Faster HIV-1 disease progression among Brazilian individuals recently infected with CXCR4-utilizing strains

CCR5∆32 and SDF1 3'A: Gene Variants, Expression and Influence on Biological Markers for the Clinical Progression to AIDS among HIV-1 Virus Controllers in a Mixed Population of the Amazon Region of Brazil

CCR5Δ32 and SDF1-3'A polymorphisms were investigated in a cohort of viremia controllers, without the use of therapy, along with their influence on CD4+ T lymphocytes (TLs), CD8+ TLs, and plasma viral load (VL). The samples were analyzed from 32 HIV-1-infected individuals classified as viremia controllers 1 and 2 and viremia non-controllers, from both sexes, mostly heterosexuals, paired with 300 individuals from a control group. CCR5∆32 polymorphism was identified by PCR amplification of a fragment of 189 bp for the wild-type allele and 157 bp for the allele with the ∆32 deletion. SDF1-3'A polymorphism was identified by PCR, followed by enzymatic digestion (restriction fragment length polymorphism) with the Msp I enzyme. The relative quantification of gene expression was performed by real-time PCR. The distribution of allele and genotype frequencies did not show significant differences between the groups. The gene expression of CCR5 and SDF1 was not different between the profiles of AIDS progression. There was no significant correlation between the progression markers (CD4+ TL/CD8+ TL and VL) and the CCR5∆32 polymorphism carrier status. The 3'A allele variant was associated with a marked loss of CD4+ TLs and a higher plasma VL. Neither CCR5∆32 nor SDF1-3'A was associated with viremia control or the controlling phenotype.

Study of Viral Photoinactivation by UV-C Light and Photosensitizer Using a Pseudotyped Model

Different light-based strategies have been investigated to inactivate viruses. Herein, we developed an HIV-based pseudotyped model of SARS-CoV-2 (SC2) to study the mechanisms of virus inactivation by using two different strategies; photoinactivation (PI) by UV-C light and photodynamic inactivation (PDI) by Photodithazine photosensitizer (PDZ). We used two pseudoviral particles harboring the Luciferase-IRES-ZsGreen reporter gene with either a SC2 spike on the membrane or without a spike as a naked control pseudovirus. The mechanism of viral inactivation by UV-C and PDZ-based PDI were studied via biochemical characterizations and quantitative PCR on four levels; free-cell viral damage; viral cell entry; DNA integration; and expression of reporter genes. Both UV-C and PDZ treatments could destroy single stranded RNA (ssRNA) and the spike protein of the virus, with different ratios. However, the virus was still capable of binding and entering into the HEK 293T cells expressing angiotensin-converting enzyme 2 (ACE-2). A dose-dependent manner of UV-C irradiation mostly damages the ssRNA, while PDZ-based PDI mostly destroys the spike and viral membrane in concentration and dose-dependent manners. We observed that the cells infected by the virus and treated with either UV-C or PDZ-based PDI could not express the luciferase reporter gene, signifying the viral inactivation, despite the presence of RNA and DNA intact genes.

Evolutive Temporal Footprint of an HIV-1 Envelope Protein in an Epidemiologically Linked Cluster

Background:

The C2V3C3 region of gp 120, encoded by the HIV-1 envelope gene (env), is an important antigenic target, a key determinant for viral evolution and essential for determining epitopes for vaccines.

Methods:

The relationships among genetic sequence diversity, selective pressure, constraints on HIV-1 envelope protein were explored and also correlated this analysis with information entropy; hypermutation; HIV tropism; CD4+ T cell counts or HIV viral load. A total of 179 HIV-1 C2V3C3 sequences derived from cell-free plasma were used, determined from serial samples, in four epidemiologically linked individuals (one infected blood donor, two transfusion recipients and a sexual partner infected by one of the recipients) over a maximum period of 8 years. This study is important because it considers the analysis of patterns in genomic sequences, without drugs and over time.

Results:

A temporal relationship among information entropy, hypermutation, tropism switch, viral load, and CD4+ T cell count was determined. Changes in information entropy were time-dependent, and an increase in entropy was observed in the C2V3C3 region at amino acids G313 and F317-I320 (related to the GPGR-motif and coreceptor tropism), and at amino acids A281 in C2 and A346 in C3, related to immune escape.

Conclusion:

The increase of information entropy over time was correlated with hypermutation and the emergence of nonR5- strains, which are both associated with more variable genomes.

