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Depletion of CD[4.sup.+] T cells from the gut occurs rapidly during acute HIV-1 infection. This has been linked to systemic inflammation and disease progression as a result of translocation of microbial products from the gut lumen into the bloodstream. Combined antiretroviral therapy (cART) substantially restores CD[4.sup.+] T cell numbers in peripheral blood, but the gut compartment remains largely depleted of such cells for poorly understood reasons. Here, we show that a lack of recruitment of CD[4.sup.+] T cells to the gut could be involved in the incomplete mucosal immune reconstitution of cART-treated HIV-infected individuals. We investigated the trafficking of CD[4.sup.+] T cells expressing the gut-homing receptors CCR9 and integrin α4β7 and found that many of these T cells remained in the circulation rather than repopulating the mucosa of the small intestine. This is likely because expression of the CCR9 ligand CCL25 was lower in the small intestine of HIV-infected individuals. The defective gut homing of CCR[9.sup.+]β[7.sup.+] CD[4.sup.+] T cells - a population that we found included most gut-homing Th17 cells, which have a critical role in mucosal immune defense - correlated with high plasma concentrations of markers of mucosal damage, microbial translocation, and systemic T cell activation. Our results thus describe alterations in CD[4.sup.+] T cell homing to the gut that could prevent efficient mucosal immune reconstitution in HIV-infected individuals despite effective cART., Introduction The immune responses to the antigens encountered along the intestinal mucosa surfaces are mainly initiated in inductive sites of the gut-associated lymphoid tissue (GALT), Peyer's patches, and mesenteric lymph [...]

A longitudinal genotypic analysis of the virus found in cellular reservoirs was conducted in 32 patients with undetectable viral loads on highly active antiretroviral therapy (HAART) for investigating whether HIV-1 genetic evolution might lead to changes in virus coreceptor usage during HAART. An R5 to X4 switch in the majority virus population could occur despite of effective HAART, suggesting that potent antiretroviral therapy produces the conditions necessary for the gradual emergence of X4 variants in cellular reservoirs.

Abstract Background HIV-1 subtype D infections have been associated with rapid disease progression and phenotypic assays have shown that CXCR4-using viruses are very prevalent. Recent studies indicate that the genotypic algorithms used routinely to assess HIV-1 tropism may lack accuracy for non-B subtypes. Little is known about the genotypic determinants of HIV-1 subtype D tropism. Results We determined the HIV-1 coreceptor usage for 32 patients infected with subtype D by both a recombinant virus phenotypic entry assay and V3-loop sequencing to determine the correlation between them. The sensitivity of the Geno2pheno10 genotypic algorithm was 75% and that of the combined 11/25 and net charge rule was 100% for predicting subtype D CXCR4 usage, but their specificities were poor (54% and 68%). We have identified subtype D determinants in the V3 region associated with CXCR4 use and built a new simple genotypic rule for optimizing the genotypic prediction of HIV-1 subtype D tropism. We validated this algorithm using an independent GenBank data set of 67 subtype D V3 sequences of viruses of known phenotype. The subtype D genotypic algorithm was 68% sensitive and 95% specific for predicting X4 viruses in this data set, approaching the performance of genotypic prediction of HIV-1 subtype B tropism. Conclusion The genotypic determinants of HIV-1 subtype D coreceptor usage are slightly different from those for subtype B viruses. Genotypic predictions based on a subtype D-specific algorithm appear to be preferable for characterizing coreceptor usage in epidemiological and pathophysiological studies.

Hidden in plain sight: Human platelets carry out several immune functions as well as hemostasis and interact with infectious pathogens including HIV in vitro. Real et al. now report that platelets from HIV-infected individuals can harbor replication-competent HIV, despite successful viral suppression by antiretroviral drug therapy (ART). Moreover, in their study, >80% of virally suppressed HIV-infected individuals with platelets containing HIV showed poor restoration of immune status even 1 year after ART treatment initiation. Platelets carrying HIV may provide an alternative pathway for HIV dissemination in HIV-infected individuals on ART with viral suppression and poor CD4+ T cell recovery. In addition to hemostasis, human platelets have several immune functions and interact with infectious pathogens including HIV in vitro. Here, we report that platelets from HIV-infected individuals on combined antiretroviral drug therapy (ART) with low blood CD4+ T cell counts (<350 cells/μl) contained replication-competent HIV despite viral suppression. In vitro, human platelets harboring HIV propagated the virus to macrophages, a process that could be prevented with the biologic abciximab, an anti–integrin αIIb/β3 Fab. Furthermore, in our cohort, 88% of HIV-infected individuals on ART with viral suppression and with platelets containing HIV were poor immunological responders with CD4+ T cell counts remaining below <350 cells/μl for more than one year. Our study suggests that platelets may be transient carriers of HIV and may provide an alternative pathway for HIV dissemination in HIV-infected individuals on ART with viral suppression and poor CD4+ T cell recovery. [ABSTRACT FROM AUTHOR]

