Drug resistance and coreceptor usage in HIV type 1 subtype C-infected children initiating or failing highly active antiretroviral therapy in South Africa

Global, regional, and national prevalence of HIV-1 drug resistance in treatment-naive and treatment-experienced children and adolescents: a systematic review and meta-analysis

Background

Despite significant reductions in mother-to-child HIV-1 transmission risks due to the advancements and scale-up of antiretroviral therapy (ART), the global burden of HIV-1 drug resistance (HIVDR) in treatment-naive and treatment-experienced children and adolescents remains poorly understood. In this study, we conducted a systematic review and meta-analysis to estimate the prevalence of HIVDR in these populations globally, regionally, and at the country level.

Methods

We systematically searched PubMed, Embase, and Web of Science for studies reporting HIVDR in treatment-naive and treatment-experienced children and adolescents from inception to June 28, 2024. Eligible studies reported at least ten successfully genotyped cases. We excluded studies where drug resistance was not reported separately for children and adults or for treatment-naive and treatment-experienced populations. The methodological quality of eligible studies was assessed, and random-effect models were used for meta-analysis to determine the pooled overall and regimen-specific prevalence of one or more HIVDR mutations in these populations globally, regionally, or at the country level. This study is registered with PROSPERO under the number CRD42023424483.

Findings

Of 2282 records identified, 136 studies (28,539 HIV-1-infected children from 52 countries) were included for analysis. The overall prevalence of HIVDR is 26.31% (95% CI, 20.76-32.25) among treatment-naive children and 74.16% (95% CI, 67.74-80.13) among treatment-experienced children (p < 0.0001). HIVDR varied widely across subregion with the highest prevalence in Southern Africa (37.80% [95% CI, 26.24-50.08]) and lowest in South America (11.79% [95% CI, 4.91-20.84]) for treatment-naive children while highest in Asia (80.85% [95% CI, 63.76-93.55]) and lowest in Europe (54.39% [95% CI, 28.61-79.03]) for treatment-experienced children. The proportion of viral failure (VF) presented positive correlation with DR prevalence for treatment-experienced children, which increased from 61.23% (95% CI, 47.98-73.72) in proportion of VF <50%-81.17% (95% CI, 71.57-89.28) in proportion of 100%. Meta-regression analysis for both groups showed that only age (naive: p = 0.0005; treated: p < 0.0001) was the sources of heterogeneity. Non-nucleoside reverse transcriptase inhibitor (NNRTI) resistances were the most seen mutations among the treatment-naive group, with the HIVDR prevalence more than 10% in Southern Africa, Western and Central Africa, Eastern Africa, Asia, and North America. Both nucleoside reverse transcriptase inhibitor (NRTI) and NNRTI resistances were commonly seen among the treatment-experienced group, varying from 36.33% (95% CI, 11.96-64.93) in North America to 77.54% (95% CI, 62.70-89.58) in South America for NRTI and from 39.98% (95% CI, 13.47-69.97) in Europe to 68.86 (95% CI, 43.91-89.17) in Asia for NNRTI, respectively.

Interpretation

This study underscores the significant burden of HIVDR among children and adolescents worldwide, particularly pronounced in sub-Saharan Africa and low-income countries. It emphasizes the critical importance of surveillance in all HIV-1-infected children and advocates for the adoption of dolutegravir (DTG) or other optimal formulations as first-line ART in settings where NNRTI resistance exceeds the WHO's 10% threshold. DTG's high resistance barrier, potent antiviral efficacy, and favorable safety profile makes it a superior choice for managing drug-resistant HIV-1, surpassing traditional antiretroviral therapies.

Funding

This work was supported by the Science and Technology Innovation Committee of Shenzhen Municipality (No. JCYJ20220531102202005) and the Natural Science Foundation of Guangdong Province (No. 2024A1515012118).

