Immune Response In Infants Research Articles

#11 Development of a Kinetic ELISA (kELISA) and Reactive B Cell Frequency (RBF) Assay to Detect Respiratory Syncytial Virus (RSV) Pre-Fusion F Protein-Specific Immune Responses in Infants

Abstract Background RSV is a major cause of pediatric respiratory disease. Antibodies to the prefusion conformation of the RSV fusion (pre-F) protein are needed for virus neutralization. Method We measured RSV-specific responses in two groups of children <3 years of age; subjects with laboratory-confirmed RSV (RSV-infected) or infants born in the period May to September and enrolled prior to their first RSV season (RSV-uninfected). RSV-infected infants had blood samples obtained at 1, 6, 9, and 12 months after infection. RSV-uninfected infants had blood samples obtained at enrollment, at the end of their first RSV season, and 6 months later. A kELISA to measure RSV pre-F-specific antibodies and an RBF assay to identify RSV F-specific B cells were developed. Results 102 subjects were enrolled; 11 were excluded due to missed visits or withdrawal. Of the 65 subjects in the RSV-uninfected group, all were kELISA positive at enrollment, consistent with maternal antibody transfer. 53 subjects had sufficient samples for analysis at multiple time points; 29 became seronegative and 24 remained seropositive. In the seronegative group, the kELISA value decreased rapidly to <0.25 by 6 months after the RSV season in 27/29 (93%), (Figure 1a). In the persistently seropositive group, all 24 subjects maintained a positive kELISA value, with some developing higher values over time, consistent with asymptomatic infection (Figure 1b). An RBF assay was used to determine whether antibodies were due to persistent maternal antibodies or endogenous production (Figure 1c). In the seronegative group, 24/29 (80%) had a negative RBF; in the seropositive group, 23/24 (96%) had a positive RBF during follow-up. There were 26 subjects in the RSV-infected group; 22 had sufficient samples for analysis at multiple time points. All were seropositive by kELISA at one month post-infection with variable kELISA values during follow-up (Figure 1d). 17/22 (77%) had a positive RBF, although 4 of the subjects without a positive RBF had indeterminate results at ≥ 1 visit. Conclusion Assays measuring F-specific immune responses in infants will be critical for RSV vaccine development. A kELISA targeting RSV pre-F epitopes, with an RBF assay targeting RSV F-specific B cells, may allow discrimination for maternal and infant-derived antibodies.

Microbial antigen in human milk: a natural vaccine?

Microbial antigen in human milk: a natural vaccine?

The safety and immunogenicity of a combined pertussis containing vaccine Tdap for HIV infected pregnant women and their newborns (WoMANPOWER) – A study protocol for a randomized clinical trial

Background: Globally there are an estimated 24.1 million cases and 160,700 deaths from pertussis annually in children under five years. The disease burden is higher in low- and middle-income countries, especially the African region, which contributes the largest proportions of cases and deaths. Immunization against pertussis in pregnancy is a recommended strategy for the prevention of infant pertussis in many high-income countries. However, vaccine immunogenicity and effectiveness may be different in immunocompromised individuals such as women living with HIV. There is a need to generate data on the impact of HIV infection in pregnancy on maternal and infant immunity to vaccines against pertussis. Methods: This is a phase II, randomized controlled observer blind clinical trial of 100 women living with HIV and 100 uninfected women randomized to either standard vaccines (tetanus diphtheria vaccine, Td) or a tetanus diphtheria-pertussis vaccine (Tdap). Participants aged 18-40 years carrying a low-risk singleton pregnancy with a gestational age between 16 and 26 weeks confirmed on ultrasound scan, with no history of receipt of tetanus or pertussis vaccines in the current pregnancy will be recruited. Women will receive either two doses of Td or a first dose of Td and second dose of Tdap vaccine. Participants will complete 14-day diary cards to monitor reactogenicity. Mother-infant dyads will be followed up until the infant is one year old. The outcomes include: safety for the pregnant woman and infant; anti-pertussis toxin (PT) and anti-filamentous haemagglutinin (FHA) IgG concentrations in maternal, cord and infant blood and breastmilk, compared by maternal HIV status. Discussion: This study will investigate whether vaccines given to women living with HIV have similar immunogenicity and reactogenicity to vaccines given to pregnant women without HIV and monitor the effect of Tdap in pregnancy on infant immune responses. clinicalTrials.gov registration: NCT04589312 (19/10/2020)

A Case Study to Dissect Immunity to SARS-CoV-2 in a Neonate Nonhuman Primate Model.

