| The microRNA, miR-155 regulates both adaptive and innate immune responses. In viral infections, miR-155 can
affect both innate immunity (interferon response, natural killer cell activity, and macrophage polarization) and
adaptive immunity (including generation of anti-viral antibodies, CD8+ cytotoxic T lymphocytes, Th17, Th2,
Th1, Tfh and Treg cells). In many viral infections, the proper and timely regulation of miR-155 expression is
critical for the induction of an effective anti-virus immune response and viral clearance without any harmful
immunopathologic consequences. MiR-155 may also exert pro-viral effects, mainly through the inhibition of the
anti-viral interferon response. Thus, dysregulated expression of miR-155 can result in virus persistence and
disruption of the normal response to viral infections. This review provides a thorough discussion of the role of
miR-155 in immune responses and immunopathologic reactions during viral infections, and highlights its potential as a therapeutic target |