Prediction of Coreceptor Tropism in HIV-1 Subtype C in Botswana

It remains unknown whether the C-C motif chemokine receptor type 5 (CCR5) coreceptor is still the predominant coreceptor used by Human Immunodeficiency Virus-1 (HIV-1) in Botswana, where the HIV-1 subtype C predominates. We sought to determine HIV-1C tropism in Botswana using genotypic tools, taking into account the effect of antiretroviral treatment (ART) and virologic suppression. HIV-1 gp120 V3 loop sequences from 5602 participants were analyzed for viral tropism using three coreceptor use predicting algorithms/tools: Geno2pheno, HIV-1C Web Position-Specific Score Matrices (WebPSSM) and the 11/25 charge rule. We then compared the demographic and clinical characteristics of people living with HIV (PLWH) harboring R5- versus X4-tropic viruses using χ2 and Wilcoxon rank sum tests for categorical and continuous data analysis, respectively. The three tools congruently predicted 64% of viruses as either R5-tropic or X4-tropic. Geno2pheno and the 11/25 charge rule had the highest concordance at 89%. We observed a significant difference in ART status between participants harboring X4- versus R5-tropic viruses. X4-tropic viruses were more frequent among PLWH receiving ART (χ2 test, p = 0.03). CCR5 is the predominant coreceptor used by HIV-1C strains circulating in Botswana, underlining the strong potential for CCR5 inhibitor use, even in PLWH with drug resistance. We suggest that the tools for coreceptor prediction should be used in combination.

Genotypic HIV-1 tropism determination might help to identify people with exhausted treatment options and advanced disease

OBJECTIVES

To evaluate HIV-1 tropism in 1382 combined antiretroviral therapy (cART)-experienced patients failing therapy to characterize those with exhausted therapeutic options.

METHODS

HIV-1 genotypic tropism was inferred through Geno2Pheno by estimating the false-positive-rate (FPR) values. Cumulative resistance and drug activity were evaluated by Stanford algorithm.

RESULTS

Overall, median (IQR) CD4 count (cells/mm3) nadir and at last genotypic resistance test (GRT) available were 98 (33-211) and 312 (155-517), respectively. Considering HIV-1 tropism, 30.5% had X4/dual-mixed strains (FPR ≤5%: 22.2%; FPR 5%-10%: 8.3%). By stratifying according to tropism, by decreasing FPR, a significant decrease of CD4 nadir and at last GRT was observed. The proportion of individuals with CD4 count <200 cells/mm3, who were perinatally infected and with a long treatment history significantly increased as FPR levels decreased. Regarding resistance, 933 (67.5%) individuals accumulated at least one class resistance, with 52.7%, 48.2%, 23.5% and 13.2% of individuals showing resistance to NRTIs, NNRTIs, PIs and INIs; while 23.2%, 27.2%, 14.3% and 2.8% harboured resistance to 1, 2, 3 and 4 classes, respectively. Individuals with FPR ≤5% showed a significantly higher level of resistance to PIs, NRTIs and INIs compared with others. The proportion of individuals harbouring strains susceptible to ≤2 active drugs was only about 2%; nonetheless, this proportion doubled (4.6%) in patients infected with FPR ≤5%.

CONCLUSIONS

Our findings showed that a small proportion of cART failing individuals have limited therapeutic options. However, tropism determination might help to identify people who have accumulated a high level of resistance and have a greater risk of advanced disease.

Spiro-β-lactam BSS-730A Displays Potent Activity against HIV and Plasmodium

The high burden of malaria and HIV/AIDS prevents economic and social progress in developing countries. A continuing need exists for development of novel drugs and treatment regimens for both diseases in order to address the tolerability and long-term safety concerns associated with current treatment options and the emergence of drug resistance. We describe new spiro-β-lactam derivatives with potent (nM) activity against HIV and Plasmodium and no activity against bacteria and yeast. The best performing molecule of the series, BSS-730A, inhibited both HIV-1 and HIV-2 replication with an IC₅₀ of 13 ± 9.59 nM and P. berghei hepatic infection with an IC₅₀ of 0.55 ± 0.14 μM with a clear impact on parasite development. BSS-730A was also active against the erythrocytic stages of P. falciparum, with an estimated IC₅₀ of 0.43 ± 0.04 μM. Time-of-addition studies showed that BSS-730A potentially affects all stages of the HIV replicative cycle, suggesting a complex mechanism of action. BSS-730A was active against multidrug-resistant HIV isolates, with a median 2.4-fold higher IC₅₀ relative to control isolates. BSS-730A was equally active against R5 and X4 HIV isolates and displayed strong synergism with the entry inhibitor AMD3100. BSS-730A is a promising candidate for development as a potential therapeutic and/or prophylactic agent against HIV and Plasmodium.

