Dynamics of viral replication in infants with vertically acquired human immunodeficiency virus type 1 infection

What explains the poor contraction of the viral load during paediatric HIV infection?

An acute HIV infection in young children differs markedly from that in adults: Children have higher viral loads (VL), and a poor contraction to a setpoint VL that is not much lower than the peak VL. As a result, children progress faster towards AIDS in the absence of treatment. We used a classical ordinary differential equation model for viral infection dynamics to study why children have a lower viral contraction ratio than adults. We performed parameter sweeps to identify factors explaining the observed difference between children and adults. We grouped parameters associated with the host, the infection, or the immune response. Based on paediatric data available from datasets within the EPIICAL project (https://www.epiical.org/), we refuted that viral replication rates differ between young children and adults, and therefore these cannot be responsible for the low VL contraction ratios seen in children. The major differences in lowering VL contraction ratio resulted from sweeping the parameters linked to the immune response. Thus, we postulate that an "ineffective" (late and/or weak) immune response is the most parsimonious explanation for the higher setpoint VL in young children, and hence the reason for their fast disease progression.

Biological Aging and Immune Senescence in Children with Perinatally Acquired HIV

Chronic HIV-infected children suffer from premature aging and aging-related diseases. Viral replication induces an ongoing inflammation process, with the release of pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs), the activation of the immune system, and the production of proinflammatory cytokines. Although combined highly active antiretroviral therapy (ART) has significantly modified the natural course of HIV infection, normalization of T and B cell phenotype is not completely achievable; thus, many HIV-infected children display several phenotypical alterations, including higher percentages of activated cells, that favor an accelerated telomere attrition, and higher percentages of exhausted and senescent cells. All these features ultimately lead to the clinical manifestations related to premature aging and comorbidities typically observed in older general population, including non-AIDS-related malignancies. Therefore, even under effective treatment, the premature aging process of HIV-infected children negatively impacts their quality and length of life. This review examines the available data on the impact of HIV and ART on immune and biological senescence of HIV-infected children.

Redirection of Cord Blood T Cells and Natural Killer Cells for Elimination of Autologous HIV-1-Infected Target Cells Using Bispecific DART® Molecules

Mother-to-child transmission of HIV-1 remains a major global health challenge. Currently, HIV-1-infected infants require strict lifelong adherence to antiretroviral therapy to prevent replication of virus from reservoirs of infected cells, and to halt progression of disease. There is a critical need for immune interventions that can be deployed shortly after infection to eliminate HIV-1-infected cells in order to promote long-term remission of viremia, or to potentially cure pediatric HIV-1-infection. Bispecific HIV × CD3 DART® molecules able to co-engage the HIV-1 envelope protein on the surface of infected cells and CD3 on cytolytic T cells have been previously shown to eliminate HIV-1 infected cells in vitro and are candidates for passive immunotherapy to reduce the virus reservoir. However, their potential utility as therapy for infant HIV-1 infection is unclear as the ability of these novel antibody-based molecules to work in concert with cells of the infant immune system had not been assessed. Here, we use human umbilical cord blood as a model of the naïve neonatal immune system to evaluate the ability of HIV x CD3 DART molecules to recruit and redirect neonatal effector cells for elimination of autologous CD4⁺ T cells infected with HIV-1 encoding an envelope gene sequenced from a mother-to-child transmission event. We found that HIV × CD3 DART molecules can redirect T cells present in cord blood for elimination of HIV-infected CD4⁺ T cells. However, we observed reduced killing by T cells isolated from cord blood when compared to cells isolated from adult peripheral blood-likely due to the absence of the memory and effector CD8⁺ T cells that are most cytolytic when redirected by bispecific DART molecules. We also found that newly developed HIV × CD16 DART molecules were able to recruit CD16-expressing natural killer cells from cord blood to eliminate HIV-infected cells, and the activity of cord blood natural killer cells could be substantially increased by priming with IL-15. Our results support continued development of HIV-specific DART molecules using relevant preclinical animal models to optimize strategies for effective use of this immune therapy to reduce HIV-1 infection in pediatric populations.

Accelerated aging in perinatally HIV-infected children: clinical manifestations and pathogenetic mechanisms

Background: Premature aging and related diseases have been documented in HIV-infected adults. Data are now emerging also regarding accelerated aging process in HIV-infected children.

Methods: A narrative review was performed searching studies on PubMed published in English language in 2004-2017, using appropriate key words, including “aging”, “children”, “HIV”, “AIDS”, “immunosenescence”, “pathogenesis”, “clinical conditions”.

Results: Premature immunosenescence phenotype of B and T cells in HIV-infected children is mediated through immune system activation and chronic inflammation. Ongoing inflammation processes have been documented by increased levels of pathogen-associated molecular patterns (PAMPS), increased mitochondrial damage, higher levels of pro-inflammatory cytokines, and a positive correlation between sCD14 levels and percentages of activated CD8⁺ cells. Other reported features of premature aging include cellular replicative senescence, linked to an accelerated telomeres shortening. Finally, acceleration of age-associated methylation pattern and other epigenetic modifications have been described in HIV-infected children. All these features may favor the clinical manifestations related to premature aging. Lipid and bone metabolism, cancers, cardiovascular, renal, and neurological systems should be carefully monitored, particularly in children with detectable viremia and/or with CD4/CD8 ratio inversion.

Conclusion: Aging processes in children with HIV infection impact their quality and length of life. Further studies regarding the mechanisms involved in premature aging are needed to search for potential targets of treatment.

Prolonged Antiretroviral Therapy in Adolescents With Vertical HIV Infection Leads to Different Cytokine Profiles Depending on Viremia Persistence

BACKGROUND

We investigated immune activation, exhaustion markers and cytokine expression upon stimulation in adolescents with vertical HIV infection.

METHODS

Thirty adolescents receiving antiretroviral therapy (ART) for vertical HIV infection, including 12 with detectable viral load (HIV/DET), 18 with undetectable viral load (HIV/UND) and 30 control adolescents without HIV infection (CONTROL), were evaluated for immune activation and programmed cell death protein-1 expression by flow cytometry, and 21 cytokines by Luminex Multiple Analyte Profiling technology after in vitro peripheral blood phytohemagglutinin stimulation.

RESULTS

Lower CD4 T cells and higher T cell activation and exhaustion markers were noted on CD4 T and on CD8 T cells and memory subsets from HIV/DET group, who also produced lower in vitro IFN-gamma, IL-10, IL-13, IL-17A, IL-5 and IL-6 than HIV/UND group. HIV/UND were comparable with CONTROL group in respect to CD4 T cell counts and T cell activation and exhaustion markers, but with higher in vitro production of ITAC (a chemokine with leukocyte recruitment function), IL-4 and IL-23. An inverse correlation between cytokine production and programmed cell death protein-1 expression on CD4 T and CD8 T subsets was detected.

CONCLUSIONS

Persistent viremia despite ART leads to T cell activation and immune exhaustion with low cytokine production, whereas viral suppression by ART leads to parameters similar to CONTROL, although a different cytokine profile is observed, indicating residual HIV impact despite absence of detectable viremia.

Distinct gut microbiota profile in antiretroviral therapy-treated perinatally HIV-infected patients associated with cardiac and inflammatory biomarkers

OBJECTIVE

Persistent inflammation and higher risk to develop cardiovascular diseases still represent a major complication for HIV-infected patients despite effective antiretroviral therapy (ART). We investigated the correlation between the gut microbiota profile, markers of inflammation, vascular endothelial activation (VEA) and microbial translocation (MT) in perinatally HIV-infected patients (PHIV) under ART.

DESIGN

Cross-sectional study including 61 ART-treated PHIV (age range 3-30 years old) and 71 age-matched healthy controls. Blood and stool sample were collected at the same time and analyzed for gut microbiota composition and plasma biomarkers.

METHODS

Gut microbiota composition was determined by 16S rRNA targeted-metagenomics. Soluble markers of MT, inflammation and VEA were quantified by ELISA or Luminex assay. Markers of immune activation were analyzed by flow cytometry on CD4 and CD8T cells.

