Humoral profiles of toddlers and young children following SARS-CoV-2 mRNA vaccination.

Although young children generally experience mild symptoms following infection with SARS-CoV-2, severe acute and long-term complications can occur. SARS-CoV-2 mRNA vaccines elicit robust immunoglobulin profiles in children ages 5 years and older, and in adults, corresponding with substantial protection against hospitalizations and severe disease. Whether similar immune responses and humoral protection can be observed in vaccinated infants and young children, who have a developing and vulnerable immune system, remains poorly understood. To study the impact of mRNA vaccination on the humoral immunity of infant, we use a system serology approach to comprehensively profile antibody responses in a cohort of children ages 6 months to 5 years who were vaccinated with the mRNA-1273 COVID-19 vaccine (25 µg). Responses are compared with vaccinated adults (100 µg), in addition to naturally infected toddlers and young children. Despite their lower vaccine dose, vaccinated toddlers elicit a functional antibody response as strong as adults, with higher antibody-dependent phagocytosis compared to adults, without report of side effects. Moreover, mRNA vaccination is associated with a higher IgG3-dependent humoral profile against SARS-CoV-2 compared to natural infection, supporting that mRNA vaccination is effective at eliciting a robust antibody response in toddlers and young children.

IgA coating of vaginal bacteria is reduced in the setting of bacterial vaginosis (BV) and preferentially targets BV-associated species.

Immunoglobulin (Ig) bacterial coating has been described in the gastrointestinal tract and linked to inflammatory bowel disease; however, little is known about Ig coating of vaginal bacteria and whether it plays a role in vaginal health including bacterial vaginosis (BV). We examined Ig coating in 18 women with symptomatic BV followed longitudinally before, 1 week, and 1 month after oral metronidazole treatment. Immunoglobulin A (IgA) and/or immunoglobulin G (IgG) coating of vaginal bacteria was assessed by flow cytometry, and Ig coated and uncoated bacteria were sorted and characterized using 16S rRNA sequencing. Despite higher levels of IgG compared to IgA in cervicovaginal fluid, the predominant Ig coating the bacteria was IgA. The majority of bacteria were uncoated at all visits, but IgA coating significantly increased after treatment for BV. Despite similar amounts of uncoated and IgA coated majority taxa ( >1% total) across all visits, there was preferential IgA coating of minority taxa (0.2%-1% total) associated with BV including Sneathia, several Prevotella species, and others. At the time of BV, we identified a principal component (PC) driven by proinflammatory mediators that correlated positively with an uncoated BV-associated bacterial community and negatively with an IgA coated protective Lactobacillus bacterial community. The preferential coating of BV-associated species, increase in coating following metronidazole treatment, and positive correlation between uncoated BV-associated species and inflammation suggest that coating may represent a host mechanism designed to limit bacterial diversity and reduce inflammatory responses. Elucidating the role of Ig coating in vaginal mucosal immunity may promote new strategies to prevent recurrent BV.

Humoral profiles of toddlers and young children following SARS-CoV-2 mRNA vaccination.

Although young children generally experience mild symptoms following infection with SARS-CoV-2, severe acute and long-term complications can occur. SARS-CoV-2 mRNA vaccines elicit robust immunoglobulin profiles in children ages 5 years and older, and in adults, corresponding with substantial protection against hospitalizations and severe disease. Whether similar immune responses and humoral protection can be observed in vaccinated infants and young children, who have a developing and vulnerable immune system, remains poorly understood. To study the impact of mRNA vaccination on the humoral immunity of infant, we used a system serology approach to comprehensively profile antibody responses in a cohort of children ages 6 months to 5 years who were vaccinated with the mRNA-1273 COVID-19 vaccine (25 µg). Responses were compared with vaccinated adults (100 µg), in addition to naturally infected toddlers and young children. Despite their lower vaccine dose, vaccinated toddlers elicited a stronger functional antibody response than adults, including against variant of concerns (VOCs), without report of side effects. Moreover, mRNA vaccination was associated with a higher IgG3-dependent humoral profile against SARS-CoV-2 compared to natural infection, supporting that mRNA vaccination is effective at eliciting a robust antibody response in toddlers and young children.

