Interferon gamma production during bovine respiratory syncytial virus (BRSV) infection is diminished in calves vaccinated with formalin-inactivated BRSV

摘要

Male Holstein calves (8 weeks old) were vaccinated with formalin-inactivated bovine respiratory syncytial virus (FI-BRSV; V/M, 6 calves), challenged with live BRSV strain CA-1 (M/C, 6), or vaccinated with FI-BRSV and challenged with live virus (V/C,7). Vaccine was administered twice at a 2-week interval: challenge followed one month later. On days, 0, 5 and 10 after challenge (PC), PBMC were stimulated in vitro for 24 h with live BRSV, concanavalin A (positive control) or spent media (negative control). Supernatants were examined for interferon-gamma (IFN-gamma) using ELISA. Interferon-gamma production by BRSV-stimulated PBMC was increased in M/C and V/C calves as compared to V/M calves on day 5 PC: and increased in M/C calves compared to V/C andV/M calves on day 10 PC. IFN-gamma production increased after challenge in BRSV-stimulated PBMC from M/C calves but not in V/C calves. FI-BRSV vaccination of calves inhibited IFN-gamma production in challenged calves. Decreased IFN-gamma production mayhave contributed to impaired viral clearance and enhanced disease in FI-BRSV vaccinated calves.