HIV-1 genetic diversity and divergence and its correlation with disease progression among antiretroviral naïve recently infected individuals

HIV-1 genetic diversity evolution was deeply characterized during the first year of infection among recently-infected patients using deep sequencing technology and correlated with disease progression surrogate markers. RNA and DNA samples from twenty-five individuals (13 female) encoding the protease and reverse transcriptase regions of the pol gene, and the V3 region of the env gene were evaluated at recent infection and during established infection. Infection by a unique HIV-1 strain was inferred in 70.1% of the individuals, with no differences between genders. Infections by multiple strains were associated with higher viral loads and faster CD4⁺ T cell declines. Either low or high levels of viral loads accompanied low levels of genetic diversity and lower selective pressure. With massive sequence data from 3 distinct genomic HIV-1 regions from plasma and PBMCs over time, we propose a model for HIV-1 genetic diversity, which correlates to basal viral loads of patients.

Insights about minority HIV-1 strains in transmitted drug resistance mutation dynamics and disease progression

Objectives

The presence of minority transmitted drug resistance mutations was assessed using ultra-deep sequencing and correlated with disease progression among recently HIV-1-infected individuals from Brazil.

Methods

Samples at baseline during recent infection and 1 year after the establishment of the infection were analysed. Viral RNA and proviral DNA from 25 individuals were subjected to ultra-deep sequencing of the reverse transcriptase and protease regions of HIV-1.

Results

Viral strains carrying transmitted drug resistance mutations were detected in 9 out of the 25 patients, for all major antiretroviral classes, ranging from one to five mutations per patient. Ultra-deep sequencing detected strains with frequencies as low as 1.6% and only strains with frequencies >20% were detected by population plasma sequencing (three patients). Transmitted drug resistance strains with frequencies <14.8% did not persist upon established infection. The presence of transmitted drug resistance mutations was negatively correlated with the viral load and with CD4+ T cell count decay.

Conclusions

Transmitted drug resistance mutations representing small percentages of the viral population do not persist during infection because they are negatively selected in the first year after HIV-1 seroconversion.

Transmission patterns of HIV-1 non-R5 strains in Poland

HIV-1 env sequencing enables predictions of viral coreceptor tropism and phylogenetic investigations of transmission events. The aim of the study was to estimate the contribution of non-R5 strains to the viral spread in Poland. Partial proviral env sequences were retrieved from baseline blood samples of patients with newly diagnosed HIV-1 infection between 2008-2014, including 46 patients with recent HIV-1 infection (RHI), and 246 individuals with long-term infection (LTHI). These sequences were subjected to the genotypic coreceptor tropism predictions and phylogenetic analyses to identify transmission clusters. Overall, 27 clusters with 57 sequences (19.5%) were detected, including 15 sequences (26.3%) from patients with RHI. The proportion of non-R5 strains among all study participants was 23.3% (68/292), and was comparable between patients with RHI and LTHI (11/46, 23.9% vs 57/246, 23.2%; p = 1.000). All 11 patients with non-R5 strains and RHI were men having sex with men (MSM). Among these patients, 4 had viral sequences grouped within phylogenetic cluster with another sequence of non-R5 strain obtained from patient with LTHI, indicating potential acquisition of non-R5 HIV-1 for at least 4/46 (8.7%) patients with RHI. We were unable to confirm the contribution of patients with RHI to the forward transmission of non-R5 strains, but a relatively high proportion of non-R5 strains among them deserves attention due to the limited susceptibility to CCR5 antagonists.

CXCR7/ACKR3-targeting ligands interfere with X7 HIV-1 and HIV-2 entry and replication in human host cells

Chemokine receptors CCR5 and CXCR4 are considered the main coreceptors for initial HIV infection, replication and transmission, and subsequent AIDS progression. Over the years, other chemokine receptors, belonging to the family of G protein-coupled receptors, have also been identified as candidate coreceptors for HIV entry into human host cells. Amongst them, CXCR7, also known as atypical chemokine receptor 3 (ACKR3), was suggested as a coreceptor candidate capable of facilitating both HIV-1 and HIV-2 entry in vitro. In this study, a cellular infection model was established to further decipher the role of CXCR7 as an HIV coreceptor. Using this model, CXCR7-mediated viral entry was demonstrated for several clinical HIV isolates as well as laboratory strains. Of interest, the X4-tropic HIV-1 HE strain showed rapid adaptation towards CXCR7-mediated infection after continuous passaging on CD4- and CXCR7-expressing cells. Furthermore, we uncovered anti-CXCR7 monoclonal antibodies, small molecule CXCR7 inhibitors and the natural CXCR7 chemokine ligands as potent inhibitors of CXCR7 receptor-mediated HIV entry and replication. Even though the clinical relevance of CXCR7-mediated HIV infection remains poorly understood, our data suggest that divergent HIV-1 and HIV-2 strains can quickly adapt their coreceptor usage depending on the cellular environment, which warrants further investigation.

