Experimental animal inoculation and cross neutralization studies of bluetongue virus serotype-4

In this study, plaque purified bluetongue virus serotype-4 (BTV-4) was used with an objective of raising hyper immune serum (HIS) for serum neutralization studies. The plaque purified BTV-4 followed by RT-PCR confirmation was inoculated at a dose of 1ml of 10 6.46 TCID 50 (Tissue Culture Infective Dose 50) in Deccani sheep which were confirmed as seronegative for BTV by CELISA, along with a booster dose 15 days post infection (dpi.). Mild clinical signs were observed and the infected animals were found to sero convert to BTV on 7dpi. Sera collected from these animals were then tested for type specific neutralizing antibody titer by serum neutralization test (SNT) in Vero cells. The titre ranged from 1/80 on 7dpi. to 1/640 by 28 dpi. Interestingly, the serum was also found to neutralize BTV-9 and BTV-10 in a one way cross neutralization reaction.