RESULTS

We identified two distinct gut microbiota profiles (groups A and B) among PHIV. No different clinical parameters (age, sex, ethnicity, clinical class), dietary and sexual habits were found between the groups. The group A showed a relative dominance of Akkermansia muciniphila, whereas gut microbiota of group B was characterized by a higher biodiversity. The analysis of soluble markers revealed a significantly higher level of soluble E-selectine (P = 0.0296), intercellular adhesion molecule-1 (P = 0.0028), vascular adhesion molecule-1 (P = 0.0230), IL-6 (P = 0.0247) and soluble CD14 (P = 0.0142) in group A compared with group B.

CONCLUSION

Distinctive gut microbiota profiles are differently associated with inflammation, microbial translocation and VEA. Future studies are needed to understand the role of A. muciniphila and risk to develop cardiovascular diseases in PHIV.

Impaired Development and Expansion of Germinal Center Follicular Th Cells in Simian Immunodeficiency Virus-Infected Neonatal Macaques

Germinal center (GC) CD4⁺ follicular Th (Tfh) cells are critical for cognate B cell help in humoral immune responses to pathogenic infections. Although Tfh cells are expanded or depleted in HIV/SIV-infected adults, the effects of pediatric HIV/SIV infection on Tfh cells remain unclear. In this study, we examined changes in lymphoid follicle formation in lymph nodes focusing on GC Tfh cells, B cell development, and differentiation in SIV-infected neonatal rhesus macaques (Macaca mulatta) compared with age-matched cohorts. Our data showed that follicles and GCs of normal infants rapidly formed in the first few weeks of age, in parallel with increasing GC Tfh cells in various lymphoid tissues. In contrast, GC development and GC Tfh cells were markedly impaired in SIV-infected infants. There was a very low frequency of GC Tfh cells throughout SIV infection in neonates and subsequent infants, accompanied by high viremia, reduction of B cell proliferation/resting memory B cells, and displayed proinflammatory unresponsiveness. These findings indicate neonatal HIV/SIV infection compromises the development of GC Tfh cells, likely contributing to ineffective Ab responses, high viremia, and eventually rapid disease progression to AIDS.

Occurrence of APOBEC3G variations in West Indian HIV patients

The genetic variations in APOBEC3G gene are correlated with HIV disease progression. These variations differ in different ethnic groups. The prevalence of APOBEC3G (-90C/G, -571G/C) variations have not been studied in Indian population. Hence, we assessed the occurrence of APOBEC3G polymorphisms in HIV patients and its association with acquisition of HIV and disease progression. Polymorphisms in APOBEC3G were genotyped in a total of 153 HIV patients, naïve to ARV and 156 healthy controls by PCR-RFLP method. In single locus model, the frequency of distribution of APOBEC3G -90CG, -571 GC genotypes were higher in HIV patients as compared to healthy controls (57.5% vs. 50.0%, OR = 1.22; 17.0% vs. 12.8%, OR = 1.39). In double locus model, the dominant -571 GC + CC genotype was distributed at a much higher frequency in HIV patients as compared to healthy controls (18.3% vs. 14.1%, OR = 1.50). The frequency of APOBEC3G -571CC and CC + GC genotypes were higher in early HIV disease stage as compared to healthy controls (23.9% vs. 12.8%, OR = 2.23, P = 0.08; 28.3% vs. 14.1%, OR = 2.40, P = 0.04). APOBEC3G-571 GC and GC + CC genotypes were more prevalent in HIV patients consuming tobacco and alcohol as compared to non-users (22.7% vs. 15.3%, OR = 1.71, P = 0.56; 27.3% vs. 16.5%, OR = 1.90, P = 0.39 and 31.6% vs. 13.6%, OR = 2.31, P = 0.08; 36.8% vs14.8%, OR = 2.49, P = 0.04, respectively). In conclusion, APOBEC3G-571G/C polymorphism was associated with the early stage of HIV infection and could potentially influence HIV disease progression in alcohol users. The distribution of APOBEC3G polymorphisms and its haplotypes were not significantly different between HIV patients and healthy controls.

Early antiretroviral therapy in HIV-infected infants: can it lead to HIV remission?

Interventions to prevent mother-to-child HIV transmission have been extremely successful, but new HIV infections continue to occur in infants. Strong evidence indicates that combination antiretroviral therapy (ART) for treatment should be started in HIV-infected infants to prevent early morbidity and mortality. In 2013, the report of the Mississippi baby, who was started on ART within 30 h of life and maintained off-treatment remission for 27 months before HIV was once again detectable, generated renewed interest in very early ART initiation. The case stimulated interest in the possibility of HIV remission, which we define as maintenance of plasma viraemia below the threshold of detection in the absence of ART, after early treatment initiation. The possibility of HIV remission elicits much hope, given that children with HIV infection currently face a lifetime of treatment. The potential for early ART to lead to HIV remission in infants can be thought of in terms of six factors: rapidity of viral suppression with very early ART; initial viral suppression rate with early ART; later virological control after early treatment; the effect of early treatment on the viral reservoir size; outcomes of randomised trials of structured treatment interruption; and the likelihood of viral rebound in neonates after ART cessation. Review of existing data suggests that achieving long-term remission off treatment remains elusive, and concentrated attention and commitment of the scientific community is needed to investigate the factors that might help to reach this goal.

Early Sites of Virus Replication After Oral SIVmac251 Infection of Infant Macaques: Implications for Pathogenesis

Despite optimization of preventative measures for vertical HIV-1 transmission, daily, roughly 400 infants become HIV infected, most of them through breastfeeding. Viral entry has been presumed to occur in the gastrointestinal tract; however, the exact entry site(s) have not been defined. Therefore, we quantified simian immunodeficiency virus (SIV) RNA and DNA in oral, intestinal, and systemic tissues of 15 infant macaques within 48-96 h after oral SIV_mac251 exposure. SIV DNA was detected as early as 48 h, whereas SIV RNA was typically detected at later time points (72-96 h). Transmitted founder viruses were identical or very similar to a single genotype in the SIV_mac251 challenge stock. SIV RNA and DNA were most frequently found in lymph nodes (LNs) draining the oral cavity and in the ileum. Using in situ hybridization, SIV-infected cells in LNs were exclusively represented by CD3⁺ T cells. SIV RNA and DNA were also detected in the lungs of 20% of the animals, and 60% of the animals had detectable SIV DNA in the cerebrum. The early detection of viral RNA or DNA in lung and brain tissues emphasizes the need for early treatment of pediatric HIV infection to prevent damage not only to the immune system but also to the respiratory tract and central nervous system.

Immune activation despite preserved CD4 T cells in perinatally HIV-infected children and adolescents

BACKGROUND

HIV disease progresses more rapidly in children than adults with mortality rates exceeding 50% by 2 years of age without antiretroviral therapy (ART) in sub-Saharan Africa. Recent World Health Organization (WHO) guidelines recommend universal treatment for all living persons with HIV, yet there is limited supporting evidence in pediatric populations. The objective of this study was to determine whether CD4 cell counts reflect immunological markers associated with disease progression in ART naïve perinatally-infected HIV+ children and adolescents and their response to ART.

METHODS

PBMC and plasma samples were collected from 71 HIV negative and 132 HIV+ children (65 ART naïve and 67 on ART) between ages 1-19 years from Mombasa, Kenya. Untreated HIV+ subjects were sub-categorized by high or low CD4 T cell counts. Immune activation markers CD38, HLA-DR and Ki67 were analyzed by flow cytometry. Plasma soluble CD14 (sCD14) was quantified by ELISA.

RESULTS

HIV-infected children and adolescents with preserved CD4 cell counts had depleted CD4 percentages and CD4:CD8 ratios, and high immune activation levels. ART initiation rapidly and persistently reversed T cell activation, but failed to normalize CD4:CD8 ratios and plasma sCD14 levels.

CONCLUSIONS

Diminished CD4 percentages and CD4:CD8 ratios along with profound immune activation occur independent of CD4 cell count thresholds in ART naïve HIV+ children and adolescents. Immediate ART initiation, as recommended in the most recent WHO guidelines may protect them from pathologic sequelae associated with persistent inflammation.

