Characterization of HPIV3 matrix mutants deficient in budding

Abstract

The matrix (M) protein of human parainfluenza virus type 3 (HPIV3) is important for directing assembly and release of new virus; however, the mechanism of release remains unclear. Identifying domains of M required for proper function can help to better understand HPIV3. Alanine amino acid substitutions in regions of M result in inhibition of growth of HPIV3 and release of M protein from cells. Phenotypic revertants, containing a second site amino acid change in M, of the original amino acid substitutions have been isolated and restore growth of HPIV3. Through generation of a 3-D homology model it was hypothesized and confirmed the original alanine substitution regions are important for dimerization of M. The regions were also shown to be unessential for nuclear localization through immunofluorescent microscopy. M proteins containing the second site amino acid change did not restore dimerization of M, but could may restore oligomerization or some other function of M.