Inapparent Virus Infections and their Interactions in Pupae of the Honey Bee (Apis mellifera Linnaeus) in Australia

Abstract

When honey bee pupae from seemingly healthy Australian colonies were injected with various salt solutions, inapparent infections of black queen-cell virus (BQCV), Kashmir bee virus (KBV), sacbrood virus (SBV) and, occasionally, cricket paralysis virus were activated. The activated viruses replicated to detectable concentrations after pupae were incubated at 35.degree. C for 3 days. Inapparent infections of SBV, but not the other viruses, were also activated merely by incubating pupae at 35.degree. C. The replication of activated BQCV, KBV or SBV was specifically suppressed by injecting pupae with rabbit antisera against the particles of each virus. However, a greater proportion of activated SBV infections occurred in groups of pupae in which the replication of activated KBV was suppressed than in groups of pupae in which KBV was not suppressed. In addition, a greater proportion of activated BQCV infections occurred in pupae in which the replication of both KBV and SBV was suppressed than in groups of pupae that were not injected with KBV and SBV antisera. Results from one group of pupae treated in this way indicated that about 40% were infected with KBV, about 43% with SBV and about 15% with BQCV. There was no evidence of interference between the viruses in the establishment of inapparent infections of pupae, but clear evidence of interference during or after activation. These results have implications for the use of pupae for virus propagation.