ROLE OF THE CYTOPLASMIC DOMAINS OF VIRAL GLYCOPROTEINS IN ANTIBODY-INDUCED CELL-SURFACE MOBILITY

We have investigated the role of the cytoplasmic domains of the influe nza virus hemagglutinin (HA) and the parainfluenza virus type 3 (PI3) fusion (F) glycoproteins as a determinant of their ability to undergo antibody-induced redistribution on plasma membranes. The viral envelop e genes were truncated in their cytoplasmic domains by using oligonucl eotide-directed mutagenesis and expressed by using recombinant vaccini a viruses. In HeLa cells, the truncated HA (HAt), like the full-length HA, did not cap in response to specific antibody. In CV-1 cells, HAt showed patchy surface immunofluorescence with few caps, whereas full-l ength HA exhibited capping in many cells in response to bivalent antib ody. Quantitation of cap formation indicated a sevenfold decrease in t he frequency of capping of HAt in comparison with full-length HA. Simi larly, truncated F also exhibited a significant decrease in cap format ion in comparison with full-length F. These results indicate that the ability of influenza virus HA and PI3 F to undergo redistribution in r esponse to bivalent antibody has been altered by truncation of the vir al glycoproteins and suggest that capping may involve interactions bet ween the cytoplasmic domain of the viral glycoproteins and host cell c omponents.