RESUMEN
Alphaviruses from Africa, such as Middelburg virus (MIDV), and Sindbis virus (SINV), were detected in horses with neurologic disease in South Africa, but their host ranges remain unknown. We investigated the contribution of alphaviruses to neurologic infections and death in wildlife and domestic animals in this country. During 2010-2018, a total of 608 clinical samples from wildlife and nonequine domestic animals that had febrile, neurologic signs or unexplained deaths were tested for alphaviruses. We identified 32 (5.5%) of 608 alphavirus infections (9 SINV and 23 MIDV), mostly in neurotissue of wildlife, domestic animals, and birds. Phylogenetic analysis of the RNA-dependent RNA polymerase gene confirmed either SINV or MIDV. This study implicates MIDV and SINV as potential causes of neurologic disease in wildlife and nonequine domestic species in Africa and suggests a wide host range and pathogenic potential.
Asunto(s)
Animales Salvajes , Virus Sindbis , Animales , Animales Domésticos , Caballos , Filogenia , Sudáfrica/epidemiologíaRESUMEN
West Nile virus (WNV) lineage 2 is associated with neurologic disease in horses and humans in South Africa. Surveillance in wildlife and nonequine domestic species during 2010-2018 identified WNV in 11 (1.8%) of 608 animals with severe neurologic and fatal infections, highlighting susceptible hosts and risk for WNV epizootics in Africa.
Asunto(s)
Enfermedades de los Animales/epidemiología , Enfermedades de los Animales/virología , Animales Domésticos , Animales Salvajes , Fiebre del Nilo Occidental/veterinaria , Virus del Nilo Occidental , Enfermedades de los Animales/historia , Animales , Geografía Médica , Historia del Siglo XXI , Filogenia , Vigilancia en Salud Pública , Sudáfrica/epidemiología , Proteínas no Estructurales Virales/genética , Virus del Nilo Occidental/clasificación , Virus del Nilo Occidental/genéticaRESUMEN
Bagaza virus (BAGV) has not been reported in birds in South Africa since 1978. We used phylogenetic analysis and electron microscopy to identify BAGV as the likely etiology in neurologic disease and death in Himalayan monal pheasants in Pretoria, South Africa. Our results suggest circulation of BAGV in South Africa.
Asunto(s)
Infecciones por Flavivirus/epidemiología , Infecciones por Flavivirus/virología , Flavivirus , Flavivirus/clasificación , Flavivirus/genética , Flavivirus/ultraestructura , Infecciones por Flavivirus/historia , Historia del Siglo XXI , Humanos , Filogenia , Vigilancia en Salud Pública , Sudáfrica/epidemiología , Proteínas no Estructurales Virales/genéticaRESUMEN
Foot-and-mouth disease (FMD) virus (FMDV) isolates show variation in their ability to withstand an increase in temperature. The FMDV is surprisingly thermolabile, even though this virus is probably subjected to a strong extracellular selective pressure by heat in hot climate regions where FMD is prevalent. The three SAT serotypes, with their particularly low biophysical stability also only yield vaccines of low protective capacity, even with multiple booster vaccinations. The aim of the study was to determine the inherent biophysical stability of field SAT isolates. To characterise the biophysical stability of 20 SAT viruses from Southern Africa, the thermofluor assay was used to monitor capsid dissociation by the release of the RNA genome under a range of temperature, pH and ionic conditions. The SAT2 and SAT3 viruses had a similar range of thermostability of 48-54 °C. However, the SAT1 viruses had a wider range of thermostability with an 8 °C difference but with many viruses being unstable at 43-46 °C. The thermostable A-serotype A24 control virus had the highest thermostability of 55 °C with some SAT2 and SAT3 viruses of similar thermostability. There was a 10 °C difference between the most unstable SAT virus (SAT1/TAN/2/99) and the highly stable A24 control virus. SAT1 viruses were generally more stable compared to SAT2 and SAT3 viruses at the pH range of 6.7-9.1. The effect of ionic buffers on capsid stability showed that SAT1 and SAT2 viruses had an increased stability of 2-9 °C and 2-6 °C, respectively, with the addition of 1 M NaCl. This is in contrast to the SAT3 viruses, which did not show improved stabilisation after addition of 1 M or 0.5 M NaCl buffers. Some buffers showed differing results dependent on the virus tested, highlighting the need to test SAT viruses with different solutions to establish the most stabilising option for storage of each virus. This study confirms for the first time that more stable SAT field viruses are present in the southern Africa region. This could facilitate the selection of the most stable circulating field strains, for adaptation to cultured BHK-21 cells or manipulation by reverse genetics and targeted mutation to produce improved vaccine master seed viruses.
Asunto(s)
Cápside/metabolismo , Virus de la Fiebre Aftosa/genética , Virus de la Fiebre Aftosa/fisiología , Calor , Animales , Proteínas de la Cápside/genética , Clima , Fiebre Aftosa/virología , Genoma Viral , Inestabilidad Genómica , Concentración de Iones de Hidrógeno , Estabilidad del ARN , ARN Viral/genéticaRESUMEN
During 2008-2015 in South Africa, we conducted West Nile virus surveillance in 1,407 animals with neurologic disease and identified mostly lineage 2 cases in horses (7.4%, 79/1,069), livestock (1.5%, 2/132), and wildlife (0.5%, 1/206); 35% were fatal. Geographic correlation of horse cases with seropositive veterinarians suggests disease in horses can predict risk in humans.
Asunto(s)
Anticuerpos Antivirales/sangre , Enfermedades del Sistema Nervioso/veterinaria , ARN Viral/genética , Veterinarios , Fiebre del Nilo Occidental/veterinaria , Virus del Nilo Occidental/genética , Animales , Culex/virología , Monitoreo Epidemiológico , Enfermedades de los Caballos , Caballos/virología , Humanos , Mosquitos Vectores/virología , Enfermedades del Sistema Nervioso/epidemiología , Enfermedades del Sistema Nervioso/mortalidad , Enfermedades del Sistema Nervioso/virología , Prevalencia , Estudios Prospectivos , Estaciones del Año , Sudáfrica/epidemiología , Análisis de Supervivencia , Fiebre del Nilo Occidental/epidemiología , Fiebre del Nilo Occidental/mortalidad , Fiebre del Nilo Occidental/virología , Virus del Nilo Occidental/clasificación , Virus del Nilo Occidental/aislamiento & purificación , Virus del Nilo Occidental/patogenicidadRESUMEN
We determined complete genome sequences of lineage 2 West Nile virus (WNV) strains isolated from patients in South Africa who had mild or severe WNV infections. These strains had previously been shown to produce either highly or less neuroinvasive infection and induced genes similar to corresponding highly or less neuroinvasive lineage 1 strains in mice. Phylogenetic and amino acid comparison of highly and less neuroinvasive lineage 2 strains demonstrated that the nonstructural genes, especially the nonstructural protein 5 gene, were most variable. All South African lineage 2 strains possessed the envelope-protein glycosylation site previously postulated to be associated with virulence. Major deletions existed in the 3 noncoding region of 2 lineage 2 strains previously shown to be either less or not neuroinvasive relative to the highly neuroinvasive strains sequenced in this study.