title: Mutations altering the gammaretrovirus endoproteolytic motif affect glycosylation of the envelope glycoprotein and early events of the virus life cycle.
abstract: Previously, we found that mutation of glutamine to proline in the endoproteolytic cleavage signal of the PERV-C envelope (RQKK to RPKK) resulted in non-infectious vectors. Here, we show that RPKK results in a non-infectious vector when placed in not only a PERV envelope, but also the envelope of a related gammaretrovirus, FeLV-B. The amino acid substitutions do not prevent envelope precursor cleavage, viral core and genome assembly, or receptor binding. Rather, the mutations result in the formation of hyperglycosylated glycoprotein and a reduction in the reverse transcribed minus strand synthesis and undetectable 2-LTR circular DNA in cells exposed to vectors with these mutated envelopes. Our findings suggest novel functions associated with the cleavage signal sequence that may affect trafficking through the glycosylation machinery of the cell. Further, the glycosylation status of the envelope appears to impact post-binding events of the viral life cycle, either membrane fusion, internalization, or reverse transcription.
authors.affiliation: Gene Transfer and Immunogenicity Branch, Division of Cellular and Gene Therapies, Center for Biologics Evaluation and Research, FDA, Silver Spring, MD, USA.
authors.forename: Takele
authors.initials: T
authors.lastname: Argaw
authors.affiliation: Gene Transfer and Immunogenicity Branch, Division of Cellular and Gene Therapies, Center for Biologics Evaluation and Research, FDA, Silver Spring, MD, USA. Electronic address: carolyn.wilson@fda.hhs.gov.
authors.forename: Carolyn A
authors.initials: CA
authors.lastname: Wilson
mesh_terms: D000818:Animals; D002460:Cell Line; D004279:DNA, Viral / Q000096:biosynthesis; D020077:Endogenous Retroviruses / Q000235:genetics / Q000378:metabolism*; D015967:Gene Expression Regulation, Viral / Q000502:physiology*; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D005256:Leukemia Virus, Feline / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D011485:Protein Binding; D013552:Swine; D014759:Viral Envelope Proteins / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication / Q000235:genetics / Q000502:physiology*
chemical_list: D004279:DNA, Viral; D006023:Glycoproteins; D014759:Viral Envelope Proteins
keywords: Endoproteolytic cleavage signal; Feline leukemia virus-B; Gammaretroviruses; Glycosylation; Porcine endogenous retrovirus