Frequency and predictors of HIV-1 co-receptor switch in treatment naive patients

Identification and Implications of HIV-1 CRF01_AE Subtype in Hawai'i

Human Immunodeficiency Virus has a high propensity for genetic variation, demonstrated by its complex phylogeny and multiplicity of subtypes. Subtype B is predominant in North America as well as in Hawai'i while CRF01_AE is found in over 50% of cases in the Philippines and Southeast Asia. In a small collaborative study between the Hawai'i Center for AIDS and Philippines General Hospital, molecular phylogenetic subtyping was conducted on HIV+ participants. Two of 15 (13%) participants from the Hawai'i cohort and 12 of 21 (57%) participants from the Philippines cohort were identified as having CRF01_AE subtype of HIV-1, with remaining participants identified as subtype B. While one individual in Hawai'i with CRF01_AE had emigrated from the Philippines, the other participant from Hawai'i with CRF01_AE subtype was a local individual, born and raised in Hawai'i. The authors report that HIV subtype diversity may be increased in Hawai'i and discuss its potential clinical and public health implications.

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.

CD4 T cell decline following HIV seroconversion in individuals with and without CXCR4-tropic virus

Background

The natural clinical and immunological courses following HIV seroconversion with CXCR4-tropic or dual-mixed (X4/DM) viruses are controversial. We compared spontaneous immunological outcome in patients harbouring an X4/DM virus at the time of seroconversion with those harbouring a CCR5-tropic (R5) virus.

Methods

Data were included from patients participating in CASCADE, a large cohort collaboration of HIV seroconverters, with ≥2 years of follow-up since seroconversion. The HIV envelope gene was sequenced from frozen plasma samples collected at enrolment, and HIV tropism was determined using Geno2Pheno (false-positive rate 10%). The spontaneous CD4 T cell evolution was compared by modelling CD4 kinetics using linear mixed-effects models with random intercept and random slope.

Results

A total of 1387 patients were eligible. Median time between seroconversion and enrolment was 1 month (range 0-3). At enrolment, 202 of 1387 (15%) harboured an X4/DM-tropic virus. CD4 decrease slopes were not significantly different according to HIV-1 tropism during the first 30 months after seroconversion. No marked change in these results was found after adjusting for age, year of seroconversion and baseline HIV viral load. Time to antiretroviral treatment initiation was not statistically different between patients harbouring an R5 (20.76 months) and those harbouring an X4/DM-tropic virus (22.86 months, logrank test P = 0.32). Conclusions: In this large cohort collaboration, 15% of the patients harboured an X4/DM virus close to HIV seroconversion. Patients harbouring X4/DM-tropic viruses close to seroconversion did not have an increased risk of disease progression, estimated by the decline in CD4 T cell count or time to combined ART initiation.

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.

Longitudinal sequencing of HIV-1 infected patients with low-level viremia for years while on ART shows no indications for genetic evolution of the virus

HIV-infected patients on antiretroviral therapy (ART) may present low-level viremia (LLV) above the detection level of current viral load assays. In many cases LLV is persistent but does not result in overt treatment failure or selection of drug resistant viral variants. To elucidate whether LLV reflects active virus replication, we extensively sequenced pol and env genes of the viral populations present before and during LLV in 18 patients and searched for indications of genetic evolution. Maximum likelihood phylogenetic trees were inspected for temporal structure both visually and by linear regression analysis of root-to-tip and pairwise distances. Viral coreceptor tropism was assessed at different time points before and during LLV. In none of the patients consistent indications for genetic evolution were found over a median period of 4.8 years of LLV. As such these findings could not provide evidence that active virus replication is the main driver of LLV.

Emergence of CXCR4-tropic HIV-1 variants followed by rapid disease progression in hemophiliac slow progressors

OBJECTIVE

The association between emergence of CXCR4-tropic HIV-1 variants (X4 variants) and disease progression of HIV-1 infection has been reported. However, it is not known whether the emergence of X4 variants is the cause or result of HIV-1 disease progression. We tried to answer this question.

