Synthesis and processing of the envelope gp55-116 complex of human cytomegalovirus

Abstract

The envelope of human cytomegalovirus has been reported to contain between three and eight glycoproteins. Major constituents of the envelope include two abundant glycoproteins with estimated molecular weights of 55,000 (gp55) and 116,000 (gpll6). These two glycoproteins have been shown to exist as a disulfide-linked complex (gp55-116) within the envelope of mature virions. Utilizing a panel of monoclonal antibodies reactive with the gp55-116 complex, we characterized the synthesis and processing of these two virion proteins. Infected cells were shown to contain two glycosylated proteins of 160,000 and 150,000 daltons as well as the mature gp55 and gpll6. Pulse-chase analysis indicated that gpl50 was a precursor protein of gp160. The mature gp55 and gpll6 were generated, in turn, by cleavage of gp160. Antigenic and structural analysis revealed that gp55 and gpll6 shared little structural homology and no detectable antigenic cross-reactivity. The results of this study are discussed in relation to the synthesis of envelope proteins of other herpesviruses.

Development of novel vaccines against human cytomegalovirus

“…The furin cleavage site within the HCMV gB protein is critical for mediating HCMV gB folding into its terminal trimeric form. [71][72][73] However, in studies to express recombinant HCMV gB, the inclusion of the furin cleavage site led to low yields of monomeric gB, whereas the elimination of this site by mutation resulted in efficient production, but synthesis of mostly monomeric gB, with some higher MW forms, using a variety of mammalian and insect cells. [74][75][76][77] Recently, mutations to the fusion loops of a HCMV gB consisting of amino acid residues 78-706 resulted in a trimeric gB produced in insect cells, with the structure subsequently analyzed by X-ray crystallography.…”

The human cytomegalovirus UL37 immediate-early regulatory protein is an integral membrane N-glycoprotein which traffics through the endoplasmic reticulum and Golgi apparatus

“…gB is an HCMV structural glycoprotein and shares with gpUL37 the features of a type I integral membrane protein (12). gB is known to undergo slow folding, N-glycosylation, and oligomerization in the rough ER and the Golgi network (4,5). These results suggest that gpUL37 traffics through the ER and the Golgi network, similarly to HCMV gB.…”

Complement‐Independent neutralising monoclonal antibody with differential reactivity for strains of human cytomegalovirus

“…Based on published values for molecular weights, no fewer than 27 structural glycoproteins have been listed in the literature for the most widely studied laboratory strain of cytomegalovirus (CMV), namely AD169 [Landini and Michelson, 19881. In the native state several of these glycoproteins are known to exist in heterogeneous multimeric complexes which are held together by disulphide bonds [Britt, 1984;Britt and Auger, 1986;Farrar and Greenaway, 19861. Recently three separate families of CMV glycoproteins have been proposed, namely gcI, gcII, and gcIII, on the basis of shared reactivity with particular monoclonal antibodies (MAb) [Gretch et al, 19881. The gcI family is immunoprecipitated by a MAb (41C2) withcomplement-dependent neutralising activity against the Toledo strain of CMV but not the Towne strain [Kari et al, 19861.…”