Antibodies against the Ebola virus soluble glycoprotein are associated with long-term vaccine-mediated protection of non-human primates.

The 2013 Ebola epidemic in Central and West Africa heralded the emergence of wide-spread, highly pathogenic viruses. The successful recombinant vector vaccine against Ebola (rVSVΔG-ZEBOV-GP) will limit future outbreaks, but identifying mechanisms of protection is essential to protect the most vulnerable. Vaccine-induced antibodies are key determinants of vaccine efficacy, yet the mechanism by which vaccine-induced antibodies prevent Ebola infection remains elusive. Here, we exploit a break in long-term vaccine efficacy in non-human primates to identify predictors of protection. Using unbiased humoral profiling that captures neutralization and Fc-mediated functions, we find that antibodies specific for soluble glycoprotein (sGP) drive neutrophil-mediated phagocytosis and predict vaccine-mediated protection. Similarly, we show that protective sGP-specific monoclonal antibodies have elevated neutrophil-mediated phagocytic activity compared with non-protective antibodies, highlighting the importance of sGP in vaccine protection and monoclonal antibody therapeutics against Ebola virus.

A Practical Approach to Congenital Urogenital Anomalies in Female Pediatric Patients.

Congenital anomalies of the female reproductive tract are relatively common and can be both confusing to understand as well as challenging to diagnose and manage in a busy pediatric clinical practice. Here, we lay out some of the most common genitourinary tract anomalies in female pediatric patients. We highlight the key embryologic development, present case examples, and discuss appropriate testing, treatment, and counseling for patients and their families regarding congenital disorders of the vulva, vagina, uterus, ovaries, and associated pathology. The goal of this review is to demystify these conditions and provide a practical guide for the general pediatrician who is often at the frontline making the initial diagnosis and caring for these patients. [Pediatr Ann. 2020;49(4):e188-e195.].

Transient Immune Activation in BCG-Vaccinated Infant Rhesus Macaques Is Not Sufficient to Influence Oral Simian Immunodeficiency Virus Infection.

BCG vaccination has been demonstrated to increase levels of activated CD4+ T cells, thus potentially influencing mother-to-child transmission of human immunodeficiency virus (HIV). To assess the risk of BCG vaccination in HIV infection, we randomly assigned newborn rhesus macaques to receive BCG vaccine or remain unvaccinated and then undergo oral simian immunodeficiency virus (SIV) challenges 3 weeks later. We observed elevated levels of activated peripheral CD4+ T cells (ie, HLA-DR+CD38+CCR5+ CD4+ T cells) by week 3 after vaccination. BCG was also associated with an altered immune gene expression profile, as well as with monocyte activation in both peripheral blood and the draining axillary lymph node, indicating significant BCG vaccine-induced immune activation. Despite these effects, BCG vaccination did not increase the rate of SIV oral transmission or disease progression. Our findings therefore identify patterns of T-cell and monocyte activation that occur after BCG vaccination but do not support the hypothesis that BCG vaccination is a risk factor for postnatal HIV transmission or increased pathogenesis in infants.

Tenofovir disoproxil fumarate intravaginal ring for HIV pre-exposure prophylaxis in sexually active women: a phase 1, single-blind, randomised, controlled trial.