Pace of Coreceptor Tropism Switch in HIV-1-Infected Individuals after Recent Infection

HIV-1 entry into target cells influences several aspects of HIV-1 pathogenesis, including viral tropism, HIV-1 transmission and disease progression, and response to entry inhibitors. The evolution from CCR5- to CXCR4-using strains in a given human host is still unpredictable. Here we analyzed timing and predictors for coreceptor evolution among recently HIV-1-infected individuals. Proviral DNA was longitudinally evaluated in 66 individuals using Geno2pheno_[coreceptor] Demographics, viral load, CD4⁺ and CD8⁺ T cell counts, CCR5Δ32 polymorphisms, GB virus C (GBV-C) coinfection, and HLA profiles were also evaluated. Ultradeep sequencing was performed on initial samples from 11 selected individuals. A tropism switch from CCR5- to CXCR4-using strains was identified in 9/49 (18.4%) individuals. Only a low baseline false-positive rate (FPR) was found to be a significant tropism switch predictor. No minor CXCR4-using variants were identified in initial samples of 4 of 5 R5/non-R5 switchers. Logistic regression analysis showed that patients with an FPR of >40.6% at baseline presented a stable FPR over time whereas lower FPRs tend to progressively decay, leading to emergence of CXCR4-using strains, with a mean evolution time of 27.29 months (range, 8.90 to 64.62). An FPR threshold above 40.6% determined by logistic regression analysis may make it unnecessary to further determine tropism for prediction of disease progression related to emergence of X4 strains or use of CCR5 antagonists. The detection of variants with intermediate FPRs and progressive FPR decay over time not only strengthens the power of Geno2pheno in predicting HIV tropism but also indirectly confirms a continuous evolution from earlier R5 variants toward CXCR4-using strains.IMPORTANCE The introduction of CCR5 antagonists in the antiretroviral arsenal has sparked interest in coreceptors utilized by HIV-1. Despite concentrated efforts, viral and human host features predicting tropism switch are still poorly understood. Limited longitudinal data are available to assess the influence that these factors have on predicting tropism switch and disease progression. The present study describes longitudinal tropism evolution in a group of recently HIV-infected individuals to determine the prevalence and potential correlates of tropism switch. We demonstrated here that a low baseline FPR determined by the Geno2pheno_[coreceptor] algorithm can predict tropism evolution from CCR5 to CXCR4 coreceptor use.

Harnessing CXCR4 antagonists in stem cell mobilization, HIV infection, ischemic diseases, and oncology

CXCR4 antagonists (e.g., Plerixafor^TM ) have been successfully validated as stem cell mobilizers for peripheral blood stem cell transplantation. Applications of the CXCR4 antagonists have heralded the era of cell-based therapy and opened a potential therapeutic horizon for many unmet medical needs such as kidney injury, ischemic stroke, cancer, and myocardial infarction. In this review, we first introduce the central role of CXCR4 in diverse cellular signaling pathways and discuss its involvement in several disease progressions. We then highlight the molecular design and optimization strategies for targeting CXCR4 from a large number of case studies, concluding that polyamines are the preferred CXCR4-binding ligands compared to other structural options, presumably by mimicking the highly positively charged natural ligand CXCL12. These results could be further justified with computer-aided docking into the CXCR4 crystal structure wherein both major and minor subpockets of the binding cavity are considered functionally important. Finally, from the clinical point of view, CXCR4 antagonists could mobilize hematopoietic stem/progenitor cells with long-term repopulating capacity to the peripheral blood, promising to replace surgically obtained bone marrow cells as a preferred source for stem cell transplantation.

Uniquely altered transcripts are associated with immune preservation in HIV infection

The mechanisms underlying host HIV control hold much promise in the search for a functional HIV cure. We investigated the host genomic signatures in elite controllers or rapid progressors following recent infection and the correlates of immune reconstitution during combination antiretroviral therapy. We characterized the HIV-specific longitudinal host transcriptional response of peripheral blood mononuclear cells from elite controllers, rapid progressors, immune responders and non-responders using a RT-qPCR array in a cohort of recently HIV-infected Brazilian individuals. The elite controllers expressed unique transcripts early in infection that were closely associated with specialized cross-presentation between XCR1+ DCs and antigen-specific CD8+ T cells (XCL1). The natural suppression of HIV was also associated with the highly functional co-expression of cytokines and chemokines (CCL2, TNF and IL-10) concomitant with the maintenance of important anti-inflammatory and anticoagulant properties (Antithrombin III). Immune responders exhibited exclusively upregulated mRNAs possibly related to stem cell mobilization before combination antiretroviral therapy (neutrophil elastase). Our longitudinal approach to gene expression permitted us to discover previously unrecognized determinants that contribute to natural or antiretroviral-mediated HIV-1 immune control.