Most children are less severely affected by coronavirus-induced disease 2019 (COVID-19) than adults, and thus more difficult to study progressively. Here, we provide a neonatal nonhuman primate (NHP) deep analysis of early immune responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in blood and mucosal tissues. In addition, we provide a comparison with SARS-CoV-2-infected adult NHP. Infection of the neonate resulted in a mild disease compared with adult NHPs that develop, in most cases, moderate lung lesions. In concomitance with the viral RNA load increase, we observed the development of an early innate response in the blood, as demonstrated by RNA sequencing, flow cytometry, and cytokine longitudinal data analyses. This response included the presence of an antiviral type-I IFN gene signature, a persistent and lasting NKT cell population, a balanced peripheral and mucosal IFN-γ/IL-10 cytokine response, and an increase in B cells that was accompanied with anti-SARS-CoV-2 antibody response. Viral kinetics and immune responses coincided with changes in the microbiota profile composition in the pharyngeal and rectal mucosae. In the mother, viral RNA loads were close to the quantification limit, despite the very close contact with SARS-CoV-2-exposed neonate. This pilot study demonstrates that neonatal NHPs are a relevant model for pediatric SARS-CoV-2 infection, permitting insights into the early steps of anti-SARS-CoV-2 immune responses in infants.

Epigenetic Regulation During Maternal Schistosomiasis Results in Aberrant B cell Maturation and Tolerance

Abstract Maternal helminth infections are a global public health concern that correlate with altered infant immune responses to childhood immunizations and infection. A mechanistic understanding of how maternal infection and inflammation alters the immune responses of offspring is lacking but is critical to decrease childhood morbidity and to understand the consequences of specific long-lived immunity defects. Using our model of maternal Schistosoma mansoni infection, we have shown that murine pups born to mothers chronically infected with Schistosoma mansoni have reduced responses to vaccinations, corresponding to what has been reported in humans. To determine the origin of this humoral immunity defect, we began investigating the plasticity and functionality of progenitors of lymphoid cells critical for a protective humoral response. We found an increase in the common lymphoid progenitors (CLPs) in the bone marrow of pups from Schistosome infected mothers, but a marked decrease in immature and transitional B cells in male mice, indicating sex-specific limitations during B cell maturation. Using single cell V(D)J sequencing, we found only male pups from infected mothers have a more restricted repertoire compared to male mice from uninfected mothers after immunization, leading to decreased antigen-specific B cells in the germinal center of the draining lymph node. We hypothesize that epigenetic regulation of key immune genes is the mechanistic root of long-lived defects in humoral immunity to foreign antigens during maternal Schistosomiasis. Supported by a grant from NIH (R01 AI135045)

Crystal Structure of Human Lysozyme Complexed with N-Acetyl-α-d-glucosamine

Human lysozyme is a natural non-specific immune protein that participates in the immune response of infants against bacterial and viral infections. Lysozyme is a well-known hydrolase that cleaves peptidoglycan in bacterial cell walls. Several crystal structures of human lysozyme have been reported, but little is known regarding how it recognizes sugar molecules. In this study, the crystal structures of human lysozyme in its native and two N-acetyl-α-d-glucosamine (α-D-NAG)-bound forms were determined at 1.3 Å and 1.55/1.60 Å resolution, respectively. Human lysozyme formed a typical c-type lysozyme fold and the α-D-NAG molecule was bound to the middle of subsites C and D. The N-acetyl and glucosamine groups of α-D-NAG were stabilized by hydrophobic interactions (Val117, Ala126, and Trp127), hydrogen bonds (Asn64, Asn78, Ala126, and Val128), and water bridges. Conformational changes of Arg80, Tyr81, Val128, and Arg131 of human lysozyme were observed due to the interactions of α-D-NAG with the active-site cleft. The binding configuration of α-D-NAG in human lysozyme was distinct compared with that of other sugar-bound lysozymes. Findings from this structural analysis provide a better understanding of the sugar recognition of human lysozyme during the immune response to microbial pathogens.

Seroprotection of Hepatitis B Vaccine in Dental Students Two Decades after Infant Immunization and the Possible Need for Revaccination.

