Interplays between mouse mammary tumor virus and the cellular and humoral immune response

Mouse mammary tumor virus has developed strategies to exploit the immune re sponse. It requires vigorous immune stimulation to achieve efficient infect ion. The infected antigen-presenting cells present a viral superantigen on the cell surface which stimulates strong CD4-mediated T-cell help but CD8 T -cell responses are undetectable. Despite the high frequency of superantige n-reactive T cells, the superantigen-induced immune response is comparable to classical antigen responses in terms of T-cell priming, T-cell-B-cell co llaboration as well as follicular and extra-follicular B-cell differentiati on Induction of systemic anergy is observed, similar to classical antigen r esponses where antigen is administered systemically but does not influence the role of the superantigen-reactive T cells in the maintenance of the chr onic germinal center reaction. So far we have been unable to detect a cytot oxic T-cell response to mouse mammary tumor virus peptide antigens or to th e superantigen. This might yet represent another step in the viral infectio n strategy.