Drug resistance in HIV-infected children living in rural South Africa: Implications of an antiretroviral therapy initiated during the first year of life

INTRODUCTION

Management of antiretroviral-drug resistance in HIV-infected children is a global health concern. We compared the long-term virological outcomes of two cohorts of children living in a rural setting of South Africa. The first cohort initiated treatment before one year and the second after two years of age. The aim of this study was to describe the long-term consequences of early treatment initiation in terms of viral load and drug-resistance.

METHODS

This retrospective study was conducted at the Edendale Hospital located in a peri-urban area of KwaZulu-Natal. Children were included during their planned appointment. Drug resistance was assessed genotypically on proviral DNA.

RESULTS

From the 161 children included in this study, 93 samples were successfully genotyped. Both cohorts had comparable viral loads, but children treated early more often presented NRTI or NNRTI mutations, while there was no difference for PI mutations rates.

CONCLUSIONS

Treatment was highly effective when comparing virological outcomes in both early- and late-treated cohorts. The persistence of NNRTI mutations could lead to treatment failures in children older than 3 years initiating their therapy with a NNRTI, or for those switching from a PI to NNRTI based regimen. The accumulation of NRTI mutations may lead to a functional PI monotherapy and consequently to viral escape. To promote access to HIV genotyping in resource-limited settings is challenging but essential to avoid inappropriate therapy switches in case of virological failure, and to adapt national treatment guidelines in line with the epidemiology of resistance.

Characterization of Nucleoside Reverse Transcriptase Inhibitor-Associated Mutations in the RNase H Region of HIV-1 Subtype C Infected Individuals

The South African national treatment programme includes nucleoside reverse transcriptase inhibitors (NRTIs) in both first and second line highly active antiretroviral therapy regimens. Mutations in the RNase H domain have been associated with resistance to NRTIs but primarily in HIV-1 subtype B studies. Here, we investigated the prevalence and association of RNase H mutations with NRTI resistance in sequences from HIV-1 subtype C infected individuals. RNase H sequences from 112 NRTI treated but virologically failing individuals and 28 antiretroviral therapy (ART)-naive individuals were generated and analysed. In addition, sequences from 359 subtype C ART-naive sequences were downloaded from Los Alamos database to give a total of 387 sequences from ART-naive individuals for the analysis. Fisher's exact test was used to identify mutations and Bayesian network learning was applied to identify novel NRTI resistance mutation pathways in RNase H domain. The mutations A435L, S468A, T470S, L484I, A508S, Q509L, L517I, Q524E and E529D were more prevalent in sequences from treatment-experienced compared to antiretroviral treatment naive individuals, however, only the E529D mutation remained significant after correction for multiple comparison. Our findings suggest a potential interaction between E529D and NRTI-treatment; however, site-directed mutagenesis is needed to understand the impact of this RNase H mutation.

High-Sequence Diversity and Rapid Virus Turnover Contribute to Higher Rates of Coreceptor Switching in Treatment-Experienced Subjects with HIV-1 Viremia