The pharmacological treatment of acute HIV infections in neonates

INTRODUCTION

Recent goals of antiretroviral treatment of neonates have expanded from reducing morbidity and mortality to also aiming to facilitate HIV remission. Areas covered: In this review, we present and discuss the rationale and evidence-bases for each of these distinct goals. Next we discuss the challenges of how to identify HIV-infected neonates. Finally, we discuss the specific antiretroviral drugs that are preferred for this group, making distinctions between the use of these agents in prevention and treatment. Expert commentary: The clinical and scientific challenges of pharmacological treatment of acute HIV infection in neonates are complicated by externalities beyond biology. At the same time, these challenges are energized by the unique biological opportunities afforded by investigating this population, including a unique immune profile, ability to study both mother and neonate as well as transmitted and acquired virus, and time period spanning both the period soon after infection as well as the period of viral reservoir establishment and related damage. Given the unique scientific opportunities afforded by study of pharmacologic treatment of acute HIV infection in neonates, we hypothesize that over the next five years breakthroughs may occur that may lead to new interventions effective at achieving HIV remission.

APOBEC3B deletion impacts on susceptibility to acquire HIV-1 and its advancement among individuals in western India

APOBEC3B deletion polymorphism has been associated with risk of HIV-1 acquisition and its progression. Therefore, we aimed to investigate the association of APOBEC3B ins/del polymorphism with risk of acquisition of HIV-1 and its progression. In the present case-control study, we enrolled a total of 150 HIV-infected individuals and 150 healthy controls. Polymorphism for APOBEC3B gene was genotyped by PCR. APOBEC3B ID, DD genotypes, and D allele were associated with higher risk of acquisition of HIV-1 (p = 0.004, OR = 4.96; p = 0.03, OR = 3.55; and p = 0.004; OR = 1.60). The individuals with ID genotypes and combined genotype ID+DD of APOBEC3B in the presence of tobacco and alcohol showed the higher risk of advancement of HIV disease; however, risk could not reach statistical significance (OR = 1.14, 95% CI: 0.59-2.18; OR = 1.33, 95% CI: 0.83-2.15 and OR = 1.44, 95% CI: 0.77-2.69; OR = 1.50, 95% CI: 0.94-2.40). Individuals in advanced HIV disease stage and ID genotype and combined genotype ID + DD of APOBEC3B were more likely to be associated with advanced HIV disease stage but risk could not reach significant (OR = 1.50, 95% CI: 0.94-2.40; OR = 1.27, 95% CI: 0.88-1.84). Individuals with ID and DD genotype of APOBEC3B had influence on susceptibility to acquisition of HIV-1. This suggests that APOBEC3B deletion may attenuate innate cellular immunity against HIV-1 and thus confer the host persistence for HIV infection.

Premature aging and immune senescence in HIV-infected children

Supplemental Digital Content is available in the text

Several pieces of evidence indicate that HIV-infected adults undergo premature aging. The effect of HIV and antiretroviral therapy (ART) exposure on the aging process of HIV-infected children may be more deleterious since their immune system coevolves from birth with HIV.

Immune activation and paediatric HIV-1 disease outcome

PURPOSE OF REVIEW

The paediatric HIV epidemic is changing. Over the past decade, new infections have substantially reduced, whereas access to antiretroviral therapy (ART) has increased. Overall this success means that numbers of children living with HIV are climbing. In addition, the problems observed in adult infection resulting from chronic inflammation triggered by persistent immune activation even following ART mediated suppression of viral replication are magnified in children infected from birth.

RECENT FINDINGS

Features of immune ontogeny favour low immune activation in early life, whereas specific aspects of paediatric HIV infection tend to increase it. A subset of ART-naïve nonprogressing children exists in whom normal CD4 cell counts are maintained in the setting of persistent high viremia and yet in the context of low immune activation. This sooty mangabey-like phenotype contrasts with nonprogressing adult infection which is characterized by the expression of protective HLA class I molecules and low viral load. The particular factors contributing to raised or lowered immune activation in paediatric infection, which ultimately influence disease outcome, are discussed.

SUMMARY

Novel strategies to circumvent the unwanted long-term consequences of HIV infection may be possible in children in whom natural immune ontogeny in early life militates against immune activation. Defining the mechanisms underlying low immune activation in natural HIV infection would have applications beyond paediatric HIV.

Coding region variant 186H/R in Exon 4 of APOBEC3G among individuals of Western India

The allelic variations in the AIDS restriction genes have been associated with the acquisition of HIV-1 and its progression. The distribution of antiviral gene variants significantly differs between populations. Therefore, we aimed to evaluate the distribution of variant allele of 186H/R in exon4 of APOBEC3G between HIV infected individuals and healthy controls among western Indian.In the present cross-sectional study, we enrolled a total of 153 HIV-infected patients confirmed and 156 unrelated healthy individuals. Polymorphism for 186H/R in exon4 of APOBEC3G gene was genotyped by PCR-RFLP. With the frequency of 186HR heterozygous genotype of APOBEC3G was found to be 13% in healthy controls and none in HIV infected cases. The frequency of 186HH common genotype of APOBEC3G was observed higher in HIV infected individuals compared with healthy controls (100% vs 91.7%). The variant genotype 186RR in APOBEC3G was not found in both the groups. The frequency of 186R allele of APOBEC3G was found 4.16% in healthy controls and nil in HIV-infected cases. The frequency of 186H allele of APOBEC3G was found to be higher in HIV-infected cases compared with healthy controls (100% vs 95.83%). The frequency of 186R allele in exon4 of APOBEC3G was found to be 4.16% in healthy controls. This observation differs from the previous report published from North India stating the absence of 186R allele of APOBEC3G in the North Indian individuals. The variant 186H/R in exon4 of APOBEC3G was neither associated with risk of acquisition of HIV-1 nor its progression.

Host factors and early treatments to restrict paediatric HIV infection and early disease progression

A body of evidence indicates that a threshold level of the virus is required to establish systemic and persistent HIV infection in the host and that this level depends on virus-host interactions. Mother-to-child transmission (MTCT) of HIV is the main source of paediatric HIV infection and occurs when the host's immune system is still developing. Thus, innate resistance and immunity, rather than adaptive immune response, may be the main drivers in restricting the establishment of HIV reservoirs and the long-lived persistence of HIV infection in infants. Genetic variations in HIV co-receptors and their ligands, as well as in Toll-like receptors and defensins, key elements of innate immunity, have been demonstrated to influence the risk of perinatal HIV infection and disease progression in HIV-infected infants. Early treatments with combined antiretroviral therapy (cART) restrict paediatric infection by reducing the level of the transmitted/infecting virus to below the threshold required for the onset of immune response to the virus and also significantly reduce HIV reservoirs. However, despite long periods with no signs and symptoms of HIV infection, all early cART-treated children who later discontinued cART had a rebound of HIV, except for one case in whom a period of viral remission occurred. Which parameters predict viral remission or viral rebound after cART discontinuation? Could early cART prevent rather than just reduce the establishment of viral reservoirs? And, if so, how? Answers to these questions are also important in order to optimise the use of early cART in infants at high risk of HIV infection.

Effects of short-term intensive glycemic control on insulin, glucagon, and glucagon-like peptide-1 secretion in patients with Type 2 diabetes

BACKGROUND

Short-term intensive insulin therapy (IIT) in patients with Type 2 diabetes mellitus (T2DM) has beneficial effects on insulin secretion. However, IIT effect on glucagon and glucagon-like peptide-1 (GLP-1) secretion is unknown.

AIM

We evaluated short-term intensive glycemic control effects on insulin, glucagon, and GLP-1 secretory dynamics in T2DM.

MATERIALS AND METHODS

Twenty-six patients with T2DM were hospitalized and treated with IIT for 10-14 days. A meal tolerance test was performed before and after IIT and the differences in serum immunoreactive insulin (IRI) and C-peptide immunoreactivity (CPR) as well as plasma glucagon and active GLP-1 levels were evaluated.

RESULTS

Glycoalbumin levels decreased significantly from 23.0% before to 19.6% after IIT (p<0.001). However, pre- and post-IIT, IRI and CPR levels were not significantly different; post-IIT glucose levels were significantly decreased. The post-IIT glucagon levels at 0 and 60 min were lower than pre-IIT levels. Moreover, post- IIT area under the curve (AUC) of glucagon significantly reduced from 6755 ± 996 pg/dl · 60 min to 5796 ± 1074 pg/dl · 60 min (p<0.001). Furthermore, post-IIT GLP-1 levels and AUC were significantly higher than pre-IIT values.