Impact of HIV-1 Subtypes on AIDS Progression in a Brazilian Cohort

Viral and host factors are known to play a role in the different patterns of AIDS progression. The cocirculation of HIV-1 subtypes B, F1, B_BR, and BF1; the occasional detection of HIV-1 subtype D; and an increasing prevalence of subtype C and other recombinant forms have been described in Rio de Janeiro, Brazil. The aim of this study was to evaluate the potential association of HIV-1 subtypes circulating among HIV-1+ individuals in Rio de Janeiro with AIDS disease progression. For this purpose, 246 HIV-1 individuals under clinical and laboratory follow-up from 1986 to 2011 were classified according to their progression to AIDS in typical progressors (n = 133), rapid progressors (n = 95), and long-term nonprogressors (n = 18). The env-gp120 region was amplified and sequenced. Neighbor-joining phylogenetic inferences were performed in Mega 6 and bootscan analysis was performed in Simplot 3.5.1. The Kaplan-Meier method and Cox modeling were performed to determine the time until an AIDS-defining event based on the HIV-1 subtypes/variants. Similar AIDS progression rates were observed among individuals infected with HIV-1 subtype B and variant B_BR. However, a direct association between more rapid AIDS progression and HIV-1 subtypes, D and BF1, was confirmed in the multivariate analysis, corroborating previous results. Our findings contribute to the investigation of the possible influence of HIV-1 subtypes in AIDS outcome.

Plasma Metabolomics Biosignature According to HIV Stage of Infection, Pace of Disease Progression, Viremia Level and Immunological Response to Treatment

BACKGROUND

We evaluated plasma samples HIV-infected individuals with different phenotypic profile among five HIV-infected elite controllers and five rapid progressors after recent HIV infection and one year later and from 10 individuals subjected to antiretroviral therapy, five of whom were immunological non-responders (INR), before and after one year of antiretroviral treatment compared to 175 samples from HIV-negative patients. A targeted quantitative tandem mass spectrometry metabolomics approach was used in order to determine plasma metabolomics biosignature that may relate to HIV infection, pace of HIV disease progression, and immunological response to treatment.

RESULTS

Twenty-five unique metabolites were identified, including five metabolites that could distinguish rapid progressors and INRs at baseline. Severe deregulation in acylcarnitine and sphingomyelin metabolism compatible with mitochondrial deficiencies was observed. β-oxidation and sphingosine-1-phosphate-phosphatase-1 activity were down-regulated, whereas acyl-alkyl-containing phosphatidylcholines and alkylglyceronephosphate synthase levels were elevated in INRs. Evidence that elite controllers harbor an inborn error of metabolism (late-onset multiple acyl-coenzyme A dehydrogenase deficiency [MADD]) was detected.

CONCLUSIONS

Blood-based markers from metabolomics show a very high accuracy of discriminating HIV infection between varieties of controls and have the ability to predict rapid disease progression or poor antiretroviral immunological response. These metabolites can be used as biomarkers of HIV natural evolution or treatment response and provide insight into the mechanisms of the disease.

HIV-1 Epidemiology, Genetic Diversity, and Primary Drug Resistance in the Tyumen Oblast, Russia

Introduction. Specific molecular epidemic features of HIV infection in Tyumen Oblast (TO), Russia, were studied. Methods. The genome sequences encoding HIV-1 protease-reverse transcriptase, integrase, and major envelope protein were examined for 72 HIV-1 specimens isolated from the TO resident infected in 2000-2015. Results. The recorded prevalence of HIV-1 subtype A (A1) is 93.1%; HIV-1 subtype B continues to circulate in MSM risk group (1.4%). Solitary instances of HIV-1 recombinant forms, CRF63_02A1 (1.4%) and CRF03_AB (1.4%), were detected as well as two cases of HIV-1 URF63_A1 (2.8%). Phylogenetic analysis showed no HIV-1 clustering according to the duration of infection and risk groups but revealed different epidemic networks confirming that HIV infection spread within local epidemic foci. A high incidence of CXCR4-tropic HIV-1 variants and a higher rate of secondary mutations influencing the virus fitness (K20R, L10V, and I) are observed among the virus specimens isolated from newly infected individuals. Conclusions. The current HIV-1 epidemic in TO develops within the local epidemic networks. Similar to the previous period, HIV-1 subtype A is predominant in TO with sporadic cases of importation of HIV-1 recombinant forms circulating in adjacent areas.

