A ROLE FOR BACULOVIRUS GP41 IN BUDDED VIRUS PRODUCTION

Insect cells infected with tsB1074, a temperature-sensitive mutant of Autographa californica nuclear polyhedrosis virus, exhibit a ''single- cell-infection'' phenotype whereby the infection progresses through th e very late phase culminating in occlusion body formation, but neighbo ring cells do not become infected. Marker rescue mapping and DNA seque ncing correlated a single nucleotide substitution within the baculovir us gp41 gene with the temperature-sensitive phenotype of tsB1074. The product of the gp41 gene, GP41, is an O-glycosylated protein found in occluded but not budded virions [M. Whitford and P. Faulkner(1992). J. Virol. 66, 3324-3329]. However, budded virus was not produced in tsB1 074-infected cells at the nonpermissive temperature of 33 degrees, ind icating an additional role for GP41 in budded virus formation. Electro n microscopy revealed that nucleocapsids were produced but retained in the nucleus of tsB1074-infected cells at 33 degrees. Thus, GP41 was r equired for the egress of nucleocapsids from the nucleus in the pathwa y of budded virus synthesis. (C) 1997 Academic Press.