Studies on the pathogenesis of a bovine cytomegalo-like virus in an experimental host.

Herpesvirus Movar 33/63 is the prototype strain of a group of slow growth bovine herpesviruses which have been reported to exhibit cytomegalovirus-like characteristics. These viruses have the ability to produce long-term persistent infections of spleen and other lymphoreticular organs in both cattle and rabbits. Rabbits were inoculated with a suspension of Movar 33/63 propagated in cell culture, and sacrificed at intervals between 3 days and 49 weeks post-infection. Cell-free infectious virus was detected only in conjunctival secretions, buffy coat and spleen homogenates up to 7 days post-infection. Beyond this brief acute replication period, co-cultivation or explantation was required for the detection of viral infectivity. The spleen, the only organ from which virus was consistently recovered, exhibited the highest infectious titres as detected by infectious centre assay. The use of several cell isolation techniques (including solid-phase fractionation on ligand-coated surfaces, nylon wool filtration, affinity chromatography, immunocytolysis and plastic surface adherence) allowed separation of B-enriched, T-enriched and non-T, non-B cell fractions. Infectivity during the acute and persistent phase of the infection was associated with the non-T, non-B population which was highly enriched in adherent and non-adherent spleen mononuclear phagocytes. No virus was isolated from either T or B cells.