Summary auto-generated
This study examined how replacing the glycoprotein B (gB) gene of herpes simplex virus type 1 (HSV-1) strain ANG with sequences from strain KOS affects viral properties. Researchers conducted cotransfection experiments using genomic DNA from two ANG variants—one expressing glycoprotein C (gC) and one lacking it (C18)—combined with cloned KOS gB sequences. The majority of recombinants carrying KOS gB sequences (identified using monoclonal antibody B6) displayed altered plaque morphology, changing from syncytial (fusion-inducing) to non-syncytial phenotype in the gC-positive strain. However, in the gC-negative C18 mutant, all recombinants remained syncytial despite acquiring KOS gB sequences. Gene mapping studies localized the fusion-inducing mutation to the syn 3 locus within the gB gene. Additionally, when these recombinants were tested for pathogenicity in mice, seven of ten B6-positive recombinants proved apathogenic, suggesting the KOS gB gene confers reduced virulence. In vitro replication studies showed apathogenic and pathogenic clones replicated similarly, excluding defective growth as an explanation for reduced pathogenicity.
Key findings
- The syn (syncytial/fusion-inducing) phenotype of HSV-1 ANG strain maps to the syn 3 locus within the gB gene; replacement with KOS gB sequences converts most recombinants to non-syncytial phenotype
- Glycoprotein C plays a critical role in plaque morphology expression, as gC-negative mutants cannot be converted to non-syncytial phenotype even when receiving KOS gB sequences
- The KOS-derived BamHI G fragment containing gB sequences confers apathogenicity to the normally pathogenic ANG strain at high frequency (7 of 10 recombinants)
- gB epitope recognized by antibody B6 maps to the N-terminal surface domain, distinct from the C-terminal cytoplasmic domain containing the syn 3 locus
This summary was generated automatically from the article PDF and is not part of the original publication. Refer to the PDF for the authoritative text.
Abstract
DNA sequences encoding glycoprotein B (gB) derived from herpes simplex virus type 1 (HSV-1) strain KOS321 were transferred to HSV-1 ANG. In cotransfection experiments the cloned HSV-1 KOS BamHI G fragment served as donor, and genomic DNA of two ANG variants as recipients. One of these variants, HSV-1 ANG path, expresses gC and the other, C18, was a spontaneous gC-negative mutant. Both ANG strains are of the syncytial (syn) phenotype whereas HSV-1 KOS321 is non-syncytial (syn+). Recombinants were identified by means of a monoclonal antibody which selectively recognizes gBKOS. Among the HSV-1 ANG path/gBKOS recombinants, the majority displayed an altered plaque morphology, i.e. they were of the syn+ phenotype. In contrast all of the C18/gBKOS recombinants were of the syn phenotype. The possibility that the mutant C18 carries a syn mutation not present in the parental strain could be excluded. Marker transfer experiments involving subfragments of the gB gene mapped the syn mutation of HSV-1 ANG path to a locus within the gene that has been previously termed syn 3. Subclones of HSV-1 ANG path were established either directly or after intermittent transfection or cotransfection with the KOS BamHI G fragment. The pathogenicity in mice of these clones was compared. The data obtained indicated that at high frequency, the BamHI G fragment confers apathogenicity.