Together, these results suggest that a) genetic deletion of SOD2 decreased the expression and activity of MnSOD, but it had no effect on the expression of other members of the SOD family, b) myocardial expression of SOD1 and SOD3 were not changed in response to Tc infection, c) the expression and activity of MnSOD was significantly decreased by chronic Tc infection in WT mice, and it was further worsened in MnSOD+/- mice. This evidence concerns the gene SOD3 and infection.