Isolation of a Human Anti-HIV gp41 Membrane Proximal Region Neutralizing Antibody by Antigen-Specific Single B Cell Sorting

Broadly neutralizing antibodies are not commonly produced in HIV-1 infected individuals nor by experimental HIV-1 vaccines. When these antibodies do occur, it is important to be able to isolate and characterize them to provide clues for vaccine design. CAP206 is a South African subtype C HIV-1-infected individual previously shown to have broadly neutralizing plasma antibodies targeting the envelope gp41 distal membrane proximal external region (MPER). We have now used a fluoresceinated peptide tetramer antigen with specific cell sorting to isolate a human neutralizing monoclonal antibody (mAb) against the HIV-1 envelope gp41 MPER. The isolated recombinant mAb, CAP206-CH12, utilized a portion of the distal MPER (HXB2 amino acid residues, 673–680) and neutralized a subset of HIV-1 pseudoviruses sensitive to CAP206 plasma antibodies. Interestingly, this mAb was polyreactive and used the same germ-line variable heavy (VH1-69) and variable kappa light chain (VK3-20) gene families as the prototype broadly neutralizing anti-MPER mAb, 4E10 (residues 672–680). These data indicate that there are multiple immunogenic targets in the C-terminus of the MPER of HIV-1 gp41 envelope and suggests that gp41 neutralizing epitopes may interact with a restricted set of naive B cells during HIV-1 infection

Heterogeneity in human reproduction: An analysis of seasonal and racial variation in birth outcomes

This dissertation is composed of three analyses examining the presence of seasonal and racial heterogeneity in human reproductive outcomes. The initial analysis represents the first multivariate examination of the extreme seasonality of births in Matlab, Bangladesh. A discrete-time hazards analysis is used to model the simultaneous effects of seasonal variation in labor-related migration, temperature, breast feeding cessation, and nutrition upon the monthly probability of conception. Seasonality in conceptions--and therefore births--is found to result from the synergistic effect of each of these influences upon the population fecundity level. The second analysis examines differences in the etiology of interuterine growth retarded and premature births for black and white residents of Philadelphia. A series of logistic regressions with race-interactive terms model the odds of the occurrence of either of these adverse birth outcomes. It is shown that the racial gap in the prevalence of intrauterine growth retarded and premature births stems both from race-specific differences in the effects and from levels of a set of demographic, behavioral, and medical risk factors. The final analysis goes into greater depth in examining the racial differences in gestational duration. Ordinary least squares and quantile regressions are used to show a three to four day shorter average gestational duration among blacks net of a set of social and medical controls. Additional ordinary least squares regressions are used to demonstrate higher mean birth weights and APGAR scores at younger gestational ages among black neonates. The hypothesis is proposed that this apparent increase in black neonatal fitness earlier in gestation may be the result of an evolutionary adaptation to chronic, endemic African malaria

Predictors of Compliance with the Postpartum Visit among Women Living in Healthy Start Project Areas

Objectives: Few studies have examined factors associated with compliance with a postpartum visit (PPV). The identification of such factors is of particular importance in populations with high rates of unintended pregnancies and medical complications of pregnancy. This study seeks to determine factors associated with compliance with a PPV among low-income women in the population served by fourteen Healthy Start sites. Methods: Data from the Healthy Start Survey of Postpartum Women were reviewed to identify variables associated with compliance with a PPV at or beyond 6 weeks. Multiple logistic regression models were created, based on a sociobehavioral model of health services use, to examine which types of factors (demographic, social, enabling or need) are most strongly associated with the use of a PPV. Results: The study population consisted of survey respondents interviewed six weeks or more following delivery. Eighty-five percent of respondents had had a PPV at time of interview. In a multiple regression analysis, enabling factors such as multiple moves (OR (95% CI)=0.34 (0.18, 0.67)), trouble understanding the provider (OR (95% CI)=0.65 (0.43, 0.99)) and appointment reminders (OR (95% CI)=2.37 (1.40, 4.02)) were most strongly associated with a PPV. Conclusions: This work finds that women with unstable housing, transportation barriers, and difficulties communicating with providers are at risk for not receiving a PPV. This suggests that access to postpartum health services in the Healthy Start communities studied may not be entirely equitable. Policies aimed at improving interconception care will need to address these barriers to accessing health services