DESIGN

HIV-1 env sequences around the V3 region were analyzed in serially stocked samples in order to determine whether X4 variants emerged before or after the fall in CD4+ T-cell count.

METHODS

The study subjects were five HIV-1-infected hemophiliac slow progressors. Deep sequencing around the HIV-1 env V3 region was conducted in duplicate. Tropism was predicted by geno2pheno [coreceptor] 2.5 with cutoff value of false positive ratio at <5%. When X4 variant was identified in the latest stocked sample before the introduction of antiretroviral therapy, we checked viral genotype in previously stocked samples to determine the time of emergence of X4 variants.

RESULTS

Emergence of X4 variants was noted in two of the five patients when their CD4+ T-cell counts were still high. The rate of decrease of CD4+ T-cell count or of rise of HIV-1 load accelerated significantly after the emergence of X4 variants in these two cases. Phylogenetic analysis showed that these X4 variants emerged from CCR5-tropic HIV-1 viruses with several amino acid changes in the V3 region.

CONCLUSIONS

The emergence of X4 variants preceded HIV-1 disease progression in two hemophiliac slow progressors.

HIV co-receptor tropism prediction remains stable over time in treatment-naïve patients

HIV co-receptor tropism determination is essential before prescribing the CCR5 antagonist maraviroc. British HIV Association guidelines suggest tropism testing may remain valid for only 90 days in antiretroviral-naïve patients. We aimed to determine the accuracy of this figure. Tropism was assessed in 26 antiretroviral-naïve patients with ongoing viral replication, sampled yearly from first clinic visit. The V3 region of HIV-1 was sequenced in triplicate, then tropism predicted using the Geno2Pheno system. Baseline tropism prediction remained valid for a median of 52 months (range 7-81). For 19/26 individuals baseline tropism remained unchanged throughout a median of 54 months follow-up; 18 R5 tropic and 1 X4 tropic. In seven patients (27%) baseline tropism switched at least once (range 1-4 switches) during follow-up; however, their baseline tropism prediction remained valid for a median of 45 months. Co-receptor tropism in treatment-naïve patients with ongoing viral replication appears highly stable over time, suggesting that baseline genotypic tropism prediction may be valid for a longer duration in patients delaying ART initiation. In this study, baseline tropism prediction remained valid for a median of 52 months, suggesting current guidelines recommending repeat testing after 90 days may be excessively conservative in their assessment of tropism stability.

Parameters Influencing Baseline HIV-1 Genotypic Tropism Testing Related to Clinical Outcome in Patients on Maraviroc

OBJECTIVES

We analysed the impact of different parameters on genotypic tropism testing related to clinical outcome prediction in 108 patients on maraviroc (MVC) treatment.

METHODS

87 RNA and 60 DNA samples were used. The viral tropism was predicted using the geno2pheno[coreceptor] and T-CUP tools with FPR cut-offs ranging from 1%-20%. Additionally, 27 RNA and 28 DNA samples were analysed in triplicate, 43 samples with the ESTA assay and 45 with next-generation sequencing. The influence of the genotypic susceptibility score (GSS) and 16 MVC-resistance mutations on clinical outcome was also studied.

RESULTS

Concordance between single-amplification testing compared to ESTA and to NGS was in the order of 80%. Concordance with NGS was higher at lower FPR cut-offs. Detection of baseline R5 viruses in RNA and DNA samples by all methods significantly correlated with treatment success, even with FPR cut-offs of 3.75%-7.5%. Triple amplification did not improve the prediction value but reduced the number of patients eligible for MVC. No influence of the GSS or MVC-resistance mutations but adherence to treatment, on the clinical outcome was detected.

CONCLUSIONS

Proviral DNA is valid to select candidates for MVC treatment. FPR cut-offs of 5%-7.5% and single amplification from RNA or DNA would assure a safe administration of MVC without excluding many patients who could benefit from this drug. In addition, the new prediction system T-CUP produced reliable results.

