Persistent CCR5 Utilization and Enhanced Macrophage Tropism by Primary Blood Human Immunodeficiency Virus Type 1 Isolates from Advanced Stages of Disease and Comparison to Tissue-Derived Isolates

Abstract

Viral phenotype, tropism, coreceptor usage, and envelope gene diversity were examined in blood isolates collected from 27 individuals at different stages of human immunodeficiency virus type 1 (HIV-1) disease and tissue derived isolates from 10 individuals with AIDS. The majority (89%) of blood and all tissue HIV-1 isolates from all stages of infection were non-syncytium inducing and macrophage (M) tropic. Tropism and productive infection by HIV isolates in both monocytes and monocyte-derived macrophages (MDM) increased in advanced disease (HIV tropism for monocytes, 1 of 6 from categories I and II versus 11 of 21 [P = 0.05] from category IV and II [CD4 < 250]; and high-level replication in MDM, 1 of 6 from categories I and II versus 16 of 21 from categories IV and II [P = 0.015]). There was a high level of replication of blood and tissue isolates in T lymphocytes without restriction at any stage. Overall, the level of replication in MDM was 5- to 10-fold greater than in monocytes, with restriction in the latter occurring mainly at entry and later stages of replication. Only three blood isolates were identified as syncytium inducing, and all had a dualtropic phenotype. There was a significant increase of HIV envelope gene diversity, as shown by a heteroduplex mobility assay, in advanced disease; this may partly underlie the increase of HIV replication in MDM. Unlike blood isolates (even those from patients with advanced disease), tissue isolates displayed greater similarities (90%) in productive infection between MDM and monocytes. The majority (87%) of all isolates, including those from patients with advanced disease, used CCR5, and only 5 of 37 isolates showed expanded coreceptor usage. These results indicate that in the late stage of disease with increasing viral load and diversity, CCR5 utilization and M-tropism persist in blood and tissue and the replicative ability in macrophages increases. This suggests that these characteristics are advantageous to HIV and are important to disease progression.

Analysis and dissociation of anti‐HIV effects of shRNA to CCR5 and the fusion inhibitor C46

“…The pseudotypes were developed by cloning virus isolates from patients and with further examination of the plasmid clones. [36][37][38] These had varying levels of efficiency with regard to co-receptor usage, with low, medium and high efficiency at infecting CCR5+ cells, whereas most had no CXCR4 usage capability. Details on these pseudotypes and their derivation are provided in the Supporting information (Doc.…”

HIV-1 fitness and macrophages

“…The virus replication cycle in macrophages relative to lymphocytes can require extended time because of limitations of nucleotide precursors in macrophages [14]. Yet, some virus strains replicate with similar kinetics in both macrophages and lymphocytes [13] and levels of replication by primary isolates in macrophages can exceed levels of virus produced by lymphocytes [56,75]. Consequently, environmental differences, based on the type of cell that is targeted for infection or the cell type that produces the virus, set up conditions that impact fitness.…”

“…In contrast, SI/X4 viruses display heterogeneous phenotypes. A majority of primary SI/X4 viruses replicate efficiently in both macrophages and T cell lines, use CXCR4 either alone or in combination with CCR5, and are dual (D)-tropic [56,75,76,81,82], while X4 viruses that fail to display tropism for macrophages, but maintain an ability to replicate in T cell lines, have a T-X4 phenotype.…”

“…One characteristic that can distinguish among M-R5 viruses is a range of levels of replication in macrophages. R5 viruses from individuals in late-stage disease display increased replication in MDM cultures in comparison to restricted replication in MDM by R5 viruses isolated during acute or early infection, or over the course of chronic infection in individuals who remain asymptomatic for years [56,75]. [99,152,153].…”

Down-regulation of CXCR-4 and CCR-5 expression by interferon-γis associated with inhibition of chemotaxis and human immunodeficiency virus (HIV) replication but not HIV entry into human monocytes

“…Although monocytic cells express both CCR-5 and CXCR-4 receptors, infection by HIV in this cell type is mediated by interaction of viral gp120 with CD4 and CCR5 [6,9,10]. Primary HIV-1 infection typically involves a CCR5-using (R5) variant, and the switch to a CXCR-4-using (X4) strain is associated with a rapid decline in CD4 + T cell numbers and with disease progression [6,8,11,12].…”