Vitamin D status among preterm and full-term infants at birth

Background: Risk factors for maternal vitamin D deficiency and preterm birth overlap but the distribution of 25-hydroxyvitamin D (25(OH)D) levels among preterm infants is not known. We aimed to determine associations between 25(OH)D levels and gestational age. Methods: We measured umbilical cord plasma levels of 25(OH)D from 471 infants born at Brigham and Women’s Hospital in Boston. We used generalized estimating equations to determine whether preterm (<37 weeks’ gestation) or very preterm (<32 weeks’ gestation) infants had greater odds of 25(OH)D levels < 20 ng/ml than more mature infants. We adjusted for potential confounding by season of birth, maternal age, race, marital status and singleton or multiple gestation. Results: Mean cord plasma 25(OH)D level was 34.0 ng/ml (range 4.1 to 95.3, and SD 14.1). Infants born before 32 weeks’ gestation had increased odds of 25(OH)D levels < 20 ng/ml in unadjusted (OR 2.2, 95% CI 1.1, 4.3) and adjusted models (OR 2.4, 95% CI 1.2, 5.3) compared to more mature infants. Conclusion: Infants born < 32 weeks’ gestation are at higher risk than more mature infants for low 25(OH)D levels. Further investigation of the relationships between low 25(OH)D levels and preterm birth and its sequelae is thus warranted

Preeclampsia

Inadequate invasion of the uterus by cytotrophoblasts is speculated to result in pregnancy-induced disorders such as preeclampsia. However, the molecular mechanisms that govern appropriate invasion of cytotrophoblasts are unknown. Here, we demonstrate that under low-oxygen conditions (2.5% oxygen), 2-methoxyestradiol (2-ME), which is a metabolite of estradiol and is generated by catechol-o-methyltransferase (COMT), induces invasion of cytotrophoblasts into a naturally-derived, extracellular matrix. Neither low-oxygen conditions nor 2-ME alone induces the invasion of cytotrophoblasts in this system; however, low-oxygen conditions combined with 2-ME result in the appropriate invasion of cytotrophoblasts into the extracellular matrix. Cytotrophoblast invasion under these conditions is also associated with a decrease in the expression of hypoxia-inducible factor-1α (HIF-1α), transforming growth factor-β3 (TGF-β3), and tissue inhibitor of metalloproteinases-2 (TIMP-2). Pregnant COMT-deficient mice with hypoxic placentas and preeclampsia-like features demonstrate an up-regulation of HIF-1α, TGF-β3, and TIMP-2 when compared with wild-type mice; normal levels are restored on administration of 2-ME, which also results in the resolution of preeclampsia-like features in these mice. Indeed, placentas from patients with preeclampsia reveal lower levels of COMT and higher levels of HIF-1α, TGF-β3, and TIMP-2 when compared with those from normal pregnant women. We demonstrate that low-oxygen conditions of the placenta are a critical co-stimulator along with 2-ME for the proper invasion of cytotrophoblasts to facilitate appropriate vascular development and oxygenation during pregnancy.Chemistry and Chemical Biolog

Racial and ethnic variations in phthalate metabolite concentration changes across full-term pregnancies

Higher concentrations of certain phthalate metabolites are associated with adverse reproductive and pregnancy outcomes, as well as poor infant/child health outcomes. In non-pregnant populations, phthalate metabolite concentrations vary by race/ethnicity. Few studies have documented racial/ethnic differences between phthalate metabolite concentrations at multiple time points across the full-course of pregnancy. The objective of the study was to characterize the change in phthalate metabolite concentrations by race/ethnicity across multiple pregnancy time points. Women were participants in a prospectively collected pregnancy cohort who delivered at term (≥37 weeks) and had available urinary phthalate metabolite concentrations for ≥ 3 time points across full-term pregnancies (n = 350 women). We assessed urinary concentrations of eight phthalate metabolites that were log-transformed and specific gravity-adjusted. We evaluated the potential racial/ethnic differences in phthalate metabolite concentrations at baseline (median 10 weeks gestation) using ANOVA and across pregnancy using linear mixed models to calculate the percent change and 95% confidence intervals adjusted for sociodemographic and lifestyle factors. Almost 30% of the population were non-Hispanic black or Hispanic. With the exception of mono-(3 carboxypropyl) (MCPP) and di-ethylhexyl phthalate (DEHP) metabolites, baseline levels of phthalate metabolites were significantly higher in non-whites (Po0.05). When evaluating patterns by race/ethnicity, mono-ethyl phthalate (MEP) and MCPP had significant percent changes across pregnancy. MEP was higher in Hispanics at baseline and decreased in mid-pregnancy but increased in late pregnancy for non-Hispanic blacks. MCPP was substantially higher in non-Hispanic blacks at baseline but decreased later in pregnancy. Across pregnancy, non-Hispanic black and Hispanic women had higher concentrations of certain phthalate metabolites. These differences may have implications for racial/ethnic differences in adverse pregnancy and child health outcomes

Pregnancy urinary phthalate metabolite concentrations and gestational diabetes risk factors

