 598 at-risk workers at the us army medical research institute of infectious diseases (usamriid) were vaccinated as part of an occupational safety and health program. the subjects of t ...199910501248
the rift valley fever virus nonstructural protein nss is phosphorylated at serine residues located in casein kinase ii consensus motifs in the carboxy-terminus.the s segment of rift valley fever virus (bunyaviridae, phlebovirus) codes for two proteins, the nucleoprotein n and the nonstructural protein nss. the nss protein is a phosphoprotein of unknown function that is localized in the cytoplasm and the nuclei of infected cells where it forms filamentous structures. to characterize further the protein expressed in vc10 cells infected with the mp12 strain, we analyzed its phosphorylation states and showed that phosphorylated forms were found in both com ...199910544123
an epizootic of rift valley fever in egypt in epizootic of rift valley fever (rvf) occurred in egypt between april and august 1997. the signs among infected cattle and sheep were high fever, icterus, bloody diarrhoea and abortion. aborted sheep foetuses and sera from the affected herds were collected in the aswan and assiut provinces, upper egypt, for virological and serological examination. a cytopathic effect was detected in vero cell cultures 48 h after inoculation with the foetal liver and spleen suspensions. the same suspensions cau ...199910588018
host feeding of mosquitoes (diptera: culicidae) associated with the recurrence of rift valley fever in 1993, rift valley fever (rvf) virus reappeared in egypt. we determined the prevalence and feeding patterns of mosquitoes in 5 villages where the virus was active. of 10 species recovered, aedes caspius (pallas), culex pipiens l., cx. antennatus (becker), and cx. perexiguus theobald constituted 99% of > 35,000 mosquitoes captured in dry ice-baited cdc light traps. ae. caspius was most prevalent, except at nag' el hagar where it was replaced by cx. perexiguus. cx. pipiens ranked 2nd, except at ...199910593070
the s segment of rift valley fever phlebovirus (bunyaviridae) carries determinants for attenuation and virulence in mice.unlike all the other rift valley fever virus strains (bunyaviridae, phlebovirus) studied so far, clone 13, a naturally attenuated virus, does not form the filaments composed of the nss nonstructural protein in the nuclei of infected cells (r. muller, j. f. saluzzo, n. lopez, t. drier, m. turell, j. smith, and m. bouloy, am. j. trop. med. hyg. 53:405-411, 1995). this defect is correlated with a large in-frame deletion in the nss coding region of the s segment of the tripartite genome. here, we sh ...200010627566
the s segment of rift valley fever phlebovirus (bunyaviridae) carries determinants for attenuation and virulence in mice.unlike all the other rift valley fever virus strains (bunyaviridae, phlebovirus) studied so far, clone 13, a naturally attenuated virus, does not form the filaments composed of the nss nonstructural protein in the nuclei of infected cells (r. muller, j. f. saluzzo, n. lopez, t. drier, m. turell, j. smith, and m. bouloy, am. j. trop. med. hyg. 53:405-411, 1995). this defect is correlated with a large in-frame deletion in the nss coding region of the s segment of the tripartite genome. here, we sh ...200010627566
an outbreak of west nile fever among migrants in kisangani, democratic republic of february 1998, an outbreak of acute febrile illness was reported from the kapalata military camp in kisangani, the democratic republic of congo. the illness was characterized by an acute onset of fever associated with severe headache, arthralgia, backache, neurologic signs, abdominal pain, and coughing. in 1 individual, hemorrhagic manifestations were observed. the neurologic signs included an altered level of consciousness, convulsions, and coma. malaria was initially suspected, but the pati ...199910674664
[present status of an arbovirus infection: yellow fever, its natural history of hemorrhagic fever, rift valley fever].in the early 20th century, when it was discovered that the yellow fever virus was transmitted in its urban cycle by aedes aegypti, measures of control were introduced leading to its disappearance. progressive neglect of the disease, however, led to a new outbreak in 1927 during which the etiological agent was isolated; some years later a vaccine was discovered and yellow fever disappeared again. in the 1960s, rare cases of encephalitis were observed in young children after vaccination and the ad ...199910690474
