An increased DNA polymerase activity associated with virulence of Toxoplasma gondii.

DNA polymerase activity of the virulent RH strain of Toxoplasma gondii was significantly higher than that of the avirulent ME49 strain, whereas sensitivity of the activities of both strains to salt, Mg2+, and inhibitors of mammalian DNA polymerases were almost the same. It is suggested that this increased enzyme activity of the virulent strain contributes to a faster rate of multiplication of the organisms as compared with that of the avirulent strain.