Tropism, Cytotoxicity, and Inflammatory Properties of Two Envelope Genes of Murine Leukemia Virus Type-Endogenous Retroviruses of C57BL/6J Mice

Abstract

Envelope (env) proteins of certain endogenous retroviruses (ERVs) participate in various pathophysiological processes. In this study, we characterized pathophysiologic properties of two murine leukemia virus-type ERV (MuLV-ERV)envgenes cloned from the ovary of C57BL/6J mice. The twoenvgenes (namedENVOV1andENVOV2), with 1,926\,bp coding region, originated from two MuLV-ERV loci on chromosomes 8 and 18, respectively.ENVOV1andENVOV2were ~75 kDa and predominantly expressed on the cell membrane. They were capable of producing pseudotype murine leukemia virus virions. Tropism trait and infectivity ofENVOV2were similar to the polytropicenv; however,ENVOV1had very low level of infectivity. Overexpression ofENVOV2, but notENVOV1, exerted cytotoxic effects and induced expression of COX-2, IL-1β, IL-6, and iNOS. These findings suggest that theENVOV1andENVOV2are capable of serving as anenvprotein for virion assembly, and they exert differential cytotoxicity and modulation of inflammatory mediators.