Project description:Bluetongue virus (BTV) is an arbovirus transmitted to domestic and wild ruminants by certain species of Culicoides midges. The disease resulting from infection with BTV is economically important and can influence international trade and movement of livestock, the economics of livestock production, and animal welfare. Recent changes in the epidemiology of Culicoides-transmitted viruses, notably the emergence of exotic BTV genotypes in Europe, have demonstrated the devastating economic consequences of BTV epizootics and the complex nature of transmission across host-vector landscapes. Incursions of novel BTV serotypes into historically enzootic countries or regions, including the southeastern United States (US), Israel, Australia, and South America, have also occurred, suggesting diverse pathways for the transmission of these viruses. The abundance of BTV strains and multiple reassortant viruses circulating in Europe and the US in recent years demonstrates considerable genetic diversity of BTV strains and implies a history of reassortment events within the respective regions. While a great deal of emphasis is rightly placed on understanding the epidemiology and emergence of BTV beyond its natural ecosystem, the ecological contexts in which BTV maintains an enzootic cycle may also be of great significance. This review focuses on describing our current knowledge of ecological factors driving BTV transmission in North America. Information presented in this review can help inform future studies that may elucidate factors that are relevant to longstanding and emerging challenges associated with prevention of this disease.
Project description:Sheep and goats sampled in Kuwait during February 2010 were seropositive for bluetongue virus (BTV). BTV isolate KUW2010/02, from 1 of only 2 sheep that also tested positive for BTV by real-time reverse transcription-PCR, caused mild clinical signs in sheep. Nucleotide sequencing identified KUW2010/02 as a novel BTV serotype.
Project description:Over the last 20 years, Italy has experienced multiple incursions of different serotypes of Bluetongue virus (BTV), a Culicoides-borne arbovirus, the causative agent of bluetongue (BT), a major disease of ruminants. The majority of these incursions originated from Northern Africa, likely because of wind-blown dissemination of infected midges. Here, we report the first identification of BTV-3 in Sardinia, Italy. BTV-3 circulation was evidenced in sentinel animals located in the province of Sud Sardegna on September 19, 2018. Prototype strain BTV-3 SAR2018 was isolated on cell culture. BTV-3 SAR2018 sequence and partial sequences obtained by next-generation sequencing from nucleic acids purified from the isolate and blood samples, respectively, were demonstrated to be almost identical (99-100% of nucleotide identity) to BTV-3 TUN2016 identified in Tunisia in 2016 and 2017, a scenario already observed in past incursions of other BTV serotypes originating from Northern Africa.
Project description:The full genome sequence (19,177 bp) of an Indian strain (IND1988/02) of bluetongue virus (BTV) serotype 23 was determined. This virus was isolated from a sheep that had been killed during a severe bluetongue outbreak that occurred in Rahuri, Maharashtra State, western India, in 1988. Phylogenetic analyses of these data demonstrate that most of the genome segments from IND1988/02 belong to the major "eastern" BTV topotype. However, genome segment 5 belongs to the major "western" BTV topotype, demonstrating that IND1988/02 is a reassortant. This may help to explain the increased virulence that was seen during this outbreak in 1988. Genome segment 5 of IND1988/02 shows >99% sequence identity with some other BTV isolates from India (e.g., BTV-3 IND2003/08), providing further evidence of the existence and circulation of reassortant strains on the subcontinent.
Project description:We announce the complete coding genome sequence of a novel bluetongue virus (BTV) serotype (BTV-n = putative BTV-27) detected in goats in Corsica, France, in 2014. Sequence analysis confirmed the closest relationship between sequences of the novel BTV serotype and BTV-25 and BTV-26, recently discovered in Switzerland and Kuwait, respectively.
Project description:The genome of NIG1982/10, a Nigerian bluetongue virus serotype 16 (BTV-16) strain, was sequenced (19,193 bp). Comparisons to BTV strains from other areas of the world show that all 10 genome segments of NIG1982/10 are derived from a western lineage (w), indicating that it represents a suitable reference strain of BTV-16w.
Project description:Bluetongue virus is the "type" species of the genus Orbivirus, family Reoviridae. Twenty four distinct bluetongue virus (BTV) serotypes have been recognized for decades, any of which is thought to be capable of causing "bluetongue" (BT), an insect-borne disease of ruminants. However, two further BTV serotypes, BTV-25 (Toggenburg orbivirus, from Switzerland) and BTV-26 (from Kuwait) have recently been identified in goats and sheep, respectively. The BTV genome is composed of ten segments of linear dsRNA, encoding 7 virus-structural proteins (VP1 to VP7) and four distinct non-structural (NS) proteins (NS1 to NS4). We report the entire BTV-26 genome sequence (isolate KUW2010/02) and comparisons to other orbiviruses. Highest identity levels were consistently detected with other BTV strains, identifying KUW2010/02 as BTV. The outer-core protein and major BTV serogroup-specific antigen "VP7" showed 98% aa sequence identity with BTV-25, indicating a common ancestry. However, higher level of variation in the nucleotide sequence of Seg-7 (81.2% identity) suggests strong conservation pressures on the protein of these two strains, and that they diverged a long time ago. Comparisons of Seg-2, encoding major outer-capsid component and cell-attachment protein "VP2" identified KUW2010/02 as 26th BTV, within a 12th Seg-2 nucleotype [nucleotype L]. Comparisons of Seg-6, encoding the smaller outer capsid protein VP5, also showed levels of nt/aa variation consistent with identification of KUW2010/02 as BTV-26 (within a 9th Seg-6 nucleotype - nucleotype I). Sequence data for Seg-2 of KUW2010/02 were used to design four sets of oligonucleotide primers for use in BTV-26, type-specific RT-PCR assays. Analyses of other more conserved genome segments placed KUW2010/02 and BTV-25/SWI2008/01 closer to each other than to other "eastern" or "western" BTV strains, but as representatives of two novel and distinct geographic groups (topotypes). Our analyses indicate that all of the BTV genome segments have evolved under strong purifying selection.
Project description:Flanders virus (FLAV; family Rhabdoviridae) is a mosquito-borne hapavirus with no known pathology that is frequently isolated during arbovirus surveillance programs. Here, we document the presence of FLAV in Culex tarsalis mosquitoes and a Canada goose (Branta canadensis) collected in western North America, outside of the currently recognized range of FLAV. Until now, FLAV-like viruses detected in the western United States were assumed to be Hart Park virus (HPV, family Rhabdoviridae), a closely related congener. A re-examination of archived viral isolates revealed that FLAV was circulating in California as early as 1963. FLAV also was isolated in Nebraska, Colorado, South Dakota, North Dakota, and Saskatchewan, Canada. Phylogenetic analysis of the U1 pseudogene for 117 taxa and eight nuclear genes for 15 taxa demonstrated no distinct clustering between western FLAV isolates. Assuming the range of FLAV has been expanding west, these results indicate that FLAV likely spread west following multiple invasion events. However, it remains to be determined if the detection of FLAV in western North America is due to expansion or is a result of enhanced arbovirus surveillance or diagnostic techniques. Currently, the impact of FLAV infection remains unknown.