Bluetongue: characterization of virus types by reverse transcription-polymerase chain reaction.

Abstract

Bluetongue virus (BTV) is the prototype of the member of the Orbivirus genus within the family Reoviridae. The BTV serogroup contains 24 serotypes. Traditionally, viruses have been isolated in cultured cells, suckling mouse brain or embryonated chicken eggs before their identification and biochemical, antigenic and biological characterization. These procedures are time-consuming and may fail to detect low levels of infectious virus or strains of BTV which fail to replicate in eggs, mice or tissue culture. In the past decade, traditional procedures for virus characterization, such as ELISA and serum neutralisation with serotype-specific antisera, have been supplemented by reverse transcriptase-polymerase chain reaction (RT-PCR) and sequencing. A number of procedures have been developed to detect the presence of BTV antigens or nucleic acids. RT-PCR technique has appeared to be a powerful tool in the field of BTV diagnosis. Polymerase chain reaction techniques may be used not only to detect the presence of viral nucleic acid but also to 'serogroup' orbiviruses and provide information on the serotype and possible geographical source (topotype or genotype) of BTV isolates within a few days of receipt of a clinical sample such as infected sheep blood. Real-time PCRs have recently been developed.