This study aimed to assess hepatitis B surface antibody (anti-HBs) persistence among dental students two decades after infant vaccination and immune response after revaccination or booster dose in nonimmune groups. A cross-sectional study was performed using laboratory reports for anti-HBs performed to dental students at the Umm al-Qura University from 2016 to 2020. Reports were classified according to baseline antibody titer into group I (titer <10 mIU/mL), group II (titer 10 to <100 mIU/mL), and group III (titer ≥100 mIU/mL). The basal antibody titer of each group was correlated to student's gender and birth year and compared with postrevaccination or booster dose titer in groups I and II. Data of baseline and postrevaccination anti-HBs antibody titers were analyzed using Statistical Package for Social Science (SPSS). One-way ANOVA was used to compare between different means for antibody titers of students as well as baseline and postrevaccination antibody levels for nonimmune students with nonprotective antibody titers. Pairwise multiple comparison of the difference between baseline and postrevaccination anti-HBs antibody titers were done by post hoc Tukey's honestly significant difference (HSD) test. Chi-squared test was used for comparing between the frequencies. A p-Value of ≤0.05 was considered significant and p < 0.01 was considered highly significant. A significant percentage (73.6%) of students had antibody titer <10 mIU/mL, while only 4.8% had antibody titer ≥100 mIU/mL with nonsignificant difference between both genders (χ 2 =3.784, p = 0.151). A statistically nonsignificant difference was also found between the three categories of anti-HBs antibody titers among students with different birth dates (χ 2 = 13.817, p = 0.182). After revaccination of nonimmune students, 100% of them showed strongly protective antibody titers with mean of 842.88 to 844.58 mIU/mL. A highly significant difference was observed between the mean baseline and postrevaccination antibody titers in both genders, with a higher mean of post revaccination (p = 0.000). Two decades after infant immunization, a significant percentage of dental students failed to maintain the anti-HBs seroprotective titer. So titer measurement should be made compulsory before they begin their clinical training and revaccination or booster dose should be given to nonimmune students to maintain a high protection level.

Effects of maternal antibodies in infants on the immunogenicity and safety of inactivated polio vaccine in infants

ABSTRACT The presence of maternal poliovirus antibodies may interfere with the immune response to inactivated polio vaccine (IPV), and its influence on the safety of vaccination is not yet understood. A total of 1146 eligible infants were randomly assigned (1:1) to the IPV and Sabin IPV (SIPV) groups to compare and analyze the efficacy of the two vaccines in preventing poliovirus infection. We pooled the SIPV and IPV groups and reclassified them into the maternal poliovirus antibody-positive group (MAPG; ≥1: 8) and the maternal poliovirus antibody-negative group (MANG; <1: 8). We evaluated the impact of maternal poliovirus antibodies by comparing the geometric mean titer (GMT), seroconversion rate, and geometric mean increase (GMI) of types I–III poliovirus neutralizing antibodies post-vaccination, and incidence rates of adverse reactions following vaccination between the MAPG and MANG. Respective seroconversion rates in the MAPG and MANG were 94% and 100%, 79.27% and 100%, and 93.26% and 100% (all serotypes, P < .01) for types I—III poliovirus, respectively. The GMT of all types of poliovirus antibodies in the MAPG (1319.13, 219.91, 764.11, respectively) were significantly lower than those in the MANG (1584.92, 286.73, 899.59, respectively) (P < .05). The GMI in the MAPG was significantly lower than that in the MANG (P < .05). No statistically significant difference in the incidence of local and systemic adverse reactions was observed between the MAPG and MANG. Thus, the presence of maternal poliovirus antibodies does not affect the safety of IPV but can negatively impact the immune responses in infants after IPV vaccination.

Are SARS-CoV-2 Antibodies Detectable in Human Milk After Vaccination Against COVID-19?

