Combination treatment with zidovudine, didanosine, and nevirapine in infants with human immunodeficiency virus type 1 infection

Influence of Combination Antiretroviral Therapy on HIV-1 Serological Responses and Their Implications: A Systematic Review and Meta-Analysis

We aimed to analyze HIV-1 seroreversion caused by combination antiretroviral therapy (cART) and to explore antibody levels of anti-HIV-1 as an alternative biomarker of HIV-1 reservoir. We searched PubMed, Embase, the Cochrane Library, and Web of Science up to August 2021 for publications about the performance of HIV-1 serological assays or the association between antibody responses against HIV-1 and HIV-1 reservoirs. Potential sources of heterogeneity were explored by meta-regression analysis, including the year of publication, country, pretreatment viral load, sample size, the timing of treatment, time on cART, and principle or type of serological assay. Twenty-eight eligible studies with a total population of 1,883 were included in the meta-analysis. The pooled frequency of HIV-1 seronegativity is 38.0% (95% CI: 28.0%–49.0%) among children with vertical HIV-1 infection and cART initiation at the age of less than 6 months, while the percentage of HIV-1 seronegativity declined to 1.0% (95% CI: 0%–3.0%) when cART was initiated at the age of >6 months. For adult patients, 16.0% (95% CI: 9.0%–24.0%) of them were serologically negative when cART was initiated at acute/early infection of HIV-1, but the seronegative reaction was rarely detected when cART was started at chronic HIV-1 infection. Substantial heterogeneity was observed among the studies to estimate the frequency of HIV-1 seronegativity in the early-cART population (I² ≥ 70%, p < 0.05 and all), while mild heterogeneity existed for the deferred-cART subjects. Moreover, anti-HIV-1 antibody response positively correlates with HIV-1 reservoir size with a pooled rho of 0.43 (95% CI: 0.28–0.55), suggesting that anti-HIV antibody level may be a feasible biomarker of HIV-1 reservoir size.

Pharmacokinetics and safety of early nevirapine-based antiretroviral therapy for neonates at high risk for perinatal HIV infection: a phase 1/2 proof of concept study

BACKGROUND

With increasing intention to treat HIV as early as possible, evidence to confirm the safety and therapeutic drug concentrations of a nevirapine-based antiretroviral regimen in the early neonatal period is needed. This study aims to establish dosing of nevirapine for very early treatment of HIV-exposed neonates at high risk of HIV acquisition.

METHODS

IMPAACT P1115 is a multinational phase 1/2 proof-of-concept study in which presumptive treatment for in-utero HIV infection is initiated within 48 h of birth in HIV-exposed neonates at high risk of HIV acquisition. Participants were neonates who were at least 34 weeks gestational age at birth and enrolled within 48 h of birth, born to women with presumed or confirmed HIV infection who had not received antiretrovirals during this pregnancy. The regimen consisted of two nucleoside reverse transcriptase inhibitors plus nevirapine dosed at 6 mg/kg twice daily for term neonates (≥37 weeks gestational age) or 4 mg/kg twice daily for 1 week and 6 mg/kg twice daily thereafter for preterm neonates (34 to <37 weeks gestational age). Here, we report the secondary outcomes of the study: nevirapine exposures in study weeks 1 and 2 and treatment-associated grade 3 or 4 adverse events at least possibly related to study treatment up to study week 4. A population pharmacokinetic model to assess nevirapine exposure was developed from dried blood spot and plasma nevirapine concentrations at study weeks 1 and 2. Nevirapine exposure was assessed in all patients with available blood samples and safety was assessed in all participants. This trial is registered at ClinicalTrials.gov (NCT02140255).

FINDINGS

Between Jan 23, 2015, and Sept 4, 2017, 438 neonates were enrolled and included in analyses; 36 had in-utero HIV infection and 389 (89%) were born at term. Neonates without confirmed in-utero HIV infection received nevirapine for a median of 13 days (IQR 7-14). Measured dried blood spot nevirapine concentrations were higher than the minimum HIV treatment target (3 μg/mL) in 314 (90%, 95% CI 86-93) of 349 neonates at week 1 and 174 (87%, 81-91) of 201 at week 2. In Monte-Carlo simulations, week 1 nevirapine concentrations exceeded 3 μg/mL in 80% of term neonates and 82% of preterm neonates. DAIDS grade 3 or 4 adverse events at least possibly related to antiretrovirals occurred in 30 (7%, 95% CI 5-10) of 438 infants but did not lead to nevirapine cessation in any neonates; neutropenia (25 [6%] neonates) and anaemia (six [1%]) were most common.

INTERPRETATION

Nevirapine at the dose studied was confirmed to be safe and provides therapeutic exposure concentrations. These data support nevirapine as a component of presumptive HIV treatment in high-risk neonates.

FUNDING

National Institute of Allergy and Infectious Diseases, Eunice Kennedy Shriver National Institute of Child Health and Human Development, and the National Institute of Mental Health.

Network Patterns of Herbal Combinations in Traditional Chinese Clinical Prescriptions

As a well-established multidrug combinations schema, traditional Chinese medicine (herbal prescription) has been used for thousands of years in real-world clinical settings. This paper uses a complex network approach to investigate the regularities underlying multidrug combinations in herbal prescriptions. Using five collected large-scale real-world clinical herbal prescription datasets, we construct five weighted herbal combination networks with herb as nodes and herbal combinational use in herbal prescription as links. We found that the weight distribution of herbal combinations displays a clear power law, which means that most herb pairs were used in low frequency and some herb pairs were used in very high frequency. Furthermore, we found that it displays a clear linear negative correlation between the clustering coefficients and the degree of nodes in the herbal combination network (HCNet). This indicates that hierarchical properties exist in the HCNet. Finally, we investigate the molecular network interaction patterns between herb related target modules (i.e., subnetworks) in herbal prescriptions using a network-based approach and further explore the correlation between the distribution of herb combinations and prescriptions. We found that the more the hierarchical prescription, the better the corresponding effect. The results also reflected a well-recognized principle called “Jun-Chen-Zuo-Shi” in TCM formula theories. This also gives references for multidrug combination development in the field of network pharmacology and provides the guideline for the clinical use of combination therapy for chronic diseases.

Quantitative Human Immunodeficiency Virus (HIV)-1 Antibodies Correlate With Plasma HIV-1 RNA and Cell-associated DNA Levels in Children on Antiretroviral Therapy

BACKGROUND

This study measured serial plasma human immunodeficiency virus (HIV)-1-specific antibody (Ab) levels in children who initiated antiretroviral therapy (ART) prior to 2 years of age, and evaluated their relationship to peripheral blood HIV-1 RNA and DNA levels.

METHODS

We studied 46 HIV-1-infected children, stratified by age at ART initiation (<3 mo, early therapy [ET]; >3 mo-2 years, late therapy [LT]) and by virologic response (R) or non-response (NR), before and up to 4 years following ART. We studied 20 HIV-1-uninfected children born to HIV-1-infected mothers (seroreverters [SR]) as controls. Plasma immunoglobulin G (IgG) Ab levels directed against HIV-1 envelope (gp160, gp41), gag (capsid, p24; matrix, p17), reverse transcriptase (p66/51), and integrase (p31) were serially measured using quantitative enzyme-linked immunosorbent assays. HIV-1 Ab rates of decline were estimated over the first 15 months of the study.

RESULTS

The HIV-1 Ab rates of decline in the ET-R group were similar to those in the SR group for all Ab specificities, except for p17 (P = .01). Ab decline rates in the LT-R group and the NR group were significantly slower than in the SR group for all tested Ab specificities. After 1 year of age, Ab levels to p31 and p17 were significantly associated with HIV-1 RNA levels (P < .001); Ab levels to gp160 (P < .001) and gp41 (P < .001) were significantly associated with cell-associated HIV-1 DNA levels.

