TABLE 3.

Neutralizing antibody responses on the day of challenge

Challenge group	Neutralizing antibody responsea			Protection?
	TCLA SIVmac251	Primary SIVmac251	Cloned SIVmac239
5 week
1472	231	15	<4	No
1474	304	9	<4	No
1476	1,093	<4	<4	No
1478	1,014	9	<4	No
1480b	<20	<4	<4	No
10 week
1482	1,499	22	9	No
1484	409	29	10	No
1488	2,613	8	7	Yes
1490	1,549	<4	10	Yes
1492b	<20	<4	<4	No
15 week
1494	3,288	22	26	Yes
1496	3,904	25	10	Yes
1498	898	<4	<4	Yes
1502	350	<4	<4	Yes
1504b	<20	<4	<4	No
25 week
1506	774	9	16	Yes
1510	3,625	<4	29	No
1512	2,747	<4	20	Yes
1514	9,039	74	23	Yes
1516b	<20	<4	<4	No

^aReciprocal serum dilution to yield a 50% reduction in virus-induced cell killing in CEMx174 cells. 

^bNonimmunized control animal.