In utero HIV infection is associated with an increased risk of nevirapine resistance in ugandan infants who were exposed to perinatal single dose nevirapine

Trends in Drug Resistance Prevalence, HIV-1 Variants and Clinical Status in HIV-1-infected Pediatric Population in Madrid: 1993 to 2015 Analysis

BACKGROUND

The expanded use of long-term antiretroviral treatments in infected children may exacerbate the problem of drug resistance mutations selection, which can compromise treatment efficiency.

OBJECTIVE

We describe the temporal trends of HIV drug resistance mutations and the HIV-1 variants during 23 years (1993 to March 2016) in the Madrid cohort of HIV-infected children and adolescents.

METHODS

We selected patients with at least one available HIV-1 pol sequence/genotypic resistance profile, establishing different groups according to the sampling year of first resistance data. We determined the prevalence of transmitted drug resistance mutations or acquired drug resistance mutations (DRM), the drug susceptibility among resistant viruses and HIV-1 variants characterized by phylogeny across time.

RESULTS

A total of 245 pediatric patients were selected, being mainly female, Spanish native, perinatally infected and carrying HIV-1 subtype B. At first sampling, most pediatric patients were on antiretroviral therapy and heavily pretreated. During 1993 to 2016, transmitted drug resistance mutations was found in 13 (26%) of 50 naive children [non-nucleoside reverse transcriptase inhibitors (NNRTI), 14.6%; nucleoside reverse transcriptase inhibitors (NRTI), 10.4%; protease inhibitors, 8.7%]. DRM appeared in 139 (73.2%) of 190 pretreated patients (NRTI, 64.5%; NNRTI, 36%; protease inhibitors, 35.1%). DRM to NNRTI was higher in last 5 years. Non-B variants infected 14.5% of children and adolescents of the Madrid Cohort, being mainly intersubtype recombinants (76.5%), including complex unique recombinant strains. They caused 3.4% infections before 2000, rising to 85.7% during 2011 to 2016.

CONCLUSIONS

Periodic surveillance resistance and molecular epidemiology studies in long-term pretreated HIV-infected pediatric populations are required to optimize treatment regimens. Results will permit a better understanding of long-time dynamics of viral resistance and HIV-1 variants in Spain.

Long-Range HIV Genotyping Using Viral RNA and Proviral DNA for Analysis of HIV Drug Resistance and HIV Clustering

The goal of the study was to improve the methodology of HIV genotyping for analysis of HIV drug resistance and HIV clustering. Using the protocol of Gall et al. (A. Gall, B. Ferns, C. Morris, S. Watson, M. Cotten, M. Robinson, N. Berry, D. Pillay, and P. Kellam, J Clin Microbiol 50:3838-3844, 2012, doi:10.1128/JCM.01516-12), we developed a robust methodology for amplification of two large fragments of viral genome covering about 80% of the unique HIV-1 genome sequence. Importantly, this method can be applied to both viral RNA and proviral DNA amplification templates, allowing genotyping in HIV-infected subjects with suppressed viral loads (e.g., subjects on antiretroviral therapy [ART]). The two amplicons cover critical regions across the HIV-1 genome (including pol and env), allowing analysis of mutations associated with resistance to protease inhibitors, reverse transcriptase inhibitors (nucleoside reverse transcriptase inhibitors [NRTIs] and nonnucleoside reverse transcriptase inhibitors [NNRTIs]), integrase strand transfer inhibitors, and virus entry inhibitors. The two amplicons generated span 7,124 bp, providing substantial sequence length and numbers of informative sites for comprehensive phylogenic analysis and greater refinement of viral linkage analyses in HIV prevention studies. The long-range HIV genotyping from proviral DNA was successful in about 90% of 212 targeted blood specimens collected in a cohort where the majority of patients had suppressed viral loads, including 65% of patients with undetectable levels of HIV-1 RNA loads. The generated amplicons could be sequenced by different methods, such as population Sanger sequencing, single-genome sequencing, or next-generation ultradeep sequencing. The developed method is cost-effective-the cost of the long-range HIV genotyping is under $140 per subject (by Sanger sequencing)-and has the potential to enable the scale up of public health HIV prevention interventions.