Coreceptor switching from CCR5 to CXCR4 is common during chronic HIV-1 infection, but is even more common in individuals who have failed antiretroviral therapy (ART). Prior studies have suggested rapid mutation and/or recombination of HIV-1 envelope (env) genes during coreceptor switching. We compared the functional and genotypic changes in env of viruses from viremic subjects who had failed ART just before and after coreceptor switching and compared those to viruses from matched subjects without coreceptor switching. Analysis of multiple unique functional env clones from each subject revealed extensive diversity at both sample time points and rapid diversification of sequences during the 4-month interval in viruses from both 9 subjects with coreceptor switching and 15 control subjects. Only two subjects had envs with evidence of recombination. Three findings distinguished env clones from subjects with coreceptor switching from controls: (1) lower entry efficiency via CCR5; (2) longer V1/V2 regions; and (3), lower nadir CD4 T cell counts during prior years of infection. Most of these subjects harbored virus with lower replicative capacity associated with protease (PR) and/or reverse transcriptase inhibitor resistance mutations, and the extensive diversification tended to lead either to improved entry efficiency via CCR5 or the gain of entry function via CXCR4. These results suggest that R5X4 or X4 variants emerge from a diverse, low-fitness landscape shaped by chronic infection, multiple ART resistance mutations, the availability of target cells, and reduced entry efficiency via CCR5.

Monophylogenetic HIV-1C epidemic in Ethiopia is dominated by CCR5-tropic viruses-an analysis of a prospective country-wide cohort

Background

CCR5 coreceptor using HIV-1 subtype C (HIV-1C) has been reported to dominate the Ethiopian epidemic. However, almost all data have been obtained from two large cities in the central and north-west regions and recent data is lacking.

Methods

Plasma were obtained from 420 treatment-naïve patients recruited 2009–2011 to a large country-wide Ethiopian cohort. The V3 region was sequenced and the co-receptor tropism was predicted by the clinical and clonal models of the geno2pheno tool at different false positive rates (fpr) and for subtype. In an intention to treat analysis the impact of baseline tropism on outcome of antiretroviral therapy was evaluated.

Results

V3 loop sequencing was successful in 352 (84%) patients. HIV-1C was found in 350 (99.4%) and HIV-1A in two (0.6%) patients. When comparing the geno2pheno fpr10% clonal and clinical models, 24.4% predictions were discordant. X4-virus was predicted in 17.0 and 19.0%, respectively, but the predictions were concordant in only 6%. At fpr5%, concordant X4-virus predictions were obtained in 3.1%. The proportion of X4-tropic virus (clonal fpr10%) increased from 5.6 to 17.3% (p < 0.001) when 387 Ethiopian V3 loop sequences dated from 1984 to 2003 were compared with ours. In an intention to treat analysis, 67.9% reached treatment success at month 6 and only 50% at month 12. Only age and not tropism predicted therapy outcome and no difference was found in CD4+ cell gain between R5-tropic and X4-tropic infected patients. At viral failure, R5 to X4 switch was rare while X4 to R5 switch occurred more frequently (month 6: p = 0.006; month 12: p = 0.078).

Conclusion

The HIV-1C epidemic is monophylogenetic in all regions of Ethiopia and R5-tropic virus dominates, even in patients with advanced immunodeficiency, although the proportion of X4-tropic virus seems to have increased over the last two decades. Geno2pheno clinical and clonal prediction models show a large discrepancy at fpr10%, but not at fpr5%. Hence further studies are needed to assess the utility of genotypic tropism testing in HIV-1C. In ITT analysis only age and not tropism influenced the outcome.

Tackling virological failure in HIV-infected children living in Africa

Drug resistance in HIV-infected children is one of the main contributors to antiretroviral treatment (ART) failure, especially in developing countries. Sub-Saharan Africa has the largest burden of pediatric HIV infection in the world. Herein, we systematically review the current status of ART failure in HIV-infected African children. A literature search for publications within 10 years was performed through PubMed to identify relevant articles. Included studies examined the impact of timing of ART initiation, criteria for diagnosing therapeutic failure, predictors of therapeutic failure, management strategies and future directions to minimize failure rates in these pediatric populations. Although there is scale-up of ART programs in Africa, novel therapeutic and management strategies are needed to overcome current challenges.

HIV-1 co-receptor tropism and disease progression in children and young adults with perinatally acquired HIV-1 infection. The HICCUP Study

OBJECTIVES

Retrospective analysis of evolution of HIV tropism and association with disease progression in perinatal HIV-1 infection (PaHIV).