CONCLUSIONS

Quantitative HIV-1-specific Ab levels may be useful for screening children on ART for viral suppression or for residual, cell-associated HIV-1 DNA levels.

CLINICAL TRIALS REGISTRATION

NCT00000872.

Quantitative HIV-1-specific antibodies as predictors of peripheral blood cell-associated HIV-1 DNA concentrations

OBJECTIVE

This study evaluated HIV-1 antibody levels as predictors of cell-associated HIV-1 DNA levels in perinatally infected (PHIV) children with long-term viral suppression on antiretroviral therapy (ART).

DESIGN

HIV-1 antibody and HIV-1 DNA levels were measured in blood specimens from 61 children and adolescents from the Pediatric HIV/AIDS Cohort Study: Adolescent Master Protocol. Twenty perinatally HIV-1-exposed, uninfected children studied through 2 years served as controls.

METHODS

HIV-1 IgG antibodies to six HIV-1 proteins were measured by quantitative ELISA; HIV-1 DNA levels were measured by droplet digital PCR.

RESULTS

Among 13 children with viral suppression at less than 1 year, antibodies to gp160 and gp41 were low but stable longitudinally; antibodies to p17, p24, and RT decreased, and antibodies to p31 were low or undetectable. Among 48 children with viral suppression between 1 and 5 years, antibody levels to all six HIV-1 proteins were higher than in children with earlier viral suppression and remained high over time. A receiver operator curve approach identified gp41 and gp160 as useful predictors of HIV-1 DNA less than 10 or less than 100 copies per million PBMC (cpm); C-statistics including all antibodies ranged from 0.75 to 0.77. An ensemble learning approach also identified gp41 and gp160 as important predictors of HIV-1 DNA less than 10 or less than 100 cpm; area under the curve estimates utilizing all HIV-1 antibodies ranged from 0.70 to 0.81.

CONCLUSION

Quantitative HIV-1 gp41 and gp160 antibody levels may serve as rapid, inexpensive screening tools for low PBMC HIV-1 DNA levels in children with viral suppression on ART, facilitating inclusion into remission protocols.

Predictors of faster virological suppression in early treated infants with perinatal HIV from Europe and Thailand

Supplemental Digital Content is available in the text

Objective:

To identify predictors of faster time to virological suppression among infants starting combination antiretroviral therapy (cART) early in infancy.

Design:

Cohort study of infants from Europe and Thailand included in studies participating in the European Pregnancy and Paediatric HIV Cohort Collaboration.

Methods:

Infants with perinatal HIV starting cART aged less than 6 months with at least 1 viral load measurement within 15 months of cART initiation were included. Multivariable interval-censored flexible parametric proportional hazards models were used to assess predictors of faster virological suppression, with timing of suppression assumed to lie in the interval between last viral load at least 400 and first viral load less than 400 copies/ml.

Results:

Of 420 infants, 59% were female and 56% from Central/Western Europe, 26% United Kingdom/Ireland, 15% Eastern Europe and 3% Thailand; 46 and 54% started a boosted protease inhibitor-based or nonnucleoside reverse transcriptase inhibitor-based regimen, respectively. At cART initiation, the median age, CD4⁺% and viral load were 2.9 [interquartile range (IQR): 1.4–4.1] months, 34 (IQR: 24–45)% and 5.5 (IQR: 4.5–6.0) log₁₀ copies/ml, respectively. Overall, an estimated 89% (95% confidence interval: 86–92%) achieved virological suppression within 12 months of cART start. In multivariable analysis, younger age [adjusted hazard ratio (aHR): 0.84 per month older; P < 0.001], higher CD4⁺% (aHR: 1.11 per 10% higher; P = 0.010) and lower log₁₀ viral load (aHR: 0.85 per log₁₀ higher; P < 0.001) at cART initiation independently predicted faster virological suppression.

Conclusion:

We observed a significant independent effect of age at cART initiation, even within a narrow 6 months window from birth. These findings support the earliest feasible cART initiation in infants and suggest that early therapy influences key virological and immunological parameters that could have important consequences for long-term health.

Reactivity of Routine HIV Antibody Tests in Children With Perinatally Acquired HIV-1 in England: Cross-sectional Analysis

We assessed HIV antibody prevalence in children with perinatally acquired HIV in England. Eighteen percent (10/55) of those starting combination antiretroviral therapy <6 months of age were seronegative at median age 9.1 years and had lower viral load at diagnosis and combination antiretroviral therapy start and fewer viral rebounds, than 45 of 55 seropositives. Implications for patient selection for HIV cure research, and interpretation of routine antibody testing, are discussed.

Early Combination Antiretroviral Therapy Limits HIV-1 Persistence in Children

Globally, 240,000 infants are newly infected with HIV-1 each year and 3.2 million children are living with the infection. Combination antiretroviral therapy (cART) has reduced HIV-1-related disease and mortality in children but is not curative owing to the early generation of a latent reservoir of long-lived memory CD4(+) T cells bearing replication-competent HIV-1 provirus integrated into cellular DNA. This review focuses on recent advances in our understanding of the establishment of HIV-1 persistence in children and how early initiation of cART in the setting of the developing infant immune system limits the formation of the long-lived latent CD4(+) cell reservoir that remains a barrier to remission or cure.

Early Combination Antiretroviral Therapy Limits Exposure to HIV-1 Replication and Cell-Associated HIV-1 DNA Levels in Infants

The primary aim of this study was to measure HIV-1 persistence following combination antiretroviral therapy (cART) in infants and children. Peripheral blood mononuclear cell (PBMC) HIV-1 DNA was quantified prior to and after 1 year of cART in 30 children, stratified by time of initiation (early, age <3 months, ET; late, age >3 months-2 years, LT). Pre-therapy PBMC HIV-1 DNA levels correlated with pre-therapy plasma HIV-1 levels (r = 0.59, p<0.001), remaining statistically significant (p = 0.002) after adjustment for prior perinatal antiretroviral exposure and age at cART initiation. PBMC HIV-1 DNA declined significantly after 1 year of cART (Overall: -0.91±0.08 log10 copies per million PBMC, p<0.001; ET: -1.04±0.11 log10 DNA copies per million PBMC, p<0.001; LT: -0.74 ±0.13 log10 DNA copies per million PBMC, p<0.001) but rates of decline did not differ significantly between ET and LT. HIV-1 replication exposure over the first 12 months of cART, estimated as area-under-the-curve (AUC) of circulating plasma HIV-1 RNA levels, was significantly associated with PBMC HIV-1 DNA at one year (r = 0.51, p = 0.004). In 21 children with sustained virologic suppression after 1 year of cART, PBMC HIV-1 DNA levels continued to decline between years 1 and 4 (slope -0.21 log10 DNA copies per million PBMC per year); decline slopes did not differ significantly between ET and LT. PBMC HIV-1 DNA levels at 1 year and 4 years of cART correlated with age at cART initiation (1 year: p = 0.04; 4 years: p = 0.03) and age at virologic control (1 and 4 years, p = 0.02). Altogether, these data indicate that reducing exposure to HIV-1 replication and younger age at cART initiation are associated with lower HIV-1 DNA levels at and after one year of age, supporting the concept that HIV-1 diagnosis and cART initiation in infants should occur as early as possible.

HIV type 1 (HIV-1) proviral reservoirs decay continuously under sustained virologic control in HIV-1-infected children who received early treatment

BACKGROUND

Early initiation of combination antiretroviral therapy (cART) to human immunodeficiency virus type 1 (HIV-1)-infected infants controls HIV-1 replication and reduces mortality.

