Establishment of cytomegaloviral infection in mice: role of a macrophage-enriched subpopulation.

The role of a macrophage-enriched subpopulation in acute intraperitoneal infection of mice with cytomegalovirus was investigated. Virus was not detectable in extracellular fluid after the first day, but it could be isolated from peritoneal exudate cells for at least three weeks after infection. The virus was found in adherent and nonadherent cells after plastic-adherence separation. Infection of recipient mice was achieved by adoptive transfer of either subpopulation two or 21 days after infection. Further study of the macrophage-enriched adherent subpopulation revealed no evidence of significant viral replication. Pretreatment of mice to activate macrophages did not impair dissemination of the virus. Thus, cytomegalovirus can infect a subpopulation of cells enriched in macrophages, and although little replication occurs, such infection facilitates the establishment of persistent infection.