Analysis of dominant HIV quasispecies suggests independent viral evolution within spinal granulomas co-infected with Mycobacterium tuberculosis and HIV-1 subtype C.
AIDS Res Hum Retroviruses. 2015 Nov 12;
Authors: Danaviah S, de Oliveira T, Gordon M, Govender S, Chelule P, Pillay S, Naicker T, Cassol S, Ndung’u T
OBJECTIVES: Extrapulmonary tuberculosis (TB) is a significant public health challenge in South Africa and worldwide, largely fuelled by the HIV epidemic. In spinal TB, Mycobacteria infect the spinal column without dissemination to the spinal cord. The immune microenvironment, target cell characteristics and other evolutionary forces within granulomas during HIV/TB co-infection are poorly characterized. We investigated whether spinal TB granulomas represent a sequestered anatomical site where independent HIV evolution occurs, and assessed the role of macrophages as a target cell for both HIV and Mycobacteria.
METHODS: RNA was extracted from plasma and granulomatous tissue from six antiretroviral-naïve HIV-1/spinal TB co-infected patients; RT-PCR amplified and the C2-V5 env segment was cloned and sequenced. Analysis of genetic diversity, phylogenetic reconstruction and coalescence patterns was performed on clonal sequences. To investigate their role in HIV sequestration, macrophages and the HIV-1 p24 protein were immune-localised and ultra-structural features studied.
RESULTS: Inter-compartment diversity measurements and phylogenetic reconstruction revealed anatomically distinct monophyletic HIV-1 clusters in 4/6 patients. Genotypic CCR5-tropic variants were predominant (98.9%) with conservation of putative N-linked glycosylation sites in both compartments. CD68+ reactivity was associated with higher tissue viral load (r = 1.0; p<0.01) but not greater intra-patient diversity (r = 0.60; p>0.05). Ultra-structural imaging revealed the presence of bacterial and virus-like particles within membrane bound intracellular compartments of macrophages.
CONCLUSION: Spinal tuberculous granulomas may form anatomically discreet sites of divergent viral evolution. Macrophages in these granulomas harbored both pathogens suggesting that they may facilitate the process of viral sequestration within this compartment.
PMID: 26564424 [PubMed – as supplied by publisher]