METHODS

Plasma viremia (lower limit of detection, <2 copies/mL), T-cell activation, HIV-1-specific immune responses, and the persistence of cells carrying replication-competent virus were quantified during long-term effective combination antiretroviral therapy (cART) in 4 perinatally HIV-1-infected youth who received treatment early (the ET group) and 4 who received treatment late (the LT group). Decay in peripheral blood mononuclear cell (PBMC) proviral DNA levels was also measured over time in the ET youth.

RESULTS

Plasma viremia was not detected in any ET youth but was detected in all LT youth (median, 8 copies/mL; P = .03). PBMC proviral load was significantly lower in ET youth (median, 7 copies per million PBMCs) than in LT youth (median, 181 copies; P = .03). Replication-competent virus was recovered from all LT youth but only 1 ET youth. Decay in proviral DNA was noted in all 4 ET youth in association with limited T-cell activation and with absent to minimal HIV-1-specific immune responses.

CONCLUSIONS

Initiation of early effective cART during infancy significantly limits circulating levels of proviral and replication-competent HIV-1 and promotes continuous decay of viral reservoirs. Continued cART with reduction in HIV-1 reservoirs over time may facilitate HIV-1 eradication strategies.

Etravirine in treatment-experienced, HIV-1-infected children and adolescents: 48-week safety, efficacy and resistance analysis of the phase II PIANO study

OBJECTIVES

PIANO (Paediatric study of Intelence As an NNRTI Option; TMC125-C213; NCT00665847) assessed the safety/tolerability, antiviral activity and pharmacokinetics of etravirine plus an optimized background regimen (OBR) in treatment-experienced, HIV-1-infected children (≥ 6 to < 12 years) and adolescents (≥ 12 to < 18 years) over 48 weeks.

METHODS

In a phase II, open-label, single-arm study, 101 treatment-experienced patients (41 children; 60 adolescents) with screening viral load (VL) ≥ 500 HIV-1 RNA copies/mL received etravirine 5.2 mg/kg (maximum dose 200 mg) twice a day (bid) plus OBR.

RESULTS

Sixty-seven per cent of patients had previously used efavirenz or nevirapine. At week 48, the most common treatment-related grade ≥ 2 adverse event (AE) was rash (13%); 12% experienced grade 3 AEs. Only two grade 4 AEs occurred (both thrombocytopaenia, not etravirine related). At week 48, 56% of patients (68% children; 48% adolescents) achieved a virological response (VL<50 copies/mL; intent-to-treat, noncompleter=failure). Factors predictive of response were adherence > 95%, male sex, low baseline etravirine weighted genotypic score and high etravirine trough concentration (C0h ). Seventy-six patients (75%) completed the trial; most discontinuations occurred because of protocol noncompliance or AEs (8% each). Sixty-five per cent of patients were > 95% adherent by questionnaire and 39% by pill count. Forty-one patients experienced virological failure (VF; time-to-loss-of-virological-response non-VF-censored algorithm) (29 nonresponders; 12 rebounders). Of 30 patients with VF with paired baseline/endpoint genotypes, 18 (60%) developed nonnucleoside reverse transcriptase inhibitor (NNRTI) mutations, most commonly Y181C. Mean etravirine area under the plasma concentration-time curve over 12 h (AUC0-12h ; 5216 ng h/mL) and C0h (346 ng/mL) were comparable to adult target values.

CONCLUSIONS

Results with etravirine 5.2 mg/kg bid (with OBR) in this treatment-experienced paediatric population and etravirine 200 mg bid in treatment-experienced adults were comparable. Etravirine is an NNRTI option for treatment-experienced paediatric patients.

Anti-HIV designer T cells progressively eradicate a latently infected cell line by sequentially inducing HIV reactivation then killing the newly gp120-positive cells

The current antiretroviral therapy (ART) can effectively reduce plasma HIV loads to undetectable levels, but cannot eliminate latently infected resting memory CD4 T cells that persist for the lifetime of infected patients. Therefore, designing new therapeutic approaches to eliminate these latently infected cells or the cells that produce HIV upon reactivation from latency is a priority in the ART era in order to progress to a cure of HIV. Here, we show that "designer" T cells expressing chimeric antigen receptor (CAR), CD4-CD28-CD3ζ, can target and kill HIV Env-expressing cells. Further, they secrete effector cytokines upon contact with HIV Env+ target cells that can reactivate latent HIV in a cell line model, thereby exposing those cells to recognition and killing by anti-HIV CAR+ T cells. Taken to the limit, this process could form the basis for an eventual functional or sterilizing cure for HIV in patients.

Exploiting drug-resistant enzymes as tools to identify thienopyrimidinone inhibitors of human immunodeficiency virus reverse transcriptase-associated ribonuclease H

The thienopyrimidinone 5,6-dimethyl-2-(4-nitrophenyl)thieno[2,3-d]pyrimidin-4(3H)-one (DNTP) occupies the interface between the p66 ribonuclease H (RNase H) domain and p51 thumb of human immunodeficiency virus reverse transcriptase (HIV RT), thereby inducing a conformational change incompatible with catalysis. Here, we combined biochemical characterization of 39 DNTP derivatives with antiviral testing of selected compounds. In addition to wild-type HIV-1 RT, derivatives were evaluated with rationally designed, p66/p51 heterodimers exhibiting high-level DNTP sensitivity or resistance. This strategy identified 3',4'-dihydroxyphenyl (catechol) substituted thienopyrimidinones with submicromolar in vitro activity against both wild type HIV-1 RT and drug-resistant variants. Thermal shift analysis indicates that, in contrast to active site RNase H inhibitors, these thienopyrimidinones destabilize the enzyme, in some instances reducing the Tm by 5 °C. Importantly, catechol-containing thienopyrimidinones also inhibit HIV-1 replication in cells. Our data strengthen the case for allosteric inhibition of HIV RNase H activity, providing a platform for designing improved antagonists for use in combination antiviral therapy.

False-negative post-18-month confirmatory HIV tests in HIV DNA PCR-positive children: a retrospective analysis

OBJECTIVE

The WHO guidelines for children less than 18 months old diagnosed with HIV based on presumptive clinical diagnosis or one virologic test recommend confirmatory HIV antibody testing after 18 months of age. This study describes post-18-month HIV test results following this WHO-recommended confirmatory testing strategy.

DESIGN

Case series and retrospective review of routine program data.

METHODS

Children enrolled at the Baylor Children's Clinical Center of Excellence, a pediatric and family HIV clinic in Maseru, Lesotho from December 2005 through January 2009 with a positive HIV DNA PCR at less than 18 months of age and HIV rapid test results after 18 months of age were included. Post-18-month confirmatory HIV test results are described. Factors associated with non-positive confirmatory rapid tests were determined using binary logistic regression.

RESULTS

Of the 109 children meeting inclusion criteria, 22 (20.2%) had negative and 27 (24.8%) discordant confirmatory rapid tests. Forty-six of these 49 were on antiretroviral therapy (ART). Among these 49, 11 of 24 post-18-month HIV DNA PCRs were negative, whereas nine of 10 post-18-month HIV ELISAs were positive; 29 were definitively and 17 probably HIV-infected, two were uninfected, and one had undetermined status. Only age less than 9 months at ART initiation (odds ratio 4.25, P = 0.002) was associated with non-positive rapid tests.

CONCLUSION

False-negative post-18-month confirmatory rapid tests and HIV DNA PCRs in children on ART are common, associated with early ART initiation, and may lead to inappropriate ART discontinuation and discharge from care of truly HIV-infected children.