first field evidence for natural vertical transmission of west nile virus in culex univittatus complex mosquitoes from rift valley province, kenya.west nile virus is a mosquito borne flavivirus endemic over a large geographic area including africa, asia, and the middle east. although the virus generally causes a mild, self-limiting febrile illness in humans, it has sporadically caused central nervous system infections during epidemics. an isolate of west nile virus was obtained from a pool of four male culex univittatus complex mosquitoes while we were conducting an investigation of rift valley fever along the kenya-uganda border in februa ...200010813479
serosurvey for selected infectious disease agents in free-ranging black and white rhinoceros in africa.two hundred and eighty one serum samples collected from free-ranging black (diceros bicornis) and white (ceratotherium simum) rhinoceros, in the republic of south africa (rsa), namibia, and kenya from 1987-97, were examined for antibody to 16 different infectious agents. positive antibody titers were detected against akabane (59.8%), bluetongue (55%), african horse sickness (27.9%), epizootic haemorrhagic disease of deer (19.4%), parainfluenza type 3 (25.3%), bovine herpes virus 1 (3.1%), equine ...200010813614
the potential role of rodents in the enzootic cycle of rift valley fever virus in senegal.wild rodents (214) of fourteen species were trapped at seven sites in senegal. arvicanthis niloticus and mastomys erythroleucus were among the most frequently collected species (77.2% of total capture). all rodents were examined for the presence of anti-rift valley fever virus (rvfv) antibody; the prevalence over all sampled species was 3.8%, varying widely with respect to species and location. four of 14 species of rodents were found to have anti-rvfv antibodies: rattus rattus (one positive of ...200010817634
[viruses and civilization].a few million years ago, when primates moved from the east african forest to the savannah, they were already infected with endogenous viruses and occultly transmitted them to the prime homo species. however it was much later with the building of the first large cities in mesopotamia that interhuman viral transmission began in earnest. spreading was further enhanced with the organization of the egyptian, greek, roman, and arab empires around the mediterranean. discovery of the new world in 1492 l ...199910901842
communicable disease surveillance with limited resources: the scope to link human and veterinary programmes.zoonoses are an important cause of human disease in much of africa, but limitations in current diagnosis and surveillance strategies restrict the effectiveness of control and prevention programmes. outbreaks of disease, ranging from ebola virus infection to rift valley fever, that have occurred recently in africa have demonstrated the need for improved disease surveillance and monitoring. strategies are suggested for co-ordinating human and animal disease surveillance programmes, at the district ...200010913758
pathogen-specific resistance to rift valley fever virus infection is induced in mosquito cells by expression of the recombinant nucleoprotein but not nss non-structural protein sequences.rift valley fever virus (rvfv) is an arbovirus of the bunyaviridae: family, causing recurrent disease outbreaks in africa. natural vertebrate hosts include cattle and humans. several mosquito species belonging to the aedes: and culex: genera act as vectors of this phlebovirus. to test whether pathogen-derived resistance against rvfv could be induced by expressing genomic sequences in mosquito cells, as has been shown for la crosse and dengue 2 viruses, we generated various recombinant semliki fo ...200010950972
resistance to rift valley fever virus in rattus norvegicus: genetic variability within certain 'inbred' strains.rift valley fever virus (rvfv) is the causative agent of rift valley fever, a widespread disease of domestic animals and humans in sub-saharan africa. laboratory rats have frequently been used as an animal model for studying the pathogenesis of rift valley fever. it is shown here that lewis rats (lew/mol) are susceptible to infection with rvfv, whereas wistar-furth (wf/mol) rats are resistant to rvfv infection. lew/mol rats developed acute hepatitis and died after infection with rvfv strain zh54 ...200011038380
rift valley fever, saudi arabia, august-october 2000. 200011143817
outbreak of rift valley fever, yemen, august-october 2000. 200011144616
