Manganese superoxide dismutase (MnSOD) and autoantibodies against MnSOD in acute viral infections

Abstract

Sera of 146 patients with acute EBV, HAV, HBV, CMV, HSV, and rubella virus infections, and sera from 35 healthy controls were tested for the antioxidant enzyme manganese superoxide dismutase (MnSOD). An enzyme immunoassay that detects all isomeres of the enzyme was developed. The mean MnSOD value of healthy controls was 107 ng/ml. In HAV, HBV and EBV infections characterized by viral replication in internal organs, there was an average 5-fold rise of serum MnSOD, whereas in viral infections with low direct cytopathogenity, such as rubella, CMV and HSV, the MnSOD levels showed only minor rises. These sera were also tested for autoantibodies against MnSOD using a novel sensitive indirect enzyme immunoassay. The average IgM anti-MnSOD concentration in sera of healthy controls was 112 GU. In sera of patients with acute HBV, CMV, HSV or rubella virus infections IgM anti-MnSOD values were only slightly raised above the cut-off level. In contrast, in some patients with acute EBV infections anti-MnSOD concentrations rose up to 20-fold of normal values. In HAV infections the same phenomenon was observed in patients who had reactivated EBV infections. These findings indicate that EBV may facilitate the B-cell response to MnSOD. These autoantibodies may inhibit the protective function of MnSOD and prolong the disease by oxygen injury. Our concept on the pathogenic effect of the autoantibodies against MnSOD emphasizes the importance of the antioxidant enzyme in viral infections.