Nevirapine exposure with WHO pediatric weight band dosing: enhanced therapeutic concentrations predicted based on extensive international pharmacokinetic experience

Nevirapine (NVP) is a nonnucleoside reverse transcriptase inhibitor (NNRTI) used worldwide as part of combination antiretroviral therapy in infants and children to treat HIV infection. Dosing based on either weight or body surface area has been approved by the U.S. Food and Drug Administration (FDA) but can be difficult to implement in resource-limited settings. The World Health Organization (WHO) has developed simplified weight band dosing for NVP, but it has not been critically evaluated. NVP pharmacokinetic data were combined from eight pediatric clinical trials (Pediatric AIDS Clinical Trials Group [PACTG] studies 245, 356, 366, 377, 403, 1056, and 1069 and Children with HIV in Africa Pharmacokinetics and Adherence of Simple Antiretroviral Regimens [CHAPAS]) representing subjects from multiple continents and across the pediatric age continuum. A population pharmacokinetic model was developed to characterize developmental changes in NVP disposition, identify potential sources of NVP pharmacokinetic variability, and assess various pediatric dosing strategies and their impact on NVP exposure. Age, CYP2B6 genotype, and ritonavir were independent predictors of oral NVP clearance. The Triomune fixed-dose tablet was an independent predictor of bioavailability compared to the liquid and other tablet formulations. Monte Carlo simulations of the final model were used to assess WHO weight band dosing recommendations. The final pharmacokinetic model indicated that WHO weight band dosing is likely to result in a percentage of children with NVP exposure within the target range similar to that obtained with FDA dosing. Weight band dosing of NVP proposed by the WHO has the potential to provide a simple and effective dosing strategy for resource limited settings.

Role of non-nucleoside reverse transcriptase inhibitors in treating HIV-infected children

The first-generation non-nucleoside reverse transcriptase inhibitors (NNRTIs), efavirenz and nevirapine, fulfil key roles in antiretroviral therapy for HIV-infected paediatric patients, from lowering the incidence of mother-to-child transmission during pregnancy and birth to treatment throughout childhood and adolescence. Both agents have established efficacy, safety and tolerability profiles, and also offer advantages over other classes of therapy in terms of regimen simplicity and availability across different treatment settings. Although the role of NNRTIs in paediatric treatment strategies is largely determined by experience in adult patients, results of the recent phase II/III PENPACT-1 trial in infants and children aged between 30 days and 18 years have shown that there are no significant differences in 4-year virological, immunological or clinical outcomes between NNRTIs and protease inhibitors as first- and second-line agents. However, results from the IMPAACT P1060 study (cohort 2), conducted in resource-limited settings, showed that infants under 36 months unexposed to NNRTIs were significantly more likely to fail treatment when started on a nevirapine-based regimen than those on a lopinavir/ritonavir-based regimen. Unfortunately, the use of efavirenz and nevirapine in children can be limited by rapid development of high-level resistance to one or both agents, which may reduce the availability of viable treatment options, particularly in resource-limited settings. Several therapeutic strategies addressing this issue are currently under investigation, but a significant need for new NNRTI-based treatment options remains. The more recently approved NNRTI, etravirine, has demonstrated efficacy and safety benefits in HIV-1-infected, NNRTI-resistant adult patients, with a higher genetic barrier to the development of resistance relative to the first-generation NNRTIs. Another NNRTI, rilpivirine (TMC278), is approved for use in HIV-1-infected, treatment-naïve adult patients and has demonstrated an improved tolerability profile compared with efavirenz. Although available data on etravirine in children are currently limited, ongoing trials will provide important information on the potential for their use in novel paediatric treatment strategies. This review examines the role of efavirenz and nevirapine in paediatric antiretroviral therapy in children within different treatment settings. In addition, this review also outlines available clinical data on etravirine and rilpivirine in the context of how these antiretrovirals may address some of the limitations of efavirenz and nevirapine in paediatric patients.

Short- and long-term immunological and virological outcome in HIV-infected infants according to the age at antiretroviral treatment initiation

The clinical benefit of antiretroviral therapy in infants is established. In this cohort collaboration, we compare immunological and virological response to treatment started before or after 3 months of age. Early initiation provides a better short-term response, although evolution after 12 months of age is similar in both groups.

Early antiretroviral therapy in HIV-1-infected infants, 1996-2008: treatment response and duration of first-line regimens

OBJECTIVE

To investigate virological and immunological response to antiretroviral therapy (ART), and predictors of switching and interrupting treatment among infants starting ART across Europe.

DESIGN

Cohort study.

METHODS

Nine cohorts from 13 European countries contributed data on HIV-infected infants born 1996-2008 and starting ART before age 12 months. Logistic and linear regression, and competing risks methods were used to assess predictors of virological (viral load <400 copies/ml) and immunological (change in CD4 Z-score) response, switching to second-line ART and treatment interruptions with viral load less than 400 copies/ml.

RESULTS

A total of 437 infants were followed for median 5.9 (interquartile range 2.3-7.6) years after starting ART; 30% had an AIDS diagnosis prior to ART initiation. 53% had suppressed viral load <400 copies/ml at 12 months in 1996-1999, increasing to 77% in 2004-2008. Virological and immunological responses at 12 months varied by initial ART type (P < 0.001 and P = 0.03, respectively), with four-drug nonnucleoside reverse transcriptase inhibitor (NNRTI)-based regimens being superior [virological response <400 copies/ml adjusted odds ratio = 3.00, 95% confidence interval (CI) 1.24-7.23; mean increase in CD4 Z-score coefficient = 0.64, 95% CI 0.10-1.17] to both three-drug NNRTI-based (reference) and boosted protease inhibitor regimens which were similar. Rates of switching to second-line ART were lower among children starting four-drug NNRTI-based and boosted protease inhibitor-based regimens compared with three-drug NNRTI regimens (P = 0.03). Sixty five percent of infants remained on first-line ART without treatment interruption after 5 years.

CONCLUSION

Effective and prolonged responses to first-line ART can now be achieved in infants starting early ART outside trial settings. Superior responses to four-drug NNRTI compared with boosted protease inhibitor or three-drug NNRTI regimens need further evaluation, as does treatment interruption following early ART.

Post-HAART outcomes in pediatric populations: comparison of resource-limited and developed countries

CONTEXT

No formal comparison has been made between the pediatric post-highly active antiretroviral therapy (HAART) outcomes of resource-limited and developed countries.

OBJECTIVE

To systematically quantify and compare major baseline characteristics and clinical end points after HAART between resource-limited and developed settings.

METHODS

Published articles and abstracts (International AIDS Society 2009, Conference on Retroviruses and Opportunistic Infections 2010) were examined from inception (first available publication for each search engine) to March 2010. Publications that contained data on post-HAART mortality, weight-for-age z score (WAZ), CD4 count, or viral load (VL) changes in pediatric populations were reviewed. Selected studies met the following criteria: (1) patients were younger than 21 years; (2) HAART was given (≥ 3 antiretroviral medications); and (3) there were >20 patients. Data were extracted for baseline age, CD4 count, VL, WAZ, and mortality, CD4 and virologic suppression over time. Studies were categorized as having been performed in a resource-limited country (RLC) or developed country (DC) on the basis of the United Nations designation. Mean percentage of deaths per cohort and deaths per 100 child-years, baseline CD4 count, VL, WAZ, and age were calculated for RLCs and DCs and compared by using independent samples t tests.

RESULTS

Forty RLC and 28 DC publications were selected (N = 17 875 RLCs; N = 1835 DC). Mean percentage of deaths per cohort and mean deaths per 100 child-years after HAART were significantly higher in RLCs than DCs (7.6 vs 1.6, P < .001, and 8.0 vs 0.9, P < .001, respectively). Mean baseline CD4% was 12% in RLCs and 23% in DCs (P = .01). Mean baseline VLs were 5.5 vs 4.7 log(10) copies per mL in RLCs versus DCs (P < .001).

