Experimental studies concerning the possibility of a latent carrier state in bovine herpes mammillitis (BHM)

Adult bovines, young calves and young rats were infected with bovine herpes mammillitis (BHM) virus providing a group of BHM-recovered animals in which to investigate a possible latent carrier state. The progression of the acute infection and serological response was essentially similar to that previously reported. The effect of natural (calving, littering) and artificial (corticosteroid treatment) stress on these animals following recovery from infection was investigated, but reactivation of BHM was never detected. Long term observation of cocultures of BHM virus infected-and-recovered bovine teat dermis with bovine embryo cells failed to reveal any evidence for the induction of BHM virus replication even in those cocultures treated with mitomycin C or bromodeoxyuridine. Similarly, cocultures utilizing lumbar dorsal root ganglia from the same animals were also negative with respect to the induction of virus replication. Experiments using cytosine arabinoside indicated that an artificial in vitro latent carrier state of BHM virus could be maintained for 6 days with subsequent sporadic virus reactivation, but an attempt to maintain such a state for 12 days was unsuccessful, with no subsequent virus reactivation.