CONCLUSIONS

Our results suggest that patients with T2DM who received shortterm IIT demonstrated decreased postprandial glucagon levels and increased GLP-1 levels following a meal tolerance test.

The Potentials of Fas Receptors and Ligands in Monitoring HIV-1 Disease in Children in Yaoundé, Cameroon

OBJECTIVE

Difficulties in systematically monitoring HIV viral load in resource-limited settings prompt the search for alternate approaches. The authors aimed at assessing the correlation between the plasma levels of soluble forms of Fas receptors (Fas) and Fas ligands (FasL) with standard indicators of HIV disease progression in children.

METHODS

Twenty-two HIV-1-positive children were enrolled in Yaounde. CD4 counts, CD4% counts, plasma levels of Fas, FasL, and HIV-1 RNA levels were assayed.

RESULTS

The correlation coefficients (P values) between FasL levels and each of HIV-1 viral load, CD4 counts, and CD4% were, respectively, .56 (.01), -.29 (.18), and .30 (.18). On the other hand, the respective correlation coefficients (P values) with Fas levels were .12 (.60), -.30 (.18), and -.29 (.19).

CONCLUSION

The significant correlation between levels of HIV-1 viral load and FasL suggests that the latter needs to be further studied as a potential biomarker to monitor HIV-1 disease progression in children in resource-limited setting.

The impact of HIV-1 infection and exposure on natural killer (NK) cell phenotype in Kenyan infants during the first year of life

Natural killer (NK) cells play an important role in the containment of HIV replication during primary infection, though their functions are impaired during chronic HIV infection. Infants experience more rapid HIV disease progression than adults, but contributions of infant NK cells to containing HIV infection are unknown. The aim of this study was to determine the impact of HIV infection on infant NK cell phenotype by evaluating samples and data from a cohort study of women and their infants, conducted in Nairobi, Kenya between 1999 and 2003. The percentage and phenotype of NK cells was evaluated longitudinally by multi-parameter flow cytometry over the first year of life in HIV-infected (HIV+, = 16), HIV-exposed uninfected (HIV-EU, n = 6), and healthy unexposed controls (HIV–, n = 4). At birth, NK subset distributions based on expression of CD56 and CD16 did not differ between HIV+, HIV-EU, or HIV– infants. However, HIV infection was associated with a subsequent decline in NK cells as a percentage of total lymphocytes (p < 0.001), and an expanding proportion of CD56-CD16+ NK cells (p < 0.001). Activated CD38^brightCD69+ NK cells were more frequent in the HIV+ infants, followed by HIV-EU and HIV- infants, in both CD56^dim (p = 0.005) and CD56^bright compartments (p = 0.03). HIV infection and exposure was also associated with a significant decline in the percentage of perforin-expressing NK cells in the CD56^dim compartment over the first year of life, with HIV+ infants losing approximately 2.5% (p < 0.001) and HIV-EU infants losing 3.0% (p = 0.01) of perforin+ cells per month. Thus, infant HIV infection is associated with alterations in NK cell subsets, activation, and cytolytic potential that could contribute to their poor control over HIV infection. Furthermore, exposure to HIV infection in infants who escaped infection is also associated with alterations in NK cells that may contribute to the reduced ability to fight infections that is observed in HIV-EU infants.

The role of genetic variants of Stromal cell-Derived Factor 1 in pediatric HIV-1 infection and disease progression

Stromal cell-Derived Factor 1 (SDF1) is the natural ligand of CXCR4, the coreceptor of HIV-1 X4 viruses. This study investigated the role of the single nucleotide polymorphism (SNP) rs1801157 (NM_000609.5:c.*519G>A) of the SDF1 gene in the natural history of mother-to-child transmission of HIV-1 and disease progression of HIV-1-infected children. The study was conducted in 428 children born to HIV-1-seropositive mothers, who had not undergone antiretroviral therapy (ART) during pregnancy, and in 120 HIV-1-infected children for whom the end-point was the onset of AIDS or the initiation of ART; 16 children developed early AIDS (<24 months of life), 13 from 24 to 84 months of age, and 14 had late AIDS (>84 months). The rs1801157 SNP was not associated with risk of perinatal infection in any genetic models tested. By contrast, this SNP influenced disease progression in a time-dependent manner. rs1801157 GA heterozygous children had a higher risk of late AIDS (HR = 6.3, 95%CI 1.9–20.7, p = 0.002) than children with the rs1801157 GG genotype. Children were studied for viral coreceptor usage at birth, after 84 months of age and/or at AIDS onset. While R5 viruses using CCR5 coreceptor were predominant at birth (94%) and at early AIDS (85%), viruses using CXCR4 coreceptor emerged during the course of infection and were detected in 49% of children older than 84 months and in 62% of late AIDS. The rs1801157 SNP did not influence the emergence of R5X4 viruses, but children with the rs1801157 GA genotype and R5X4 viruses were at significantly higher risk of late AIDS than children with rs1801157 GG genotype (OR = 8.0, 95% CI 1.2–52.2, p = 0.029). Our results indicate that the rs1801157 SNP does not influence perinatal infection, but impacts disease progression. This effect is time-dependent and linked to the coreceptor-usage of viral variants that undergo evolution during the course of HIV-1 infection.

Polymorphisms of innate immunity genes influence disease progression in HIV-1-infected children

Toll-like receptors (TLRs) and defensins (DEFs) play a crucial role in the host's innate immunity and may influence HIV-1 disease progression. We investigated the impact of TLR9 +1174G > A, 1635A > G and DEFβ1 -44C > G, -52G > A single nucleotide polymorphisms on the clinical outcome of 95 HIV-1-infected children. The TLR9 1635AG genotype and TLR9 [G;G] haplotype were associated with rapid disease progression, whereas the DEFβ1 -44CG genotype and DEFβ1 [G;G] haplotype correlated with a better clinical outcome.

HIV-1 envelope-dependent restriction of CXCR4-using viruses in child but not adult untransformed CD4+ T-lymphocyte lines

Phytohemagglutin-stimulated child and adult leukocytes equally supported CCR5-dependent (R5) and CXCR4-dependent (X4) HIV-1 replication. In contrast, when phytohemagglutin-stimulated leukocytes from either healthy or congenitally immunodeficient children were cultured on feeder cells, they well supported R5, but not X4 HIV-1 replication, whereas both viruses equally spread in adult cells maintained in similar conditions. Both child and adult cells showed similar levels of proliferation and surface expression of CD4, CCR5, CXCR4, CD25, CD69, and HLA-DR. Lack of X4 HIV-1 replication in child versus adult cells was not caused by a differential expression of several known HIV-1 restriction factors. Similar levels of HIV DNA synthesis occurred in child cells infected with R5 and X4 viruses up to 48 hours after infection when R5 HIV-1 showed a significantly superior capacity to spread in culture than X4 virus. Cultured child cells well supported single round vescicular stomatitis virus-G pseudotyped virus replication, whereas superinfection of R5-infected cells with X4 HIV-1 (or vice versa) rescued the replication of this latter virus. Thus, child cells exposed to feeder cell culture represent a novel model system in which the superior capacity of R5 versus X4 viruses to spread can be investigated in primary, untransformed CD4+ cells.

