The vaccinia virus N1L protein is an intracellular homodimer that promotes virulence

J Gen Virol. 2002 Aug;83(Pt 8):1965-1976. doi: 10.1099/0022-1317-83-8-1965.


The vaccinia virus (VV) N1L gene encodes a protein of 14 kDa that was identified previously in the concentrated supernatant of virus-infected cells. Here we show that the protein is present predominantly (>90%) within cells rather than in the culture supernatant and it exists as a non-glycosylated, non-covalent homodimer. The N1L protein present in the culture supernatant was uncleaved at the N terminus and was released from cells more slowly than the VV A41L gene product, a secreted glycoprotein that has a conventional signal peptide. Bioinformatic analyses predict that the N1L protein is largely alpha-helical and show that it is conserved in many VV strains, in other orthopoxviruses and in members of other chordopoxvirus genera. However, database searches found no non-poxvirus proteins with significant amino acid similarity to N1L. A deletion mutant lacking the N1L gene replicated normally in cell culture, but was attenuated in intranasal and intradermal murine models compared to wild-type and revertant controls. The conservation of the N1L protein and the attenuated phenotype of the deletion mutant indicate an important role in the virus life-cycle.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Computational Biology
  • Dermis / virology
  • Dimerization
  • Disease Models, Animal
  • Female
  • Fluorescent Antibody Technique
  • Gene Deletion
  • Humans
  • Immunoblotting
  • Mice
  • Mice, Inbred BALB C
  • Molecular Sequence Data
  • Nose / virology
  • Recombination, Genetic
  • Vaccinia / physiopathology*
  • Vaccinia / virology*
  • Vaccinia virus / growth & development
  • Vaccinia virus / pathogenicity*
  • Viral Proteins / chemistry*
  • Viral Proteins / genetics
  • Viral Proteins / metabolism*
  • Virulence
  • Virus Replication


  • N1L protein, Vaccinia virus
  • Viral Proteins

Associated data

  • GENBANK/AF095689
  • GENBANK/AF451287
  • GENBANK/AF455803
  • GENBANK/AF455804
  • GENBANK/AF455805
  • GENBANK/AF455806