METHODOLOGY

Eligible patients with PaHIV were grouped as slow, rapid or long-term non-progressors (LTNP). The V3 region of gp120 was sequenced from stored plasma samples and tropism determined by geno2pheno algorithm (FPR 5.75%). Logistic regression with generalised estimating equations assessed factors associated with R5 virus. Time to tropism change was assessed using standard survival methods.

RESULTS

At baseline (n=48) median age was 12 years (IQR 9.3-14.8), 52% were female, 79% were Black African, 96% were non-B subtypes and 81% (39/48) had R5-using virus. Median follow-up was 7.7 years (308.6 person-years), with a median of five (range 1-14) samples per subject (total 252). Analysing all samples, R5 virus was associated with higher current CD4 cell count (median 520 cells/mm(3) R5 vs 202 for X4, P=0.0005), LTNP (35% vs 11%, P=0.05), non-Black ethnicity (74% vs 89%, P=0.05) and female gender (55% vs 28%, P=0.005). Twelve of 38 (31%) with R5 virus at baseline switched to X4/dual-using virus, with an estimated 5-year risk of switch of 24.4% (95% CI 9.7-39.2%) predicted by lower current CD4 cell count (unadjusted HR 0.62/50 cells higher, 95% CI 0.47-0.81, P=0.0006). Eleven of 19 (58%) with X4/dual-using virus subsequently had R5 virus at one or more time points.

CONCLUSION

Maraviroc was a treatment option for 81% at 12 years, falling to 56% at 18 years, with lower CD4 cell count predictive of co-receptor switching. Paediatric studies of CCR5 antagonists should be expedited to ensure they are an early treatment option before tropism switching occurs.

Sustained favourable HIV viral load response in South African patients during concomitant HAART and cancer therapy

HIV infection has led to an increase of both AIDS defining and non-AIDS defining cancers. Immunosuppressive cancer therapy had been noted for increased HIV viral load in cancer patients infected with HIV before the advent of highly active antiretroviral therapy (HAART). Assessing the outcome of concomitant HAART and cancer treatment in regions endemic for HIV is thus important. From a cohort of 34 cancer patients infected with HIV, 10 (six underwent radiotherapy and four chemotherapy) had at least three serial samples collected before, during and after treatment. From each sample, HIV viral load, CD4 +  and CD8 +  cell count was investigated. HIV genotypic drug resistance was assessed for six patients with a detectable HIV viral load at baseline. Of the 10 patients; one was HIV positive only, three were HIV and HBV co-infected and six were HIV, HBV and HCV triple infected. Four patients were HAART experienced at recruitment, while six were HAART naive with detectable HIV viral loads. A significant HIV viral load decrease (P = 0.0128) was observed in all six patients with detectable baseline HIV viral loads. The four patients on HAART at recruitment maintained lower than detectable HIV viral load status throughout cancer therapy. A positive correlation between the rise in CD4 +  cell count and attaining a lower than detectable HIV viral load was also observed (P = 0.0439). This pilot study supports concomitant treatment of HIV/AIDS and cancer in HIV endemic regions irrespective of the type of cancer diagnosed, prescribed cancer therapy or other viral (HBV, HCV or both) co-infections.

Increased CXCR4 use of HIV-1 subtype C identified by population sequencing in patients failing antiretroviral treatment compared with treatment-naive patients in Botswana

