Isotype-specific antibody responses to bovine herpesvirus 1 in sera and mucosal secretions of calves after experimental reinfection and after reactivation

Abstract

Isotype-specific antibody responses to bovine herpesvirus 1 (BHV1) were measured in sera, nasal, ocular and genital secretions of calves that were reinfected with BHV1 and 6 weeks later treated with corticosteroids to reactivate putative latent virus. After reinfection and after reactivation, no BHV1-specific IgM antibody response was detected. The serum IgA response was only transiently detectable after reinfection and again appeared rapidly after reactivation in most calves. Most calves showed an increase in nasal and ocular IgA titres after reinfection and reactivation; some calves also had IgA antibodies in genital secretions. A salient finding was that after reinfection and reactivation more calves showed a serum IgA response than virus shedding or an increase in serum IgG1 or IgG2 titres. This suggests that the serum IgA response would be the most sensitive indicator to detect BHV1 reinfection and reactivation. No correlation was found between nasal IgA titre at the time of reinfection or corticosteroid treatment and the period of virus shedding, suggesting that nasal IgA does not play a major role in protection against reinfection with BHV1.

Isotype-specific antibody responses to foot-and-mouth disease virus in sera and secretions of ‘carrier’ and ‘non-carrier’ cattle

“…The findings reported here support the inclusion of testing for FMDV-specific IgA in serum in addition to mucosal fluid samples. Indeed, Madic and colleagues [63] have suggested that serum IgA was the most sensitive indicator of bovine herpesvirus 1 reinfection or reactivation. We found greater individual variation in the IgA responses in serum than in probang samples in the 'carrier' cattle.…”

Analysis of isotype-specific antibody responses to bovine herpesviruses 1.1 and 1.2a allows to estimate the stage of infection

“…IgA levels were low at 180 days pi, but reactivation led to a new IgA peak. IgA was also found to rise upon reactivation by others (8). Therefore, the presence of elevated levels of IgA, concomitant with elevated IgG1 and IgG2 and absence of IgM may provide additional evidence to indicate that calves have been through a recent reactivation process.…”

“…During reactivation, no rise in IgM levels was detected, following an expected profile (5, 8). This may be useful for distinguishing the phases of infection, in that the analysis of the IgM profile can provide a way to differentiate acute infections from reactivation.…”

“…Class and subclass-specific immunoglobulin levels were studied following BoHV1 primary infection, reinfection and reactivation (3, 6–8). After a primary experimental infection -or vaccination - calves develop an immune response revealed by a transient rise in specific IgM and IgA antibodies, followed by IgG1 and IgG2 responses (3, 5, 7, 8). BoHV1.2b induces seems to induce a lower degree of stimulation of humoral immune response, as estimated by the comparative amount of specific antibody production when compared to BoHV1.1 (1).…”

“…Antibodies of all subclasses may be capable of inducing neutralization of BoHV1 in vitro (7, 8). However, early IgM and IgA antibodies, which here were detected earlier than neutralizaing antibodies (see below Figs 2 and 3) at least at this stage of infection seem not to contribute significantly to neutralization.…”