Optimisation of antiretroviral therapy in HIV-infected children under 3 years of age

BACKGROUND

In the absence of antiretroviral therapy (ART), over 50% of HIV-infected infants progress to AIDS and death by 2 years of age. However, there are challenges to initiation of ART in early life, including the possibility of drug resistance in the context of prevention of mother-to-child transmission (PMTCT) programs, a paucity of drug choices , uncertain dosing for some medications and long-term toxicities. Key management decisions include when to start ART, what regimen to start, and whether and when to substitute drugs or interrupt therapy. This review, an update of a previous review, aims to summarize the currently available evidence on this topic and inform the ART management in HIV-infected children less than 3 years of age.

OBJECTIVES

To evaluate 1) when to start ART in young children (less than 3 years); 2) what ART to start with, comparing first-line non-nucleoside reverse transcriptase inhibitor (NNRTI) and protease inhibitor (PI)-based regimens; and 3) whether alternative strategies should be used to optimize antiretroviral treatment in this population: induction (initiation with 4 drugs rather than 3 drugs) followed by maintenance ART, interruption of ART and substitution of PI with NNRTI drugs once virological suppression is achieved on a PI-based regimen.

SEARCH METHODS

Search methodsWe searched for published studies in the Cochrane HIV/AIDS Review Group Trials Register, The Cochrane Library, Pubmed, EMBASE and CENTRAL. We screened abstracts from relevant conference proceedings and searched for unpublished and ongoing trials in clinical trial registries (ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform).

SELECTION CRITERIA

We identified RCTs that recruited perinatally HIV-infected children under 3 years of age without restriction of setting. We rejected trials that did not include children less than 3 years of age, did not provide stratified outcomes for those less than 3 years or did not evaluate either timing of ART initiation, choice of drug regimen or treatment switch/interruption strategy.

DATA COLLECTION AND ANALYSIS

Two reviewers independently applied study selection criteria, assessed study quality and extracted data. Effects were assessed using the hazard ratio (HR) for time-to-event outcomes, relative risk for dichotomous outcomes and weighted mean difference for continuous outcomes.

MAIN RESULTS

A search of the databases identified a total of 735 unique, previously unreviewed studies, of which 731 were excluded to leave 4 new studies to incorporate into the review. Four additional studies were identified in conference proceedings, for a total of 8 studies addressing when to start treatment (n=2), what to start (n=3), whether to substitute lopinavir/ritonavir (LPV/r) with nevirapine (NVP) (n=1), whether to use an induction-maintenance ART strategy (n=1) and whether to interrupt treatment (n=1).Treatment initiation in asymptomatic infants with good immunological status was associated with a 75% reduction (HR=0.25; 95%CI 0.12-0.51; p=0.0002) in mortality or disease progression in the one trial with sufficient power to address this question. In a smaller pilot trial, median CD4 cell count was not significantly different between early and deferred treatment groups 12 months after ART.Regardless of previous exposure to nevirapine for PMTCT, the hazard for treatment failure at 24 weeks was 1.79 (95%CI 1.33, 2.41) times higher in children starting ART with a NVP-based regimen compared to those starting with a LPV/r-based regimen (p=0.0001) with no clear difference in the effect observed for children younger or older than 1 year. The hazard for virological failure at 24 weeks was overall 1.84 (95%CI 1.29, 2.63) times higher for children starting ART with a NVP-based regimen compared to those starting with a LPV/r-based regimen (p=0.0008) with a larger difference in time to virological failure (or death) between the NVP and LPV/r-based regimens when ART was initiated in the first year of life.Infants starting a LPV/r regimen and achieving sustained virological suppression who then substituted LPV/r with NVP after median 9 months on LPV/r were less likely to develop virological failure (defined as at least one VL greater than 50 copies/mL) compared with infants who started and stayed on LPV/r (HR=0.62, 95%CI 0.41, 0.92, p=0.02). However the hazard for confirmed failure at a higher viral load (>1000 copies/mL) was greater among children who switched to NVP compared to those who remained on LPV/r (HR=10.19, 95% CI 2.36, 43.94, p=0.002).Children undergoing an induction-maintenance ART approach with a 4-drug NNRTI-based regimen for 36 weeks, followed by 3-drug ART, had significantly greater CD4 rise than children receiving a standard 3-drug NNRTI-based ART at 36 weeks (mean difference 1.70 [95%CI 0.61, 2.79] p=0.002) and significantly better viral load response at 24 weeks (OR 1.99 [95%CI 1.09, 3.62] p=0.02). However, the immunological and virological benefits were short-term.The one trial of treatment interruption that compared children initiating continuous ART from infancy with children interrupting ART was terminated early because the duration of treatment interruption was less than 3 months in most infants. Children interrupting treatment had similar growth and occurrence of serious adverse events as those in the continuous arm.

