The relationship between cellular immune response to foot-and-mouth disease virus Asia 1 and viral persistence in Indian cattle (Bosindicus)

Foot-and-mouth disease (FMD), the most contagious animal disease, is associated with persistent viral infection in ruminants, despite the induction of systemic immune response. The present study was performed to decipher the relation between the persistent FMD virus (FMDV) infection and cellular immune response in Indian cattle (Bosindicus) following experimental inoculation of FMDV Asia 1. Persistent viral infection (carriers) was detected by antigen capture RT-PCR on the oesophageal–pharyngeal fluid. Viral excretion was found to be intermittent and strongly variable among the persistently infected Indian cattle. Lymphocyte proliferative (LP) response, assessed as reactivity of peripheral blood mononuclear cells to FMDV Asia 1 antigen (Ag) was of low magnitude indicating a weak primary cellular immune response following infection. LP response to FMDV Ag was higher among the non-carriers than carriers of FMDV Asia 1. An enhanced LP response was associated with the lack of virus shedding in the OPF. The findings of this study are suggestive of relationship between cellular immune response and virus excretion during persistence of FMDV Asia 1 in infected cattle.