BACKGROUND: An intravaginal ring that releases the tenofovir prodrug, tenofovir disoproxil fumarate, provided 100% protection in macaques against simian HIV and was safe in a 14-day clinical trial in sexually abstinent women. We aimed to assess the safety and pharmacokinetics of this intravaginal ring over 90 days in sexually active women. METHODS: We did a phase 1, single-blind, randomised, placebo-controlled trial to assess safety, pharmacokinetics, and acceptability of a tenofovir disoproxil fumarate intravaginal ring used continuously with monthly ring changes for 3 months. Sexually active women who were HIV negative were randomly assigned (3:1) to a tenofovir disoproxil fumarate ring or placebo ring. Primary safety endpoint was the proportion of women who had grade 2 or higher genitourinary adverse events judged related to study product and any grade 2 or higher adverse event as defined by the Division of AIDS Table for Grading the Severity of Adult and Pediatric Adverse Events. We quantified tenofovir disoproxil fumarate and tenofovir concentrations in cervicovaginal fluid, tenofovir in plasma, and tenofovir diphosphate, the active metabolite, in cervical tissue and dried blood spots 1 month after each ring insertion. We compared changes over time in cervicovaginal fluid cytokine and chemokine concentrations and vaginal microbiota. The study was electively stopped early and is registered with ClinicalTrials.gov, number NCT02762617. FINDINGS: Between Feb 24 and July 20, 2017, 17 women were enrolled before study termination. 12 were assigned to receive the tenofovir disoproxil fumarate ring and five were assigned to receive the placebo ring. Two participants in the tenofovir disoproxil fumarate ring group completed 3 months of continuous ring use; eight were asked to discontinue ring use early because of ulcerations (grade 1) near the ring; in the remaining two women, rings were electively removed by study staff on day 20 and day 23. Ulcers were detected a mean of 32 days after ring use (range 23-56). Four of eight participants with ulcers were symptomatic with vaginal discharge; four had ulcers identified when examined; three had two ulcers; all ulcers resolved after ring removal. No participants in the placebo group developed ulcers. No grade 2 product-related adverse events were reported in either group and four non-product-related grade 2 adverse events were reported in the tenofovir disoproxil fumarate ring group. Cervicovaginal fluid tenofovir concentrations did not differ at day 14 (p=0·14) comparing the eight patients who did (median 1·0 × 105 ng/mL [IQR 9·1 × 104-1·1 × 105]) with the four who did not (6·0 × 104 ng/mL [5·6 × 104-1·1 × 105]) develop ulcers. No significant changes in vaginal microbiota were detected in either group. Concentrations of multiple inflammatory cytokines and chemokines were significantly higher at days 14 and 28 compared with baseline in the tenofovir disoproxil fumarate ring group but not the placebo group. INTERPRETATION: Future studies are needed to establish whether the unanticipated finding of ulcerations is specific to this tenofovir disoproxil fumarate ring or generalisable to other sustained topical release formulations of tenofovir or its prodrugs. FUNDING: National Institutes of Health.

Feeding-Related Gut Microbial Composition Associates With Peripheral T-Cell Activation and Mucosal Gene Expression in African Infants.

Background: Exclusive breastfeeding reduces the rate of postnatal human immunodeficiency virus (HIV) transmission compared to nonexclusive breastfeeding; however, the mechanisms of this protection are unknown. Our study aimed to interrogate the mechanisms underlying the protective effect of exclusive breastfeeding. Methods: We performed a prospective, longitudinal study of infants from a high-HIV-prevalence, low-income setting in South Africa. We evaluated the role of any non-breast milk feeds, excluding prescribed medicines on stool microbial communities via 16S rRNA gene sequencing, peripheral T-cell activation via flow cytometry, and buccal mucosal gene expression via quantitative polymerase chain reaction assay. Results: A total of 155 infants were recruited at birth with mean gestational age of 38.9 weeks and mean birth weight of 3.2 kg. All infants were exclusively breastfed (EBF) at birth, but only 43.5% and 20% remained EBF at 6 or 14 weeks of age, respectively. We observed lower stool microbial diversity and distinct microbial composition in exclusively breastfed infants. These microbial communities, and the relative abundance of key taxa, were correlated with peripheral CD4+ T-cell activation, which was lower in EBF infants. In the oral mucosa, gene expression of chemokine and chemokine receptors involved in recruitment of HIV target cells to tissues, as well as epithelial cytoskeletal proteins, was lower in EBF infants. Conclusions: These data suggest that nonexclusive breastfeeding alters the gut microbiota, increasing T-cell activation and, potentially, mucosal recruitment of HIV target cells. Study findings highlight a biologically plausible mechanistic explanation for the reduced postnatal HIV transmission observed in EBF infants.

T Cell Activation in South African HIV-Exposed Infants Correlates with Ochratoxin A Exposure.