Mother-to-infant transmission of simian immunodeficiency virus is rare in sooty mangabeys and is associated with low viremia

Mother-to-child transmission of human immunodeficiency virus type 1 (HIV-1) occurs in utero, intrapartum, and through breastfeeding, with a cumulative rate of transmission of 35 to 40%. As a result, ∼ 400,000 children become infected each year. Little is known about mother-to-infant transmission (MTIT) during natural simian immunodeficiency virus (SIV) infection of sooty mangabeys (SMs) that typically is nonpathogenic despite high viral loads. In this study, we retrospectively investigated the rates of MTIT in a large colony of naturally SIV-infected SMs using serological (anti-SIV antibody by enzyme-linked immunosorbent assay [ELISA] and Western blot analysis) and virological (SIV(smm) real-time reverse transcription-PCR) methods. We examined 161 SM infants born to SIV-infected mothers and found that 150 (93.2%) were infected by non-MTIT (n = 120) or remained uninfected (n = 30). The remaining 11 SM infants (6.8%) were defined as acquiring SIV by presumptive MTIT based on (i) the presence of anti-SIV antibodies without seroreversion and (ii) a viral load of >500 copies/ml of serum in the first year of life. SM infants infected with SIV by presumptive MTIT did not show any increased morbidity or mortality, indicating that the infection is nonpathogenic even when acquired early in life. Interestingly, viral loads of SIV-infected SM infants with presumptive MTIT were 2-log lower than those of SIV-infected adult SMs living in the same colony (i.e., ∼ 1,000 and 100,000 copies/ml, respectively). These results indicate that MTIT is substantially less frequent in naturally SIV-infected SMs than in HIV-1-infected humans and results in nonpathogenic infection associated with low SIV viremia. Evolutionary pressure to reduce MTIT may have contributed to the restriction of SIV pathogenesis in natural hosts.

HIV-1 co-receptor usage: influence on mother-to-child transmission and pediatric infection

Viral CCR5 usage is not a predictive marker of mother to child transmission (MTCT) of HIV-1. CXCR4-using viral variants are little represented in pregnant women, have an increased although not significant risk of transmission and can be eventually also detected in the neonates. Genetic polymorphisms are more frequently of relevance in the child than in the mother. However, specific tissues as the placenta or the intestine, which are involved in the prevalent routes of infection in MTCT, may play an important role of selective barriers. The virus phenotype of the infected children, like that of adults, can evolve from R5 to CXCR4-using phenotype or remain R5 despite clinical progression to overt immune deficiency. The refined classification of R5 viruses into R5(narrow) and R5(broad) resolves the enigma of the R5 phenotype being associated with the state of immune deficiency. Studies are needed to address more in specific the relevance of these factors in HIV-1 MTCT and pediatric infection of non-B subtypes.

Simian immunodeficiency virus selectively infects proliferating CD4+ T cells in neonatal rhesus macaques

Infants infected with HIV have a more severe course of disease and persistently higher viral loads than HIV-infected adults. However, the underlying pathogenesis of this exacerbation remains obscure. Here we compared the rate of CD4(+) and CD8(+) T-cell proliferation in intestinal and systemic lymphoid tissues of neonatal and adult rhesus macaques, and of normal and age-matched simian immunodeficiency virus (SIV)-infected neonates. The results demonstrate infant primates have much greater rates of CD4(+) T-cell proliferation than adult macaques, and that these proliferating, recently "activated" CD4(+) T cells are infected in intestinal and other lymphoid tissues of neonates, resulting in selective depletion of proliferating CD4(+) T cells in acute infection. This depletion is accompanied by a marked increase in CD8(+) T-cell activation and production, particularly in the intestinal tract. The data indicate intestinal CD4(+) T cells of infant primates have a markedly accelerated rate of proliferation and maturation resulting in more rapid and sustained production of optimal target cells (activated memory CD4(+) T cells), which may explain the sustained "peak" viremia characteristic of pediatric HIV infection. Eventual failure of CD4(+) T-cell turnover in intestinal tissues may indicate a poorer prognosis for HIV-infected infants.

Detection of low levels of human immunodeficiency virus (HIV) may be critical for early diagnosis of pediatric HIV infection by use of dried blood spots

We compared a DNA-based assay with a total nucleic acid-based assay for early detection of infant human immunodeficiency virus (HIV) infection. The codetection of DNA and RNA did not result in an overall higher sensitivity compared to that of DNA alone. Discordant results were associated with low levels of HIV DNA, indicating that the sample amount may be critical.

Changes in the HIV type 1 envelope gene from non-subtype B HIV type 1-infected children in Kenya

A switch of coreceptor usage from CCR5 to CXCR4 occurs in about half of HIV-1-infected individuals in the natural course of infection. To investigate whether antiretroviral therapy (ART) enhances the coreceptor switch of HIV-1, we genotypically analyzed the env-V3 amino acid sequences from 81 HIV-1-infected children in Kenya whose plasma samples were obtained between 2000 and 2007. Of 41 children on ART, 35 had HIV-1 using CCR5 as a coreceptor at baseline. In 7 (20%) of them HIV-1 switched the coreceptor usage during the follow-up period. The mean duration of ART to the time of coreceptor switch was 2.6 years (range: 0.5-5.2). Of the remaining 40 children without ART, 32 had HIV-1 using CCR5 as a coreceptor at baseline and in 3 (9.4%) HIV-1 switched the coreceptor usage. The mean age of the children with HIV-1 coreceptor switch with and without ART was 7.3 and 9.7 years, respectively. The difference in the rate and age of coreceptor switch between treated and untreated children was not significant (p = 0.38 and 0.31, respectively). Of the HIV-1-infected children, 10 started ART by the age of 5 years (rapid progressors) and 23 did not need ART by the age of 10 years (slow progressors). The rate of coreceptor switch was strongly higher in rapid progressors (40%) than slow progressors (8.7%) (p = 0.053). These results suggest that switching of coreceptor usage from CCR5 to CXCR4 among HIV-1-infected children is not influenced by ART, but by factors responsible for rapid disease progression.

Early Therapy in HIV-1-Infected Children: Effect on HIV-1 Dynamics and HIV-1-Specific Immune Response

Background

Perinatal HIV-1 infection is acquired in the milieu of a developing immune system, leading to high levels of uncontrolled viral replication. Few data have been reported that address the viral dynamics and immunological response in infants who initiated aggressive antiretroviral therapy (ART) shortly after birth.

Methods

Six HIV-1-infected infants who started ART within 3 months of age were studied. The median follow-up was 61 months. Plasma HIV-1 RNA, cell-associated HIV-1 DNA, unspliced and multiply spliced HIV-1 mRNAs, HIV-1 antibodies, and CD4+ and CD8+ T-cell subsets were assessed in sequential peripheral blood samples. HIV-1 cellular immune response was measured by EliSpot assay.

Results

All children showed a decline in plasma viraemia to undetectable levels. HIV-1 DNA persisted in four children, but only two of these had detectable HIV-1 mRNA. All viral parameters remained persistently negative in two children. Only two children produced HIV-1 antibodies, while the others, after having lost maternal antibodies, remained seronegative. No HIV-1 cellular immune response was observed in any child. Therapy interruption was performed in two children: one HIV-1-seropositive and one HIV-1-seronegative with persistently undetectable levels of all viral parameters. Rebound of HIV-1 plasma viraemia in the seronegative child was more rapid and higher than that observed in the seropositive child.

Conclusions

Early ART treatment in infants modifies the natural course of infection by controlling HIV-1 replication and reducing viral load to below the threshold levels required for onset of HIV-1 immune response, but does not prevent the establishment of a reservoir of latently infected cells that precludes virus eradication.

Biological and genetic evolution of HIV type 1 in two siblings with different patterns of disease progression

To investigate the immunological and virological factors that may lead to different patterns of disease progression characteristic of HIV-1-infected children, two HIV-1-infected siblings, a slow and a fast progressor, were followed prospectively before the onset of highly active antiretroviral therapy. Viral coreceptor usage, including the use of CCR5/CXCR4 chimeric receptors, macrophage tropism, and sensitivity to the CC-chemokine RANTES, has been studied. An autologous and heterologous neutralizing antibody response has been documented using peripheral blood mononuclear cells- and GHOST(3) cell line-based assays. Viral evolution was investigated by env C2-V3 region sequence analysis. Although both siblings were infected with HIV-1 of the R5 phenotype, their viruses showed important biological differences. In the fast progressor there was a higher RANTES sensitivity of the early virus, an increased trend to change the mode of CCR5 receptor use, and a larger genetic evolution. Both children developed an autologous neutralizing antibody response starting from the second year with evidence of the continuous emergence of resistant variants. A marked viral genetic and phenotypic evolution was documented in the fast progressor sibling, which is accompanied by a high viral RANTES sensitivity and persistent neutralizing antibodies.

