Endogenous Mtv-encoded superantigens are not required for development of murine AIDS

Murine AIDS requires CD154/CD40L expression by the CD4 T cells that mediate retrovirus-induced disease: Is CD4 T cell receptor ligation needed?

LP-BM5, a retroviral isolate, induces a disease featuring an acquired immunodeficiency syndrome termed murine AIDS (MAIDS). Many of the features of the LP-BM5-initiated disease are shared with HIV/AIDS. Our lab has shown that the interaction of B and CD4 T cells that is central to MAIDS pathogenesis requires ligation of CD40 on B cells by CD154 on CD4 T cells. Despite this strict requirement for CD154 expression, whether CD4 T cell receptor (TCR) occupancy is essential for the induction of MAIDS is unknown. To block TCR engagement, Tg mouse strains with monoclonal TCR of irrelevant peptide/MHC specificities, all on MAIDS-susceptible genetic backgrounds, were tested: the study of a panel of TCR Tg CD4 T cells controlled for the possibility of serendipitous crossreactive recognition of virus-associated or induced-self peptide, or superantigen, MHC complexes by a given TCR. The results argue that TCR engagement is not necessary for the induction of MAIDS.

Induction of endogenous mammary tumor virus in lymphocytes infected with murine acquired immunodeficiency syndrome virus

Mice infected with murine acquired immunodeficiency syndrome (MAIDS) virus developed lymphoadenopathy and profound immunodeficiency. Concomitantly the expression of endogenous mammary tumor virus (MTV) mRNA increased significantly, especially for the 1.7-kb 3' open reading frame (ORF) mRNA encoding MTV superantigen. B cell lines that are established from MAIDS mice and exhibit superantigen activity also express a high level of 1.7-kb endogenous MTV and mRNA. Infection of a B cell tumor line in vitro with retrovirus containing the cloned MAIDS virus gene induced superantigen activity and this cell line also expressed the 1.7-kb superantigen coding MTV 3' ORF mRNA. These results strongly suggest a link between MAIDS virus infection and the induction of endogenous superantigen activity. This may play an important role in the pathogenesis of the MAIDS virus.