The introduction of non-breastmilk foods to HIV-infected infants is associated with increased levels of immune activation, which can impact the rate of HIV disease progression. This is particularly relevant in countries where mother-to-child transmission of HIV still occurs at unacceptable levels. The goal of this study was to evaluate the levels of the toxic food contaminant ochratoxin A (OTA) in HIV-exposed South African infants that are either breastfed or consuming non-breast milk foods. OTA is a common mycotoxin, found in grains and soil, which is toxic at high doses but has immunomodulatory properties at lower doses. Samples from HIV-exposed and HIV-unexposed infants enrolled in prospective observational cohort studies were collected and analyzed at birth through 14 weeks of age. We observed that infants consuming non-breast milk foods had significantly higher plasma levels of OTA at 6 weeks of age compared to breastfed infants, increasing until 8 weeks of age. The blood levels of OTA detected were comparable to levels observed in OTA-endemic communities. OTA plasma levels correlated with HIV target cell activation (CCR5 and HLADR expression on CD4+ T cells) and plasma levels of the inflammatory cytokine CXCL10. These findings provide evidence that elevated OTA levels in South African infants are associated with the consumption of non-breastmilk foods and activation of the immune system. Reducing infant OTA exposure has the potential to reduce immune activation and provide health benefits, particularly in those infants who are HIV-exposed or HIV-infected.

The oral mucosa immune environment and oral transmission of HIV/SIV.

The global spread of human immunodeficiency virus (HIV) is dependent on the ability of this virus to efficiently cross from one host to the next by traversing a mucosal membrane. Unraveling how mucosal exposure of HIV results in systemic infection is critical for the development of effective therapeutic strategies. This review focuses on understanding the immune events associated with the oral route of transmission (via breastfeeding or sexual oral intercourse), which occurs across the oral and/or gastrointestinal mucosa. Studies in both humans and simian immunodeficiency virus (SIV) monkey models have identified viral changes and immune events associated with oral HIV/SIV exposure. This review covers our current knowledge of HIV oral transmission in both infants and adults, the use of SIV models in understanding early immune events, oral immune factors that modulate HIV/SIV susceptibility (including mucosal inflammation), and interventions that may impact oral HIV transmission rates. Understanding the factors that influence oral HIV transmission will provide the foundation for developing immune therapeutic and vaccine strategies that can protect both infants and adults from oral HIV transmission.

A comprehensive two-dimensional retention time alignment algorithm to enhance chemometric analysis of comprehensive two-dimensional separation data.

A comprehensive two-dimensional (2D) retention time alignment algorithm was developed using a novel indexing scheme. The algorithm is termed comprehensive because it functions to correct the entire chromatogram in both dimensions and it preserves the separation information in both dimensions. Although the algorithm is demonstrated by correcting comprehensive two-dimensional gas chromatography (GC x GC) data, the algorithm is designed to correct shifting in all forms of 2D separations, such as LC x LC, LC x CE, CE x CE, and LC x GC. This 2D alignment algorithm was applied to three different data sets composed of replicate GC x GC separations of (1) three 22-component control mixtures, (2) three gasoline samples, and (3) three diesel samples. The three data sets were collected using slightly different temperature or pressure programs to engender significant retention time shifting in the raw data and then demonstrate subsequent corrections of that shifting upon comprehensive 2D alignment of the data sets. Thirty 12-min GC x GC separations from three 22-component control mixtures were used to evaluate the 2D alignment performance (10 runs/mixture). The average standard deviation of first column retention time improved 5-fold from 0.020 min (before alignment) to 0.004 min (after alignment). Concurrently, the average standard deviation of second column retention time improved 4-fold from 3.5 ms (before alignment) to 0.8 ms (after alignment). Alignment of the 30 control mixture chromatograms took 20 min. The quantitative integrity of the GC x GC data following 2D alignment was also investigated. The mean integrated signal was determined for all components in the three 22-component mixtures for all 30 replicates. The average percent difference in the integrated signal for each component before and after alignment was 2.6%. Singular value decomposition (SVD) was applied to the 22-component control mixture data before and after alignment to show the restoration of trilinearity to the data, since trilinearity benefits chemometric analysis. By applying comprehensive 2D retention time alignment to all three data sets (control mixtures, gasoline samples, and diesel samples), classification by principal component analysis (PCA) substantially improved, resulting in 100% accurate scores clustering.