The human cytomegalovirus glycoprotein B gene (ORF UL55) is expressed early in the infectious cycle.

Northern hybridizations were carried out using mRNA preparations of human cytomegalovirus (HCMV)-infected cultures and gene-specific antisense RNA probes for transcriptional analysis of the gene cluster composed of genes for DNA polymerase, glycoprotein B (gB), herpes simplex virus-infected cell protein 18.5 homologue p130 and a major DNA-binding protein corresponding to open reading frames (ORFs) UL54-UL57, respectively. Monocistronic transcripts of 5 kb and 3.7 kb were found for ORFs UL54 and UL55, respectively, and five additional high molecular mass overlapping transcripts of 14 kb, 10 kb, 10 kb, 8 kb and 6 kb were found. Mapping of 5' ends showed that transcription was initiated at the expected distance downstream of predicted TATA elements; in the case of a UL56-specific transcript two potential initiation sites were identified. Transcription was found to terminate at the expected distance downstream of either of two prominent polyadenylation consensus motifs in the region of UL54. All transcripts were identified early in the infectious cycle, except for the UL55 (gB)-specific transcript of 3.7 kb which was not synthesized until late post-infection. However, specific immunoreactions demonstrated the presence of a gB-specific polypeptide early after infection in the absence of viral DNA synthesis. It is suggested that a bicistronic transcript of 8 kb encoded by ORFs UL55 and UL54 is involved in biosynthesis of early HCMV gB.

Nuclear translocation of mutagenized forms of human cytomegalovirus glycoprotein B (gpUL55).

To define structural elements involved in translocation of human cytomegalovirus (HCMV) glycoprotein B (gB) to the inner nuclear membrane (INM) compartment, mutagenized gB derivatives with deletions of the potential membrane anchor domains or of portions of the cytoplasmic tail were stably expressed in human astrocytoma cells. Subcellular localization examined by immunofluorescence and cell fractionation suggested that all gB derivatives reached the INM; however, reduced amounts were found after deletion of the extreme carboxy terminus [amino acids 856-906; gB(Del3)]. Pulse-chase analysis revealed accumulation in nuclear fractions of all gB derivatives during the chase, except for gB(Del3), which exhibited impaired nuclear retention. A carboxy-terminal nucleoplasmin-like signal localized within the respective deletion may thus be involved in nuclear transport and retention of HCMV gB. Immunoprecipitation after 32P-radiolabelling of the gB transfectants verified that the gB molecule is phosphorylated at a carboxy-terminal consensus motif for casein kinase II.

Initiation of chemical studies on the immunoreactive glycolipids of adult Ascaris suum.

There is a general lack of basic information concerning one class of glycoconjugate, the glycolipids, from parasitic nematodes. As the prototype, the neutral glycolipid fraction derived from adult males of Ascaris suum was investigated as to its chromatographic, differential chemical staining, antigenic and chemical properties. The thin-layer chromatography-resolved neutral fraction glycolipids could be classified into components of fast and slow migrating band groups. Immunoreactivity was restricted to the latter as detected by IgG and IgM anti-neutral fraction glycolipid antibody levels in serial infection sera of mice. Similarities of chromatography, antigenicity and serological cross-reactivity have been extended to the neutral glycolipid fractions of other parasitic nematodes: Litomosoides carinii and Nippostrongylus brasiliensis. Chemical, differential chemical staining and enzymatic analyses identified the Ascaris suum antigenic, slow migrating band group of components as amphoteric glycosphingolipids, and not the originally hypothesized glycoglycerolipids or glycosylphosphatidylinositols, that contained typical neutral monosaccharide constituents and a zwitterionic phosphodiester linkage, most probably phosphocholine. Glycosphingolipid-immunoreactivity is eliminated on cleavage of the zwitterionic phosphodiester linkage by hydrofluoric acid treatment.