CONCLUSIONS

Baseline CD4% and VL differ markedly between DCs and RLCs, as does mortality after pediatric HAART. Earlier diagnosis and treatment of pediatric HIV in RLCs would be expected to result in better HAART outcomes.

Recovery of replication-competent residual HIV-1 from plasma of a patient receiving prolonged, suppressive highly active antiretroviral therapy

The clinical significance of persistent residual viremia in patients on prolonged highly active antiretroviral therapy (HAART) is not clear. Moreover, it remains to be demonstrated whether residual viremia consists of viruses capable of spreading infection in vivo upon termination of therapy. Using residual viral RNAs (vRNAs) isolated from a HAART-treated patient's plasma, we cloned full-length viral genomes and found that most of them could produce infectious, replication-competent HIVs when transfected into TZM-bl cells, suggesting that residual viruses produced in the absence of therapy can initiate fresh cycles of infection and spread in host cells. The data further indicate that residual viremia may pose a major concern with regard to the emergence of drug-resistant HIVs during periods of low adherence to therapy.

Mother-to-child transmission of HIV: a global perspective

HIV-1 infection is a significant global source of childhood morbidity and mortality, and mother-to-child transmission (MTCT) is the major mode of infection. Research over the past two decades has improved our understanding of the pathogenesis of MTCT and pediatric HIV-1 infection, lending to the development of effective preventive and therapeutic strategies. However, successful implementation of these strategies has been limited in resource-constrained settings, where the majority of new pediatric HIV infections now occur. Continued efforts are necessary to better understand MTCT and to refine preventive and therapeutic strategies to allow their successful implementation in the most needed places.

Low-cost HIV-1 diagnosis and quantification in dried blood spots by real time PCR

Background

Rapid and cost-effective methods for HIV-1 diagnosis and viral load monitoring would greatly enhance the clinical management of HIV-1 infected adults and children in limited-resource settings. Recent recommendations to treat perinatally infected infants within the first year of life are feasible only if early diagnosis is routinely available. Dried blood spots (DBS) on filter paper are an easy and convenient way to collect and transport blood samples. A rapid and cost effective method to diagnose and quantify HIV-1 from DBS is urgently needed to facilitate early diagnosis of HIV-1 infection and monitoring of antiretroviral therapy.

Methods and Findings

We have developed a real-time LightCycler (rtLC) PCR assay to detect and quantify HIV-1 from DBS. HIV-1 RNA extracted from DBS was amplified in a one-step, single-tube system using primers specific for long-terminal repeat sequences that are conserved across all HIV-1 clades. SYBR Green dye was used to quantify PCR amplicons and HIV-1 RNA copy numbers were determined from a standard curve generated using serially diluted known copies of HIV-1 RNA. This assay detected samples across clades, has a dynamic range of 5 log₁₀, and %CV <8% up to 4 log₁₀ dilution. Plasma HIV-1 RNA copy numbers obtained using this method correlated well with the Roche Ultrasensitive (r = 0.91) and branched DNA (r = 0.89) assays. The lower limit of detection (95%) was estimated to be 136 copies. The rtLC DBS assay was 2.5 fold rapid as well as 40-fold cheaper when compared to commercial assays. Adaptation of the assay into other real-time systems demonstrated similar performance.

Conclusions

The accuracy, reliability, genotype inclusivity and affordability, along with the small volumes of blood required for the assay suggest that the rtLC DBS assay will be useful for early diagnosis and monitoring of pediatric HIV-1 infection in resource-limited settings.

Pharmacotherapy of pediatric and adolescent HIV infection

Significant advances have been made in the treatment of human immunodeficiency virus (HIV) infection over the past two decades. Improved therapy has prolonged survival and improved clinical outcome for HIV-infected children and adults. Sixteen antiretroviral (ART) medications have been approved for use in pediatric HIV infection. The Department of Health and Human Services (DHHS) has issued "Guidelines for the Use of Antiretroviral Agents in Pediatric HIV Infection", which provide detailed information on currently recommended antiretroviral therapies (ART). However, consultation with an HIV specialist is recommended as the current therapy of pediatric HIV therapy is complex and rapidly evolving.

Low-level plasma HIVs in patients on prolonged suppressive highly active antiretroviral therapy are produced mostly by cells other than CD4 T-cells

The cellular source(s) and the clinical significance of persistent low-level viremia, below 50 HIV RNA copies per ml of plasma, achieved in many patients with high adherence to highly active antiretroviral therapy (HAART) remain unclear. Also, it is not clear if residual plasma HIVs during HAART can become predominant populations in the rebounding plasma viral loads after therapy interruption. Since, different HIV quasispecies tend to compartmentalize in various cell types and tissue locations in patients during chronic infection, the phylogenetic relationships between HIV sequences amplified from residual plasma viruses and CD4 T cells of five patients on long-term suppressive therapy were examined. Three of these patients stopped therapy voluntarily for 3 weeks, but only one of them demonstrated viral load rebound in plasma. In phylogenetic analyses, the residual plasma viruses were found to be distinct genetically from the majority of CD4 T cell-associated virus populations in four of five patients. The compartmental analyses revealed that in all patients, plasma- and CD4 T cell-derived viral sequences were compartmentalized separately. Interestingly, the plasma sequences obtained before and after HAART-off in two patients were produced apparently from the same compartment, which was different from the circulating CD4 T cell-compartment. These results suggest the possibility that residual plasma viruses in patients on long-term suppressive HAART may be produced persistently from a cellular source yet to be identified, and are capable of spreading quickly in vivo, accounting for the rapid rebound of viral loads in plasma after therapy interruption.

Current and future antiretroviral treatment options in paediatric HIV infection

Because of a lack of prevention policies or problems in implementing prevention of mother-to-child transmission (P-MTCT), most of the 1500 daily new HIV infections in children aged<15 years are caused by MTCT. Fifteen percent of all HIV-infected individuals are children, but the vast majority lack access to highly active antiretroviral therapy (HAART), which can drastically reduce morbidity and mortality. There are 22 antiretroviral drugs currently approved by the US FDA for use in the treatment of HIV-infected adults and adolescents, but only 12 of these drugs are approved for use in children. Antiretroviral drugs belong to four major classes: nucleoside and nucleotide analogue reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs), protease inhibitors and fusion inhibitors. According to international guidelines developed by organizations including WHO, the Paediatric European Network for Treatment of AIDS (PENTA) and the US National Institutes of Health (US-NIH), the treatment of choice for HIV-infected children and adults is a combination of two NRTIs (backbone treatment) plus a third potent agent from a different class, either an NNRTI or a ritonavir-boosted protease inhibitor. There are specific challenges in treating HIV-infected children, including uncertainty about the best time to start treatment, the need for more paediatric formulations, the lack of pharmacokinetic studies for new drugs, and incomplete dosing guidelines. Furthermore, the most appropriate regimen for an individual child depends on a variety of factors, including the age of the child; the availability of appropriate drug formulations; the potency, complexity and toxicity of the drug regimen; the home situation; the child and caregiver's ability to adhere to the regimen; and the child's antiretroviral treatment history. In addition, antiretroviral drugs are not licensed for all age groups and the drugs are often not affordable. This review describes NNRTI and protease inhibitors as key components of first- and second-line antiretroviral therapy (ART), focusing on the rationale for choosing an NNRTI- versus protease inhibitor-based regimen based on the results of available phase II and III studies. Some of the new agents available for children as second-line and salvage therapy both on- and off-label are also discussed. The drug regimens described in this review are relevant to clinicians in developed and developing countries. The availability of new, potent compounds with different resistance and toxicity profiles may represent an alternative option to interclass switching and could redefine ART strategy, including the option of first-line NRTI-sparing regimens.

