Early infant HIV diagnosis and entry to HIV care cascade in Thailand: an observational study

Background: Early infant diagnosis of HIV is crucial for timely initiation of antiretroviral therapy (ART) in infected children who are at high risk of mortality. Early infant diagnosis with dried blood spot testing was provided by the National AIDS Programme in Thailand from 2007. We report ART initiation and vital status in children with HIV after 7 years of rollout in Thailand. / Methods: Dried blood spot samples were collected from HIV-exposed children in hospitals in Thailand and mailed to the Faculty of Associated Medical Sciences, Chiang Mai University, where HIV DNA was assessed with real-time PCR to establish HIV infection. We linked data from children with an HIV infection to the National AIDS Programme database to ascertain ART and vital status. / Findings: Between April 5, 2007, and Oct 1, 2014, 16 046 dried blood spot samples were sent from 8859 children in 364 hospitals in Thailand. Median age at first dried blood spot test was 2·1 (IQR 1·8–2·5) months. Of 7174 (81%) children with two or more samples, 223 (3%) were HIV positive (including five unconfirmed). Of 1685 (19%) children with one sample, 70 (4%) were unconfirmed positive. Of 293 (3%) children who were HIV positive, 220 (75%) registered for HIV care and 170 (58%) initiated ART. Median age at ART initiation decreased from 14·2 months (IQR 10·2–25·6) in 2007 to 6·1 months (4·2–9·2) in 2013, and the number of children initiating ART aged younger than 1 year increased from five (33%) of 15 children initiating ART in 2007 to ten (83%) of 12 initiating ART in 2013. 15 (9%) of 170 children who initiated ART died and 16 (32%) of 50 who had no ART record died. / Interpretation: Early infant diagnosis with dried blood spot testing had high uptake in primary care settings. Further improvement of linkage to HIV care is needed to ensure timely treatment of all children with an HIV infection

Restricted Genetic Diversity of HIV-1 Subtype C Envelope Glycoprotein from Perinatally Infected Zambian Infants

Background: Mother-to-child transmission of HIV-1 remains a significant problem in the resource-constrained settings where anti-retroviral therapy is still not widely available. Understanding the earliest events during HIV-1 transmission and characterizing the newly transmitted or founder virus is central to intervention efforts. In this study, we analyzed the viral env quasispecies of six mother-infant transmission pairs (MIPs) and characterized the genetic features of envelope glycoprotein that could influence HIV-1 subtype C perinatal transmission. Methodology and Findings: The V1-V5 region of env was amplified from 6 MIPs baseline samples and 334 DNA sequences in total were analyzed. A comparison of the viral population derived from the mother and infant revealed a severe genetic bottleneck occurring during perinatal transmission, which was characterized by low sequence diversity in the infant. Phylogenetic analysis indicates that most likely in all our infant subjects a single founder virus was responsible for establishing infection. Furthermore, the newly transmitted viruses from the infant had significantly fewer potential N-linked glycosylation sites in Env V1-V5 region and showed a propensity to encode shorter variable loops compared to the nontransmitted viruses. In addition, a similar intensity of selection was seen between mothers and infants with a higher rate of synonymous (dS) compared to nonsynonymous (dN) substitutions evident (dN/dS\u3c1). Conclusions: Our results indicate that a strong genetic bottleneck occurs during perinatal transmission of HIV-1 subtype C. This is evident through population diversity and phylogenetic patterns where a single viral variant appears to be responsible for infection in the infants. As a result the newly transmitted viruses are less diverse and harbored significantly less glycosylated envelope. This suggests that viruses with the restricted glycosylation in envelope glycoprotein appeared to be preferentially transmitted during HIV-1 subtype C perinatal transmission. In addition, our findings also indicated that purifying selection appears to predominate in shaping the early intrahost evolution of HIV-1 subtype C envelope sequences