AUTHORS' CONCLUSIONS

ART initiation in asymptomatic children under 1 year of age reduces morbidity and mortality, but it remains unclear whether there are clinical benefits to starting ART in asymptomatic children diagnosed with HIV infection between 1-3 years.The available evidence shows that a LPV/r-based first-line regimen is more efficacious than a NVP-based regimen, regardless of PMTCT exposure status. New formulations of LPV/r are urgently required to enable new WHO recommendations to be implemented. An alternative approach to long-term LPV/r is substituting LPV/r with NVP once virological suppression is achieved. This strategy looked promising in the one trial undertaken, but may be difficult to implement in the absence of routine viral load testing.A 4-drug induction-maintenance approach showed short-term virological and immunological benefits during the induction phase but, in the absence of sustained benefits, is not recommended as a routine treatment strategy. Treatment interruption following early ART initiation in infancy was challenging for children who were severely immunocompromised in the context of poor clinical immunological condition at ART initiation due to the short duration of interruption, and is therefore not practical in ART treatment programmes where close monitoring is not feasible.

Drug resistance in the HIV-1-infected paediatric population worldwide: a systematic review

BACKGROUND

Drug resistance monitoring of the paediatric HIV-1-infected population is required to optimize treatment success and preserve future treatment options.

OBJECTIVES

To explore the current knowledge of HIV drug resistance (HIVDR) in naive and pretreated HIV-1-infected paediatric populations across diverse settings and sampling time periods.

METHODS

PubMed database screened until May 2013. We selected publications including data on transmitted (TDR) and acquired drug resistance mutation (DRM) rates and/or pol sequences for HIVDR testing in paediatric patients. We recorded the children's country, age, study period, number of children with pol sequences, presence or absence of antiretroviral treatment (ART) at sampling time, viral region sequenced, HIVDR rate to the three main drug classes (single, double or triple), the considered resistance mutation list and performed assay, specimen type, HIV-1 variants and subtyping methodology when available.

RESULTS

Forty-one selected studies showed HIVDR data from 2538 paediatric HIV-1-infected patients (558 naive and 1980 pretreated) from 30 countries in Africa (11), Asia (6), America (10) and Europe (3). Both TDR and DRM prevalence were reported in 9 studies, only TDR in 6 and only DRM in 26. HIVDR prevalence varied across countries and periods. Most studies used in-house resistance assays using plasma or infected cells. HIV-1 non-B variants were prevalent in 18 paediatric cohorts of the 24 countries with reported subtypes. Only five countries (Uganda, Spain, the UK, Brazil and Thailand) presented resistance data in ≥200 patients.

CONCLUSIONS

Systematic and periodic studies among infected children are crucial to design a more suitable first- or second-line therapy.

Optimization of antiretroviral therapy in HIV-infected children under 3 years of age: a systematic review

BACKGROUND

Treatment of young HIV-infected children is challenging because of rapid disease progression, high viral loads and few drug options. This review was undertaken to update evidence on the management of young HIV-infected children and to inform the development of the 2013 WHO guidelines for antiretroviral therapy (ART) in low and middle-income countries.

DESIGN

A systematic review and meta-analysis.

METHODS

We identified and critically assessed randomized controlled trials that evaluated treatment strategies in perinatally HIV-infected infants and young children (aged <3 years).

