EXPRESSION AND MATURATION OF HUMAN FOAMY VIRUS GAG PRECURSOR POLYPEPTIDES

In this report, we address the processing of the Gag polypeptides of h uman foamy virus previously reported to be atypical. In the cytoplasm or the nucleus of infected cells as well as in free virus particles, t wo Gag precursor polypeptides were identified at approximately 72 and 68 kDa, p72 giving rise to p68 by a maturation process. Efficient matu ration of Gag precursors was observed only in two situations: (i) duri ng the early steps of virus adsorption and (ii) under experimental con ditions, including treatment with DNase I, known to dissociate actin p olymers associated with high ionic strength and ionic detergents. Rath er than being a defective viral protease function, an association of G ag precursors with a cytoskeleton network might be responsible for the low rate of Gag protein maturation through inhibition of their cleava ge by the protease.