HIV-Specific Antibodies Capable of ADCC Are Common in Breastmilk and Are Associated with Reduced Risk of Transmission in Women with High Viral Loads

There are limited data describing the functional characteristics of HIV-1 specific antibodies in breast milk (BM) and their role in breastfeeding transmission. The ability of BM antibodies to bind HIV-1 envelope, neutralize heterologous and autologous viruses and direct antibody-dependent cell cytotoxicity (ADCC) were analyzed in BM and plasma obtained soon after delivery from 10 non-transmitting and 9 transmitting women with high systemic viral loads and plasma neutralizing antibodies (NAbs). Because subtype A is the dominant subtype in this cohort, a subtype A envelope variant that was sensitive to plasma NAbs was used to assess the different antibody activities. We found that NAbs against the subtype A heterologous virus and/or the woman's autologous viruses were rare in IgG and IgA purified from breast milk supernatant (BMS) – only 4 of 19 women had any detectable NAb activity against either virus. Detected NAbs were of low potency (median IC50 value of 10 versus 647 for the corresponding plasma) and were not associated with infant infection (p = 0.58). The low NAb activity in BMS versus plasma was reflected in binding antibody levels: HIV-1 envelope specific IgG titers were 2.2 log10 lower (compared to 0.59 log10 lower for IgA) in BMS versus plasma. In contrast, antibodies capable of ADCC were common and could be detected in the BMS from all 19 women. BMS envelope-specific IgG titers were associated with both detection of IgG NAbs (p = 0.0001)and BMS ADCC activity (p = 0.014). Importantly, BMS ADCC capacity was inversely associated with infant infection risk (p = 0.039). Our findings indicate that BMS has low levels of envelope specific IgG and IgA with limited neutralizing activity. However, this small study of women with high plasma viral loads suggests that breastmilk ADCC activity is a correlate of transmission that may impact infant infection risk

The role of neutralizing antibodies in prevention of HIV-1 infection: what can we learn from the mother-to-child transmission context?

International audienceIn most viral infections, protection through existing vaccines is linked to the presence of vaccine-induced neutralizing antibodies (NAbs). However, more than 30 years after the identification of AIDS, the design of an immunogen able to induce antibodies that would neutralize the highly diverse HIV-1 variants remains one of the most puzzling challenges of the human microbiology. The role of antibodies in protection against HIV-1 can be studied in a natural situation that is the mother-to-child transmission (MTCT) context. Indeed, at least at the end of pregnancy, maternal antibodies of the IgG class are passively transferred to the fetus protecting the neonate from new infections during the first weeks or months of life. During the last few years, strong data, presented in this review, have suggested that some NAbs might confer protection toward neonatal HIV-1 infection. In cases of transmission, it has been shown that the viral population that is transmitted from the mother to the infant is usually homogeneous, genetically restricted and resistant to the maternal HIV-1-specific antibodies. Although the breath of neutralization was not associated with protection, it has not been excluded that NAbs toward specific HIV-1 strains might be associated with a lower rate of MTCT. A better identification of the antibody specificities that could mediate protection toward MTCT of HIV-1 would provide important insights into the antibody responses that would be useful for vaccine development. The most convincing data suggesting that NAbs migh confer protection against HIV-1 infection have been obtained by experiments of passive immunization of newborn macaques with the first generation of human monoclonal broadly neutralizing antibodies (HuMoNAbs). However, these studies, which included only a few selected subtype B challenge viruses, provide data limited to protection against a very restricted number of isolates and therefore have limitations in addressing the hypervariability of HIV-1. The recent identification of highly potent second-generation cross-clade HuMoNAbs provides a new opportunity to evaluate the efficacy of passive immunization to prevent MTCT of HIV-1

Envelope glycoproteins of Human Immunodeficiency Virus type 1 variants issued from mother-infant pairs display a wide spectrum of biological properties

