ABSENCE OF SPLENIC LATENCY IN MURINE GAMMAHERPESVIRUS 68-INFECTED B-CELL-DEFICIENT MICE

Murine gammaherpesvirus 68 (MHV-68) is a natural pathogen of mice whic h causes an acute lung infection and establishes a latent infection in B lymphocytes. In this paper we describe the infection in transgenic B cell-deficient (mu MT) mice, to determine whether a latent infection can be established in a mouse lacking circulating B lymphocytes. Litt le difference was observed in the acute lung infection, although there was a slight delay in virus clearance in the mu MT mice. This indicat es that antiviral antibody is of little importance in the resolution o f the lung infection. Neither free nor latent virus could be detected in the spleen in the mu MT mice. In addition, these mice did not devel op MHV-68-induced splenomegaly. These data suggest that within the lym phoid compartment B lymphocytes are the sole reservoir for MHV-68 infe ction in vivo, confirming earlier work which identified B cells as the site of latent infection based on cell fractionation studies. In addi tion, our study shows that CD4-driven lymphocyte expansion leading to splenomegaly is dependent on the presence of MHV-68-infected B cells i n the spleen. Although no free virus was detected (using conventional biological assays) in the lung after the resolution of the acute infec tion, MHV-68 genome was detected in the lungs of both control and mu M T mice by PCR analysis. This suggests that cells in the lung may act a s a reservoir of latent virus which is independent of the B lymphocyte infection.