POLYCLONAL B-LYMPHOCYTE ACTIVATION-INDUCED BY MOUSE HEPATITIS-VIRUS A59 INFECTION

Mouse hepatitis viruses (MHV) diversely affect immune responses, depen ding on the viral strain and the mouse genetic background. Here, we st udied the effect of MHV-A59 infection on B cell responses of 129/Sv an d CBA mice. Our results indicate that in these strains, MHV-A59 induce s spleen cell activation that leads to enlargement of the spleen witho ut structural alteration. Infection triggers production by B lymphocyt es of large amounts of immunoglobulin G2a, mostly without viral specif icity. This polyclonal immunoglobulin production is dependent on the p resence of functional T helper cells. This polyclonal B lymphocyte act ivation induced by MHV-A59 infection can have pathological implication s, such as the enhancement of concomitant autoimmune reactions.