Differential evolution of a CXCR4-using HIV-1 strain in CCR5wt/wt and CCR5∆32/∆32 hosts revealed by longitudinal deep sequencing and phylogenetic reconstruction

Rare individuals homozygous for a naturally-occurring 32 base pair deletion in the CCR5 gene (CCR5∆32/∆32) are resistant to infection by CCR5-using ("R5") HIV-1 strains but remain susceptible to less common CXCR4-using ("X4") strains. The evolutionary dynamics of X4 infections however, remain incompletely understood. We identified two individuals, one CCR5wt/wt and one CCR5∆32/∆32, within the Vancouver Injection Drug Users Study who were infected with a genetically similar X4 HIV-1 strain. While early-stage plasma viral loads were comparable in the two individuals (~4.5-5 log10 HIV-1 RNA copies/ml), CD4 counts in the CCR5wt/wt individual reached a nadir of <20 CD4 cells/mm(3) within 17 months but remained >250 cells/mm(3) in the CCR5∆32/∆32 individual. Ancestral phylogenetic reconstructions using longitudinal envelope-V3 deep sequences suggested that both individuals were infected by a single transmitted/founder (T/F) X4 virus that differed at only one V3 site (codon 24). While substantial within-host HIV-1 V3 diversification was observed in plasma and PBMC in both individuals, the CCR5wt/wt individual's HIV-1 population gradually reverted from 100% X4 to ~60% R5 over ~4 years whereas the CCR5∆32/∆32 individual's remained consistently X4. Our observations illuminate early dynamics of X4 HIV-1 infections and underscore the influence of CCR5 genotype on HIV-1 V3 evolution.

Disease progression of HIV-1 infection in symptomatic and asymptomatic seroconverters in Osaka, Japan: a retrospective observational study

Background

Estimates of the interval from HIV-1 infection to disease progression may be affected by selection bias, and data concerning asymptomatic early seroconverters are limited. We examined the interval until disease progression in HIV-1 seroconverters in whom the timing of infection could be estimated within 1 year before diagnosis.

Methods

Subjects included newly diagnosed patients at Osaka National Hospital between 2003 and 2010 who had either (1) symptomatic acute HIV-1 infection with a negative or intermediate reaction on Western blotting and a positive reaction on an HIV RNA test (symptomatic acute group) or (2) a positive reaction on Western blotting at diagnosis and a <1-year interval from the last negative HIV test until the first positive test. The latter was divided into symptomatic recent or asymptomatic recent groups based on the presence or absence, respectively, of any transient fever between the last negative and first positive tests. Disease progression was defined as a fall in the CD4 count to <350 cells/microL on 2 consecutive tests, the start of anti-HIV therapy, or the onset of AIDS-indicator diseases. Information was retrospectively collected from medical records.

Results

Subjects included 210 patients: 91 in the symptomatic acute group, 72 in the symptomatic recent group, and 47 in the asymptomatic recent group. In the symptomatic acute (0.8 years) and symptomatic recent (2.2 years) groups, the Kaplan-Meier estimate of median interval until disease progression was significantly shorter than that in the asymptomatic recent group (2.9 years). Multivariate analysis by Cox’s proportional hazards test showed that the symptomatic acute group (vs. asymptomatic recent group: hazard ratio: 1.93; 95% confidence interval: 1.14–3.36; p = 0.0140) and a baseline CD4 count of <400 cells/microL (hazard ratio: 3.88; 95% confidence interval: 2.57–5.96; p < 0.0001) were independent prognostic factors associated with early disease progression.

Conclusions

Symptomatic seroconversion was associated with early disease progression. Furthermore, the estimated median interval until the CD4 count was <350 cells/microL was only 2.9 years even in patients with asymptomatic seroconversion. These results suggest the importance of early diagnosis in early seroconverters.