BackgroundHuman milk (HM) permits transfer of immunity against infections to infants via bioactive factors. The role of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies in HM is poorly understood [1, 2]. This study evaluated SARS-CoV-2 antibodies in the HM of vaccinated healthcare workers (HCW).Methods and ResultsThis prospective study of 122 HCWs was performed from February to April 2021 at the Hospital Universitario Nuestra Señora de Candelaria. Immunoglobulin G (IgG) against nucleocapsid protein and IgG, immunoglobulin M (IgM), and immunoglobulin A (IgA) antibodies against spike 1 protein receptor-binding domain against SARS-CoV-2 (anti-SARS-CoV-2 RBD-S1) were analyzed. Unvaccinated breastfeeding mothers without COVID-19 were the control group.The 98 vaccinated participants underwent serum and HM evaluation 14 days after receiving 2 doses of either BNT162b2 mRNA (94%) or mRNA-1273 (6%) coronavirus disease 2019 (COVID-19) vaccines. The mean SARS-CoV-2 RBD-S1 IgG serum concentration was 3379.64 binding antibody units (BAUs)/mL with neutralizing antibody titers >560.9 BAUs/mL. Serum SARS-CoV-2 antibodies in the 24 unvaccinated participants were negative. The HM from vaccinated participants had anti-SARS-CoV-2 RBD-S1 IgG with a mean of 12.19 BAUs/mL compared to 0.02 BAUs/mL (P < .001) in HM from unvaccinated participants. Anti-SARS-CoV-2 S1 IgA was noted in 89% of HM from vaccinated women; no anti-SARS-CoV-2 S1 IgM was detected.A positive correlation was reported between anti-SARS-CoV-2 RBD-S1 IgG in serum and HM (r = 0.36; P < .001). This association was stronger if breastfeeding had been <24 months (r = 0.67; P < .001) vs ≥24 months (r = 0.32; P = 0.19). In subgroup analysis, breastfeeding for >24 months and high serum anti-SARS-CoV-2 RBD-S1 IgG levels predicted high HM IgG levels. This was an independent association in both linear and multiple regression models. Compared with breastfeeding <24 months, lactation >24 months was associated with increased HM anti-SARS-CoV-2 RBD-S1 levels.CommentsThis study in breastfeeding HCWs showed that the HM antibody levels were higher in women who had been breastfeeding for >24 months prior to receiving 2 doses of COVID-19 vaccine compared to participants who had been breastfeeding <24 months. Limitations include lack of in vitro plaque reduction neutralization tests which is the gold standard for evaluating SARS-CoV-2 antibody deactivation effectiveness. The study was conducted at a single site and did not assess infant serology or clinical outcome.According to the authors, breastfeeding by vaccinated women during a pandemic when young children are ineligible for vaccination may be encouraged. These results support findings from other studies of vaccines, such as influenza, in which the HM of vaccinated women may confer protection to their infants [3]. The benefits of maternal immunization, including the duration of protection afforded by HM from maternal recipients of mRNA COVID-19 vaccines, are research areas deserving of additional exploration. Additionally, further understanding of the association of the duration of receipt of HM from vaccinated women on infant immune responses would be beneficial in understanding the potential for passive protection through nutrition.

Effect of early life antibiotic use on serologic responses to oral rotavirus vaccine in the MAL-ED birth cohort study

BackgroundOral rotavirus vaccine efficacy is lower in low- and middle-income countries (LMICs) than in high-income countries. The degree to which antibiotic use impacts rotavirus vaccine immunogenicity in LMICs is unknown. Using data from a multisite prospective birth cohort study of malnutrition and enteric disease, MAL-ED, we examined the effect of early life antibiotic use on the immune response to rotavirus vaccine. MethodsWe assessed whether antibiotic use from birth up to 7 days following rotavirus vaccine series completion was associated with rotavirus seropositivity at 7 months of age in Brazil, Peru, and South Africa using a modified Poisson regression. We then used parametric g-computation to estimate the impact of hypothetical interventions that treated all children and alternatively prevented inappropriate antibiotic treatments on seropositivity. ResultsOf 537 children, 178 (33%) received at least one antibiotic course during the exposure window. Probability of seropositivity was 40% higher among children who had at least one course of antibiotics compared with those with no antibiotic exposure (PR: 1.40, 95% CI: 1.04, 1.89). There was no significant difference by the number of antibiotic courses received or total duration of antibiotics. Treating all children with antibiotics would be associated with a 19% (95% CI: 18%, 21%) absolute increase in seropositivity at 7 months. In contrast, removing inappropriate antibiotics would result in a 4% absolute reduction (95% CI: −5%, −2%) in seropositivity. ConclusionsEarly life antibiotic use was associated with increased seropositivity. However, a hypothetical intervention to remove inappropriate antibiotics would have little effect on overall seropositivity. Further investigation into the underlying mechanisms of antibiotic use on the infant gut microbiome and immune response are needed.

