Feline leukemia virus T entry is dependent on both expression levels and specific interactions between cofactor and receptor

Virology. 2007 Mar 1;359(1):170-8. doi: 10.1016/j.virol.2006.09.004. Epub 2006 Oct 13.


Feline leukemia virus (FeLV) subgroup T uses both a multiple membrane-spanning receptor, FePit1, and a soluble cofactor, FeLIX, to enter feline cells. FeLIX is expressed from endogenous FeLV-related sequence and resembles the receptor binding domain (RBD) of the viral envelope protein. It remains unclear whether FeLV-T receptor activity requires specific residues within FePit1 and FeLIX and/or a threshold level of receptor/cofactor expression. To address this, we examined FeLV-T infection of cells expressing variable levels of FePit1 and other gammaretroviral receptors in the presence of variable amounts of soluble cofactor, either RBD or the envelope surface subunit (SU). Cofactor-receptor pairs fall into three groups with regard to mediating FeLV-T infection: those that are efficient at all concentrations tested, such as FePit1 and FeLIX; those requiring high expression of both cofactor and receptor; and those that are non-functional as receptors even at high expression. This suggests that both expression levels and specific interactions with receptor and cofactor are critical for mediating entry of FeLV-T.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Fibroblasts / virology
  • Humans
  • Leukemia Virus, Feline / growth & development
  • Leukemia Virus, Feline / physiology*
  • Membrane Proteins / biosynthesis
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Mice
  • Receptors, Virus / biosynthesis
  • Receptors, Virus / genetics
  • Receptors, Virus / metabolism*
  • Viral Envelope Proteins / genetics
  • Viral Envelope Proteins / metabolism*
  • Virus Internalization*


  • FeLIX protein, feline leukemia virus
  • Membrane Proteins
  • Receptors, Virus
  • Viral Envelope Proteins