Effective highly active antiretroviral therapy in patients with primary HIV-1 infection prevents the evolution of the avidity of HIV-1-specific antibodies

OBJECTIVE

To evaluate if the administration of highly active antiretroviral therapy (HAART) during primary HIV infection (PHI) may affect the antibody avidity evolution.

METHODS

In 13 subjects with symptomatic PHI, of whom 8 initiated HAART at diagnosis, the Avidity Index (AI) and Western blot evolution patterns were analyzed on serial serum/plasma samples for 1 year. In 4 patients, who subsequently interrupted HAART, additional specimens were analyzed.

RESULTS

At diagnosis, the range of HIV viremia was 0.003 to 38 x 10(6) copies/mL. In untreated patients, viremia reached the set point in 4 to 6 months, whereas in treated patients, early suppression of viremia was observed, remaining undetectable during therapy. At diagnosis, the median AI was low in untreated (0.42, range: 0.33 to 0.43) and treated (0.44, range: 0.40 to 0.72) patients. At 3, 6, and 12 months, the AI progressively increased in untreated patients, whereas it remained <0.80 in all treated patients. In the 4 patients interrupting HAART, the AI increased after therapy interruption to greater than 0.80 in < or = 6 months. The Western blot pattern transiently/partially reversed during HAART in 2 patients.

CONCLUSIONS

Antibody avidity maturation takes place only in the presence of ongoing viral replication. These results may have relevant implications in understanding the complex mechanism of maturation of the immune response to HIV.

Early response to highly active antiretroviral therapy in HIV-1-infected Kenyan children

OBJECTIVES

To describe the early response to World Health Organization (WHO)-recommended nonnucleoside reverse transcriptase inhibitor (NNRTI)-based first-line highly active antiretroviral therapy (HAART) in HIV-1-infected Kenyan children unexposed to nevirapine.

DESIGN

Observational prospective cohort.

METHODS

HIV-1 RNA level, CD4 lymphocyte count, weight for age z score, and height for age z score were measured before the initiation of HAART and every 3 to 6 months thereafter. Children received no nutritional supplements.

RESULTS

Sixty-seven HIV-1-infected children were followed for a median of 9 months between August 2004 and November 2005. Forty-seven (70%) used zidovudine, lamivudine (3TC), and an NNRTI (nevirapine or efavirenz), whereas 25% used stavudine (d4T), 3TC, and an NNRTI. Nevirapine was used as the NNRTI by 46 (69%) children, and individual antiretroviral drug formulations were used by 63 (94%), with only 4 (6%) using a fixed-dose combination of d4T, 3TC, and nevirapine (Triomune; Cipla, Mumbai, India). In 52 children, the median height for age z score and weight for age z score rose from -2.54 to -2.17 (P<0.001) and from -2.30 to -1.67 (P=0.001), respectively, after 6 months of HAART. Hospitalization rates were significantly reduced after 6 months of HAART (17% vs. 58%; P<0.001). The median absolute CD4 count increased from 326 to 536 cells/microL (P<0.001), the median CD4 lymphocyte percentage rose from 5.8% before treatment to 15.4% (P<0.001), and the median viral load fell from 5.9 to 2.2 log10 copies/mL after 6 months of HAART (P<0.001). Among 43 infants, 47% and 67% achieved viral suppression to less than 100 copies/mL and 400 copies/mL, respectively, after 6 months of HAART.

CONCLUSION

Good early clinical and virologic response to NNRTI-based HAART was observed in HIV-1-infected Kenyan children with advanced HIV-1 disease.

Latent reservoirs for HIV-1

Combination therapy for HIV-1 infection can reduce viremia to undetectable levels, suggesting that prolonged treatment might eradicate the infection. However, one potential mechanism for viral persistence involves the establishment of a state of latent infection. Recent studies have directly confirmed that HIV-1 establishes a state of latent infection in resting memory CD4(+) T cells in vivo. This reservoir is likely to frustrate current efforts to eradicate the infection with combination therapy.

Effectiveness of early initiation of protease inhibitor-sparing antiretroviral regimen in human immunodeficiency virus-1 vertically infected infants

Each of the 17 vertically infected infants born to HIV-1-infected mothers in Belgian HIV reference centers since 1996 was treated with a combination of 3 reverse transcription inhibitors as soon as the diagnosis was established. Treatment was initiated in all patients before 66 days of life. Twelve patients, including 11/13 infants treated with the combination of zidovudine, lamivudine and nevirapine, experienced a complete viral suppression (<50 copies/mL) with their first drug regimen. At last follow-up, 12 patients were asymptomatic, 2 were CDC stage A and 3 were stage B; 15 had HIV-1 RNA levels of <50 copies/mL and 14 had >or=25% CD4 lymphocytes. These results suggest that early initiation of treatment with 3 reverse transcription inhibitors is highly effective to inhibit viral replication and to prevent clinical and immunologic progression of HIV infection in vertically infected infants.

Disease Progression Among HIV-Infected Children Who Receive Perinatal Zidovudine Prophylaxis

BACKGROUND

Studies of perinatal HIV infection have reported mixed results regarding the prognosis of HIV-infected infants exposed to perinatal zidovudine prophylaxis (PZP).

METHODS

We have followed a population-based cohort of children with perinatal HIV infection to evaluate whether early HIV disease progression was more common among those who received PZP and whether subsequent antiretroviral therapy (ART) was less effective in preventing early disease progression.

RESULTS

We identified 73 children with perinatal HIV infection born between 1994 and 2001 with at least 3 years of follow-up and with information concerning PZP administration. Children who received PZP started subsequent ART at an earlier age than those who did not receive PZP (median age at starting treatment: 2 months for PZP vs. 6 months for no PZP; P = 0.0002). PZP was associated with decreased early HIV progression: 21% (7 of 33) of children who received PZP progressed to a category C diagnosis by 3 years compared with 45% (18 of 40) of children who did not receive PZP (P = 0.047). Children who did not receive PZP progressed to a category C diagnosis at a younger age than children who received PZP (median: 4 vs. 11 months; P = 0.061). ART was as effective in preventing early HIV progression in children who received PZP as in children who did not receive PZP.

CONCLUSIONS

In our population-based cohort of perinatally HIV-infected children, those who received PZP started ART at a significantly earlier age than those who did not receive PZP and also demonstrated decreased HIV disease progression by the age of 3 years.

Outcomes for human immunodeficiency virus-1-infected infants in the United kingdom and Republic of Ireland in the era of effective antiretroviral therapy

BACKGROUND

There are few data about disease progression and response to antiretroviral therapy (ART) in vertically HIV-infected infants in the era of effective therapy.

DESIGN

Cohort study.

METHODS

We examined progression to acquired immunodeficiency syndrome (AIDS) and death over calendar time for infants reported to the National Study of HIV in Pregnancy and Childhood in the United Kingdom/Ireland. The use of ART and CD4 and HIV-1 RNA responses were assessed in a subset in the Collaborative HIV Pediatric Study.

RESULTS

Among 481 infants, mortality was lower in those born after 1997 (HR 0.30; P < 0.001), with no significant change in progression to AIDS. Of 174 infants born since 1997 in the Collaborative HIV Pediatric Study, 41 (24%) were followed from birth, 77 (44%) presented pre-AIDS and 56 (32%) presented with AIDS. Of 125 (72%) children on 3- or 4-drug ART by the age of 2 years, 59% had HIV-1 RNA <400 at 12 months; median CD4 percentage increased from 24% to 35%. Among 41 infants followed from birth, 12 progressed to AIDS (5 while ART naive) and 3 died; 1 of 10 infants initiating ART before 3 months of age progressed clinically.

