HIV type 1 molecular clones able to use the Bonzo/STRL-33 coreceptor for virus entry

We describe the cloning of env genes from the mother-infant HIV-1 isolate p air P6-v3 and M6-v3. These viruses are unusual in that they can use the cor eceptor Bonzo/STRL33 as well as CCR5 and, in the case of M6, CXCR4, to ente r transfected cell lines in vitro. The phenotype of the parental isolates i s generally reflected by the properties of the cloned env genes, when these are used in an Env-complementation assay of virus entry. Chimeric viruses were also made that contain the env genes of P6-v3 and M6-v3 inserted into the background of the infectious molecular clone, HIV-1 NL4-3. Some of the chimeric viruses derived from HIV-1 P6-v3 were able to use Bonzo for entry into transfected cell lines, albeit to a lesser extent than they could use CCR5. There are some indications that one of these chimeric viruses, P6-v3- 22-1, can use a coreceptor other than CCR5, perhaps Bonzo, to enter mitogen -stimulated PBMC, although only weakly. However, formal proof that this vir us can use Bonzo in primary cells has not been obtained. The P6-v3-22-1 chi meric virus was unable to infect CD4-negative, placental cell lines, in the presence or absence of soluble CD4. Env sequence analysis revealed several differences among viruses with different tropisms, most notably a four ami no acid deletion in the central region of the V3 loop that distinguishes th e R5 virus P6-v3-25-4 from the R5, Bonzo virus P6-v3-22-1.