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 virus encodes a myristylated virion protein and that the U(L)11 gene enables efficient virion envelopment and export from infected cells. A rabbit polyclonal antibody directed against an affinity-purified U(L)11-glutathione-S-transferase fusion protein was made and used to study the properties of the U(L)11 protein and its distribution in infected cells. 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 protein in the perinuclear space and in sites within the nucleus; (iii) immune electron microscopic studies indicated that the U(L)11 gene products were associated with the inner nuclear membrane, with cytoplasmic membranes and ribbon-like cytoplasmic structures resembling membranous organelles, with nuclear bodies shown by fluorescence microcopy to be different from nucleoli in which U(L)11 protein accumulates, and with enveloped virions but not with nuclear capsids; and (iv) the nuclear bodies containing U(L)11 protein were reminiscent both of type IV morphotypes consisting of an electron-dense core containing the U(L)11 proteins surrounded by a more electron-transluscent core and of type V morphotypes consisting of material homogenous in electron opacity. We conclude that (i) the U(L)11 protein is processed after synthesis; (ii) the localization of U(L)11 protein with virions and membranes is consistent with the hypothesis that U(L)11 plays a role in the transport of virions to the extracellular space; and (iii) although the significance of the association of U(L)11 proteins with nuclear bodies is unknown, the results indicate that nuclear bodies differ with respect to their morphologies and contents of viral protein and suggest that U(L)11 protein may have more than one function in the infected cell.