Infant immune response to hepatitis B vaccine after fetal exposure to telbivudine

ABSTRACT Whether telbivudine (LdT) treatment to pregnant women with hepatitis B surface antigen (HBsAg) affects infant immune response to hepatitis B vaccine (HepB) has not been investigated. A total of 127 HBsAg positive mothers and their neonates were enrolled and followed up at 11–13 months. Mothers took LdT (LdT group) or did not receive antiviral therapy (control group). Infant anti-HBs, immune cells and cytokines were measured after HepB was administered according to 0-1-6 procedure. We performed a 1:3 propensity score matching (PSM). Immune indexes in the two groups were compared. Baseline characteristics of mother-baby pairs were comparable in LdT group and control group. Infant anti-HBs geometric mean concentration (GMC) did not differ significantly between the two groups [767.70 (745.35) vs. 711.90 (819.60), P = .599]. There was no difference between the two groups in infant positive rate of anti-HBs [97.8% (91/93) vs. 97.1% (33/34), P = .999] and strong positive rate of anti-HBs [40.9% (38/93) vs. 44.1% (15/34), P = .742]. Infants with negative, low, medium, and high anti-HBs levels were similarly distributed between the two groups (P = .511). No differences in proportion of helper T cells, cytotoxic T cells, B cells, myeloid dendritic cells, and plasmacytoid dendritic cells of infants (P > .05) were detected between the two groups. Children in the LdT and control group had comparable levels of interleukin-2, interleukin-4, interleukin-6, interleukin-10, interleukin-12, interferon-α, interferon-γ and tumor necrosis factor-α (P > .05). Intrauterine exposure to LdT was safe to infant immune response to HepB after birth.

NRF2 Protects against Altered Pulmonary T Cell Differentiation in Neonates Following In Utero Ultrafine Particulate Matter Exposure.

Early life exposure to particulate matter (PM) air pollution negatively impacts neonatal health. The underlying mechanisms following prenatal exposure, particularly to ultrafine particles (UFP, diameter ≤ 0.1 μm), are not fully understood; To evaluate the role of Nrf2 in response to in utero UFP exposure, we exposed time-mated Nrf2-deficient (Nrf2−/−) or wildtype (WT) mice to filtered air (FA) or 100 μg/m3 ultrafine PM daily throughout pregnancy. Offspring were evaluated for pulmonary immunophenotypes and pulmonary/systemic oxidative stress on postnatal day 5, a timepoint at which we previously demonstrated viral respiratory infection susceptibility; Nrf2−/− offspring exposed to FA had significantly lower average body weights compared to FA-exposed WT pups. Moreover, PM-exposed Nrf2−/− offspring weighed significantly less than PM-exposed WT pups. Notably, PM-exposed Nrf2−/− offspring showed a decreased pulmonary Th1/Th2 ratio, indicating a Th2 bias. Th17 cells were increased in FA-exposed Nrf2−/− neonates yet decreased in PM-exposed Nrf2−/− neonates. Analysis of oxidative stress-related genes in lung and oxidative stress biomarkers in liver tissues did not vary significantly across exposure groups or genotypes. Collectively, these findings indicate that the lack of Nrf2 causes growth inhibitory effects in general and in response to gestational UFP exposure. Prenatal UFP exposure skews CD4+ T lymphocyte differentiation toward Th2 in neonates lacking Nrf2, signifying its importance in maternal exposure and infant immune responses.

Effect of ofatumumab on pregnancy, parturition, and lactation in cynomolgus monkeys

Knowledge of the impacts of the anti-CD20 monoclonal antibody ofatumumab on the developing immune system is limited. This study examined the effects of intravenous ofatumumab on pregnancy, parturition, and lactation, and on pre- and postnatal survival and development in cynomolgus monkeys, an established model for developmental toxicity assessment. Pregnant cynomolgus monkeys (n = 42) were randomized to receive vehicle only (control group; n = 14), low-dose ofatumumab (n = 14), or high-dose ofatumumab (n = 14). Survival, clinical outcomes, and clinical pathology investigations were evaluated regularly until lactation day (maternal animals) and postnatal day 180±1 (infants). Anatomic pathology was investigated in euthanized infants and unscheduled terminations of maternal animals and infants. Ofatumumab treatment was not associated with maternal toxicity or embryotoxicity and had no effect on the growth and development of offspring. As expected, B-cell depletion occurred in maternal animals and their offspring, with a reduced humoral immune response in infants of mothers on high-dose ofatumumab. Both effects were reversible. In the high-dose group, perinatal deaths of 3 infants were attributed to infections, potentially secondary to pharmacologically induced immunosuppression. The no-observed adverse-effect level for initial/maintenance ofatumumab doses was 100/20 mg, and 10/3 mg/kg for pharmacological effects in infant animals, which are associated with exposures significantly higher than those following therapeutic doses in humans. In this study with cynomolgus monkeys, ofatumumab treatment was not associated with maternal toxicity or embryotoxicity and had no effect on the growth and development of offspring.

