Two Distinct Mechanisms Leading to Loss of Virological Control in the Rare Group of Antiretroviral Therapy-Naive, Transiently Aviremic Children Living with HIV.

HIV-specific CD8+ T cells play a central role in immune control of adult HIV, but their contribution in pediatric infection is less well characterized. Previously, we identified a group of ART-naive children with persistently undetectable plasma viremia, termed "elite controllers," and a second group who achieved aviremia only transiently. To investigate the mechanisms of failure to maintain aviremia, we characterized in three transient aviremic individuals (TAs), each of whom expressed the disease-protective HLA-B*81:01, longitudinal HIV-specific T-cell activity, and viral sequences. In two TAs, a CD8+ T-cell response targeting the immunodominant epitope TPQDLNTML (Gag-TL9) was associated with viral control, followed by viral rebound and the emergence of escape variants with lower replicative capacity. Both TAs mounted variant-specific responses, but only at low functional avidity, resulting in immunological progression. In contrast, in TA-3, intermittent viremic episodes followed aviremia without virus escape or a diminished CD4+ T-cell count. High quality and magnitude of the CD8+ T-cell response were associated with aviremia. We therefore identify two distinct mechanisms of loss of viral control. In one scenario, CD8+ T-cell responses initially cornered low-replicative-capacity escape variants, but with insufficient avidity to prevent viremia and disease progression. In the other, loss of viral control was associated with neither virus escape nor progression but with a decrease in the quality of the CD8+ T-cell response, followed by recovery of viral control in association with improved antiviral response. These data suggest the potential for a consistently strong and polyfunctional antiviral response to achieve long-term viral control without escape. IMPORTANCE Very early initiation of antiretroviral therapy (ART) in pediatric HIV infection offers a unique opportunity to limit the size and diversity of the viral reservoir. However, only rarely is ART alone sufficient to achieve remission. Additional interventions that likely include contributions from host immunity are therefore required. The HIV-specific T-cell response plays a central role in immune control of adult HIV, often mediated through protective alleles such as HLA-B*57/58:01/81:01. However, due to the tolerogenic and type 2 biased immune response in early life, HLA-I-mediated immune suppression of viremia is seldom observed in children. We assessed a rare group of HLA-B*81:01-positive, ART-naive children who achieved aviremia, albeit only transiently, and investigated the role of the CD8+ T-cell response in the establishment and loss of viral control. We identified a mechanism by which the HIV-specific response can achieve viremic control without viral escape that can be explored in strategies to achieve remission.

An HLA-I signature favouring KIR-educated Natural Killer cells mediates immune control of HIV in children and contrasts with the HLA-B-restricted CD8+ T-cell-mediated immune control in adults.

Natural Killer (NK) cells contribute to HIV control in adults, but HLA-B-mediated T-cell activity has a more substantial impact on disease outcome. However, the HLA-B molecules influencing immune control in adults have less impact on paediatric infection. To investigate the contribution NK cells make to immune control, we studied >300 children living with HIV followed over two decades in South Africa. In children, HLA-B alleles associated with adult protection or disease-susceptibility did not have significant effects, whereas Bw4 (p = 0.003) and low HLA-A expression (p = 0.002) alleles were strongly associated with immunological and viral control. In a comparator adult cohort, Bw4 and HLA-A expression contributions to HIV disease outcome were dwarfed by those of protective and disease-susceptible HLA-B molecules. We next investigated the immunophenotype and effector functions of NK cells in a subset of these children using flow cytometry. Slow progression and better plasma viraemic control were also associated with high frequencies of less terminally differentiated NKG2A+NKp46+CD56dim NK cells strongly responsive to cytokine stimulation and linked with the immunogenetic signature identified. Future studies are indicated to determine whether this signature associated with immune control in early life directly facilitates functional cure in children.

Early Initiation of Antiretroviral Therapy Following In Utero HIV Infection Is Associated With Low Viral Reservoirs but Other Factors Determine Viral Rebound.