genetic evidence for an interferon-antagonistic function of rift valley fever virus nonstructural protein nss.rift valley fever virus (rvfv), a phlebovirus of the family bunyaviridae, is a major public health threat in egypt and sub-saharan africa. the viral and host cellular factors that contribute to rvfv virulence and pathogenicity are still poorly understood. all pathogenic rvfv strains direct the synthesis of a nonstructural phosphoprotein (nss) that is encoded by the smallest (s) segment of the tripartite genome and has an undefined accessory function. in this report, we show that mp12 and clone 1 ...200111152510
single-tube and nested reverse transcriptase-polymerase chain reaction for detection of rift valley fever virus in human and animal sera.rift valley fever (rvf) is an anthropozoonosis caused by a phlebovirus (bunyaviridae family) that has re-emerged recently in east and west africa in 1997-1998. this emphasizes the need for early and rapid detection of the virus and an efficient surveillance system. to this goal, a single tube or a nested reverse transcriptase-polymerase chain reaction (rt-pcr) method focusing on the nss coding region of the s segment was developed and used to detect the rvf virus (rvfv) genome, resulting respect ...200111164489
infections by viruses of the families bunyaviridae and filoviridae.rift valley fever is the most important bunyaviral disease of animals in africa. the virus, transmitted by mosquitoes, causes abortions and mortality in young animals in addition to haemorrhagic fevers in humans. although vaccines against this virus are available, the uses of these vaccines are limited because of deleterious effects or incomplete protection, justifying further studies to improve the existing vaccines or to develop others. nairobi sheep disease is transmitted by ticks. the diseas ...200011189728
activity of toscana and rift valley fever virus transcription complexes on heterologous templates.a transcription system for toscana virus (tosv) (a member of the family bunyaviridae:, genus phlebovirus:) was constructed. for in vivo expression, the tosv transcription system uses the viral n and l proteins and an s-like rna genome containing the chloramphenicol acetyltransferase reporter gene in the antisense orientation flanked by the viral genomic 5'- and 3'-terminal s sequences. it was found that the n and l proteins represent the minimal protein requirement for an active transcription co ...200111257182
first isolation of the rift valley fever virus from culex poicilipes (diptera: culicidae) in nature.following the reemergence of rift valley fever (rvf) virus in southeastern mauritania in 1998, an entomological survey was undertaken in the boundary area in senegal to assess the extent of the virus circulation. during this study, rvf virus (36 strains) was isolated for the first time from culex poicilipes in nature. the possible role of cx. poicilipes as an rvf vector is discussed regarding its biology and ecology.200011304058
response of laboratory staff to vaccination with an inactivated rift valley fever vaccine--tsi-gsd 200.laboratory staff and students were vaccinated with a formalin-inactivated rift valley fever (rvf) vaccine. this study showed that the vaccine used (tsi-gsd 200) was able to bring about the production of antibodies in recipients. for the production of a high titered antibody response, three doses of the vaccine were required. one or two doses of the vaccine did not produce a greater than four-fold rise in antibody titre. a greater than four-fold rise in antibody titre following vaccination, is co ...200011379456
climate-disease connections: rift valley fever in kenya.all known rift valley fever(rvf) outbreaks in kenya from 1950 to 1998 followed periods of abnormally high rainfall. on an interannual scale, periods of above normal rainfall in east africa are associated with the warm phase of the el niño/southern oscillation (enso) phenomenon. anomalous rainfall floods mosquito-breeding habitats called dambos, which contain transovarially infected mosquito eggs. the eggs hatch aedes mosquitoes that transmit the rvf virus preferentially to livestock and to human ...200111426274
arbovirus surveillance from 1990 to 1995 in the barkedji area (ferlo) of senegal, a possible natural focus of rift valley fever virus.surveillance for mosquito-borne viruses was conducted in barkedji area from 1990 to 1995, following an outbreak of rift valley fever (rvf) virus in southern mauritania. mosquitoes, sand flies, and midges were collected from human bait and trapped by solid-state u.s. army battery-powered cdc miniature light traps baited with dry ice or animals (sheep or chickens) at four ponds. overall, 237,091 male and female mosquitoes representing 52 species in eight genera, 214,967 phlebotomine sand flies, an ...200111476327