RESULTS

Eight studies were included. Antiretroviral therapy (ART) initiation in asymptomatic infants led to 74% reduction in mortality or disease progression [hazard ratio 0.36, 95% confidence interval (CI) 0.18-0.74, P = 0.0002]. Regardless of previous exposure to prevention of mother to child transmission (PMTCT), treatment failure at 24 weeks was more likely in children starting nevirapine-based than in those starting lopinavir/ritonavir (lopinavir/r)-based ART (hazard ratio 1.79, 95% CI 1.33-2.41, P = 0.0001). Infants starting lopinavir/r-based ART and substituting lopinavir/r with nevirapine once virologic suppression was achieved were less likely to experience viral load more than 50 copies/ml (hazard ratio 0.62, 95% CI 0.41-0.92, P = 0.02) but more likely to have confirmed virologic failure (>1000 copies/ml) than those remaining on lopinavir/r (hazard ratio 10.19, 95% CI 2.36-43.94, P = 0.002). Children receiving induction-maintenance ART (four-drug NNRTI-based regimen for 36 weeks followed by three-drug ART) showed better short-term immunologic and virologic responses, but no long-term benefits. The only trial comparing continuous ART from infancy with interrupted ART beyond infancy was terminated early because the duration of treatment interruption was less than 3 months in most infants.

CONCLUSION

ART initiation in asymptomatic infants reduces morbidity and mortality. Lopinavir/r-based first-line ART is superior to nevirapine-based regimens in young children, regardless of PMTCT exposure, but lopinavir/r use is challenging. Substituting lopinavir/r with nevirapine following virologic suppression may be feasible where viral load testing is available. Considering current evidence, induction-maintenance and treatment interruption strategies are not recommended. This review contributed to the evidence base for the 2013 WHO guidelines on antiretroviral therapy, which recommend that all children below 3 years start lopinavir/r-based ART and that lopinavir/r can be substituted with nevirapine once sustained virologic suppression is achieved.

Effectiveness of antiretroviral therapy in HIV-infected children under 2 years of age

BACKGROUND

In the absence of antiretroviral therapy (ART), over 50% of HIV-infected infants progress to AIDS and death by 2 years of age. However, there are challenges to initiate ART in early life, including the possibility of drug resistance in the context of prevention of mother-to-child transmission (PMTCT) programs, a paucity of drug choices , uncertain dosing for some medications and long-term toxicities. Key management decisions include when to start ART, what regimen to start, and whether and when to switch or interrupt therapy. This review aims to summarize the currently available evidence on this topic and inform the ART management in HIV-infected children less than 2 years of age.

OBJECTIVES

To evaluate 1) when to start ART in young children; 2) what ART to start with, comparing first-line non-nucleoside reverse transcriptase inhibitor (NNRTI) and PI-based regimens; and 3) whether and when ART should be stopped or switched from a PI-based regimen to an NNRTI-based regimen.

SEARCH METHODS

We searched for published studies in the Cochrane HIV/AIDS Review Group Trials Register, The Cochrane Library, Pubmed, EMBASE and CENTRAL. We screened abstracts from relevant conference proceedings and searched for unpublished and ongoing trials in clinical trial registries (ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform).

SELECTION CRITERIA

We identified RCTs that recruited perinatally HIV-infected children under 2 years of age without restriction of setting. We rejected trials that did not include children less than 2 years of age, or did not evaluate either timing of ART initiation, choice of drug regimen or treatment switch/interruption strategy.

DATA COLLECTION AND ANALYSIS

Two reviewers independently applied study selection criteria, assessed study quality and extracted data. Effects were assessed using the hazard ratio (HR) for time-to-event outcomes, relative risk for dichotomous outcomes and weighted mean difference for continuous outcomes.

MAIN RESULTS

Of 1921 records retrieved, 5 studies were eligible for inclusion in the review, addressing when to start treatment (n=2), what to start (n=2) and whether to switch regimen (n=1). Three ongoing studies that address the question of treatment interruption were also identified.Early infant treatment was associated with a 75% reduction (HR=0.25; 95%CI 0.12-0.51; p=0.0002) in mortality or disease progression in the one trial with sufficient power to address this question. In a smaller trial,median CD4 cell count was not significantly different between early and deferred treatment groups 12 months after ART.Regardless of previous exposure to nevirapine for PMTCT, the hazard for treatment failure was 2.01 (95%CI 1.47, 2.77) times higher in children starting ART with a NVP-based regimen compared to those starting with a LPV/r-based regimen (p<0.0001) with no clear difference in effect by age group. The hazard for virological failure was overall 2.28 (95%CI 1.55, 3.34) times higher for children starting ART with a NVP-based regimen compared to those starting with a LPV/r-based regimen (p=0.0005) with a larger difference in time to virological failure (or death) between the NVP and LPV/r-based regimens when ART was initiated in the first year of life. By contrast, increases in weight z-score (MD=0.37, 95%CI 0.08, 0.65, p=0.01) and height z-score (MD=0.23, 95%CI 0.04, 0.42, p=0.02) were larger in the NVP arm compared to the LPV/r arm .Infants starting on a LPV/r regimen but who then switched to a NVP-based regimen after a median time of 9 months on LPV/r were less likely to develop virological failure (defined as at least one VL greater than 50 copies/mL) compared with infants who started and stayed on LPV/r (HR=0.62, 95%CI 0.41, 0.92, p=0.02). However the hazard for confirmed failure at a higher viral load (>1000 copies/mL) was higher among children who switched to NVP compared to those who remained on LPV/r (HR=10.19, 95% CI 2.36, 43.94, p=0.002).