BACKGROUND: Early HIV diagnosis allows combination antiretroviral therapy (cART) initiation in the first days of life following in utero (IU) infection. The impact of early cART initiation on infant viral reservoir size in the setting of high-frequency cART nonadherence is unknown. METHODS: Peripheral blood total HIV DNA from 164 early treated (day 0-21 of life) IU HIV-infected South African infants was measured using droplet digital PCR at birth and following suppressive cART. We evaluated the impact of cART initiation timing on HIV reservoir size and decay, and on the risk of subsequent plasma viremia in cART-suppressed infants. RESULTS: Baseline HIV DNA (median 2.8 log10 copies/million peripheral blood mononuclear cells, range 0.7-4.8) did not correlate with age at cART initiation (0-21 days) but instead with maternal antenatal cART use. In 98 infants with plasma viral suppression on cART, HIV DNA half-life was 28 days. However, the probability of maintenance of plasma aviremia was low (0.46 at 12 months) and not influenced by HIV DNA load. Unexpectedly, longer time to viral suppression was associated with protection against subsequent viral rebound. CONCLUSIONS: With effective prophylaxis against mother-to-child transmission, cART initiation timing in the first 3 weeks of life is not critical to reservoir size.

Pharmacokinetics and safety of coformulated bictegravir, emtricitabine, and tenofovir alafenamide in children aged 2 years and older with virologically suppressed HIV: a phase 2/3, open-label, single-arm study.

BACKGROUND: Coformulated bictegravir, emtricitabine, and tenofovir alafenamide is a single-tablet regimen and was efficacious and well tolerated in children and adolescents with HIV (aged 6 years to <18 years) in a 48-week phase 2/3 trial. In this study, we report data from children aged at least 2 years and weighing 14 kg to less than 25 kg. METHODS: We conducted this open-label, multicentre, multicohort, single-arm study in South Africa, Thailand, Uganda, and the USA. Participants were virologically suppressed children with HIV, aged at least 2 years, weighing 14 kg to less than 25 kg. Participants received bictegravir (30 mg), emtricitabine (120 mg), and tenofovir alafenamide (15 mg) once daily, switching to bictegravir (50 mg), emtricitabine (200 mg), and tenofovir alafenamide (25 mg) upon attaining a bodyweight of at least 25 kg. The study included pharmacokinetic evaluation at week 2 to confirm the dose of coformulated bictegravir, emtricitabine, and tenofovir alafenamide for this weight band by comparing with previous adult data. Primary outcomes were bictegravir area under the curve over the dosing interval (AUCtau) and concentration at the end of the dosing interval (Ctau) at week 2, and incidence of treatment-emergent adverse events and laboratory abnormalities until the end of week 24 in all participants who received at least one dose of bictegravir, emtricitabine, and tenofovir alafenamide. This study is registered with ClinicalTrials.gov, NCT02881320. FINDINGS: Overall, 22 participants were screened (from Nov 14, 2018, to Jan 11, 2020), completed treatment with bictegravir, emtricitabine, and tenofovir alafenamide (until week 48), and entered an extension phase. The geometric least squares mean (GLSM) ratio for AUCtau for bictegravir was 7·6% higher than adults (GLSM ratio 107·6%, 90% CI 96·7-119·7); Ctau was 34·6% lower than adults (65·4%, 49·1-87·2). Both parameters were within the target exposure range previously found in adults, children, or both". Grade 3-4 laboratory abnormalities occurred in four (18%) participants by the end week 24 and six (27%) by the end of week 48. Drug-related adverse events occurred in three participants (14%) by the end of week 24 and week 48; none were severe. No Grade 3-4 adverse events, serious adverse events, or adverse events leading to discontinuation occurred by the end of week 24 and week 48. INTERPRETATION: Data support the use of single-tablet coformulated bictegravir (30 mg), emtricitabine (120 mg), and tenofovir alafenamide (15 mg) for treatment of HIV in children aged at least 2 years and weighing 14 kg to less than 25 kg. FUNDING: Gilead Sciences.

Identification of human endogenous retrovirus-specific T cell responses in vertically HIV-1-infected subjects.

Human endogenous retrovirus (HERV)-specific T cell responses in HIV-1-infected adults have been reported. Whether HERV-specific immunity exists in vertically HIV-1-infected children is unknown. We performed a cross-sectional analysis of HERV-specific T cell responses in 42 vertically HIV-1-infected children. HERV (-H, -K, and -L family)-specific T cell responses were identified in 26 of 42 subjects, with the greatest magnitude observed for the responses to HERV-L. These HERV-specific T cell responses were inversely correlated with the HIV-1 plasma viral load and positively correlated with CD4(+) T cell counts. These data indicate that HERV-specific T cells may participate in controlling HIV-1 replication and that certain highly conserved HERV-derived proteins may serve as promising therapeutic vaccine targets in HIV-1-infected children.