Immune reconstitution in human immunodeficiency virus type 1-infected children with different virological responses to anti-retroviral therapy

Immune repopulation, despite virological failure, often occurs in children under highly active anti-retroviral therapy (HAART). The aim of this study was to analyse the characteristics of immune repopulation and activation in children with and without virological response to HAART. Fourteen human immunodeficiency virus type 1 (HIV-1)-infected children with suppression of HIV-1 plasma viraemia (virological responders, VR) and 16 virological non-responders (VNR) to therapy were studied at baseline and after approximately 2 years of HAART. During therapy, CD4+ T cells increased in both groups, but were higher in the VR than in the VNR group. All CD4+ T cell subsets (naive, central memory, effector/memory and CD38+) increased significantly in VR children, while there was a significant increase only in naive cells in VNR children. Naive CD8+ T cells and T cell receptor rearrangement excision circles (TREC), an indicator of thymic output, increased in both VR and VNR children. Activated CD8+ CD38+ T cells decreased in VR but remained high in VNR children. Levels of circulating lipopolysaccharide (LPS), an indicator of microbial translocation, further increased in VNR children. In conclusion, HAART induced an increase in naive cells in all children, regardless of their virological response. However, the persistence of viraemia resulted in an impaired expansion of memory CD4+ T cells susceptible to HIV-1 infection, and together with the microbial translocation sustained the persistence of a high level of immune activation.

High frequency of rapid immunological progression in African infants infected in the era of perinatal HIV prophylaxis

OBJECTIVES

To determine the natural history of HIV infection following peripartum single-dose nevirapine (sd-NVP) prophylaxis in a resource-limited country, and to assess implications for antiretroviral therapy (ART) roll-out programmes.

METHODS

Infants of HIV-infected mothers in KwaZulu-Natal, South Africa, were tested on days 1 and 28 to detect intrauterine (IU) and intrapartum (IP) infection. Infant follow-up included monthly viral load and CD4 cell measurement. ART was initiated at infant CD4 cell% < or = 20%.

RESULTS

In 740 infants born to 719 HIV-infected women, mother-to-child transmission (MTCT) was 10.3% (69% IU, 31% IP). Median viral load was higher in mothers of infants infected IP than IU (279 000 versus 86 600 copies/ml; P = 0.039) and lower in mothers of uninfected infants (median 26 750 copies/ml; P < 0.001). Peak viraemia was higher in infants infected IP than IU (5 160 000 versus 984 000 copies/ml; P < 0.001). Median viral load at birth in IU-infected infants (155 000 copies/ml) fell 1.4 log to 6510 copies/ml by day 5 and was beneath the detection limit using dried blood spot analysis in 38% of infants. CD4 cell% declined rapidly, to < or = 20% in 70% and < or = 25% in 85% [current World Health Organization (WHO) criteria for initiating ART] of infants by 6 months.

CONCLUSIONS

MTCT was reduced by sd-NVP through an effect on IP transmission. Where MTCT occurred despite NVP, two-thirds of transmissions arose IU; IP-infected babies were born to mothers with very high viral load. Disease progression was particularly rapid, 85% infants meeting WHO criteria for ART within 6 months. These findings argue for more effective MTCT-prevention programmes in resource-limited countries.

Polymorphisms in Nef associated with different clinical outcomes in HIV type 1 subtype C-infected children

The human immunodeficiency virus type 1 (HIV-1) negative factor, or Nef, has a variety of functions that are important in viral pathogenesis. Sequence analysis has identified nef mutations that are linked to the rate of disease progression in adults and children infected with HIV-1 subtype B. Here we have sequenced and analyzed HIV-1 subtype C nef sequences from 34 children with rapid (RP) or slow progressing (SP) disease and identified polymorphisms associated with disease stage including motifs involved in specific pathogenic functions. Unlike subtype B, insertions and deletions in the N-terminal variable region were observed exclusively in SP children (8 out of 25). Strong positive selection pressures were found in sites of known functional importance among SP sequences, whereas RP had strong negative selection across the gene. A lineage analysis of selection pressures indicated weaker pressure across the nef gene in SP sequences bearing a deletion in region 8-12, suggesting this deletion has functional importance in vivo. Together these results suggest a differential adaptation of certain Nef functions related to disease progression, some of which may be attributable to immune-imposed pressures. These data broadly reflect previous studies on subtype B, corroborate the decreased cytopathicity of SP viruses, but also highlight potential subtype differences that require further investigation.

Viral dynamics after starting first-line HAART in HIV-1-infected children

BACKGROUND

After starting HAART, the plasma HIV-1 RNA (pVL) declines rapidly to undetectable levels in most treated adults and children. The viral dynamics in children are assumed to differ from those in adults. Therefore viral decay and time to reach a pVL of < 400 copies/ml during the first weeks after starting HAART were studied in a cohort of HIV-1-infected children.

METHODS

Viral decay expressed as half-life and time to reach a pVL of < 400 copies/ml in 39 HIV-1-infected children starting HAART were calculated and correlated with age, pretreatment with antiretroviral mono- or duo-therapy, and baseline pVL.

RESULTS

Baseline pVL correlated with age (r, -0.41; P = 0.01). Median half-life of the virus was 2.1 days (interquartile range, 1.8-3.0 days). No correlation was found between the half-life of the virus and the baseline pVL at the start of treatment, antiretroviral pretreatment or age. Eight children did not reach a pVL of < 400 copies/ml with the first allocated medication regimen. These children were significantly younger than those in whom HIV was successfully suppressed (P = 0.009). The remaining 31 children reached a pVL of < 400 copies/ml in a median of 8.1 weeks after the start of therapy; time to reach a pVL of < 400 copies/ml was only correlated with baseline pVL.

CONCLUSIONS

These results suggest that pVL at baseline correlated with age. HAART was able to suppress pVL below the lower limit of detection in children with a viral decay rate of 2.1 days, similar to adults and irrespective of baseline pVL.

Features of whey protein concentrate supplementation in children with rapidly progressive HIV infection

HIV infection is associated with subnormal GSH levels. An increase in glutathione levels has been observed in HIV-infected adults under oral whey protein supplementation. We studied the features associated with a whey protein concentrate supplementation in children with rapidly progressive AIDS. A prospective double-blind clinical trial was carried out for 4 months with 18 vertically HIV-infected children (1.98-6.37 years), under antiretroviral therapy, who had received whey protein, maltodextrin (placebo) or none. Erythrocyte glutathione concentration, T lymphocyte counts (CD4+ and CD8+) and occurrence of associated co-infections were evaluated. Wilcoxon's and Fischer's Exact tests were used to assess differences between whey protein-supplemented and control (placebo and non-supplemented) groups. A significant median increase of 16.14 mg/dl (p = 0.018) in erythrocyte glutathione levels was observed in the whey protein-supplemented group; the TCD4/CD8 lymphocyte ratio showed a non significant increase and lower occurrence of associated co-infections was also observed. In conclusion, whey protein concentrate supplementation can stimulate glutathione synthesis and, possibly, decrease the occurrence of associated co-infections.

Treatment of intestinal helminths does not reduce plasma concentrations of HIV-1 RNA in coinfected Zambian adults

BACKGROUND

Infection with intestinal helminths may stimulate dysfunctional immune responses in human immunodeficiency virus (HIV)-infected persons. Studies have yielded conflicting results regarding the impact of antihelminthic treatment on plasma concentrations of HIV-1 RNA.Methods. We conducted a prospective study of 54 HIV-1- and helminth-coinfected and 57 HIV-1-infected, helminth-uninfected asymptomatic adults living in Lusaka, Zambia, to assess the impact of antihelminthic treatment on plasma concentrations of HIV-1 RNA.

RESULTS

Median baseline viral load was 0.33 log(10) copies/mL lower in the helminth-infected group than in the uninfected group. Mean viral load between pretreatment and posttreatment visits increased in the helminth-infected (mean, 4.23 vs. 4.29 log(10) copies/mL; P=.6) and helminth-uninfected (mean, 4.39 vs. 4.52 log(10) copies/mL; P=.2) groups. Helminth-infected participants with high pretreatment viral loads had a mean 0.25-log(10) copies/mL decrease after treatment (P=.3), and helminth-uninfected participants had a mean 0.02-log(10) copies/mL decrease (P=.8).