AUTHORS' CONCLUSIONS

Immediate ART reduces morbidity and mortality among infants and may improve neurodevelopmental outcome. However It remains unclear whether all children diagnosed with HIV infection between 1-2 years of age should start ART, as has been recommended by the World Health Organization on practical grounds.The available evidence suggests that a LPV/r-based first-line regimen is more potent than NVP, regardless of PMTCT exposure status. However, this finding provides a dilemma to policy-makers because higher cost, poor palatability, inconvenient formulation and cold chain requirements make LPV/r a more costly and challenging first-line regimen. An alternative approach to long-term LPV/r is switching to NVP (maintaining the NRTI backbone) once virological suppression is achieved. This strategy looked promising in the one trial undertaken, but may be difficult to implement in the absence of VL testing. Ongoing trials are exploring the possibility of starting early ART and interrupting treatment beyond the critical period of rapid disease progression and neurological development. Further evidence is urgently required to better inform policy on first-line treatment recommendations in young children and more robust data addressing non-virological outcomes are also needed.

Slower clearance of nevirapine resistant virus in infants failing extended nevirapine prophylaxis for prevention of mother-to-child HIV transmission

Nevirapine resistance mutations arise commonly following single or extended-dose nevirapine (ED-NVP) prophylaxis to prevent mother-to-child transmission (PMTCT) of human immunodeficiency virus (HIV), but decay within 6-12 months of single-dose exposure. Use of ED-NVP prophylaxis in infants is expected to rise, but data on decay of nevirapine resistance mutations in infants in whom ED-NVP failed remain limited. We assessed, in Ethiopian infants participating in the Six-Week Extended Nevirapine (SWEN) Trial, the prevalence and persistence of nevirapine resistance mutations at 6 and 12 months following single-dose or up to 6 weeks of ED-NVP, and correlated their presence with the timing of infection and the type of resistance mutations. Standard population genotyping followed by high-throughput cloning were done on dried blood spot samples collected during the trial. More infants who received ED-NVP had nevirapine resistance detected by standard population genotyping (high frequencies) at age 6 months compared with those who received single-dose nevirapine (SD-NVP) (58% of 24 vs. 26% of 19, respectively; p = 0.06). Moreover, 56% of ED-NVP-exposed infants with nevirapine resistance at age 6 months still had nevirapine resistance mutations present at high frequencies at age 1 year. Infants infected before 6 weeks of age who received either SD- or ED-NVP were more likely to have Y181C or K103N; these mutations were also more likely to persist at high frequencies through 1 year of age. HIV-infected infants in whom ED-NVP prophylaxis fails are likely to experience delayed clearance of nevirapine-resistant virus in the first year of life, which in turn places them at risk for early selection of multidrug-resistant HIV after initial therapy with nonnucleoside reverse transcriptase inhibitor-based regimens.

Analysis of nevirapine resistance in HIV-infected infants who received extended nevirapine or nevirapine/zidovudine prophylaxis

BACKGROUND

In the Post Exposure Prophylaxis of Infants (PEPI)-Malawi trial, infants received up to 14 weeks of extended nevirapine (NVP) or extended NVP with zidovudine (NVP + ZDV) to prevent postnatal HIV transmission. We examined emergence and persistence of NVP resistance in HIV-infected infants who received these regimens prior to HIV diagnosis.

METHODS

Infant plasma samples collected at 14 weeks of age were tested using the ViroSeq HIV Genotyping System and a sensitive point mutation assay, LigAmp (for K103N and Y181C). Samples collected at 6 and 12 months of age were analyzed using LigAmp.

