TABLE 2.

Distribution of nonecotropic proviral sequences in wild mice^a

Species	Strain	No. of fragments for:
		Xenotropic MLV-related provirus					Polytropic MLV-related provirus
		X-I (KT-55)	X-II (KT-51)	X-III (KT-53)	X-IV (KT-59-60)	Xltr	P-I (Pltr)	P-II (Mltr)	P-III (KT-69b)	P-IV (KT-58)	P-V (KT-76)
M. musculus (laboratory strains)	AKR/J	6	4	19	2	25	38	24	>1	0	0
	HRS/J	10	2	7	2	19	46	23	0	0	0
	C3H/HeJ	6	3	12	0	16	34	17	0	0	0
	C57BL/6J	19	13	20	2	36	46	26	>2	0	0
M. musculus	SF/CamEi	4	4	4	0	13	41	40	>1	0	0
	PERA/Rk	1	0	2	4	6	21	30	>1	0	0
	PERC/Ei	0	0	0	5	5	20	34	>1	2	2
M. m. castaneus	CAST/Ei	2	8	6	0	35	30	5	0	0	0
	CASA/Rk	6	9	6	0	33	37	11	0	0	0
M. m. musculus	CZECH II/Ei	31	>60	12	19	>100	23	1	>50	2	0
M. m. molossinus	MOLC/Rk	>50	>50	>100	2	>100	14	6	0	0	0
	MOLF/Ei	>50	>50	>100	2	>100	14	3	0	0	0
	MOLG/Dn	>50	>50	>100	2	>100	14	5	0	0	0
M. m. domesticus	WSB/Ei	2	0	0	2	9	39	35	>5	0	2
	ZALENDE/Ei	0	0	0	0	11	23	>50	>3	2	2
M. spretus	SPRET/Ei	0	0	0	0	5	15	2	0	2	2
M. hortulanus	PANCEVO/Ei	0	0	0	2	0	0	0	0	0	0
	Halbturn	0	0	0	2	0	0	0	0	0	0
M. cervicolor		0	0	0	0	0	0	0	0	0	0
M. caroli		0	0	0	0	0	0	0	0	0	0
M. cookii		0	0	0	0	0	0	0	0	0	0

^aNumbers of fragments after PvuII digestion and hybridization of dried agarose gels with the probes are shown. Note that an intact provirus gives rise to two such fragments. 

^bThis probe is not strictly specific (see text).