The utility of different bioinformatics algorithms for genotypic HIV-1 tropism testing in a large clinical cohort with multiple subtypes

OBJECTIVES

HIV-1 tropism needs to be determined before the use of CCR5 antagonist drugs such as maraviroc (MVC), which are ineffective against CXCR4-using HIV-1. This study assessed how different computational methods for predicting tropism from HIV sequence data performed in a large clinical cohort. The value of adding clinical data to these algorithms was also investigated.

DESIGN AND METHODS

PCR amplification and sequence analysis of the HIV-1 gp120 V3 loop region was performed on triple replicates of plasma viral RNA or proviral DNA extracted from peripheral blood monocytes (PBMCs) in 242 patients. Coreceptor usage was predicted from V3 sequences using seven bioinformatics interpretation algorithms, combined with clinical data where appropriate. An intention-to-treat approach was employed for exploring outcomes and performance for different viral subtypes was examined.

RESULTS

The frequency of R5 predictions varied by 22.6%, with all seven algorithms agreeing for only 75.3% of tests. The identification of individuals likely to fail was poor for all algorithms. The addition of clinical data improved this, but at the expense of their ability to predict success. The clinical algorithms varied across subtypes, whereas other algorithms were more consistent. Furthermore, individuals with discordant clonal and clinical predictions were more likely to fail MVC treatment.

CONCLUSION

Eligibility for MVC varied depending on the algorithm method used. The addition of clinical parameters alongside sequence data may help predict X4 emergence during treatment. It could be that V3 loop analysis in isolation may not be the best method for selecting individuals for MVC.

Evolution of HIV-1 tropism at quasispecies level after 5 years of combination antiretroviral therapy in patients always suppressed or experiencing episodes of virological failure

OBJECTIVES

Tropism evolution of HIV-1 quasispecies was analysed by ultra-deep pyrosequencing (UDPS) in patients on first-line combination antiretroviral therapy (cART) always suppressed or experiencing virological failure episodes.

METHODS

Among ICONA patients, two groups of 20 patients on cART for ≥5 years, matched for baseline viraemia and therapy duration, were analysed [Group I, patients always suppressed; and Group II, patients experiencing episode(s) of virological failure]. Viral tropism was assessed by V3 UDPS on plasma RNA before therapy (T0) and on peripheral blood mononuclear cell proviral DNA before-after therapy (T0-T1), using geno2pheno false positive rate (FPR) (threshold for X4: 5.75). For each sample, quasispecies tropism was assigned according to X4 variant frequency: R5, <0.3% X4; minority X4, 0.3%-19.9% X4; and X4, ≥20% X4. An R5-X4 switch was defined as a change from R5/minority X4 in plasma/proviral genomes at T0 to X4 in provirus at T1.

RESULTS

At baseline, mean FPR and %X4 of viral RNA were positively correlated with those of proviral DNA. After therapy, proviral DNA load significantly decreased in Group I; mean FPR of proviral quasispecies significantly decreased and %X4 increased in Group II. An R5-X4 switch was observed in five patients (two in Group I and three in Group II), all harbouring minority X4 variants at T0.

CONCLUSIONS

UDPS analysis reveals that the tropism switch is not an 'on-off' phenomenon, but may result from a profound re-shaping of viral quasispecies, even under suppressive cART. However, episodes of virological failure seem to prevent reduction of proviral DNA and to accelerate viral evolution, as suggested by decreased FPR and increased %X4 at T1 in Group II patients.

Deep sequencing: becoming a critical tool in clinical virology

Population (Sanger) sequencing has been the standard method in basic and clinical DNA sequencing for almost 40 years; however, next-generation (deep) sequencing methodologies are now revolutionizing the field of genomics, and clinical virology is no exception. Deep sequencing is highly efficient, producing an enormous amount of information at low cost in a relatively short period of time. High-throughput sequencing techniques have enabled significant contributions to multiples areas in virology, including virus discovery and metagenomics (viromes), molecular epidemiology, pathogenesis, and studies of how viruses to escape the host immune system and antiviral pressures. In addition, new and more affordable deep sequencing-based assays are now being implemented in clinical laboratories. Here, we review the use of the current deep sequencing platforms in virology, focusing on three of the most studied viruses: human immunodeficiency virus (HIV), hepatitis C virus (HCV), and influenza virus.