RESULTS

At 14 weeks of age, NVP resistance was detected in samples from 82 (75.9%) of 108 HIV-infected infants. Although the frequency of NVP resistance detected by ViroSeq was lower in the extended NVP + ZDV arm than in the extended NVP arm, the difference was not statistically significant (38/55 = 69.1% vs. 44/53 = 83.0%, P = 0.12). Similar results were obtained using LigAmp. Using LigAmp, the proportion of infants who still had detectable NVP resistance at 6 and 12 months was similar among infants in the two study arms (at 6 months: 17/20 = 85.0% for extended NVP vs. 21/26 = 80.8% for extended NVP + ZDV, P = 1.00; at 12 months: 9/16 = 56.3% for extended NVP vs.10/13 = 76.9% for extended NVP + ZDV, P = 0.43).

CONCLUSION

Infants exposed to extended NVP or extended NVP + ZDV had high rates of NVP resistance at 14 weeks of age, and resistant variants frequently persisted for 6-12 months. Frequency and persistence of NVP resistance did not differ significantly among infants who received extended NVP only vs. extended NVP + ZDV prophylaxis.

Maternal and nenonatal tenofovir and emtricitabine to prevent vertical transmission of HIV-1: tolerance and resistance

OBJECTIVE

Viral resistance occurs with a high frequency after single-dose nevirapine. We aimed to evaluate the tolerance and resistance profiles of a combination of tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC) given to HIV-1-infected delivering women and their newborns.

DESIGN

An open-label phase I/II trial in Cambodia, Côte d'Ivoire and South Africa.

METHODS

HIV-1-infected pregnant women received zidovudine from the enrollment until the beginning of labor, when single-dose nevirapine and two tablets of TDF/FTC were given. One daily tablet of TDF/FTC was then administered for 7 days postpartum. All infants received single-dose nevirapine with single-dose TDF (13 mg/kg) and single-dose FTC (2 mg/kg) and 1 week of zidovudine. Mothers and infants were followed for 2 months. Serious adverse events, kinetic of maternal plasma HIV-1 RNA, pediatric HIV infection and genotypic resistance and viral subtype were assessed.

RESULTS

Thirty-six HIV-1-infected pregnant women were enrolled: median age 28 years (interquartile range: 26-31 years), median CD4 cell count 462 cells/μl (interquartile range: 376-632) and median HIV-1 RNA 3.7 log10 copies/ml (interquartile range: 2.95-4.11). Two infants had clinical serious adverse events, including one who died (neonatal sepsis). One transient grade 3 neutropenia and two grade 3/4 hyperbilirubinemia were also reported in neonates. One HIV pediatric in-utero infection was diagnosed (2.8%; 95% confidence interval 0-15.4%). Genotypic viral resistance to nevirapine was detected in one mother out of 34 (2.9%) at one month postpartum, but was also detectable at enrollment.

CONCLUSION

The combination of TDF/FTC to delivering women and their neonates appears well tolerated and to minimize the occurrence of nevirapine viral resistance.

Analysis of drug resistance in children receiving antiretroviral therapy for treatment of HIV-1 infection in Uganda

We analyzed drug resistance in HIV-infected Ugandan children who received antiretroviral therapy in a prospective, observational study (2004-2006); some children had prior single-dose nevirapine (sdNVP) exposure. Children received stavudine (d4T), lamivudine (3TC), and nevirapine (NVP); treatment was continued if they were clinically and immunologically stable. Samples with >1,000 copies/ml HIV RNA were analyzed by using the ViroSeq HIV Genotyping System (ViroSeq). Subtype A and D pretreatment samples also were analyzed with the LigAmp assay (for K103N, Y181C, and G190A). ViroSeq results were obtained for 74 pretreatment samples (35 from sdNVP-exposed children (median age, 19 months) and 39 from sdNVP-unexposed children (median age, 84 months). This included 39 subtype A, 22 subtype D, 1 subtype C, and 12 inter-subtype recombinant samples. One sample had nonnucleoside reverse transcriptase inhibitor (NNRTI) resistance, one had nucleoside reverse transcriptase inhibitor (NRTI) resistance, and three had protease inhibitor (PI) resistance. Y181C was detected by using LigAmp in five pretreatment samples [four (14.8%) of 37 samples from sdNVP-exposed children, one (4.2%) of 24 samples from children without prior sdNVP exposure; p = 0.35]. Among children who were not virally suppressed at 48 weeks of treatment, all 12 tested had NNRTI resistance, as well as resistance to 3TC and emtricitibine (FTC); three had resistance to other NRTIs. Seven of those children had a ViroSeq result at 96 weeks of treatment; four of the seven acquired resistance to additional NRTIs by 96 weeks. In Uganda, clinically and immunologically stable children receiving nonsuppressive antiretroviral treatment regimens are at risk for development of drug resistance.

