title: Vaccinia virus envelope H3L protein binds to cell surface heparan sulfate and is important for intracellular mature virion morphogenesis and virus infection in vitro and in vivo.
abstract: An immunodominant antigen, p35, is expressed on the envelope of intracellular mature virions (IMV) of vaccinia virus. p35 is encoded by the viral late gene H3L, but its role in the virus life cycle is not known. This report demonstrates that soluble H3L protein binds to heparan sulfate on the cell surface and competes with the binding of vaccinia virus, indicating a role for H3L protein in IMV adsorption to mammalian cells. A mutant virus defective in expression of H3L (H3L(-)) was constructed; the mutant virus has a small plaque phenotype and 10-fold lower IMV and extracellular enveloped virion titers than the wild-type virus. Virion morphogenesis is severely blocked and intermediate viral structures such as viral factories and crescents accumulate in cells infected with the H3L(-) mutant virus. IMV from the H3L(-) mutant virus are somewhat altered and less infectious than wild-type virions. However, cells infected by the mutant virus form multinucleated syncytia after low pH treatment, suggesting that H3L protein is not required for cell fusion. Mice inoculated intranasally with wild-type virus show high mortality and severe weight loss, whereas mice infected with H3L(-) mutant virus survive and recover faster, indicating that inactivation of the H3L gene attenuates virus virulence in vivo. In summary, these data indicate that H3L protein mediates vaccinia virus adsorption to cell surface heparan sulfate and is important for vaccinia virus infection in vitro and in vivo. In addition, H3L protein plays a role in virion assembly.
authors.affiliation: Graduate Institute of Life Science, National Defense Medical Center and Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, Republic of China.
authors.forename: C L
authors.initials: CL
authors.lastname: Lin
authors.forename: C S
authors.initials: CS
authors.lastname: Chung
authors.forename: H G
authors.initials: HG
authors.lastname: Heine
authors.forename: W
authors.initials: W
authors.lastname: Chang
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D017931:DNA Primers; D015967:Gene Expression Regulation, Viral; D006497:Heparan Sulfate / Q000378:metabolism*; D007106:Immune Sera; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D011485:Protein Binding; D017386:Sequence Homology, Amino Acid; D014616:Vaccinia virus / Q000254:growth & development / Q000378:metabolism* / Q000502:physiology; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D014771:Virion
chemical_list: D002352:Carrier Proteins; D017931:DNA Primers; D006497:Heparan Sulfate; D007106:Immune Sera; D014759:Viral Envelope Proteins; C406065:envelope H3L protein, Vaccinia virus