Pseudotyping of glycoprotein D-deficient herpes simplex virus type 1 with vesicular stomatitis virus glycoprotein G enables mutant virus attachment and entry

The use of herpes simplex virus (HSV) vectors for in vivo gene therapy will require the targeting of vector infection to specific cell types in certai n in vivo applications. Because:HSV glycoprotein D (gD) imparts a broad hos t range for viral infection through recognition of ubiquitous host cell rec eptors, vector targeting will require the manipulation of go to provide new cell recognition specificities in a manner designed to preserve go's essen tial role in virus entry. In this study, we have determined whether an entr y-incompetent HSV mutant with deletions of all Us glycoproteins, including go, can be complemented by a foreign attachment/entry protein,vith a differ ent receptor-binding specificity, the vesicular stomatitis virus glycoprote in G (VSV-G). The results showed that transiently expressed VSV-G was incor porated into gD-deficient HSV envelopes and that the resulting pseudotyped virus formed plaques on go-expressing VD60 cells, albeit at a 50-fold reduc ed level compared to that of wild type go. This reduction maybe related to differences in the entry pathways used by VSV and HSV or to the observed lo wer rate of incorporation of VST-G into virus envelopes than that of go. Th e rate of VSV-G incorporation was greatly improved by using recombinant mol ecules in which the transmembrane domain of HSV glycoprotein B or D was sub stituted for that of VSV-G, but these recombinant molecules failed to promo te virus entry. These results show that foreign glycoproteins can be incorp orated into the HSV envelope during replication and that go can be dispense d with on the condition that a suitable attachment/ entry function is provi ded.