Surveillance of transmitted resistance to antiretroviral drug classes among young children in the Western Cape Province of South Africa

There are limited data on transmitted antiretroviral resistance in young children who require antiretroviral therapy. We adapted the World Health Organization surveillance strategy, testing antiretroviral naive infants (<18 months) in the Western Cape Province of South Africa, and detecting only 3 non-nucleoside reverse transcriptase inhibitors (NNRTI) and no NRTI or protease inhibitor surveillance mutations in 49 patients. The estimated NRTI and protease inhibitor transmitted antiretroviral resistance prevalence is low (<5%), predicting good therapeutic response in Western Cape infants.

Resistance considerations in sequencing of antiretroviral therapy in low-middle income countries with currently available options

PURPOSE OF REVIEW

Access to antiretroviral therapy (ART) has been scaled-up in low-middle income countries (LMICs), where the majority of the world's HIV-1-infected population is living. Concerns towards the emergence and spread of HIV-1 drug resistance exist, given the lack of virological monitoring which may give rise to accumulation of resistance as well as the use of suboptimal ART in pregnant women with the aim to reduce perinatal transmission. Knowledge of the prevalence of transmitted and emerging drug resistance as well as its specific patterns is of help in guiding the selection of appropriate ART types and sequencing strategies.

RECENT FINDINGS

Whereas transmitted drug resistance in LMIC is still limited, resistance in pregnant women as a consequence of suboptimal ART for the prevention of vertical transmission is frequent and dependent on viral subtype and load. Accumulation of drug resistance during first-line ART depends on the frequency of monitoring, whereas mutational patterns are influenced by type of ART and, partly, viral subtype.

SUMMARY

Optimized ART for prevention of mother-to-child transmission and closer monitoring of ART programs with the inclusion of viral load may help reducing unnecessary development of HIV drug resistance in LMIC and preserve the limited available treatment options.

Addition of extended zidovudine to extended nevirapine prophylaxis reduces nevirapine resistance in infants who were HIV-infected in utero

BACKGROUND

In the Post-Exposure Prophylaxis of Infants (PEPI)-Malawi trial, most women received single-dose nevirapine (NVP) at delivery, and infants in the extended study arms received single-dose NVP along with 1 week of daily zidovudine (ZDV), followed by either extended daily NVP or extended daily NVP and ZDV up to 14 weeks of age. Although extended NVP prophylaxis reduces the risk of postnatal HIV transmission, it may increase the risk of NVP resistance among infants who are HIV-infected despite prophylaxis.

METHODS

We analyzed 88 infants in the PEPI-Malawi trial who were HIV-infected in utero and who received prophylaxis for a median of 6 weeks prior to HIV diagnosis. HIV genotyping was performed using the ViroSeq HIV Genotyping System.

RESULTS

At 14 weeks of age, the proportion of infants with NVP resistance was lower in the extended NVP and ZDV arm than in the extended NVP arm (28/45, 62.2% vs. 37/43, 86.0%; P = 0.015). None of the infants had ZDV resistance. Addition of extended ZDV to extended NVP was associated with reduced risk of NVP resistance at 14 weeks if prophylaxis was stopped by 6 weeks (54.5 vs. 85.7%, P = 0.007) but not if prophylaxis was continued beyond 6 weeks (83.3 vs. 87.5%, P = 1.00).

CONCLUSION

Addition of extended ZDV to extended NVP prophylaxis significantly reduced the risk of NVP resistance at 14 weeks in infants who were HIV-infected in utero, provided that HIV infection was diagnosed and the prophylaxis was stopped by 6 weeks of age.