Common inbred strains of the laboratory mouse that are susceptible to infection by mouse xenotropic gammaretroviruses and the human derived XMRV.
Baliji S,
Liu Q,
Kozak CA.
Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases Bethesda, MD 20892.
Abstract
Laboratory mouse strains carry endogenous copies of the xenotropic leukemia viruses (X-MLVs), named for their inability to infect cells of the laboratory mouse. This resistance to exogenous infection is due to a nonpermissive variant of the XPR1 gammaretrovirus receptor, a resistance that also limits in vivo expression of germline X-MLV proviruses capable of producing infectious virus.
They carry MLV's from way back they they have changed the receptor MLV's need to get in - so they can't infect from the outside
Because laboratory mice vary widely in their proviral content and in virus expression pattern, we screened inbred strains for sequence and functional variants of the XPR1 receptor. We also typed inbred strains and wild mouse species for an
endogenous provirus, Bxv1, that is capable of producing infectious X-MLV (!) and that also contributes to the generation of pathogenic recombinant MLVs.
We identified the active Bxv1 provirus in many common inbred strains and in some Japanese M. molossinus mice,
its possible that many mice can produce infectious MLV's - they are carriers
Our screening for Xpr1 variants identified the permissive Xpr1(sxv) allele in 7 strains of laboratory mice including a Bxv1 positive strain, F/St, which is characterized by lifelong X-MLV viremia. Cells from three strains carrying Xpr1(sxv), SWR, SJL and SIM.R, were shown to be infectible by X-MLV and XMRV;
Laboratory mice have a receptor which does allow them to get infected by XMRV and they found which cells can get infected - XMRV can infect these mice (but does it?). Someone apparently looked at a lot of mice and couldn't find it......another XMRV conundrum 