Influence of avian reovirus infection on the Bursa and immune-reactions in chickens

Abstract:

The influences of avian reovirus (ARV) infection at 1 day of age on bursa development，antibody responses after vaccinations to avian influenza virus (AIV)，Newcastle disease virus (NDV) and infectious bursal disease virus (IBDV)，and pathogenecity of virulent IBDV (v-IBDV) were studied in chickens of SPF-origin. The results indicated that LY strain ARV infection in 1-day-old chickens caused atrophy of the Bursa and decreased lymphocyte numbers in the bursa，but it gave no significant negative effects on growth rates and antibody titers to AIV and NDV after vaccination. LY strain ARV infection decreased antibody titers to IBDV in B87 vaccinated birds but all vaccinated birds infected with ARV were still full protected from death or clinical syndromes after v-IBDV challenge. Although all B87-vaccinated birds were full protected from death after v-IBDV challenges，the antibody titers to AIV or NDV after vaccinations with inactivated vaccines were significantly lower in v-IBDV challenged birds than controls. Supprisingly，ARV infection at ages of 1～7 days could compromise the immune suppression induced by v-IBDV in B87-vaccinated birds as HI antibody titers to AIV and NDV in ARV-infected groups were significantly higher than chicknes with no ARV infection. A discussion was made on the interactions between ARV infection and vaccine IBDV or v-IBDV to explain such sophisticated phenomena in the bird experiments.