CONCLUSION

Mortality in HIV-infected infants is significantly lower in the era of effective ART, but symptomatic disease rates remain high. Infrequent clinic attendance and poor compliance with cotrimoxazole prophylaxis and/or ART in infants born to diagnosed HIV-infected women and late presentation of infants identified after birth appear to be major contributors. Poor virologic response to ART during infancy is of concern because of increased likelihood of early development of resistance.

Perinatally Acquired HIV-1 Infection: Prevention and Evaluation of HIV-Exposed Infants

Perinatal transmission of human immunodeficiency virus type 1 (HIV-1) is the primary cause of pediatric HIV infections. In recent years, perinatal HIV-1 transmission rates in the United States have declined markedly because of several factors that include enhanced voluntary counseling and HIV-1 testing (VCT) for pregnant women, widespread use of antiretroviral prophylaxis or combination antiretroviral therapy, avoidance of breastfeeding, and elective cesarean delivery. However, perinatal transmission of HIV-1 still occurs, and 300 to 400 infected infants are born annually, primarily because of missed prevention opportunities. The pediatrician plays a vital role in the prevention of perinatal transmission of HIV-1 by identifying newborns born to infected mothers who were not tested during pregnancy, administering antiretroviral prophylaxis, and ensuring follow-up to confirm or exclude the diagnosis of HIV-1 infection in early infancy. This article reviews recent advances in the prevention of perinatal transmission of HIV-1, discusses evaluation and treatment of infants exposed to HIV-1, and highlights certain unique features of HIV-1 infections in infants, with a focus on early diagnosis, clinical manifestations, treatment, and prognosis.

Triple nucleoside reverse transcriptase inhibitor therapy in children

Much of the success attributed to HIV therapy in the last few years has resulted from improved ways of using existing drugs in combination therapy regimens. The availability of new, more potent drugs such as protease inhibitors and more accurate viral load tests to aid decisions to start or change treatment has also contributed to the success. Published recommendations for pediatric HIV therapy, generated by a panel of experts and specialists, are readily available and regularly updated. Preferred regimens of 'potent' therapy (referred to as highly active antiretroviral therapy, or HAART) currently consist of two nucleoside reverse transcriptase inhibitors (NRTIs) combined with either a non-nucleoside reverse transcriptase inhibitor (NNRTI) or a protease inhibitor. More intense four-drug regimens using an NNRTI or a second protease inhibitor as a fourth drug are being evaluated. Problems with HAART include: unpalatable drug formulations and adverse effects, coupled with lack of data on the pharmacokinetics, efficacy, and safety of various drug combinations. Adherence is a major factor influencing the efficacy and outcome of antiretroviral therapy. Many children cannot adhere to complex multidrug regimens, which cause virologic failure, despite excellent CD4+ cell count responses. This means a rapid progression through the limited number of treatment regimens available. Simpler regimens such as those containing three NRTIs have been proposed as a method of treatment that will allow suppression of the virus, yet circumvent many of the problems previously mentioned. An additional benefit would be the preservation of antiretroviral drugs from other classes for future treatment options if required. The major advantages of triple NRTI regimens are the simplicity of the regimen, good tolerability, few drug-drug interactions, and infrequent adverse effects coupled with a low pill burden. However, abacavir hypersensitivity remains a major problem. Up to 3% of patients may develop an early idiosyncratic hypersensitivity reaction - fever, malaise, and mucositis with or without rash, which can progress to more advanced stages of shock and death. A major concern is the apparently inferior virologic control of triple NRTI therapy as demonstrated in the AIDS Clinical Trials Group A5095 study with zidovudine/lamivudine/abacavir (Trizivir) combination in adults. Such a combination should only be considered in special situations. Examples cited include informed patient choice based on anticipated poor adherence on other treatment regimens, or if concomitant drugs such as tuberculosis medication are prescribed. The low pill burden of triple NRTI regimens (especially if combined in a single pill such as Trizivir), offers hope that regimen simplification may still be possible in the future.

A series of diaryltriazines and diarylpyrimidines are highly potent nonnucleoside reverse transcriptase inhibitors with possible applications as microbicides

An in vitro model of monocyte-derived dendritic cells (MO-DC) and CD4(+) T cells, representing the primary targets of sexual human immunodeficiency virus (HIV) transmission, was used to evaluate the antiviral and immune suppressive activity of new classes of nonnucleoside reverse transcriptase inhibitors, diaryltriazines (DATAs) and diarylpyrimidines (DAPYs), compared to the reference compounds UC-781 and PMPA. Antiviral activity (as reflected by the 50% effective concentration [EC(50)]) was determined by treating HIV-infected MO-DC/CD4(+)-T-cell cocultures with a dose range of a compound during 14 days, followed by analysis of supernatants in HIV p24 antigen enzyme-linked immunosorbent assay. A limited, 24-h treatment evaluated the compounds as microbicides. Viral rescue was evaluated in a PCR by monitoring proviral DNA in secondary cultures with phytohemagglutinin-interleukin-2 blasts. We determined 50% immunosuppressive concentrations in mixed leukocyte cultures of MO-DC and allogeneic T cells, with compound either continuously present or present only during the first 24 h. The EC(50) values of DATA and DAPY compounds ranged from 0.05 to 3 nM compared to 50 nM for UC-781 and 89 nM for PMPA. When evaluated in the "microbicide" setting, the most potent compounds completely blocked HIV infection at 10 to 100 nM. The immunosuppressive concentrations were well above the EC(50), resulting in favorable therapeutic indices for all compounds tested. The DATA and DAPY compounds described here are more potent than earlier reverse transcriptase inhibitors and show favorable pharmacological profiles in vitro. They could strengthen the antiretroviral armamentarium and might be useful as microbicides.

Salvage lopinavir-ritonavir therapy in human immunodeficiency virus-infected children

OBJECTIVE

To study the control of viral replication in human immunodeficiency virus (HIV)-infected children on different salvage therapies.

DESIGN AND SETTING

A retrospective observational study in 120 HIV-infected children was conducted. The children were divided into 3 groups according to their salvage therapies: (1) children receiving first line highly active antiretroviral therapy (HAART); (2) protease inhibitor-experienced children receiving second line HAART; (3) protease inhibitor-experienced children receiving HAART including lopinavir-ritonavir (LPV/r). The outcome variables examined were time to achieve viral load (VL) < or =400 copies/mL, success in achieving VL < or =400 copies/mL and time to virologic failure (VL >400 copies/mL).

METHODS

VL (HIV-RNA copies/mL) was quantified with reverse transcription-polymerase chain reaction molecular assay. For each protocol, survival analyses were conducted to determine the probability of achieving VL < or =400 copies/mL and rebound of VL.

RESULTS

VL < or =400 copies/mL was achieved by 52.4% of children receiving first line HAART, 48.3% receiving second line HAART and 71.5% receiving HAART including LPV/r. Children receiving HAART including LPV/r reached VL < or =400 copies/mL in a shorter time than children receiving second line HAART (P = 0.017), but quite similar to children receiving first line HAART. In terms of adjusted relative risk, children receiving HAART including LPV/r were 3.36 [95% confidence interval (95% CI), 1.59, 7.07] more likely to achieve VL < or =400 copies/mL than children receiving a different second line HAART. VL rebound occurred in 68.2% children receiving first line HAART, 73.4% receiving second line HAART and 32.4% receiving HAART including LPV/r. Children receiving HAART that includes LPV/r has less incidence of VL rebound (P=0.013) and 3.29 (95% CI 1.04, 10.3) times less risk to achieve a VL rebound than children receiving a different second line HAART.

CONCLUSIONS

HAART that includes LPV/r is able to control HIV replication more efficiently than other classic salvage antiretroviral therapies.