HIV-1 uses the coreceptors CCR5 and/or CXCR4 for cell entry. Monotropic CCR5-using variants are found early in the infection while CXCR4-using variants may appear after progression to AIDS. CXCR4 use may consist of both monotropic and dualtropic viruses. The viral phenotype is important in evaluating the response to CCR5 inhibitors, a new class of antiviral drugs. The coreceptor use of HIV-1 was investigated using population sequencing in 24 patients from Botswana, carrying HIV-1 subtype C and failing antiretroviral treatment, while 26 treatment-naive patients acted as controls. Single genome sequencing was used to discern minor HIV-1 populations in the treatment-experienced group. The Geno2Pheno method was employed to predict the coreceptor use phenotype from HIV-1 env gp120 V3 DNA sequences. The glycan-charge model adjusted for subtype C was also used for phenotype prediction. The viral phenotype of population sequences was predicted using Geno2Pheno in 24/24 treatment-experienced patients, of whom eight (33%) were predicted to harbor CXCR4-using strains as compared to 2/26 in the treatment-naive group (p=0.03). Single genome sequencing generated 4-23 clones/patient in the treatment-experienced group. Altogether, 90/295 (31%) putative CXCR4-using clones were identified. In 10/24 (42%) treated patients at least one clone was predicted to be CXCR4-using, further increasing the amount of identified treatment-experienced patients with CXCR4 use. Although subtype C is usually associated with comparatively little CXCR4 use, the frequency of CXCR4 use in treatment-experienced patients with subtype C can be higher, which may have implications for the administration of CCR5 inhibitors in this patient group.

Association of X4 tropism with disease progression in antiretroviral-treated children and adolescents living with HIV/AIDS in São Paulo, Brazil

Management of children with HIV/AIDS is specially challenging. Age-related issues do not allow for direct transposition of adult observations to this population. CXCR4 tropism has been associated with disease progression in adults. The geno2pheno web-base is a friendly tool to predict viral tropism on envelope V3 sequences, generating a false positive rate for a CXCR4 prediction. We evaluated the association of HIV-1 tropism prediction with clinical and laboratory outcome of 73 children with HIV/AIDS in São Paulo, Brazil. The CXCR4 tropism was strongly associated with a lower (nadir) CD4 documented during follow-up (p < 0.0001) and with disease severity (clinical event and/or CD4 below 200 cells/mm³) at the last observation, using commonly applied clinical cutoffs, such as ^10%FPR_clonal (p = 0.001). When variables obtained during follow-up are included, both treatment adherence and viral tropism show a significant association with disease severity. As for viremia suppression, 30% (22/73) were undetectable at the last observation, with only adherence strongly associated with suppression after adjustment. The study brings further support to the notion that antiretroviral treatment adherence is pivotal to management of HIV disease, but suggests that tropism prediction may provide an additional prognostic marker to monitor HIV disease in children.

Viral tropism and antiretroviral drug resistance in HIV-1 subtype C-infected patients failing highly active antiretroviral therapy in Johannesburg, South Africa

Reports show that up to 30% of antiretroviral drug-naive patients in Johannesburg have CXCR4-utilizing HIV-1 subtype C. We assessed whether HIV-1 subtype C-infected individuals failing highly active antiretroviral therapy (HAART) have a higher proportion of CXCR4-utilizing viruses compared to antiretroviral drug-naive patients. The V3 loop was sequenced from plasma from 100 randomly selected HAART-failing patients, and tropism was established using predictive algorithms. All patients harbored HIV-1 subtype C with at least one antiretroviral drug resistance mutation. Viral tropism prediction in individuals failing HAART revealed similar proportions (29%) of X4-utilizing viruses compared to antiretroviral drug-naive patients (30%). Findings are in contrast to reports from Durban in which 60% of HAART-failing subjects harbored X4/dual/mixed-tropic viruses. Despite differences in proportions of X4-tropism within South Africa, the high proportion of thymidine analogue mutations (TAMs) and CXCR4-utilizing HIV-1 highlights the need for intensified monitoring of HAART patients and the predicament of diminishing drug options, including CCR5 antagonists, for patients failing therapy.

Drug resistance in children at virological failure in a rural KwaZulu-Natal, South Africa, cohort

Background

Better understanding of drug resistance patterns in HIV-infected children on antiretroviral therapy (ART) is required to inform public health policies in high prevalence settings. The aim of this study was to characterise the acquired drug resistance in HIV-infected children failing first-line ART in a decentralised rural HIV programme.

Methods

Plasma samples were collected from 101 paediatric patients (≤15 yrs of age) identified as failing ART. RNA was extracted from the plasma, reverse transcribed and a 1.3 kb region of the pol gene was amplified and sequenced using Sanger sequencing protocols. Sequences were edited in Geneious and drug resistance mutations were identified using the RegaDB and the Stanford resistance algorithms. The prevalence and frequency of mutations were analysed together with selected clinical and demographic data in STATA v11.

