Background:  HIV-1 infects renal epithelial cells that may play a role in the pathogenesis of HIV-associated nephropathy (HIVAN). To gain further insight into infection of renal epithelial cells, we characterized the tropism of HIV-1 envelope (env) derived from the peripheral blood mononuclear cells (PBMC) and renal epithelium of HIV-1-infected patients with the renal diseases of RB-5 and RB-23.

Methods:  Four kidney- and 3 peripheral blood-derived env were cloned in frame with gp41 derived from pNL4-3 to create the full-length gp160. The latter was swapped into the pNL4-3 backbone (env deleted). Replication-competent chimeric viruses were generated using a human kidney 293 T-cell line transfected with env genes isolated from renal tubules or PBMC. Primary cells, as well as a panel of engineered cell lines expressing single co-receptors, were infected with chimeric NL4-3 viruses containing kidney- or blood-derived env. A human proximal tubule cell line (HPT-1) was infected with the replication-competent viruses as well. A monoclonal anti-CCR5 antibody and an R5 entry inhibitor (TAK-779) were used to determine specific receptors used for entry.

Results:  All replication-competent chimeric viruses containing kidney- or blood-derived env succeeded in infecting cell lines expressing CD4/CCR5. Three kidney-derived env and 2 blood-derived env were dual tropic for CCR5 and CXCR4. Three kidney-derived env and all blood-derived env could use an alternative co-receptor CCR3. Three kidney env were able to infect HPT-1 kidney cell line as measured by p24 production. All replication-competent chimeric viruses derived from kidney or blood env replicated in PHA-activated primary CD⁴ T cells from healthy donors. The monoclonal anti-CCR5 antibody completely blocked entry of chimeric NL4-3 viruses containing kidney env into cell lines expressing CD4/CCR5. The pre-treatment of cell lines expressing CD4/CCR5 with an R5 entry-inhibitor TAK-779 before infection with the kidney-derived viruses blocked entry of the virus as well, confirming the use of this co-receptor.

Conclusion:  Our preliminary results demonstrated that the patterns of co-receptor usage were heterogeneous, with no clear distinctions between kidney and blood env clones to account for renal compartmentalization. The evolution of distinct quasi-species within the kidney compartment is not manifested by a distinct co-receptor usage pattern.

Keywords: HIV-1; HIV-1 envelopes; Renal Diseases