Novel bluetongue virus serotype from Kuwait

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. Bluetongue virus (BTV) infects ruminants, camelids, and occasionally large carnivores. Clinical signs of bluetongue disease (BT) are usually more severe in sheep or white-tailed deer, particularly in populations previously unexposed to the virus; cattle and goats are often asymptomatic. Initial diagnosis of BT based on clinical signs can be confirmed by virus isolation and characterization or identification of viral RNA by reverse transcription PCR. BTV particles contain 3 concentric protein layers surrounding 10 linear double-stranded RNA genome segments, identified as segment-1 to segment-10 (Seg-1 to Seg-10) in order of decreasing size (from 3,954 bp to 822 bp). Twenty-five BTV serotypes have been identified on the basis of the specificity of reactions with neutralizing antibodies generated by their mammalian hosts. Consequently, BTV outer capsid proteins, particularly viral protein (VP) 2 (encoded by Seg-2), show sequence variations that determine virus serotype.

Other BTV proteins, including subcore shell protein VP3(T2) encoded by Seg-3, are more highly conserved. Phylogenetic comparisons of Seg-3 sequences have been used to identify different BTV topotypes and distinguish different Orbivirus species. BTV has been reported in several Middle Eastern countries (Egypt, Jordan, Syria, Turkey, Cyprus, and Iraq) since 1951. In 2008, Egypt reported the absence of BT, and Egypt is the only country in the region to have prohibited BTV vaccination. Iran reported outbreaks of BT in 2008, and Saudi Arabia reported infection without clinical signs, although the serotype(s) were not identified. Multiple serotypes were detected in Israel during 2008 and Oman in 2009. We report characterization of a novel BTV serotype identified in Kuwait in 2010.

Emerging Infectious Diseases
May 17, 2011

Original web page at Emerging Infectious Diseases