A diagnostic HIV-1 tropism system based on sequence relatedness

Key clinical studies for HIV coreceptor antagonists have used the phenotyping-based Trofile test. Meanwhile various simpler-to-do genotypic tests have become available that are compatible with standard laboratory equipment and Web-based interpretation tools. However, these systems typically analyze only the most prominent virus sequence in a specimen. We present a new diagnostic HIV tropism test not needing DNA sequencing. The system, XTrack, uses physical properties of DNA duplexes after hybridization of single-stranded HIV-1 env V3 loop probes to the clinical specimen. Resulting "heteroduplexes" possess unique properties driven by sequence relatedness to the reference and resulting in a discrete electrophoretic mobility. A detailed optimization process identified diagnostic probe candidates relating best to a large number of HIV-1 sequences with known tropism. From over 500 V3 sequences representing all main HIV-1 subtypes (Los Alamos database), we obtained a small set of probes to determine the tropism in clinical samples. We found a high concordance with the commercial TrofileES test (84.9%) and the Web-based tool Geno2Pheno (83.0%). Moreover, the new system reveals mixed virus populations, and it was successful on specimens with low virus loads or on provirus from leukocytes. A replicative phenotyping system was used for validation. Our data show that the XTrack test is favorably suitable for routine diagnostics. It detects and dissects mixed virus populations and viral minorities; samples with viral loads (VL) of <200 copies/ml are successfully analyzed. We further expect that the principles of the platform can be adapted also to other sequence-divergent pathogens, such as hepatitis B and C viruses.

Function-oriented development of CXCR4 antagonists as selective human immunodeficiency virus (HIV)-1 entry inhibitors

Motivated by the pivotal role of CXCR4 as an HIV entry co-receptor, we herein report a de novo hit-to-lead effort on the identification of subnanomolar purine-based CXCR4 antagonists against HIV-1 infection. Compound 24, with an EC50 of 0.5 nM against HIV-1 entry into host cells and an IC50 of 16.4 nM for inhibition of radioligand stromal-derived factor-1α (SDF-1α) binding to CXCR4, was also found to be highly selective against closely related chemokine receptors. We rationalized that compound 24 complementarily interacted with the critical CXCR4 residues that are essential for binding to HIV-1 gp120 V3 loop and subsequent viral entry. Compound 24 showed a 130-fold increase in anti-HIV activity compared to that of the marketed CXCR4 antagonist, AMD3100 (Plerixafor), whereas both compounds exhibited similar potency in mobilization of CXCR4(+)/CD34(+) stem cells at a high dose. Our study offers insight into the design of anti-HIV therapeutics devoid of major interference with SDF-1α function.

Homogenous HIV-1 subtype B quasispecies in Brazilian men and women recently infected via heterosexual transmission

HIV has extraordinary genetic mutability, both among individuals and at the population level. However, studies of primary HIV-1 infection and serum-converters indicate that the viral population is homogeneous at the sequence level, which suggests clonal HIV transmission. It remains unclear whether this feature applies to the female population. Ten single genome amplification sequences were generated from ten individuals (five females) with recent heterosexually acquired HIV infection as determined by the serologic testing algorithm for recent HIV seroconversion. Intra-individual genetic diversity was equally low in both genders (<2 %), with mean and median variations of 0.8 and 0 %, respectively. All of the subjects were infected with clade B. Three subjects (two females) appeared to be infected by two related viral populations, and four subjects harbored non-R5 strains. Our results support the hypothesis of clonal selection for sexual transmission of HIV-1 in both genders. Future studies that generate a larger number of clones, preferably by next generation deep sequencing, are needed to confirm these results.

Short communication: HIV type 1 tropism determination in a novel dried blood spot membrane and the use of a mixture of outer nested polymerase chain reaction primers

Genotropism was determined in 608 Brazilian samples collected in dried blood spots using Polyethersulfone collection cards. Patients were infected by subtype B (88.8%), F (5.6%), C (3.3%), A (1.8%), and G (0.5%). All patients were exposed to three classes of antiretrovirals, and 59.8% of the samples harbored R5 viruses, 35% non-R5-tropic viruses, and 5.1% harbored mixtures of R5 and non-R5-tropic viruses, with non-R5 more prevalent among clade B-infected patients as compared to non-B (42.8% versus 19.1%; p<0.0003). A strategy using a mixture of outer nested polymerase chain reaction (PCR) primers reduced the number of negative PCR results from 39% to 19%.