Background: Epidemiologic studies suggest phthalate metabolite concentrations are associated with type 2 diabetes. GDM is a strong risk factor for type 2 diabetes. Little is known about phthalates and GDM risk factors (i.e. 1st trimester body mass index (BMI), gestational weight gain (GWG), and 2nd trimester glucose levels). Methods: A total of 350 women participating in Lifecodes pregnancy cohort (Boston, MA), delivered at term and had pregnancy urinary phthalate metabolite concentrations. Nine specific gravity-adjusted urinary phthalate metabolites were evaluated. General linear regression was used to assess associations between quartiles of phthalate metabolites and continuous 1st trimester BMI and late 2nd trimester blood glucose. Linear mixed models were used for total GWG. Multivariable logistic regression was used for phthalate concentrations and categorized GWG and impaired glucose tolerance defined as glucose≥140 mg/dL based on a 50-gram glucose load test. Models were adjusted for potential confounders. Results: There were no associations between 1st trimester urinary phthalate metabolite concentrations and 1st trimester BMI. Mono-ethyl phthalate concentrations averaged across pregnancy were associated with a 2.17 increased odds of excessive GWG (95% CI: 0.98, 4.79). Second trimester mono-ethyl phthalate was associated with increased odds of impaired glucose tolerance (adj. OR: 7.18; 95% CI: 1.97, 26.15). A summary measure of di-2- ethylhexyl phthalate metabolite concentrations were inversely associated with impaired glucose tolerance (adj. OR: 0.25; adj. 95% CI: 0.08, 0.85). Conclusions: Higher exposure to mono-ethyl phthalate, a metabolite of the parent compound of di-ethyl phthalate, may be associated with excessive GWG and impaired glucose tolerance; higher di-2 ethylhexyl phthalate was associated with reduced odds of impaired glucose tolerance

Risk of COVID-19 after natural infection or vaccinationResearch in context

Background: While vaccines have established utility against COVID-19, phase 3 efficacy studies have generally not comprehensively evaluated protection provided by previous infection or hybrid immunity (previous infection plus vaccination). Individual patient data from US government-supported harmonized vaccine trials provide an unprecedented sample population to address this issue. We characterized the protective efficacy of previous SARS-CoV-2 infection and hybrid immunity against COVID-19 early in the pandemic over three-to six-month follow-up and compared with vaccine-associated protection. Methods: In this post-hoc cross-protocol analysis of the Moderna, AstraZeneca, Janssen, and Novavax COVID-19 vaccine clinical trials, we allocated participants into four groups based on previous-infection status at enrolment and treatment: no previous infection/placebo; previous infection/placebo; no previous infection/vaccine; and previous infection/vaccine. The main outcome was RT-PCR-confirmed COVID-19 >7–15 days (per original protocols) after final study injection. We calculated crude and adjusted efficacy measures. Findings: Previous infection/placebo participants had a 92% decreased risk of future COVID-19 compared to no previous infection/placebo participants (overall hazard ratio [HR] ratio: 0.08; 95% CI: 0.05–0.13). Among single-dose Janssen participants, hybrid immunity conferred greater protection than vaccine alone (HR: 0.03; 95% CI: 0.01–0.10). Too few infections were observed to draw statistical inferences comparing hybrid immunity to vaccine alone for other trials. Vaccination, previous infection, and hybrid immunity all provided near-complete protection against severe disease. Interpretation: Previous infection, any hybrid immunity, and two-dose vaccination all provided substantial protection against symptomatic and severe COVID-19 through the early Delta period. Thus, as a surrogate for natural infection, vaccination remains the safest approach to protection. Funding: National Institutes of Health

Risk of COVID-19 after natural infection or vaccinationResearch in context

Summary: Background: While vaccines have established utility against COVID-19, phase 3 efficacy studies have generally not comprehensively evaluated protection provided by previous infection or hybrid immunity (previous infection plus vaccination). Individual patient data from US government-supported harmonized vaccine trials provide an unprecedented sample population to address this issue. We characterized the protective efficacy of previous SARS-CoV-2 infection and hybrid immunity against COVID-19 early in the pandemic over three-to six-month follow-up and compared with vaccine-associated protection. Methods: In this post-hoc cross-protocol analysis of the Moderna, AstraZeneca, Janssen, and Novavax COVID-19 vaccine clinical trials, we allocated participants into four groups based on previous-infection status at enrolment and treatment: no previous infection/placebo; previous infection/placebo; no previous infection/vaccine; and previous infection/vaccine. The main outcome was RT-PCR-confirmed COVID-19 >7–15 days (per original protocols) after final study injection. We calculated crude and adjusted efficacy measures. Findings: Previous infection/placebo participants had a 92% decreased risk of future COVID-19 compared to no previous infection/placebo participants (overall hazard ratio [HR] ratio: 0.08; 95% CI: 0.05–0.13). Among single-dose Janssen participants, hybrid immunity conferred greater protection than vaccine alone (HR: 0.03; 95% CI: 0.01–0.10). Too few infections were observed to draw statistical inferences comparing hybrid immunity to vaccine alone for other trials. Vaccination, previous infection, and hybrid immunity all provided near-complete protection against severe disease. Interpretation: Previous infection, any hybrid immunity, and two-dose vaccination all provided substantial protection against symptomatic and severe COVID-19 through the early Delta period. Thus, as a surrogate for natural infection, vaccination remains the safest approach to protection. Funding: National Institutes of Health