interferon-induced rat mx proteins confer resistance to rift valley fever virus and other arthropod-borne proteins belong to the interferon (ifn)-induced antiviral defense. the rat genome contains three mx genes, ratmx1, ratmx2, and ratmx3. the mx gene products differ in their subcellular localization and antiviral specificity. the nuclear ratmx1 protein confers resistance to influenza a virus, and the cytoplasmic ratmx2 is active against vesicular stomatitis virus (vsv), whereas the cytoplasmic ratmx3 protein is antivirally inactive. to investigate the antiviral potential of the rat mx proteins ...200111576460
quantitative real-time pcr detection of rift valley fever virus and its application to evaluation of antiviral compounds.the rift valley fever virus (rvfv), a member of the genus phlebovirus (family bunyaviridae) is an enveloped negative-strand rna virus with a tripartite genome. until 2000, rvfv circulation was limited to the african continent, but the recent deadly outbreak in the arabian peninsula dramatically illustrated the need for rapid diagnostic methods, effective treatments, and prophylaxis. a method for quantifying the small rna segment by a real-time detection reverse transcription (rt)-pcr using taqma ...200111724861
rift valley fever outbreak, mauritania, 1998: seroepidemiologic, virologic, entomologic, and zoologic investigations.a rift valley fever outbreak occurred in mauritania in 1998. seroepidemiologic and virologic investigation showed active circulation of the rift valley fever virus, with 13 strains isolated, and 16% (range 1.5%-38%) immunoglobulin (ig) m-positivity in sera from 90 humans and 343 animals (sheep, goats, camels, cattle, and donkeys). one human case was fatal.200111747742
[microbiological surveillance: viral hemorrhagic fever in central african republic: current serological data in man].an investigation was conducted between 1994 and 1997 in forested areas of the central african republic (car) to determine the seroprevalence of igg antibodies against several haemorrhagic fever viruses present in the region. sera were obtained from 1762 individuals in two groups (pygmy and bantu locuted populations) living in 4 forested areas in the south of the country. sera were tested for igg antibodies against ebola, marburg, rift valley fever (rvf), yellow fever (yf) and hantaviruses by enz ...200011775321
a reassortant bunyavirus isolated from acute hemorrhagic fever cases in kenya and late 1997 and early 1998, a large outbreak of hemorrhagic fever occurred in east africa. clinical samples were collected in kenya and southern somalia, and 27 of 115 (23%) hemorrhagic fever patients tested showed evidence of acute infection with rift valley fever (rvf) virus as determined by igm detection, virus isolation, detection of virus rna by reverse transcription-polymerase chain reaction (rt-pcr), or immunohistochemistry. however, two patients (one from kenya and the other from somali ...200111878887
antivirally active mxa protein sequesters la crosse virus nucleocapsid protein into perinuclear complexes.bunyaviruses replicate in the cytoplasm of infected cells. new viral particles are formed by budding of nucleocapsids into the golgi apparatus. we have previously shown that the ifn-induced human mxa protein inhibits bunyavirus replication by an unknown mechanism. here we demonstrate that mxa binds to the nucleocapsid protein of la crosse virus (lacv) and colocalizes with the viral protein in cytoplasmic complexes. electron microscopy revealed that these complexes accumulated in the perinuclear ...200211880649
an outbreak of rift valley fever in northeastern kenya, december 1997, 170 hemorrhagic fever-associated deaths were reported in garissa district, kenya. laboratory testing identified evidence of acute rift valley fever virus (rvfv). of the 171 persons enrolled in a cross-sectional study, 31(18%) were anti-rvfv immunoglobulin (ig) m positive. an age-adjusted igm antibody prevalence of 14% was estimated for the district. we estimate approximately 27,500 infections occurred in garissa district, making this the largest recorded outbreak of rvfv in eas ...200211897064
isolation of west nile and sindbis viruses from mosquitoes collected in the nile valley of egypt during an outbreak of rift valley part of an evaluation of potential vectors of arboviruses during a rift valley fever (rvf) outbreak in the nile valley of egypt in august 1993, we collected mosquitoes in villages with known rvf viral activity. mosquitoes were sorted to species, pooled, and processed for virus isolation both by intracerebral inoculation into suckling mice and by inoculation into cell culture. a total of 33 virus isolates was made from 36,024 mosquitoes. viruses were initially identified by indirect fluorescen ...200211931267
