Restriction factors: a defense against retroviral infection

Trends Microbiol. 2003 Jun;11(6):286-91. doi: 10.1016/s0966-842x(03)00123-9.


Susceptibility to retroviral infection is determined, in part, by host genes with antiviral activity. The Fv1 gene, which inhibits murine leukemia virus infection in mice, encodes one such resistance factor, and was long thought to be unique in that it restricts post-entry, pre-integration steps of retroviral replication. However, recent findings suggest the existence of similar restriction factors in primates, including humans. These factors, termed Lv1 and Ref1, can inhibit a range of retroviruses, including human immunodeficiency virus type 1 and its relatives. Fv1, Lv1 and Ref1 target capsid determinants to block infection but can be saturated by incoming virions. Primate- and murine-retrovirus restriction factors have diverse and overlapping specificities, and some variants of Lv1, as well as Ref1, apparently recognize and inhibit infection by widely divergent retroviruses.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Carbon-Oxygen Lyases / genetics
  • DNA-(Apurinic or Apyrimidinic Site) Lyase*
  • Humans
  • Immunity, Innate
  • Lentivirus / genetics
  • Mammals
  • Mice
  • Models, Biological
  • Molecular Sequence Data
  • Proteins / genetics
  • Proteins / metabolism
  • Retroviridae / growth & development
  • Retroviridae Infections / genetics
  • Retroviridae Infections / immunology
  • Retroviridae Infections / metabolism*
  • Retroviridae Infections / virology


  • Fv1 protein, mouse
  • Proteins
  • Carbon-Oxygen Lyases
  • APEX1 protein, human
  • Apex1 protein, mouse
  • DNA-(Apurinic or Apyrimidinic Site) Lyase