Role of Early Life Cytotoxic T Lymphocyte and Natural Killer Cell Immunity in Paediatric HIV Cure/Remission in the Anti-Retroviral Therapy Era.

Only three well-characterised cases of functional cure have been described in paediatric HIV infection over the past decade. This underlines the fact that early initiation of combination antiretroviral therapy (cART), whilst minimising the size of the viral reservoir, is insufficient to achieve cure, unless other factors contribute. In this review, we consider these additional factors that may facilitate functional cure in paediatric infection. Among the early life immune activity, these include HIV-specific cytotoxic T-lymphocyte (CTL) and natural killer (NK) cell responses. The former have less potent antiviral efficacy in paediatric compared with adult infection, and indeed, in early life, NK responses have greater impact in suppressing viral replication than CTL. This fact may contribute to a greater potential for functional cure to be achieved in paediatric versus adult infection, since post-treatment control in adults is associated less with highly potent CTL activity, and more with effective antiviral NK cell responses. Nonetheless, antiviral CTL responses can play an increasingly effective role through childhood, especially in individuals expressing then 'protective' HLA-I molecules HLA-B*27/57/58:01/8101. The role of the innate system on preventing infection, in shaping the particular viruses transmitted, and influencing outcome is discussed. The susceptibility of female fetuses to in utero mother-to-child transmission, especially in the setting of recent maternal infection, is a curiosity that also provides clues to mechanisms by which cure may be achieved, since initial findings are that viral rebound is less frequent among males who interrupt cART. The potential of broadly neutralising antibody therapy to facilitate cure in children who have received early cART is discussed. Finally, we draw attention to the impact of the changing face of the paediatric HIV epidemic on cure potential. The effect of cART is not limited to preventing AIDS and reducing the risk of transmission. cART also affects which mothers transmit. No longer are mothers who transmit those who carry genes associated with poor immune control of HIV. In the cART era, a high proportion (>70% in our South African study) of transmitting mothers are those who seroconvert in pregnancy or who for social reasons are diagnosed late in pregnancy. As a result, now, genes associated with poor immune control of HIV are not enriched in mothers who transmit HIV to their child. These changes will likely influence the effectiveness of HLA-associated immune responses and therefore cure potential among children.

Robust HIV-specific CD4+ and CD8+ T-cell responses distinguish elite control in adolescents living with HIV from viremic nonprogressors.

BACKGROUND: Elite controllers are therapy-naive individuals living with HIV capable of spontaneous control of plasma viraemia for at least a year. Although viremic nonprogressors are more common in vertical HIV-infection than in adults' infection, elite control has been rarely characterized in the pediatric population. DESIGN: We analyzed the T-cell immunophenotype and the HIV-specific response by flow cytometry in four pediatric elite controllers (PECs) compared with age-matched nonprogressors (PNPs), progressors and HIV-exposed uninfected (HEUs) adolescents. RESULTS: PECs T-cell populations had lower immune activation and exhaustion levels when compared with progressors, reflected by a more sustained and preserved effector function. The HIV-specific T-cell responses among PECs were characterized by high-frequency Gag-specific CD4+ T-cell activity, and markedly more polyfunctional Gag-specific CD8+ activity, compared with PNPs and progressors. These findings were consistently observed even in the absence of protective HLA-I molecules such as HLA-B∗27/57/81. CONCLUSION: Pediatric elite control is normally achieved after years of infection, and low immune activation in PNPs precedes the increasing ability of CD8+ T-cell responses to achieve immune control of viraemia over the course of childhood, whereas in adults, high immune activation in acute infection predicts subsequent CD8+ T-cell mediated immune control of viremia, and in adult elite controllers, low immune activation is therefore the consequence of the rapid CD8+ T-cell mediated immune control generated after acute infection. This distinct strategy adopted by PECs may help identify pathways that facilitate remission in posttreatment controllers, in whom protective HLA-I molecules are not the main factor.

HIGH-FREQUENCY failure of combination antiretroviral therapy in paediatric HIV infection is associated with unmet maternal needs causing maternal NON-ADHERENCE.

