Many questions remain regarding imm

Many questions remain regarding immune system function during pregnancy and how possible alterations may affect susceptibility to pathogens. Classical self/nonself models of the immune system suggest that maternal immunity must be suppressed or deviated to support tolerance of the fetus. Our data contradicts the idea of systemic immunosuppression during pregnancy by the fact that pregnant mice rapidly clear virus from all nonreproductive tissues assayed in a similar manner as the nonpregnant cohort and generation of protective immunity occurs normally in pregnant mice. This data is consistent with an evolving alternative model of the immune system where the decision between activation or tolerance is not based on self/nonself considerations, but instead on tissue-specific signals of stress or dysregulation (43, 44, 45). By classical models, the fact that pregnant mice failed to clear virus from the maternal-fetal interface may be the result of local immune suppression or alteration. However, alternative views of the immune system might posit a unique interaction between LCMV and the specialized cells or proteins existing at that site. An example of this model is the interaction of malaria with the placenta (46).The immunologic mechanisms resulting in persistent LCMV infection of the placenta are a matter for future study. Research in this general area is critical to understand tissue-specific immune responses, the interaction of innate and adaptive immunity at the maternal-fetal interface, and develop strategies that optimize maternal immune responses to specific pathogens to provide protection against pathogens in the perinatal period and beyond.