ISOTYPE-SPECIFIC ANTIBODY-RESPONSES IN SERA AND MUCOSAL SECRETIONS OFCALVES EXPERIMENTALLY INFECTED WITH BOVINE HERPESVIRUS-1

Enzyme-linked immunosorbent assays (ELISAs) were developed for studyin g the kinetics of isotype-specific antibody responses in sera, nasal, ocular and genital secretions of calves infected with bovine herpesvir us 1 (BHV1). The BHV1-specific IgM and IgA antibodies were measured in antibody capture assays, and the IgG1 and IgG2 antibodies in indirect double antibody sandwich assays. The ELISAs were shown to be isotype- specific, sensitive and reproducible. Antibodies of all isotypes were able to neutralise the virus in vitro. Calves were infected intranasal ly with one of seven BHV1 field strains. Nine to 13 days after infecti on BHV 1-specific antibodies of the IgM isotype appeared in serum, nas al and ocular secretions and these were detectable until four weeks af ter infection. The first IgA antibodies were detected a few days later than the IgM antibodies. In serum the IgA antibodies were no longer d etectable after 3 weeks, but these did persist for prolonged periods i n mucosal secretions. The calves developed a uniform IgG1 response fro m 13 days after infection, but the IgG2 response was quite variable; b oth persisted until the end of the experiment. No antibody responses w ere detected in genital secretions. There were no marked differences i n isotype responses between calves infected with different strains of BHV1.