BACKGROUND: Early combination antiretroviral therapy (cART) reduces the size of the viral reservoir in paediatric and adult HIV infection. Very early-treated children may have higher cure/remission potential. METHODS: In an observational study of 151 in utero (IU)-infected infants in KwaZulu-Natal, South Africa, whose treatment adhered strictly to national guidelines, 76 infants diagnosed via point-of-care (PoC) testing initiated cART at a median of 26 h (IQR 18-38) and 75 infants diagnosed via standard-of-care (SoC) laboratory-based testing initiated cART at 10 days (IQR 8-13). We analysed mortality, time to suppression of viraemia, and maintenance of aviraemia over the first 2 years of life. FINDINGS: Baseline plasma viral loads were low (median 8000 copies per mL), with 12% of infants having undetectable viraemia pre-cART initiation. However, barely one-third (37%) of children achieved suppression of viraemia by 6 months that was maintained to >12 months. 24% had died or were lost to follow up by 6 months. Infant mortality was 9.3%. The high-frequency virological failure in IU-infected infants was associated not with transmitted or acquired drug-resistant mutations but with cART non-adherence (plasma cART undetectable/subtherapeutic, p<0.0001) and with concurrent maternal cART failure (OR 15.0, 95%CI 5.6-39.6; p<0.0001). High-frequency virological failure was observed in PoC- and SoC-tested groups of children. INTERPRETATION: The success of early infant testing and cART initiation strategies is severely limited by subsequent cART non-adherence in HIV-infected children. Although there are practical challenges to administering paediatric cART formulations, these are overcome by mothers who themselves are cART-adherent. These findings point to the ongoing obligation to address the unmet needs of the mothers. Eliminating the particular barriers preventing adequate treatment for these vulnerable women and infants need to be prioritised in order to achieve durable suppression of viraemia on cART, let alone HIV cure/remission, in HIV-infected children. FUNDING: Wellcome Trust, National Institutes of Health.

Strong sex bias in elite control of paediatric HIV infection.

BACKGROUND: Reports of posttreatment control following antiretroviral therapy (ART) have prompted the question of how common immune control of HIV infection is in the absence of ART. In contrast to adult infection, where elite controllers have been very well characterized and constitute approximately 0.5% of infections, very few data exist to address this question in paediatric infection. METHODS: We describe 11 ART-naive elite controllers from 10 cohorts of HIV-infected children being followed in South Africa, Brazil, Thailand, and Europe. RESULTS: All but one of the elite controllers (91%) are females. The median age at which control of viraemia was achieved was 6.5 years. Five of these 11 (46%) children lost control of viraemia at a median age of 12.9 years. Children who maintained control of viraemia had significantly higher absolute CD4 cell counts in the period of elite control than those who lost viraemic control. On the basis of data available from these cohorts, the prevalence of elite controllers in paediatric infection is estimated to be 5-10-fold lower than in adults. CONCLUSION: Although conclusions are limited by the study design, these data suggest that, whilst paediatric elite control can be achieved, compared with adult elite controllers, this occurs rarely, and takes some years after infection to achieve. Also, loss of immune control arises in a high proportion of children and often relatively rapidly. These findings are consistent with the more potent antiviral immune responses observed in adults and in females.

Conserved HIV-1 Gag p24 Epitopes Elicit Cellular Immune Responses That Impact Disease Outcome.

Although the breadth of the human immunodeficiency virus type 1 (HIV-1)-specific cellular immune response and its impact on the control of viral replication have already been addressed, reported data have proven controversial. We hypothesize that the nature of targeted epitopes, rather than the simple breadth or magnitude of responses, correlates with disease outcome. In this study, we explore the occurrence of patterns of Gag p24 recognition among untreated HIV-1-infected patients by identifying the epitopes that compose such patterns and how they distinctly associate with disease progression. Utilizing enzyme-linked immunospot (ELISPOT) interferon gamma (IFN-γ), we screened cellular responses of 27 HIV-1-infected subjects against 15-mer peptides encompassing the whole Gag p24 protein. Obtained data were used to develop a clustering analysis that allowed definition of two groups of individuals with totally distinct patterns of recognition. Although targeted Gag p24 peptides were completely different between the two groups, the breadth and magnitude of the responses were not. Interestingly, viral control and preservation of CD4+ T cells were increased in one group. In addition, we compared genetic conservation of amino acid sequences of the recognized peptides, as well as of the human leucocyte antigen class I (HLA-I)-restricted epitopes within them. Subjects presenting higher control of HIV-1 replication targeted more conserved epitopes, and higher genetic variation was present mainly in anchor residues for HLA-I molecules. We strengthen the existing evidence from cases of HIV-1 infection in humans that, cellular immune responses targeting conserved epitopes, rather than the magnitude and breadth of responses, associate with a better control of viral replication and maintenance of peripheral CD4+ T cell counts.

