Evidence of restricted viral replication in adult mink infected with Aleutian disease of mink parvovirus.

Strand-specific hybridization probes were used in in situ molecular hybridization specifically to localize cells containing replicative intermediates of Aleutian disease of mink parvovirus (ADV). When adult mink of Aleutian genotype were infected with ADV Utah I, the largest number of cells positive for viral replication (i.e., containing replicative-form DNA and RNA) were found in the mesenteric lymph nodes and spleens at 10 days after infection. The localization of positive cells in the middle of germinal centers suggested that they were B lymphoblasts. Circulating leukocytes and bone marrow cells also contained viral RNA, but the levels of replicative-form DNA were below detectability. The levels of viral DNA and RNA in adult mink cells replicating ADV were decreased compared with those in permissively infected cell cultures or neonatal mink, suggesting that the replication of ADV in adult mink might be semipermissive or restricted at some early stage of viral gene expression. The low level of viral replication and transcription in lymphoid cells might provide a mechanism for the development of immune disorders and for the maintenance of persistent infection. Single-stranded virion DNA was found in other organs, but the strand-specific probes made it possible to show that this DNA represented virus sequestration. In addition, glomerular immune complexes containing virion DNA were detected, suggesting that ADV virions, or perhaps free DNA, may have a role in the development of ADV-induced glomerulonephritis.