THE HERPES-SIMPLEX VIRUS-1 U(L)11 PROTEINS ARE ASSOCIATED WITH CYTOPLASMIC AND NUCLEAR-MEMBRANES AND WITH NUCLEAR-BODIES OF INFECTED-CELLS

Earlier studies have shown that the U(L)11 gene of herpes simplex viru s encodes a myristylated virion protein and that the U(L)11 gene enabl es efficient virion envelopment and export from infected cells. A rabb it polyclonal antibody directed against an affinity-purified U(L)11-gl utathione-S-transferase fusion protein was made and used to study the properties of the U(L)11 protein and its distribution in infected cell s. We report the following: (i) U(L)11 protein formed up to five bands (apparent M(r)s, 17,000 to 22,000) in denaturing polyacrylamide gels; (ii) fluorescent-antibody studies revealed the presence of U(L)11 pro tein in the perinuclear space and in sites within the nucleus; (iii) i mmune electron microscopic studies indicated that the U(L)11 gene prod ucts were associated with the inner nuclear membrane, with cytoplasmic membranes and ribbon-like cytoplasmic structures resembling membranou s organelles, with nuclear bodies shown by fluorescence microcopy to b e different from nucleoli in which U(L)11 protein accumulates, and wit h enveloped virions but not with nuclear capsids; and (iv) the nuclear bodies containing U(L)11 protein were reminiscent both of type IV mor photypes consisting of an electron-dense core containing the U(L)11 pr oteins surrounded by a more electron-transluscent core and of type V m orphotypes consisting of material homogenous in electron opacity. We c onclude that (i) the U(L)11 protein is processed after synthesis; (ii) the localization of U(L)11 protein with virions and membranes is cons istent with the hypothesis that U(L)11 plays a role in the transport o f virions to the extracellular space; and (iii) although the significa nce of the association of U(L)11 proteins with nuclear bodies is unkno wn, the results indicate that nuclear bodies differ with respect to th eir morphologies and contents of viral protein and suggest that U(L)11 protein may have more than one function in the infected cell.