Asymptomatic anorectal Chlamydia trachomatis and Neisseria gonorrhoeae infections are associated with systemic CD8+ T-cell activation.

BACKGROUND: Oral preexposure prophylaxis (PrEP) has been established as a pivotal strategy in HIV prevention. However, bacterial sexually transmitted infections (STIs), such as Chlamydia trachomatis and Neisseria gonorrhoeae, are also highly prevalent. Although the presence of STI-related mucosal lesions is a known risk factor for HIV acquisition, the potential increase in risk associated with asymptomatic STIs is not completely understood. Recent data demonstrated higher T-cell activation is a risk factor for sexually acquired HIV-1 infection. We examined the effect of asymptomatic C. trachomatis and N. gonorrhoeae anorectal infection on systemic immune activation, potentially increasing the risk of HIV acquisition. METHODS: We analyzed samples from participants of PrEP Brasil, a demonstration study of daily oral emtricitabine/tenofovir disoproxil fumarate HIV PrEP among healthy MSM, for T-cell activation by flow cytometry. We included 34 asymptomatic participants with anorectal swab for C. trachomatis and/or N. gonorrhoeae infection, whereas negative for other STIs, and 35 controls. RESULTS: We found a higher frequency of human leukocyte antigen DRCD38 CD8 T cells (1.5 vs. 0.9%, P < 0.005) and with memory phenotype in the group with asymptomatic C. trachomatis and/or N. gonorrhoeae infection. Exhaustion and senescence markers were also significant higher in this group. No difference was observed in the soluble CD14 levels. CONCLUSION: Our findings suggest asymptomatic anorectal C. trachomatis and/or N. gonorrhoeae increase systemic immune activation, potentially increasing the risk of HIV acquisition. Regular screening and treatment of asymptomatic STIs should be explored as adjuvant tools for HIV prevention.

Rats treated with Hypericum perforatum during pregnancy generate offspring with behavioral changes in adulthood

Abstract Drugs used in the treatment of depression can cross the placenta giving rise to questions regarding the effects these drugs exert on the fetus. Hypericum perforatum L., Hypericaceae, is a natural product used to treat depression. However, information about its toxicity and the occurrence of alterations in the central nervous system development of the offspring is scarce. This work assessed the behavior of adult male rats born from mothers treated with Hypericum extract during gestation and analyzed the fluorescence of the extract in different organs of mothers and fetuses. Male pups were divided into three treated groups, corresponding to the administration of the Hypericum extract to mothers at the dose levels of 36 mg/kg, 72 mg/kg and 144 mg/kg, and one control group in which the mothers received distilled water. At 90 days of age, the offspring underwent the following tests: rotarod, pentobarbital-induced sleep time, elevated plus maze, hole-board and forced swimming test. The observed fluorescence indicated the presence of the extract in all tissues analyzed. The obtained results suggest lasting changes in the performances displayed in the CNS, depression and anxiety tests, indicating that the use of Hypericum during gestation could interfere with the behavioral development of the offspring reducing anxiety and depression when they become adults. We suggest that these alterations are associated with the reprogramming of the brain regions related to changes in emotional reactivity.

Evaluation of postpartum behaviour in rats treated with Hypericum perforatum during gestation

Gestational depression is detrimental to the health of the mother and the offspring and contributes to the appearance of depressive and anxiety symptoms during the postnatal period. Traditional antidepressants have undesirable side effects when utilised during gestation, but Hypericum perforatum has been characterised as an efficient and safe antidepressant that prevents the recurrence of symptoms. This study verified the effects of Hypericum perforatum on the behaviour of Wistar rats that were treated during gestation and evaluated 10 and 60 days post-treatment. Pregnant Wistar rats were divided into four groups of ten animals each: one control group that received distilled water and three treatment groups that were treated orally with 36, 72 or 144 mg/kg Hypericum perforatum extract. At 10 and 60 days after parturition and post-treatment, the rats were submitted to the holeboard, the tail suspension, and the forced swim tests. The animals treated with 144 mg/kg Hypericum perforatum exhibited greater head-dipping activity in the hole-board test and reduced immobility in the tail suspension and forced swim tests, suggesting less anxiety and depression 10 and 60 days post-treatment.The results indicated that treating rats with Hypericum perforatum during the gestational period decreased depressive behaviour and anxiety 10 and 60 days post-treatment.