Immunogenicity and efficacy of childhood vaccines in HIV-1-infected children

Children infected by HIV-1 are particularly vulnerable to severe, recurrent, or unusual infections by vaccine-preventable pathogens. Routine immunisations seem to be generally safe for HIV-1-infected children, but responses may be suboptimal. Early HIV-1-induced immune attrition associated with viral replication may particularly interfere with the development of memory responses. In high HIV-1 prevalence regions, the accumulation of susceptible hosts may compromise disease-control efforts. Although early control of viral replication through treatment with highly active therapy may preserve immune function and responses to routine childhood vaccines, availability is limited in the areas most affected. In this review, we provide an overview of the immunogenicity and efficacy of childhood vaccines in HIV-1-infected children. The possible immunological bases for defective responses are discussed; unanswered questions and the need for further research are delineated.

Long-term pharmacokinetics of amprenavir in combination with delavirdine in HIV-infected children

Five heavily pretreated HIV-infected children were put on amprenavir and delavirdine plus two nucleoside inhibitors to reverse transcriptase to boost amprenavir levels and to use the antiretroviral activity of a non-nucleoside reverse transcriptase inhibitor. No data are available about this combination in children. It w;as well tolerated, and the median reduction in viral load was 1.5 log after 18 months. Delavirdine boosted amprenavir trough levels more than 10-fold, and delavirdine trough levels remained i several fold above susceptible HIV strains.

Highly active antiretroviral therapy in neonates and young infants

As techniques for early diagnosis of HIV-infected neonates and young infants become more sophisticated, neonatal nurses will be responsible for administering a variety of antiretroviral agents. Infants infected with HIV are likely to be placed on combination therapy, with the goal of suppressing viral replication and stabilizing the immune system. Combination therapy also reduces the risk of resistance mutations associated with monotherapy. The pharmacokinetics of antiretroviral agents in neonates is under study in a variety of PACTG protocols. However, the pharmacokinetics of most antiretroviral agents in premature infants has not been studied. With the exception of zidovudine, specific dosing for these agents in the preterm population is not known. The long-term effects of antiretroviral agents on growth and development also require further study. Knowledge of the management of HIV in all populations is expanding rapidly. Access to and utilization of HIV/AIDS-related resources are essential. The reader is encouraged to check for updated recommendations for the management of HIV-infected infants on the Internet at http://AIDSinfo. nih.gov.

Update on didanosine

Didanosine (ddl) has been a cornerstone of HIV management since it was made available in October 1991. Didanosine was originally introduced as an alternative to zidovudine (ZDV) for patients who were intolerant of ZDV or experienced disease progression during ZDV monotherapy. Didanosine is now used extensively as an integral component of multidrug combination regimens in both adults and children with HIV infection, and is now available for once-daily administration in the United States, Canada, and Europe. The recently approved Videx EC is an enteric-coated didanosine capsule dosed as one capsule, once daily. This paper provides an update of recently published studies on the use of ddl in combination anti-HIV therapy. In particular, these studies examine the rationale for the use of ddl as first-line anti-HIV therapy, and describe newer findings concerning its long-term efficacy, side effects, compliance, resistance, and once-daily use. The increased survival of HIV-infected patients is largely attributed to the introduction of the triple combination drug therapy but is probably also due to the long-term clinical efficacy of ddl.

Nevirapine use in HIV-1-infected children

OBJECTIVES

To evaluate the safety, efficacy, and clinical, virological, and immunological responses in HIV-1-infected children receiving nevirapine as part of combination antiretroviral therapy (ART).

METHODS

A review of case notes of all HIV-1-infected children 96 weeks after starting nevirapine, under a national compassionate access scheme between August 1997 and March 1999 in the UK. Nevirapine was dosed according to the manufacturer's guidelines.

RESULTS

Seventy-four children (36 boys, 28 naive to ART) were enrolled, with a median age of 5.2 years, viral load of 5.1 log copies/ml and CD4 lymphocyte count of 13.5%. The liquid formulation and tablets of nevirapine were well tolerated. The proportions of patients achieving undetectable viral load levels at weeks 12, 24, 48 and 96 were 30, 40, 36 and 33%, respectively (intention-to-treat analysis). Of children not on a protease inhibitor who received more than 300 mg/m2/day of nevirapine, 60% had undetectable viral loads at week 96, compared with 17% on recommended doses. Outcomes were similar for patients receiving nevirapine once or twice daily. CD4 cell count percentages increased significantly, with median values sustained above 25% by week 48 onwards. Z-scores for weight and height increased significantly during 96 weeks of treatment. Rash occurred in 20%, of which four (5%) were severe. There were no cases of Stevens-Johnson syndrome.

CONCLUSION

Nevirapine was mostly well tolerated, and was associated with encouraging clinical and immunological responses. Virological responses in this cohort support the use of nevirapine doses greater than 300 mg/m2/day, which is higher than currently recommended by the manufacturers.

Comprehensive screening reveals strong and broadly directed human immunodeficiency virus type 1-specific CD8 responses in perinatally infected children

Advances in antiviral therapy have dramatically shifted the demographics of pediatric human immunodeficiency virus type 1 (HIV-1) infection in the developed world, and a growing proportion of perinatally HIV-1-infected children are now entering their second or even third decade of life. Although cellular immune responses to HIV are known to be weak in early infancy, the magnitude, breadth, and specificity of responses later in childhood have not been characterized in detail. We performed a comprehensive characterization of HIV-1-specific CD8 responses in 18 perinatally infected children (age range, 6 to 17 years), most of whom were on antiviral therapy, using both previously defined HIV-1 epitopes and overlapping peptides spanning all HIV-1 proteins. Multispecific responses were detected in all subjects and accounted for a median of 0.25 to 0.3% of all peripheral blood mononuclear cells that was similar to the magnitude seen in HIV-infected adults. CD8 responses were broadly directed at an average of 11 epitopes (range, 2 to 27 epitopes) and targeted nearly all HIV-1 proteins, with the highest proportion in Gag. Responses were readily detected even in those children with suppressed viremia on highly active antiretroviral therapy, although the breadth (P = 0.037) and the magnitude (P = 0.021) were significantly lower in these subjects. Each child recognized only a small minority of the HIV-1 optimal epitopes defined for his or her class I HLA alleles. Together, these data indicate that perinatally infected children who survive infancy mount a robust HIV-1-specific CD8 response that is much stronger than previously thought and is comparable in magnitude and breadth to that of adults. Moreover, this response has the potential to be broadened to target more epitopes, making these children attractive candidates for immunotherapeutic interventions.

Human immunodeficiency virus and pregnancy

The recent spread of HIV infection into the heterosexual population in the United States, Europe, and Australia, as well as its earlier heterosexual presence in the developing world, has led to increased scientific and clinical attention to the role of HIV infection in pregnancy. In managing a pregnant HIV-positive woman, it is most important to treat the patient as someone who is HIV-positive rather than someone who is pregnant. Withholding antiviral or prophylactic therapies from the mother for fear of harming the child is not justified, because failure to treat the mother increases the fetal risk. The most important parameter to follow is the maternal plasma HIV-RNA level, and the most important treatment issue is to reduce this level because it is directly related to the risk of vertical transmission.

Neurologic aspects of HIV infection in infants and children: therapeutic approaches and outcome

Central nervous system (CNS) HIV-related disorders frequently have devastating consequences. Significant progress has been made in the early diagnosis and treatment of the HIV-infected patient. As a result, the prevalence and natural history of neurologic illnesses have changed. This paper reviews the epidemiology, clinical manifestations, and neuropathogenesis of HIV-related CNS disorders. Advances in antiretroviral therapy, neuroprophylaxis, and neuroprotective strategies are also discussed.