diagnostic pathology of selected diseases in wildlife.the prompt detection and effective management of infectious disease in wildlife rely greatly on field diagnosis. although clinical work is sometimes of value, the cornerstone of diagnosis is pathological examination (gross necropsy with supporting laboratory investigations). the approach and rationale to gross post-mortem examination are common to all species, despite possible significant differences in technique. likewise, the principles of sampling are usually comparable, with emphasis on stan ...200211974632
use of reverse transcriptase pcr in early diagnosis of rift valley fever.reverse transcriptase pcr (rt-pcr) for diagnosis of rift valley fever (rvf) was evaluated by using 293 human and animal sera sampled during an rvf outbreak in mauritania in 1998. results of the rt-pcr diagnostic method were compared with those of virus isolation (vi) and detection of immunoglobulin m (igm) antibodies. our results showed that rt-pcr is a specific, sensitive tool for rvf diagnosis in the early phase of the disease and that its results do not differ significantly from those obtaine ...200211986283
rapid detection and quantification of rna of ebola and marburg viruses, lassa virus, crimean-congo hemorrhagic fever virus, rift valley fever virus, dengue virus, and yellow fever virus by real-time reverse transcription-pcr.viral hemorrhagic fevers (vhfs) are acute infections with high case fatality rates. important vhf agents are ebola and marburg viruses (mbgv/ebov), lassa virus (lasv), crimean-congo hemorrhagic fever virus (cchfv), rift valley fever virus (rvfv), dengue virus (denv), and yellow fever virus (yfv). vhfs are clinically difficult to diagnose and to distinguish; a rapid and reliable laboratory diagnosis is required in suspected cases. we have established six one-step, real-time reverse transcription- ...200212089242
teratogenicity of a mutagenised rift valley fever virus (mvp 12) in sheep.a 5-fluorouracil mutagenised rift valley fever virus strain, which was shown to be attenuated and immunogenic in cattle and sheep, was evaluated for its ability to cause teratogenic effects in pregnant sheep. a group of 50 sheep at various stages of pregnancy was inoculated with the virus and the pregnancies followed to term. there were two abortions and 14% of the lambs produced by vaccinated ewes showed teratogenic effects, the most prevalent being spinal hypoplasia, hydranencephaly, brachygna ...200212092782
the 2000 epidemic of rift valley fever in saudi arabia: mosquito vector mid-september 2000, rift valley fever (rvf) virus was diagnosed as the cause of infection in humans and livestock in jizan region, saudi arabia. this is the first time that this arbovirus has been found outside africa and madagascar. collections of mosquitoes (diptera: culicidae) were therefore undertaken (from 25 september to 10 october) at eight sites during the epidemic to obtain mosquitoes for attempted rvf virus isolation. among 23 699 mosquito females tested, six isolations of rvf virus ...200212243225
development of a diagnostic one-tube rt-pcr for the detection of rift valley fever virus.diagnosis of rift valley fever (rvf) is based on serology and virus isolation. the disadvantages of the former include poor sensitivity, high cost, risks associated with using infectious virus as antigen, the lengthy duration of elisa as well as cross-reactivity with other phleboviruses. we developed, optimised and evaluated a one-tube reverse-transcription-polymerase chain reaction (rt-pcr) for the detection of rift valley fever virus (rvfv) in ruminants. the pcr primers for this assay were des ...200212356173
bidirectional infection and release of rift valley fever virus in polarized epithelial cells.rift valley fever (rvf) virus is an arbovirus and is responsible for large outbreaks of disease predominantly in sub-saharan africa. however, several aspects of rvf virus transmission, such as high viremia, multiple vector species, and broad host range, result in a pathogen with high likelihood of geographic spread. rvf virus infection in humans and livestock is characterized by broad dissemination of rvf virus antigens throughout the body. we sought insight into the high pathogenicity and broad ...200212359425
characterization of the golgi retention motif of rift valley fever virus g(n) rift valley fever (rvf) virus, and probably all members of the family bunyaviridae, matures in the golgi apparatus, the targeting of the virus glycoproteins to the golgi apparatus plays a pivotal role in the virus replication cycle. no consensus golgi localization motif appears to be shared among the glycoproteins of these viruses. the viruses of the family bunyaviridae synthesize their glycoproteins, g(n) and g(c), as a polyprotein. the golgi localization signal of rvf virus has been shown t ...200212414959