Results

A total of 101 children were enrolled and 89 (88%) were successfully genotyped; 73 on a non-nucleoside reverse-transcriptase inhibitor (NNRTI)-based regimen and 16 on a protease inhibitor (PI)-based regimen at the time of genotyping. The majority of patients on an NNRTI regimen (80%) had both nucleoside reverse-transcriptase inhibitor (NRTI) and NNRTI resistance mutations. M184V and K103N were the most common mutations amongst children on NNRTI-based and M184V among children on PI-based regimens. 30.1% had one or more thymidine analogue mutation (TAM) and 6% had ≥3 TAMs. Only one child on a PI-based regimen harboured a major PI resistance mutation.

Conclusions

Whilst the patterns of resistance were largely predictable, the few complex resistance patterns seen with NNRTI-based regimens and the absence of major PI mutations in children failing PI-based regimens suggest the need for wider access to genotypic resistance testing in this setting.

CCR5 antagonists: a therapeutic option in HIV-1 perinatally infected children experiencing virologic failure?

OBJECTIVE

The risk of virologic failure and selection of resistant strains remains a challenge in HIV-1 perinatally infected children. HIV-1 coreceptor usage was determined in HAART-failing children followed in Necker Hospital (Paris, France) in order to estimate the proportion of these patients who may benefit from CCR5-antagonists therapy.

METHODS

HIV-1 coreceptor usage was determined with the SVM(Geno2pheno10%) algorithm in 51 children with virologic failure after a median treatment exposure of 7.8 years.

RESULTS

CXCR4-tropic strains were found in 31.4% of the patients. CXCR4 usage was associated with high HIV-1 DNA (P=0.01), old age (P=0.02), long ART cumulative exposure (P=0.006), and previous exposure to high number of different drugs (P=0.03) and ART combinations (P=0.03) in univariate analysis. Selection of resistant viruses and current exposure to a darunavir-based HAART tended to be more frequent in the CXCR4 group compared with the children infected with CCR5-tropic strains (P=0.06). In multivariate analysis, CXCR4 usage was exclusively correlated with HIV-1 DNA (P=0.03), which accurately reflects the cumulative exposure to viral replication over the whole duration of HIV infection.

CONCLUSION

Two-thirds of HAART-failing children could benefit from CCR5 antagonists-based strategies, even in case of triple-class virologic failure. Such therapy should be discussed more appropriately at early stages of infection, when CCR5-tropic strains are most frequently isolated. However, before considering such strategies, further studies are needed to evaluate the efficacy and the tolerability of CCR5 antagonists in this pediatric population.

Copy Number Variation within Human β-Defensin Gene Cluster Influences Progression to AIDS in the Multicenter AIDS Cohort Study

STUDY BACKGROUND

DEFB4/103A encoding β-defensin 2 and 3, respectively, inhibit CXCR4-tropic (X4) viruses in vitro. We determined whether DEFB4/103A Copy Number Variation (CNV) influences time-to-X4 and time-to-AIDS outcomes.

METHODS

We utilized samples from a previously published Multicenter AIDS Cohort Study (MACS), which provides longitudinal account of viral tropism in relation to the full spectrum of rates of disease progression. Using traditional models for time-to-event analysis, we investigated association between DEFB4/103A CNV and the two outcomes, and interaction between DEFB4/103A CNV and disease progression groups, Fast and Slow.

RESULTS

Time-to-X4 and time-to-AIDS were weakly correlated. There was a stronger relationship between these two outcomes for the fast progressors. DEFB4/103A CNV was associated with time-to-AIDS, but not time-to-X4. The association between higher DEFB4/103A CNV and time-to-AIDS was more pronounced for the slow progressors.

CONCLUSION

DEFB4/103A CNV was associated with time-to-AIDS in a disease progression group-specific manner in the MACS cohort. Our findings may contribute to enhancing current understanding of how genetic predisposition influences AIDS progression.