TABLE 1.

Parameters of infection in study cats at times of challenge

Preinfecting virus	Cat no.	Age at challenge (mo)	RNA copies/ml of plasmaa	DNA copies/mg of PBMC DNAb	Infectious units in 106 PBMC	CD4+ T lymphocytes/ml of bloodc
FIVPET	2682	72	2,000	3,000	1	690
	3552	72	6,100	4,200	10	200
	3608	72	3,300	7,600	1	300
	3633	72	11,300	1,900	10	440
	3646	72	17,900	10,000	1	398
FIVM2	2646	57	2,100	34,100	10	250
	2647	57	5,000	62,000	100	210
	2658	57	9,000	84,700	100	326
	2664	57	20,000	87,600	100	230
	2668	57	28,000	98,300	100	408
FIVχd	2839	36	6,000	2,600	10	800
	2841	36	700	900	1	910
	2893	36	3,000	800	10	870
	3335	36	3,200	1,000	1	980
	3437	36	900	1,900	1	700
	2731	36	1,400	800	10	700
	2881	36	800	700	1	700
	2884	36	6,500	5,100	1	800
	2897	36	800	2,000	10	500
	3316	36	2,000	3,000	1	760

^aRNA copies determined with the appropriate RT-PCR-specific assay.

^bDNA copies determined with the appropriate PCR-specific assay.

^cNormal range, 1,000 to 3,500.

^dThe first five animals in this group were challenged with FIV_PET, the others with FIV_M2.