Temporal trends and molecular epidemiology of HIV type 1 infection in Rio de Janeiro, Brazil

HIV-1 molecular epidemiology studies carried out in Rio de Janeiro, Brazil have identified the prevalence of subtypes B, F1 and BF1 recombinants. A high percentage of HIV-1 subtype B isolates in Rio de Janeiro harbor the GWG motif at the V3 tip (B'' variant) instead of the canonical GPG motif (B variant). To trace the dynamics of the HIV-1 variants over time in different exposure categories in Rio de Janeiro, the HIV-1 proviral DNA from heterosexual men (HET) and men who have sex with men (MSM) from two distinct time periods (1990-1992 and 2008-2010) were extracted, and the env-gp120 region was amplified. Neighbor-joining phylogenetic analysis was performed to determine the viral subtype, and Bayesian analysis was used to trace the HIV-1 transmission networks. A predominance of subtype B was observed in both study periods, independent of the exposure risk category. An increase of non-B subtypes was observed in the HET group, but these subtypes were maintained among the MSM group. The distribution of HIV-1 subtype B signatures in the first and second periods studied were, respectively, HET (GPG) [44.8-51.5%], (GWG) [13.8-33.3%], and (GXG) [41.4-15.2%] and MSM (GPG) [34-50%], (GWG) [55.3-30.6%], and (GXG) [10.7-19.4%]. In the first period, an association between GWG and MSM was verified while a significant reduction of this association was observed during the second period. The phylogenetic tree and the BaTS program detected the clustering of isolates only according to the B signatures but not by exposure risk category. Our findings indicate a stable prevalence of HIV-1 subtypes B and F over time in Rio de Janeiro and further suggest that the B'' subclade of subtype B was possibly introduced into the MSM group in this area of Brazil.

HIV-1 coreceptor switch during 2 years of structured treatment interruptions

The purpose of this investigation was to determine the impact on human immunodeficiency virus (HIV) tropism of uncontrolled virus exposure during 2 years of intermittent highly active antiretroviral therapy (HAART). The Istituto Superiore di Sanità-Pulsed Antiretroviral Therapy (ISS-PART) randomized study compared the outcome of 2 years of structured treatment interruptions (STIs) versus standard continuous treatment in first-line HAART responder subjects. The STI schedule consisted of five STIs of 1, 1, 2, 2, and 3 months, respectively, separated by four periods of 3-month therapy. In the present study, coreceptor tropism was assessed in 12 patients of the STI arm at different time points over a period of 2 years. Tropism was determined on DNA and RNA by V3 loop region sequencing. The Geno2pheno algorithm (false-positive rate, FPR: 20%) was used for data interpretation. At baseline, 9/12 subjects (75.0%) had CCR5-tropic viruses in their HIV. Three had a CXCR4-tropic virus. Ten patients maintained the same coreceptor in DNA after 2 years, whereas in two patients, a shift occurred (one R5-X4, one X4-R5). In a patient with an R5 virus at baseline, a transient change to X4 tropism was seen in the rebounding virus during STI. Changes in tropism were not associated with the amplitude and duration of virus exposure during STIs, residual viremia at baseline, or the development of resistance mutations in the RT region. Our preliminary results suggest that viral replication, observed after short periods of treatment interruption, is not enough to drive the evolution of HIV tropism.

Transcriptomic analysis of peripheral blood mononuclear cells in rapid progressors in early HIV infection identifies a signature closely correlated with disease progression

BACKGROUND

A substantial percentage (10%-15%) of HIV-infected individuals experience a sharp decline in CD4(+) T-cell counts and progress to AIDS quickly after primary infection. Identification of biomarkers distinguishing rapid progressors (RPs) vs chronic progressors (CPs) is critical for early clinical intervention and could provide novel strategies to facilitate vaccine design and immune therapy.

METHODS

mRNA and microRNA (miRNA) expression profiles in the peripheral blood mononuclear cells (PBMCs) of RPs and CPs were investigated at 111 (22) days [mean (SD)] of HIV infection. The association of mRNA and miRNA expression with disease progression was examined by ROC analysis and Kaplan-Meier survival analysis.

RESULTS

Pathway enrichment analysis showed that genes with deregulated expression in RPs were primarily involved in apoptosis pathways. Furthermore, we found that 5 miRNAs (miR-31, -200c, -526a, -99a, and -503) in RPs were significantly decreased compared to those in CPs (P < 0.05). The decreased expression of these miRNAs was associated with a rapid disease of progression of HIV infection with a 94% predictive value as measured by the area under the curve. The upregulated predicted targets from the 5 signature miRNAs and all upregulated genes identified from mRNA microarray analysis converged to the apoptosis pathway. Moreover, overexpression of miR-31 in primary human T cells promoted their survival.

CONCLUSIONS

Our results have identified a distinct transcriptomic signature in PBMCs of RPs and provided novel insights to the pathogenesis of HIV infection.

