Phenotypic and genotypic characterization of locus Syn 5 in herpes simplex virus 1.
Previous papers have reported that the syncytial mutant HSV-1(13)S11 carries three segregable syn mutations and exhibits its altered phenotype in four different cell lines, i.e. HEp-2, VERO, BHK and HEL both at 34 degrees C and 39 degrees C. Those studies have shown that one of three syncytial loci, designated Syn 5, is located in the Bam HI Q fragment spanning map units 0.296-0.317 of the prototype arrangement. Recombinants obtained from marker transfer experiments with donor BamHI Q fragment, have shown that locus Syn 5 is able to induce cell-to-cell fusion in VERO, BHK and HEL but not in HEp-2 cells. In this paper we have characterized the syn mutant HSV-1(13)S11 with regard to plaque morphology, synthesis of viral polypeptides and glycoproteins, thymidine kinase activity and physical map position of locus Syn 5 on the genome. Pertinent to the syn phenotype, earlier papers claimed that two different polypeptides, thymidine kinase (TK) and glycoprotein H (gH), whose genes map in BamHI Q, may be responsible for the fusion activity. Functional studies on the TK of the syn mutant HSV-1(13)S11 indicate that this polypeptide accumulates normally in infected cells and is a fully active enzyme. The other gene product, gH, has been studied with SDS-PAGE and in radioimmunoprecipitation (RIP) experiments using specific monoclonal antibodies. The results indicate that the amount of gH accumulation in the syn mutant-infected cells is greater than its parental strain. However, new marker transfer experiments described here located locus Syn 5 in 663 base pairs between SstI and EcoRI restriction endonuclease sites at the right end of the BamHI Q fragment, where TK gene overlaps in opposite orientation with UL 24 gene. Altogether these results indicate that the Syn 5 locus segregates from the gene specifying gH, to a region encompassing portions of the TK and UL 24 genes, and that the syn mutation does not affect the expression or activity of TK.
Tognon
M
M
Institute of Biological Sciences, School of Medicine, University of Verona, Italy.
Guandalini
R
R
Romanelli
M G
MG
Manservigi
R
R
Trevisani
B
B
D000818:Animals; D002459:Cell Fusion / Q000235:genetics*; D002460:Cell Line; D002874:Chromosome Mapping; D005807:Genes, Overlapping; D005838:Genotype; D015726:Giant Cells; D006801:Humans; D009154:Mutation; D010641:Phenotype; D018139:Simplexvirus / Q000235:genetics* / Q000254:growth & development; D013937:Thymidine Kinase / Q000235:genetics / Q000378:metabolism; D014407:Tumor Cells, Cultured; D014759:Viral Envelope Proteins / Q000096:biosynthesis / Q000235:genetics; D010948:Viral Plaque Assay
D014759:Viral Envelope Proteins; C044200:glycoprotein H, herpes simplex virus type 1; D013937:Thymidine Kinase