Motivation The circulating recombinant form of HIV-1 CRF02-AG is the most frequent non-B subtype in Europe. Anti-HIV therapy and pathophysiological studies on the impact of HIV-1 tropism require genotypic determination of HIV-1 tropism for non-B subtypes. But genotypic approaches based on analysis of the V3 envelope region perform poorly when used to determine the tropism of CRF02-AG. We, therefore, designed an algorithm based on information from the gp120 and gp41 ectodomain that better predicts the tropism of HIV-1 subtype CRF02-AG. Results We used a bio-statistical method to identify the genotypic determinants of CRF02-AG coreceptor use. Toulouse HIV Extended Tropism Algorithm (THETA), based on a Least Absolute Shrinkage and Selection Operator method, uses HIV envelope sequence from phenotypically characterized clones. Prediction of R5X4/X4 viruses was 86% sensitive and that of R5 viruses was 89% specific with our model. The overall accuracy of THETA was 88%, making it sufficiently reliable for predicting the tropism of subtype CRF02-AG sequences. Availability and implementation Binaries are freely available for download at https://github.com/viro-tls/THETA. It was implemented in Matlab and supported on MS Windows platform. The sequence data used in this work are available from GenBank under the accession numbers MK618182-MK618417. [ABSTRACT FROM AUTHOR]

Depletion of CD4+ T cells from the gut occurs rapidly during acute HIV-1 infection. This has been linked to systemic inflammation and disease progression as a result of translocation of microbial products from the gut lumen into the bloodstream. Combined antiretroviral therapy (cART) substantially restores CD4+ T cell numbers in peripheral blood, but the gut compartment remains largely depleted of such cells for poorly understood reasons. Here, we show that a lack of recruitment of CD4+ T cells to the gut could be involved in the incomplete mucosal immune reconstitution of cART-treated HIV-infected individuals. We investigated the trafficking of CD4+ T cells expressing the gut-homing receptors CCR9 and integrin α4β7 and found that many of these T cells remained in the circulation rather than repopulating the mucosa of the small intestine. This is likely because expression of the CCR9 ligand CCL25 was lower in the small intestine of HIV-infected individuals. The defective gut homing of CCR9+β7+ CD4+ T cells -- a population that we found included most gut-homing Th17 cells, which have a critical role in mucosal immune defense -- correlated with high plasma concentrations of markers of mucosal damage, microbial translocation, and systemic T cell activation. Our results thus describe alterations in CD4+ T cell homing to the gut that could prevent efficient mucosal immune reconstitution in HIV-infected individuals despite effective cART. [ABSTRACT FROM AUTHOR]

HIV-1 coreceptor usage must be accurately determined before starting CCR5 antagonist-based treatment as the presence of undetected minor CXCR4-using variants can cause subsequent virological failure. Ultra-deep pyrosequencing of HIV-1 V3 env allows to detect low levels of CXCR4-using variants that current genotypic approaches miss. However, the computation of the mass of sequence data and the need to identify true minor variants while excluding artifactual sequences generated during amplification and ultra-deep pyrosequencing is rate-limiting. Arbitrary fixed cut-offs below which minor variants are discarded are currently used but the errors generated during ultra-deep pyrosequencing are sequence-dependant rather than random. We have developed an automated processing of HIV-1 V3 env ultra-deep pyrosequencing data that uses biological filters to discard artifactual or non-functional V3 sequences followed by statistical filters to determine position-specific sensitivity thresholds, rather than arbitrary fixed cut-offs. It allows to retain authentic sequences with point mutations at V3 positions of interest and discard artifactual ones with accurate sensitivity thresholds. [ABSTRACT FROM AUTHOR]

HIV-1 was mainly CCR5 tropic in recent seroconverters. We analyzed the coreceptor use in 239 primary HIV-1 infections (PHIs) between 1996 and 2014 using a validated recombinant virus phenotypic entry assay. CXCR4-using viruses were detected in 8.3%, 3.8%, and 6.1% of PHIs from 1996 to 2004, 2005 to 2009, and 2010 to 2014, respectively. The presence of CXCR4-using viruses was associated with the virological failure of antiretroviral treatment initiated during PHI (odds ratio, 7.9; 95% confidence interval, 1.1 to 56.5). The phenotypic tropism assay data show that the prevalence of X4 tropic transmitted viruses was stable in this French cohort of PHIs between 1996 and 2014.

Background: Genotypic predictions of HIV-1 tropism could simplify CCR5 antagonist usage. However, the genotypic algorithms built from subtype B viruses could be inadequate for non-B subtypes. We therefore performed paired genotypic and phenotypic determination of subtype C tropism., Methods: We studied 52 patients recruited in Malawi and 21 patients recruited in France. We directly sequenced the V3 env region and performed a recombinant virus phenotypic entry assay in parallel., Results: The Malawi patients had 29% of CXCR4-using subtype C viruses compared with only 5% in the patients from France. For detecting CXCR4-using subtype C viruses, the genotypic rule combining the amino acids at positions 11/25 and the net charge of V3 was 93.3% sensitive and 96.4% specific. The Geno2pheno tool was 86.7% sensitive and 89.1% specific. The WebPSSM tool with the SI/NSI matrix was 80% sensitive and 98.2% specific in its subtype B version and 93.3% sensitive and 81.8% specific in its subtype C version., Conclusions: The genotypic determinants of coreceptor usage for HIV-1 subtype C were mainly in V3 and were globally similar to those previously reported for subtype B viruses. The main genotypic algorithms built from subtype B viruses perform well when applied to subtype C viruses.