Natural evolution of CD4+ cell count in patients with CD4 >350 or >500 cells/mm3 at the time of diagnosis according to HIV-1 coreceptor tropism

The HIV-1 coreceptor usage may play a critical role in AIDS pathogenesis and the X4-using viruses are considered to be more pathogenic than the R5-tropic viruses. These observations may influence the therapeutic decisions by asking for an earlier antiretroviral (ARV) treatment for the patients infected by the X4-tropic viruses compared with those infected by the R5-tropic viruses. The natural evolution of CD4+ cell count for 109 non-treated patients infected by the R5- or X4-tropic HIV-1 viruses with CD4+ >350 and >500 cells/mm(3) at time of diagnosis was compared until the initiation of an ARV regimen. The coreceptor usage was determined from the V3 env region sequence by Geno2Pheno (false positive rate 10%). A mixed linear regression model to analyse the CD4+ data with tropism as fixed effect in the model was used. Overall, 93 (85.3%) and 16 (14.7%) were infected by R5- and X4-tropic viruses, respectively. The median age, baseline CD4+ cell count, and viral load were 34 years (IQR: 30-42), 523 cells/mm(3) (IQR: 420-604), and 4.5 log(10)  copies/ml (IQR: 3.9-5.0), respectively. There was no statistical difference in time to progression between the patients harboring R5- or X4-tropic viruses. The same results were observed for the sub-group of patients with CD4+ cell count >500 cells/mm(3). The virus tropism has no impact on the CD4+ cell count evolution in these HIV-1 patients diagnosed with CD4+ >350 or >500 cells/mm(3) suggesting that the tropism determination at time of diagnosis does not seem to be a useful tool to predict the clinical progression.

Small molecule inhibitors of CXCR4

CXCR4 is a G-protein-coupled receptor involved in a number of physiological processes in the hematopoietic and immune systems. The SDF-1/CXCR4 axis is significantly associated with several diseases, such as HIV, cancer, WHIM syndrome, rheumatoid arthritis, pulmonary fibrosis and lupus. For example, CXCR4 is one of the major co-receptors for HIV entry into target cells, while in cancer it plays an important role in tumor cell metastasis. Several promising CXCR4 antagonists have been developed to block SDF-1/CXCR4 interactions that are currently under different stages of development. The first in class CXCR4 antagonist, plerixafor, was approved by the FDA in 2008 for the mobilization of hematopoietic stem cells and several other drugs are currently in clinical trials for cancer, HIV, and WHIM syndrome. While the long-term safety data for the first generation CXCR4 antagonists are not yet available, several new compounds are under preclinical development in an attempt to provide safer and more efficient treatment options for HIV and cancer patients.

Primary CXCR4 co-receptor use in acute HIV infection leads to rapid disease progression in the AE subtype

This is a comparative study of HIV co-receptor usage in the early stages of HIV infection between two distinct patient groups, one with a low CD4 count (group 1), and the other with a high CD4 count (group 2). Group 1 progressed to a CD4 count below 200 cells/μL within 2 y, while group 2 had a CD4 count above 500 cells/μL within 2 y. Viral RNA was extracted from the plasma of these patients, and the C2-V5 region of the HIV-1 env genes were cloned and sequenced. The co-receptor usage was predicated based on V3 loop amino acid sequences using Geno2pheno and PSSM programs. Our results indicate that in acute HIV infection of rapid progressors (low CD4 count; group 1), the primary co-receptor usage is CXCR4, while in the high CD4 count group (group 2), the co-receptor usage is predominantly CCR5. One-year follow-up data from these patients showed no obvious change in HIV co-receptor usage in either group. Sequence analysis of patients from both study groups showed prevalence of the AE subtype, and therefore we can speculate that the CXCR4 co-receptor may be the primary HIV-1 co-receptor used in the HIV-1 AE subtype, and may be responsible for rapid HIV-1 disease progression in the MSM cohort.

On HIV diversity

HIV type 1 (HIV-1) displays a greater degree of genetic and antigenic variability than any other virus studied. This diversity reflects a high mutation rate during viral replication with a large turnover of virus, and a high tolerance of variation while maintaining reproductive capacity. Generation of diversity is a common property of lentiviruses such as HIV. Differences in virulence and in transmissibility are seen between different HIV-1 strains which may have clinical implications. The great degree of HIV diversity presents challenges to maintaining sensitivity to antiretroviral therapy and to the development of preventive strategies such as microbicides and vaccines.