CONCLUSIONS

We did not find an overall association between treatment of intestinal helminth infections and reduction in viral load in coinfected adults. Future studies may need to focus on adults with intense helminth infections who live in rural areas or on adults or children who harbor higher helminth burdens and plasma concentrations of HIV-1 RNA.

Longitudinal assessment of human immunodeficiency virus type 1 (HIV-1)-specific gamma interferon responses during the first year of life in HIV-1-infected infants

Human immunodeficiency virus type 1 (HIV-1) infection results in different patterns of viral replication in pediatric compared to adult populations. The role of early HIV-1-specific responses in viral control has not been well defined, because most studies of HIV-1-infected infants have been retrospective or cross-sectional. We evaluated the association between HIV-1-specific gamma interferon (IFN-gamma) release from the cells of infants of 1 to 3 months of age and peak viral loads and mortality in the first year of life among 61 Kenyan HIV-1-infected infants. At 1 month, responses were detected in 7/12 (58%) and 6/21 (29%) of infants infected in utero and peripartum, respectively (P = 0.09), and in approximately 50% of infants thereafter. Peaks of HIV-specific spot-forming units (SFU) increased significantly with age in all infants, from 251/10(6) peripheral blood mononuclear cells (PBMC) at 1 month of age to 501/10(6) PBMC at 12 months of age (P = 0.03), although when limited to infants who survived to 1 year, the increase in peak HIV-specific SFU was no longer significant (P = 0.18). Over the first year of life, infants with IFN-gamma responses at 1 month had peak plasma viral loads, rates of decline of viral load, and mortality risk similar to those of infants who lacked responses at 1 month. The strength and breadth of IFN-gamma responses at 1 month were not significantly associated with viral containment or mortality. These results suggest that, in contrast to HIV-1-infected adults, in whom strong cytotoxic T lymphocyte responses in primary infection are associated with reductions in viremia, HIV-1-infected neonates generate HIV-1-specific CD8+-T-cell responses early in life that are not clearly associated with improved clinical outcomes.

Pediatric viral human immunodeficiency virus type 1 RNA levels, timing of infection, and disease progression in African HIV-1-infected children

OBJECTIVE

To describe plasma human immunodeficiency virus type 1 (HIV-1) RNA levels in African HIV-1-infected children in relation to the timing of infection and disease progression.

METHODS

A retrospective cohort study was conducted of 80 children who were born to HIV-1-positive mothers and clinically followed from birth to 18 months of age in the ANRS 049 Ditrame project, Abidjan, Côte d'Ivoire (West Africa). The diagnosis and timing of pediatric HIV-1 infection were determined prospectively according to HIV-1 DNA polymerase chain reaction results. A total of 364 HIV-1 RNA viral load (VL) measurements were assessed retrospectively. Kaplan-Meier analyses and proportional hazards models were used to evaluate the prognostic value of pediatric VL and covariates for HIV disease progression or death.

RESULTS

Mean initial positive VL was significantly lower among children who were infected in utero (4.94 log10/mL, n = 12) than in children who were infected later (5.6-6.1 log10/mL, n = 68). In the first 6 months after diagnosis, HIV-1 RNA levels peaked (> or =6 log10/mL), regardless of timing of infection. Then, a slow decline (overall slope, -0.076 log10 copies/mL/mo) was observed until 18 months of age. A 1 log10 higher value of the pediatric peak VL (risk ratio [RR]: 1.85; 95% confidence interval [CI]: 1.0-3.44) and of the maternal VL at delivery (RR: 1.90; CI: 1.16-3.12) were independently associated with an increased risk of rapid progression to acquired immune deficiency syndrome (AIDS) or death at 18 months of life (23 AIDS diagnoses and 31 deaths). Disease progression or death was more rapid for girls than for boys (RR: 2.26; CI: 1.39-4.96).

CONCLUSIONS

In Africa, pediatric HIV-1 RNA levels are very close to those described in industrialized countries and seem to be predictive of AIDS stage or death, as in industrialized countries. With antiretroviral therapy becoming more widely available, the early identification and monitoring of pediatric HIV disease remains of paramount importance in Africa.

Simian immunodeficiency virus infection in neonatal macaques

Children with human immunodeficiency virus infection often have higher viral loads and progress to AIDS more rapidly than adults. Since the intestinal tract is a major site of early viral replication and CD4(+) T-cell depletion in adults, we examined the effects of simian immunodeficiency virus (SIV) on both peripheral and intestinal lymphocytes from 13 neonatal macaques infected with SIVmac239. Normal neonates had more CD4(+) T cells and fewer CD8(+) T cells in all tissues than adults. Surprisingly, neonates had substantial percentages of CD4(+) T cells with an activated, memory phenotype (effector CD4(+) T cells) in the lamina propria of the intestine compared to peripheral lymphoid tissues, even when examined on the day of birth. Moreover, profound and selective depletion of jejunum lamina propria CD4(+) T cells occurred in neonatal macaques within 21 days of infection, which was preceded by large numbers of SIV-infected cells in this compartment. Furthermore, neonates with less CD4(+) T-cell depletion in tissues tended to have higher viral loads. The persistence of intestinal lamina propria CD4(+) T cells in some neonates with high viral loads suggests that increased turnover and/or resistance to CD4(+) T-cell loss may contribute to the higher viral loads and increased severity of disease in neonatal hosts.

Comparison of human immunodeficiency virus type 1 viral loads in Kenyan women, men, and infants during primary and early infection

Steady-state levels of human immunodeficiency virus type 1 (HIV-1) RNA in plasma reached at approximately 4 months postinfection are highly predictive of disease progression. Several studies have investigated viral levels in adults or infants during primary and early infection. However, no studies have directly compared these groups. We compared differences in peak and set point plasma HIV-1 RNA viral loads among antiretrovirus-naive Kenyan infants and adults for whom the timing of infection was well defined. Peak and set point viral loads were significantly higher in infants than in adults. We did not observe any gender-specific differences in viral set point in either adults or infants. However, infants who acquired HIV-1 in the first 2 months of life, either in utero, intrapartum, or through early breast milk transmission, had significantly higher set point HIV-1 RNA levels than infants who were infected after 2 months of age through late breast milk transmission or adults who were infected through heterosexual transmission.

Maternal health factors and early pediatric antiretroviral therapy influence the rate of perinatal HIV-1 disease progression in children

OBJECTIVE

To determine the relationship of maternal health factors and infant antiretroviral treatment to the risk of pediatric disease progression to AIDS or death by 24 months of age.

DESIGN

Prospective perinatal HIV-1 transmission and pediatric natural history study.

SETTING

Urban medical centers in four cities in the USA.

PARTICIPANTS

A total of 2656 pregnant and postpartum HIV-infected women enrolled in the Perinatal AIDS Collaborative Transmission Study (PACTS) and 360 children determined to be HIV-infected.

MAIN OUTCOME MEASURES

Pediatric AIDS or death by 24 months of age.

RESULTS

Children born to mothers with class C disease, CD4 cell count < 200 x 106/l, or HIV-1 RNA viral load > 100 000 copies/ml progressed more rapidly than children born to mothers with less advanced disease. In a multivariate analysis, there was an increased risk of progression if mothers had Class C disease [relative risk (RR), 1.7; 95% confidence interval (CI), 1.0-2.7] or HIV-1 RNA > 100 000 copies/ml (RR, 2.4; 95% CI, 1.2-4.6) controlling for child antiretroviral therapy and year of birth. Earlier years of birth significantly increased the likelihood of rapid progression (P = 0.01) in this multivariate model. Children who received combination antiretroviral therapies with a protease inhibitor or non-nucleoside reverse transcriptase inhibitor were significantly less likely to progress compared with those receiving no therapy (P = 0.03).

CONCLUSIONS

HIV-1-infected infants born to women with advanced HIV-1 disease were at increased risk for rapid disease progression. More recent birth year and early treatment with potent antiretroviral therapy significantly diminished the likelihood of developing AIDS or dying during early childhood.

HIV exposure: neonatal considerations

The presence of human immunodeficiency virus (HIV) in pregnant women puts infants at risk for exposure through placental infection and contact with contaminated maternal blood and genital secretions. Efforts to combat this inevitably fatal disease continue to focus on preventing transmission of the virus from a mother who has HIV to her newborn during the prenatal, intrapartum, and postnatal periods. Prophylaxis against transmission and vigilant assessment for indicators of infection are hallmarks of appropriate health care for infants exposed to HIV.

