Demonstration of foot-and-mouth disease virus infection specific non-structural protein-antibodies in a vaccinated herd comprising cattle, buffaloes and goats in north India

Abstract

A serological study employing 3AB3 non-structural protein ELISA and liquid phase blocking ELISA to assess foot-and-mouth disease virus (FMDV) non-structural and structural protein antibodies (NSP- and SP-Ab) was undertaken through sampling from all resident animals of a vaccinated herd comprising 943, 377 and 211 cattle, buffaloes and goats, respectively, in north India. A considerable, though disparate proportions of animals (61.2% cattle, 29.2% buffaloes and 29.9% goats) were positive for NSP-Ab suggesting an exposure to FMDV. From the age-stratified analysis of NSP-Ab prevalence, the probable time point of virus introduction in the farm could be predicted in retrospect to be around 8 months before sampling. The proportion of animals showing ≥1.8 log10 titre against all 3 serotypes in the vaccine varied from 3.2 to 32.9% in different species indicating poor vaccinal herd immunity, which presumably might have been the reason for the outbreak in the farm.