The saga of XMRV: a virus that infects human cells but is not a human virus

Figures & data

Table 1 MuLV subgroup classification by host range

MuLV subgroup	Host range	Receptor
Ecotropic MuLV	Mouse or rat cells	CAT-1^a
Amphotropic MuLV	Mouse and non-mouse cells	PiT-2
Xenotropic MuLV	Non-mouse cells	XPR-1^b
Polytropic/MCF	Mouse and non-mouse cells	XPR-1^b

a Only CAT-1 from mice and rats binds ecotropic MuLV Env protein.

b Xpr-1 of mouse cells binds polytropic MuLV Env protein, but it does not bind xenotropic MuLV Env. Xpr-1 from non-murine species binds both xenotropic and polytropic Env.

Figure 1 Generation of the XMRV genome by recombination. The two endogenous MLV parental proviruses present in nude mice, PreXMRV-1 and -2 are shown at the top of the figure. The larger boxes at either end represent the LTRs. PreXMRV-1 has mutations (‘X’) in the gag (a 16 nt deletion) and pol (a single-nucleotide frame-shift) that render it incapable of encoding functional proteins, but the env coding sequences are intact. PreXMRV-2 has open reading frames for all three genes. The recombinations between PreXMRV-1 and -2 that generated XMRV are shown at the bottom of the figure. There are three single nucleotide substitutions and one insertion (*) that also occurred during development of infectious XMRV (the substitution in the LTR is present at either end of the provirus).