The contribution of Env and Nef to R5 AIDS HIV-1 replication

We had previously shown that CCR5 tropic (R5) HIV-1 clones obtained before the onset of AIDS (pre-AIDS clones) replicated less well and caused fewer cytopathic effects (CPE) than R5 HIV-1 isolates obtained after the onset of AIDS (AIDS clones). We chose to study further three R5 clonal isolates derived from a single patient to identify potential mechanisms for the enhanced replication of the AIDS isolates. The pre-AIDS clones, 8G9 and 32D2, and the AIDS clone, *E11, were obtained from patient 142 of the Amsterdam Cohort (ACH 142). Predicted amino acid sequences from the env genes cloned from each of these isolates differed in the V3 loop and in the bridging sheet of gp120. These differences indicated that the AIDS clone env (*E11 env) might interact with the CCR5 co-receptor in a manner different from the pre-AIDS envelopes (8G9 env and 32D2 env). A recombinant JR-CSF clone bearing the V1-V5 region from *E11 Env mediated greater CPE in SCID-hu mice than a recombinant JR-CSF bearing the V1-V5 region from 32D2 Env. Reporter viral vectors, pseudotyped with each of the complete Envelopes, were used in a single round infectivity assay. The *E11 env mediated greater infectivity than both 8G9 and 32D2 envelopes. The vectors pseudotyped with *E11 env were 7-143 times more resistant to TAK-779 and showed more rapid infection kinetics but similar resistance to a CD4 blocking mAb. The AIDS clone nef (*E11 nef) contained more residues that were identical to those found in isolates from patients who were progressing to AIDS than the nef from the pre-AIDS clones (8G9 nef and 32D2 nef). The *E11 nef was not shown to enhance infectivity or downmodulate CD4 more than the 8139 or 32D2 nef genes. The greater replication and CPE caused by the AIDS isolate that was previously observed is therefore likely due to the differential ability to use CCR5.