rift valley fever.rift valley fever virus is an arthropod-borne phlebovirus endemic in sub-saharan africa. outbreaks also have occurred in egypt, madagascar, and most recently in the arabian peninsula. large epizootics occur at irregular intervals in seasons of above-average rainfall with persistent flooding and the appearance of large numbers of floodwater-breeding aedine mosquitoes. the virus is transmitted transovarially and can remain dormant in mosquito eggs during dry interepizootic periods. low-level virus ...200212442582
genetic analysis of viruses associated with emergence of rift valley fever in saudi arabia and yemen, 2000-01.the first confirmed rift valley fever outbreak outside africa was reported in september 2000, in the arabian peninsula. as of february 2001, a total of 884 hospitalized patients were identified in saudi arabia, with 124 deaths. in yemen, 1,087 cases were estimated to have occurred, with 121 deaths. laboratory diagnosis of rift valley fever virus (rvfv) infections included virus genetic detection and characterization of clinical specimens by reverse transcription-polymerase chain reaction, in add ...200212498657
isolation and genetic characterization of rift valley fever virus from aedes vexans arabiensis, kingdom of saudi outbreak of rift valley fever in the kingdom of saudi arabia and yemen in 2000 was the first recognized occurrence of the illness outside of africa and madagascar. an assessment of potential mosquito vectors in the region yielded an isolate from aedes vexans arabiensis, most closely related to strains from madagascar (1991) and kenya (1997).200212498669
viruses of the bunya- and togaviridae families: potential as bioterrorism agents and means of control.when considering viruses of potential importance as tools for bioterrorism, several viruses in the bunya- and togaviridae families have been cited. among those in the bunyaviridae family are rift valley fever, crimean-congo hemorrhagic fever, hanta, and sandfly fever viruses, listed in order of priority. those particularly considered in the togaviridae family are venezuelan, eastern and western equine encephalitis viruses. factors affecting the selection of these viruses are the ability for them ...200312615306
rift valley fever virus infection among french troops in chad. 200312781023
pathogenicity and neurovirulence of a mutagen-attenuated rift valley fever vaccine in rhesus monkeys.rhesus macaques, intravenously inoculated with virulent rift valley fever virus, develop viremia and biochemical evidence of liver damage and serve as a model for human disease. some of these monkeys suffer more serious disease with hemorrhagic phenomena and approximately 20% die with frank hemorrhage. presently, the only rift valley fever vaccine approved for use in humans is a formalin-killed product that requires annual booster vaccinations. efforts to produce an improved vaccine to replace t ...200312798643
indirect enzyme-linked immunosorbent assay for the detection of antibody against rift valley fever virus in domestic and wild ruminant indirect enzyme-linked immunosorbent assay (i-elisa) for the detection of specific igg immunoglobulins against rift valley fever virus (rvfv) was validated in-house. a total of 3055 sera from sheep (n = 1159), goats (n = 636), cattle (n = 203), african buffalo (n = 928), and other wild ruminants (n = 129), including eland, kudu, and black wildebeest, was used. sera from domestic ruminants were collected in west (n = 10), south (n = 1654) and east africa (n = 334), and sera from wild ruminants ...200312825681
detection and identification of toscana and other phleboviruses by rt-nested-pcr assays with degenerated primers.phleboviruses are a large and widespread group of viruses that are transmitted by arthropods. toscana virus is one of the principal agents that causes meningitis in humans during the summer in italy and, possibly, in other mediterranean countries. rift valley fever virus can cause serious illness in both animals and humans, leading to high morbidity and mortality, and is considered to be a potential agent for epizootics and human epidemics. since information on this group of viruses is still sca ...200312858420
different-sized infective particles of rift valley fever virus. 195413165719
destruction of tumour cells by rift valley fever virus. 195413213987
notes on rift valley fever. 195113249478