Several studies have shown that the early virus population present in HIV-1 infected infants usually is homogeneous when compared to the highly diversified viral population present at delivery in their mothers. We explored the antigenic and functional properties of pseudotyped viruses expressing gp120 encoded by env clones issued from four mother-infant pairs infected by CRF01_AE viruses. We compared their sensitivity to neutralization and to entry inhibitors, their infectivity levels and the Env processing and incorporation levels. We found that both transmitted viruses present in infants and the variants present in their chronically infected mothers display a wide spectrum of biological properties that could not distinguish between them. In contrast, we found that all the transmitted viruses in the infants were more sensitive to neutralization by PG9 and PG16 than the maternal variants, an observation that may have implications for the development of prophylactic strategies to prevent mother-to-child transmission

Serologic characteristics of hepatitis B virus among hill-tribe children in Omkoi district, Chiangmai province, Thailand

Introduction: Thailand has integrated hepatitis B (HB) vaccination of newborns into the national Expanded Program on Immunization (EPI) in 1992. This has led to a dramatic decrease of HBsAg prevalence in children. However, HB vaccine coverage in remote areas is not well-known. This study aimed to investigate serologic characteristics of hepatitis B virus (HBV) among hill-tribe children in Omkoi District, Chiangmai Province, Thailand. Methodology: This cross-sectional study was conducted on stored samples collected from hill-tribe children attending the primary/secondary school in Omkoi District in December 2014. Sera were tested for HBsAg, anti-HBs and anti-HBc using enzyme immunoassays (MUREX, DiaSorin, Italy). Samples with anti-HBc positive were further assessed for HBV DNA using an in-house HBV DNA semi-nested polymerase chain reaction (PCR) assay. Results: Of 210 children evaluated, 4 (1.9%:95% CI 0.5-4.8) were HBsAg-positive. Of the 206 children HBsAg negative, 17 were anti-HBc and anti-HBs positive, 15 anti-HBc positive only, 26 anti-HBs positive only and 148 negative for both anti-HBc and anti-HBs. None of the children with anti-HBc were positive for HBV DNA. Conclusions: A high percentage of children had no markers of HBV protection suggesting that HB vaccine coverage was not optimal in this area. Our results warrant HBV serologic investigations in other remote areas to assess whether HB vaccine coverage needs to be improved and to identify children who should be vaccinated

Genetic analyses of HIV env associated with uveitis in antiretroviral-naive individuals

Objective: To analyze and compare HIV-1 env sequences from the eye to those from the blood of individuals with uveitis attributed to HIV with the goal of gaining insight into the pathogenesis of HIV-associated eye disease. Design: A prospective case series of five HIV-infected antiretroviral-naive individuals with uveitis negative for other pathogens. Methods: RNA from blood plasma and ocular aqueous humor was reverse transcribed using random hexamers. HIV env C2-V5 (HXB2: 6990-7668) sequences were generated by single-genome amplification using nested polymerase chain reaction followed by bidirectional Sanger sequencing. Sequence analyses by Geneious, Geno2Pheno, N-GLYCOSITE, DIVEIN, and HyPhy evaluated relationships between HIV in plasma and aqueous humor. Results: A median of 20 (range: 13-22) plasma and 15 (range: 9-18) aqueous humor sequences were generated from each individual. The frequencies of sequences with predicted-N-linked-glycosylation sites and C-X-C chemokine receptor type 4 were comparable in aqueous humor and plasma of all five patients. Aqueous humor sequences had lower median genetic diversity compared with plasma across all patients, but similar divergence, in four of five patients. Aqueous humor HIV sequences were compartmentalized from plasma across subjects by Critchlow correlation coefficient, Slatkin and Maddison, nearest-neighbor statistic, and Fixation index. Conclusion: Among antiretroviral-naive individuals with uveitis attributed to HIV, the universal compartmentalization and decreased diversity of eye compared with blood sequences suggests time-limited passage of a small subset of variants from each patient's viral population into the eye tissues, followed by limited immune selection despite the inflammatory uveitis