Immune reconstitution in HIV-1-infected children on antiretroviral therapy: role of thymic output and viral fitness

OBJECTIVE

To investigate the role of thymic output and viral fitness in immune reconstitution in HIV-1-infected children on antiretroviral therapy.

METHODS

Thymic output was studied by measuring levels of T-cell receptor rearrangement excision circles (TREC) in peripheral blood lymphocytes, using a real-time quantitative PCR assay. Recombinant viruses containing pre-therapy or post-therapy HIV-1 protease domains were evaluated for viral infectivity in a quantitative single-cycle assay.

RESULTS

Eighteen HIV-1-infected children who showed a significant increase in CD4 T-cell count after therapy were studied; HIV-1 plasma viraemia was substantially suppressed in 12 children (virological responders), but not in the other six (virological non-responders). TREC were quantified at baseline, and sequentially during the first 12 months of therapy. Both virological responders and non-responders showed an increase in TREC levels that was inversely correlated with baseline TREC and CD4 T cell counts. Changes in TREC positively correlated with CD4 T-cell count increases in virological responders, but not in non-responders; moreover, the ratios between TREC and CD4 T-cell count increases were higher in non-responders than in responders, suggesting a persistence of peripheral CD4 T-cell loss in the former. Drug-resistant viruses with reduced replicative capacity were documented in three out of six non-responders.

CONCLUSIONS

These findings indicate that recovery of thymic function is a pivotal event in immune reconstitution, and suggest that CD4 T-cell increase despite persistent viraemia is sustained by a continuous thymic output that compensates peripheral CD4 T-cell depletion which might be slowed down by emerging viruses with reduced fitness.

Coreceptor change appears after immune deficiency is established in children infected with different HIV-1 subtypes

Change of HIV-1 coreceptor use has been connected to progression of disease in children infected with HIV-1, presumably subtype B. It has not been possible to discern whether the appearance of new viral phenotypes precedes disease development or comes as a consequence of it. We studied the evolution of coreceptor use in HIV-1 isolates from 24 vertically infected children. Their clinical, virological, and immunological status was recorded and the env V3 subtype was determined by DNA sequencing. Coreceptor use was tested on human cell lines, expressing CD4 together with CCR5, CXCR4, and other chemokine receptors. The children carried five different env subtypes (nine A, five B, four C, three D, and one G) and one circulating recombinant form, CRF01_AE (n = 2). Of the 143 isolates, 86 originated from peripheral blood mononuclear cells (PBMCs) and 57 originated from plasma, received at 90 time points. In 52 of 54 paired plasma and PBMC isolates the coreceptor use was concordant. All 74 isolates obtained at 41 time points during the first year of life used CCR5. A change from use of CCR5 to use of CXCR4 occurred in four children infected with subtype A, D, or CRF01_AE after they had reached 1.5 to 5.8 years of age. There was a significant association with decreased CD4+ cell levels and severity of disease but, interestingly, the coreceptor change appeared months or even years after the beginning of the immunological deterioration. Thus CXCR4-using virus may emerge as a possible consequence of immune deficiency. The results provide new insights into AIDS development in children.

Timing of perinatal human immunodeficiency virus type 1 infection and rate of neurodevelopment. The Women and Infant Transmission Study Group

BACKGROUND

Identifying HIV-1-infected children who are at greatest risk for disease-related morbidities is critical for optimal therapeutic as well as preventive care. Several factors have been implicated in HIV-1 disease onset and severity, including maternal and infant host characteristics, viral phenotype and timing of HIV-1 infection. Early HIV-1 culture positivity, i.e. intrauterine infection, has been associated with poor immunologic, virologic and clinical outcomes in children of HIV-infected women. However, a direct effect of timing of infection on neurodevelopmental outcome in infancy has not yet been identified.

METHODS

Serial neurodevelopmental assessments were performed with 114 infants vertically infected with HIV-1 in a multicenter natural history, longitudinal study. Median mental and motor scores were compared at three time points. Longitudinal regression analyses were used to evaluate the neurodevelopmental functioning of children with early positive cultures and those with late positive cultures.

RESULTS

Early infected infants scored significantly lower than late infected infants by 24 months of age and beyond on both mental (P = 0.05) and motor (P = 0.03) measures. Early HIV-1 infection was associated with a decline in estimated motor scores of 1 standard score point per month compared with 0.28 point in the late infected group (P < 0.02). Estimated mental scores of the early infected group declined 0.72 point/ month, whereas the average decline of the late infected group was 0.30 point/month (P < 0.13).

CONCLUSION

Early HIV-1 infection increases a child's risk for poor neurodevelopmental functioning within the first 30 months of life.

Co-receptor usage of HIV-1 primary isolates, viral burden, and CCR5 genotype in mother-to-child HIV-1 transmission

OBJECTIVE

To investigate the relationship between CC chemokine receptor 5 (CCR5) genotype, viral load and co-receptor usage of maternal HIV-1 isolates in perinatal HIV-1 transmission.

PATIENTS AND METHODS

A total of 181 mothers and infants were studied at the time of delivery. Wild-type (wt) and delta32 CCR5 alleles were determined by means of polymerase chain reaction (PCR). The viral load in maternal plasma samples was determined by a quantitative reverse transcriptase-PCR assay; co-receptor usage of maternal isolates was determined by viral infection in cells stably expressing CCR5 or CXC chemokine receptor 4 (CXCR4) co-receptors.

RESULTS

HIV-1 transmission rates in wt/wt and wt/delta32 mothers (14.7 versus 15.8%), and in wt/wt and wt/delta32 infants (14.6 versus 14.3%) were similar. Mothers transmitting infection to wt/delta32 infants had significantly higher HIV-1-RNA levels than those who transmitted infection to wt/wt infants (5.4 versus 4.1 log10 copies/ml, P = 0.03). In wt/wt children there was a positive relationship between transmission rate and maternal viral load over the entire range of HIV-1 values, whereas in wt/delta32 children transmission occurred only at viral loads greater than 4.0 log10 copies/ml. Logistic regression analysis confirmed that the relationship between viral load and transmission varied according to the child's CCR5 genotype (P = 0.035; adjusted for zidovudine prophylaxis and mode of delivery, P = 0.090). Moreover, the majority of wt/wt transmitting mothers had R5-type isolates, whereas none of the wt/delta32 mothers with an R5-type virus transmitted HIV-1 to their wt/delta32 infants.

CONCLUSION

Taken together, these findings suggest that CCR5 delta32 heterozygosity exerts a protective effect against perinatal transmission in children exposed to a low maternal viral burden of an R5-type isolate.

Relationship of CD4+ T cell counts and HIV type 1 viral loads in untreated, infected adolescents. Adolescent Medicine HIV/AIDS Research Network

The REACH Project (Reaching for Excellence in Adolescent Care and Health) of the Adolescent Medicine HIV/AIDS Research Network was designed as a study of an adolescent cohort composed of HIV-1-infected and -uninfected subjects. The goal of the analysis presented was to examine the relationship of CD4+ T cell counts and HIV-1 plasma viral loads in adolescents. The CD4+ T cell counts of 84 HIV+ subjects who were 13 to 19 years of age were measured at the clinical sites, using ACTG standardized techniques. HIV-1 viral loads in frozen plasma were determined by the NASBA/NucliSens assay at a central laboratory. Past and current treatment with antiretroviral drugs was determined by medical record abstraction and interview data. The slope of the line generated by regressing log10 HIV-1 RNA (copies/ml) versus CD4+ T cell counts of REACH subjects who are antiretroviral drug naive was negative and significantly different than zero. A negative association has also been reported for antiretroviral drug-naive, adult males in the Pittsburgh Men's Study, a component of MACS (Pitt-MACS) (Mellors J, et al.: Science 1996;272:1167). These data show that in adolescents, as in adults, HIV-1 RNA concentrations are correlated with corresponding absolute CD4+ T cell count. The slopes of the lines generated with data from each cohort were different (p = 0.003). In addition to age, there are sex and racial differences in the makeup of the two cohorts. Any or all of these differences may affect the slopes of the lines.