a brain factor influencing the viability of neurotropic rift valley fever. 195513265798
propagation of rift valley fever virus in ascites hepatoma cells of the rat: production of a new variant of the virus. 195513267977
plaque formation with rift valley fever virus. 195513267991
rift valley fever virus in mice. i. general features of the infection. 195613315885
rift valley fever virus in mice. ii. adsorption and multiplication of virus. 195613315886
rift valley fever virus in mice. iii. further quantitative features of the infective process. 195613315887
rift valley fever virus in mice. iv. incomplete virus; its production and properties. 195613315888
[inhibition of multiplication of rift valley fever virus by homologous virus irradiated by ultraviolet rays]. 195513317292
the coagulation defect in rift valley fever and yellow fever virus infections. 195613340674
rift valley fever virus in mice. v. the properties of a haemagglutinin present in infective serum. 195613374199
multiplication of neurotropic rift valley fever virus in ehrlich ascites tumor cells. 195513405632
interference between active and ultraviolet-irradiated rift valley fever virus. 195713416526
a variant of rift valley fever virus. 195713495627
studies on arthropod-borne viruses of tongaland. v. isolation of bunyamwera and rift valley fever viruses from mosquitoes. 195713506705
rift valley fever virus in mice. vi. histological changes in the liver in relation to virus multiplication. 195713522505
rift valley fever in southern rhodesia. 195813573432
[further notes on the interference of the inactive virus of rift valley fever with the active homologous virus]. 195813597385
rift valley fever virus in the one-day-old chick embryo. 195913631254
[multiplication of the neurotropic strain of rift valley fever virus in the spleen and liver of mice]. 195813639453
phylogenetic analysis reveals a low rate of homologous recombination in negative-sense rna viruses.recombination is increasingly seen as an important means of shaping genetic diversity in rna viruses. however, observed recombination frequencies vary widely among those viruses studied to date, with only sporadic occurrences reported in rna viruses with negative-sense genomes. to determine the extent of homologous recombination in negative-sense rna viruses, phylogenetic analyses of 79 gene sequence alignments from 35 negative-sense rna viruses (a total of 2154 sequences) were carried out. powe ...200313679603
pharmacologically active peptides in the blood and urine of animals infected with babesia rodhaini and other pathogenic organisms.the blood and urine of mice and rats infected with babesia rodhaini contain substances which stimulate the isolated guinea-pig ileum and rat duodenum. the amount of active material excreted increases as the infection increases. the active substances are stable to boiling with hydrochloric acid but not with alkali; they pass through a cellophane membrane and are soluble in hot ethanol. they are destroyed rapidly by papain and less rapidly by chymotrypsin, but are unaffected by trypsin or pepsin. ...196013851100
neutralizing antibody response of sheep to pantropic and neutrotropic rift valley fever virus. 196213876399
the development of a formalin-killed rift valley fever virus vaccine for use in man. 196213990748
purification and electron microscopy of pantropic rift valley fever virus. 196314043418
the effect of recently isolated strains of rift valley fever virus on lamb testis cell cultures. 196314068962
a slowly sedimenting infectious component of rift valley fever virus. 196314099024
[animal hepato-neurotropic viral infections and human viral hepatitis. comparative pathological note]. 196414147320
immunization against rift valley fever virus. studies on the immunogenicity of lyophilized formalin-inactivated vaccine. 196414202259
alteration in virulence of rift valley fever virus during serial passage in lamb testis cells. 196514263453
titration of rift valley fever virus in hamster kidney cells in the absence of serum. 196514266928
protection of mice and lambs against pantropic rift valley fever virus, using immune serum. 196514269221
multiplication of rift valley fever virus in human liver cell culture with special reference to production complement fixing antigen. 195914406176
rift valley fever epidemic in saudi arabia: epidemiological, clinical, and laboratory characteristics.this cohort descriptive study summarizes the epidemiological, clinical, and laboratory characteristics of the rift valley fever (rvf) epidemic that occurred in saudi arabia from 26 august 2000 through 22 september 2001. a total of 886 cases were reported. of 834 reported cases for which laboratory results were available, 81.9% were laboratory confirmed, of which 51.1% were positive for only rvf immunoglobulin m, 35.7% were positive for only rvf antigen, and 13.2% were positive for both. the mean ...200314523773
