A polyclonal antibody-based sandwich ELISA for the detection of bluetongue virus in cell culture and blood of sheep infected experimentally

A polyclonal antibody-based sandwich ELISA (s-ELISA) was developed for the detection of bluetongue viruses (BTV) in cell culture lysates and blood samples of sheep infected experimentally. Rabbit antiserum to purified BTV particles and guineapig antiserum to core particles were used as capture antibody and detection antibody respectively. The assay has detected several of the BTV serotypes isolated in India so far. Other common viruses of small ruminants did not cross-react in the assay. The analytical sensitivity of the assay was estimated to be between 102.4 and 102.6 TCID50/ml with different serotypes of BTV. The sensitivity was compared with that of the reverse transcription polymerase chain reaction (RT-PCR) and the latter was found to be at least 100 times more sensitive. In the infected sheep, BTV antigen(s) was detected in blood as early as on 5-day post-infection (dpi) till 35 dpi. The assay may be useful for testing large number of samples in a very short time.