Enzymes as markers in virus preparations.

In the field of cell biology it is usual to characterize cellular components obtained after different separative procedures by enzyme markers characteristic for a particular cell constituent. In the field of virology such procedures are generally not in use for the characterization of virus preparations. More often the labeling of cell proteins is employed when a differentiation between virus-specific and hostspecific components is desired. It is not necessary to point out here that the labeling technique has some disadvantages. Therefore, we used different enzymes as markers for the characterization of virus preparations. For a long time neuraminidase present in myxoviruses and paramyxoviruses was the only virus-specific enzyme known to be associated with animal viruses1. In the last few years some other enzymes, e.g. RNAand DNA-polymerases 2~7, endoand exonucleases8_10, and phosphohydrolases1 1 1 6 also have been found to be associated with virus particles.