igg-sandwich and igm-capture enzyme-linked immunosorbent assay for the detection of antibody to rift valley fever virus in domestic ruminants.the recent occurrence of the first confirmed outbreaks of rift valley fever in humans and livestock outside the african region, namely in the kingdom of saudi arabia and yemen, is of global medical and veterinary concern. disadvantages of classical techniques for serological diagnosis of rift valley fever include health risk to laboratory personnel, restrictions for their use outside endemic areas and inability to distinguish between different classes of immunoglobulins. we report on the develop ...200314553896
induction of severe disease in hamsters by two sandfly fever group viruses, punta toro and gabek forest (phlebovirus, bunyaviridae), similar to that caused by rift valley fever golden hamsters inoculated subcutaneously with either of two sandfly fever group viruses, punta toro and gabek forest (phlebovirus, bunyaviridae), developed a fulminating fatal illness characterized by hepatic and splenic necrosis and interstitial pneumonitis. most animals died within three days after infection; this was accompanied by high levels of viremia. necropsy and histopathologic examination of the infected animals revealed pathologic changes involving multiple organs that resemble ...200314628943
tropical dermatology: viral tropical diseases.viruses are important pathogens in tropical areas; most of them, especially the tropical hemorrhagic fevers, produce mucocutaneous manifestations. more than any other kind of pathogen, viruses have the possibility for being widespread, since they have a greater probability of mutation than do bacteria, can cross species barriers easily, and infect both human beings and animals in habitats with a great biodiversity. tropical habitats also have been subject to major ecologic changes in the last fe ...200314639375
[pantotropic virus. iv. rift valley fever virus]. 195014781478
tfiih transcription factor, a target for the rift valley hemorrhagic fever virus.the rift valley fever virus (rvfv) is the causative agent of fatal hemorrhagic fever in humans and acute hepatitis in ruminants. we found that infection by rvfv leads to a rapid and drastic suppression of host cellular rna synthesis that parallels a decrease of the tfiih transcription factor cellular concentration. using yeast two hybrid system, recombinant technology, and confocal microscopy, we further demonstrated that the nonstructural viral nss protein interacts with the p44 component of tf ...200414980221
targeting tfiih to inhibit host cell transcription by rift valley fever the february 20 issue of cell, report that rift valley fever virus (rvfv) targets cellular transcriptional apparatus to inhibit rna polymerase ii-mediated transcription. unlike polio and vesicular stomatitis viruses, both of which target the tata binding protein (tbp), rvfv appears to target the basal transcription factor thiih to induce shut-off of host cell transcription.200414992716
a retrospective study of rift valley fever in saudi arabia.a retrospective study was undertaken to examine domestic ruminant sera for rift valley fever (rvf) virus antibodies. the sera were collected between 1992 and 1995 from cattle, sheep and goats from various locations in saudi arabia. the standard capture enzyme-linked immunosorbent assay system was employed to detect specific rvf antibodies in the animals and the results indicated an absence of rvf antibodies. this finding confirms the assumption that saudi arabia was free from rvf up until at lea ...200315005544
mapping rift valley fever vectors and prevalence using rainfall variations.high activity of the rift valley fever (rvf) virus is related to a tremendous increase of associated mosquito vectors, which follows periods of high rainfall. indeed, rainfall creates an ecologically humid environment that insures the proliferation of breeding sites and the development of rvf vectors. data collected by fontenille et al. (1998) from 1991 to 1996 in the barkedji area in the northern senegal are employed to discuss and quantify the incidence of rainfall upon the abundances of rvf v ...200415018771
rift valley fever epidemic in saudi arabia: disconcerting epidemiological defects and lack of differential diagnoses and concordance in studies. 200415156493
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