title: Improper tagging of the non-essential small capsid protein VP26 impairs nuclear capsid egress of herpes simplex virus.
abstract: To analyze the subcellular trafficking of herpesvirus capsids, the small capsid protein has been labeled with different fluorescent proteins. Here, we analyzed the infectivity of several HSV1(17(+)) strains in which the N-terminal region of the non-essential small capsid protein VP26 had been tagged at different positions. While some variants replicated with similar kinetics as their parental wild type strain, others were not infectious at all. Improper tagging resulted in the aggregation of VP26 in the nucleus, prevented efficient nuclear egress of viral capsids, and thus virion formation. Correlative fluorescence and electron microscopy showed that these aggregates had sequestered several other viral proteins, but often did not contain viral capsids. The propensity for aggregate formation was influenced by the type of the fluorescent protein domain, the position of the inserted tag, the cell type, and the progression of infection. Among the tags that we have tested, mRFPVP26 had the lowest tendency to induce nuclear aggregates, and showed the least reduction in replication when compared to wild type. Our data suggest that bona fide monomeric fluorescent protein tags have less impact on proper assembly of HSV1 capsids and nuclear capsid egress than tags that tend to dimerize. Small chemical compounds capable of inducing aggregate formation of VP26 may lead to new antiviral drugs against HSV infections.
authors.affiliation: Institute of Virology, Hanover Medical School, Hanover, Germany.
authors.forename: Claus-Henning
authors.initials: CH
authors.lastname: Nagel
authors.forename: Katinka
authors.initials: K
authors.lastname: Döhner
authors.forename: Anne
authors.initials: A
authors.lastname: Binz
authors.forename: Rudolf
authors.initials: R
authors.lastname: Bauerfeind
authors.forename: Beate
authors.initials: B
authors.lastname: Sodeik
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002213:Capsid / Q000378:metabolism* / Q000648:ultrastructure; D036022:Capsid Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism / Q000648:ultrastructure / Q000821:virology*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D045586:Intranuclear Inclusion Bodies / Q000378:metabolism / Q000648:ultrastructure; D008969:Molecular Sequence Data; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism*; D018139:Simplexvirus / Q000502:physiology*; D014764:Viral Proteins / Q000378:metabolism; D057074:Virus Release / Q000502:physiology*; D014779:Virus Replication
chemical_list: D036022:Capsid Proteins; D011993:Recombinant Fusion Proteins; C403420:UL34 protein, Human herpesvirus 1; C078035:UL36 protein, Human herpesvirus 1; D014764:Viral Proteins; C077409:capsid protein VP26, herpes simplex virus type 1; D049452:Green Fluorescent Proteins; D017346:Protein Serine-Threonine Kinases; C095207:US3 protein, Human herpesvirus 1