The DNA Polymerase Activity of HBV
Pellets made from sera highly positive for surface antigen were found to contain a weak endogenous DNA synthesizing activity (DNAp) by incorporation of tritiated precursors into acid insoluble radioactivity, In contrast, an RNA synthesizing activity was not detected in these same preparations as measured by lack of tritiated UTP incorporation (50). Some of the properties of HBV associated DNA polymerase in comparison to other polymerases are listed in Table 14. The sensitivity of the endogenous reaction product to deoxyribonuclease (DNase), but not ribonuclease (RNase), suggested that the product of the polymerase activity was DNA. However, predigestion of the pellets with RNase abolished incorporation of tritiated thymidine, suggesting DNA synthesis from an RNA template. Addition of the synthetic nucleic acid polymer rA dT, which stimulates oncornavirus reverse transcriptase activities (598), did not enhance HBV associated DNAp; nor did the addition of N-dimethyl-rifampicin or 4-N-benzyldimethyl-rifampicin, which strongly inhibit reverse transcriptase activities, have any effect upon HBV DNAp (541, 577, 599). This endogenous DNA polymerase activity did not directly correlate with highly purified small spherical or variably long HBsAg particles (48, 600, 601).
KeywordsPolymerase Activity Soluble Enzyme Tritiated Thymidine Reverse Transcriptase Activity Dane Particle
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