TABLE 1.

RT mutants unable to infect CEM (12D7) cells at any temperature^a

Mutant no.	Amino acid changes
1	K64A, K65A, K66A, D67A
3	K64R, K65A
26	K527A, K528A, E529A
29	D218A, K219A, K220A
32	R72A, K73A
32a	W71F, R72A

^aAmino acids are numbered with respect to the first residue of the HIV-1 RT protein. Infectivity was monitored by measuring the RT released into the medium from transfected CEM (12D7) cells during a 2-week (39.5 and 37°C) or 3-week (34.5°C) observation period.