title: Biological analysis of human immunodeficiency virus type 1 R5 envelopes amplified from brain and lymph node tissues of AIDS patients with neuropathology reveals two distinct tropism phenotypes and identifies envelopes in the brain that confer an enhanced tropism and fusigenicity for macrophages.
abstract: Complete envelope genes were amplified from autopsy brain tissue of five individuals who had died of AIDS and had neurological complications. Lymph node samples were included for two of the patients. Nineteen different envelope clones from the five patients had distinct V1V2 sequences. Thirteen of the envelopes were functional and conferred fusigenicity and infectivity for CD4(+) CCR5(+) cells. Infectivity and cell-cell fusion assays showed that most envelopes used both CCR5 and CCR3. One brain-derived envelope used a broad range of coreceptors, while three other brain envelopes from one individual were restricted to CCR5. However, there was no correlation between tissue of origin and coreceptor use. Envelopes showed two very distinct phenotypes depending on their capacity to infect macrophages and to exploit low levels of CD4 and/or CCR5 for infection. Envelopes that were highly fusigenic and tropic for macrophages were identified in brain tissue from four of the five patients. The enhanced macrophage tropism correlated with reduced sensitivity to inhibition by Q4120, a CD4-specific antibody, but not with sensitivity to the CCR5 inhibitor, TAK779. The highly macrophage-tropic envelopes were able to infect cells expressing low levels of CD4 and/or CCR5. Comparison with several well-characterized macrophage-tropic envelopes showed that the four identified patient envelopes were at the top limit of macrophage tropism. In contrast, all four lymph node-derived envelopes exhibited a non-macrophage-tropic phenotype and required high levels of CD4 for infection. Our data support the presence of envelopes that are highly fusigenic and tropic for macrophages in the brains of patients with neurological complications. These envelopes are able to infect cells that express low levels of CD4 and/or CCR5 and may have adapted for replication in brain macrophages and microglia, which are known to express limited amounts of CD4.
authors.affiliation: Program in Molecular Medicine and Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, Worcester MA 01605, USA.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Peters
authors.forename: Jayanta
authors.initials: J
authors.lastname: Bhattacharya
authors.forename: Samantha
authors.initials: S
authors.lastname: Hibbitts
authors.forename: Matthias T
authors.initials: MT
authors.lastname: Dittmar
authors.forename: Graham
authors.initials: G
authors.lastname: Simmons
authors.forename: Jeanne
authors.initials: J
authors.lastname: Bell
authors.forename: Peter
authors.initials: P
authors.lastname: Simmonds
authors.forename: Paul R
authors.initials: PR
authors.lastname: Clapham
mesh_terms: D015526:AIDS Dementia Complex / Q000821:virology*; D000595:Amino Acid Sequence; D001921:Brain / Q000821:virology*; D015704:CD4 Antigens / Q000378:metabolism; D002459:Cell Fusion; D002478:Cells, Cultured; D015686:Gene Products, env / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D015699:HIV Envelope Protein gp120 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015658:HIV Infections / Q000150:complications / Q000821:virology; D015497:HIV-1 / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D006801:Humans; D008198:Lymph Nodes / Q000821:virology; D008264:Macrophages / Q000821:virology; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D016133:Polymerase Chain Reaction / Q000379:methods*; D019713:Receptors, CCR5 / Q000378:metabolism
chemical_list: D015704:CD4 Antigens; D015686:Gene Products, env; D015699:HIV Envelope Protein gp120; C059762:HIV envelope protein gp120 (305-321); D010446:Peptide Fragments; D019713:Receptors, CCR5