127. Development of a Kinetic ELISA (kELISA) and Reactive B-cell Frequency (RBF) Assay to Detect Respiratory Syncytial Virus (RSV) Pre-Fusion F Protein-Specific Immune Responses in Infants

Abstract Background RSV is a major cause of pediatric respiratory disease. Antibodies to the prefusion conformation of the RSV fusion (pre-F) protein are needed for virus neutralization. Methods We measured RSV-specific responses in two groups of children &amp;lt; 3 years of age; subjects with laboratory-confirmed RSV (RSV-infected) or infants born in the period May to September and enrolled prior to their first RSV season (RSV-uninfected). RSV-infected infants had blood samples obtained at 1, 6, 9, and 12 months after infection. RSV-uninfected infants had blood samples obtained at enrollment, at the end of their first RSV season, and 6 months later. A kELISA to measure RSV pre-F-specific antibodies and an RBF assay to identify RSV F-specific B cells were developed. Results 102 subjects were enrolled; 11 were excluded due to missed visits or withdrawal. Of the 65 subjects in the RSV-uninfected group, all were kELISA positive at enrollment, consistent with maternal antibody transfer. 53 subjects had sufficient samples for analysis at multiple time points; 29 became seronegative and 24 remained seropositive. In the seronegative group, the kELISA value decreased rapidly to &amp;lt; 0.25 by 6 months after the RSV season in 27/29 (93%), (Figure 1a). In the persistently seropositive group, all 24 subjects maintained a positive kELISA value, with some developing higher values over time, consistent with asymptomatic infection (Figure 1b). An RBF assay was used to determine whether antibodies were due to persistent maternal antibodies or endogenous production (Figure 2). In the seronegative group, 24/29 (80%) had a negative RBF; in the seropositive group, 23/24 (96%) had a positive RBF during follow-up. There were 26 subjects in the RSV-infected group; 22 had sufficient samples for analysis at multiple time points. All were seropositive by kELISA at one month post-infection with variable kELISA values during follow-up (Figure 3). 17/22 (77%) had a positive RBF, although 4 of the subjects without a positive RBF had indeterminate results at ≥ 1 visit. Figure 1. kELISA values of baseline RSV-negative subjects, by subject age at time of sample. Panel A: Subjects classified as seronegative (n=29). Panel B: Subjects without known RSV classified as persistently seropositive (n=24). Figure 2. Reactive B-cell frequency assay. The first step in the RBF assay is growth of Lymphoblastoid Cell Lines (LCLs), as shown over days 1-3 (Left-Day 1, Middle-Day 2, Right-Day 3, magnification 200X). The cells circled in the figure indicate a single LCL’s growth over time. LCL supernatant is used to detect RSV F-protein specific antibodies using traditional ELISA, resulting in a positive, indeterminate, or negative result. Indeterminate results occur due to a lack of cell viability and/or failure to form LCLs, resulting in failure to exceed an optical density of 5x background. Figure 3. kELISA values of RSV-infected subjects, by subject age at time of sample. First sample was obtained at approximately one month after laboratory-confirmed RSV. Conclusion Assays measuring F-specific immune responses in infants will be critical for RSV vaccine development. A kELISA targeting RSV pre-F epitopes, with an RBF assay targeting RSV F-specific B cells, may allow discrimination for maternal and infant-derived antibodies. Disclosures Isaac Thomsen, MD, MSCI, Horizon Therapeutics (Individual(s) Involved: Self): Consultant James E. Crowe, Jr., MD, Astra Zeneca (Grant/Research Support)IDBiologics (Board Member, Grant/Research Support, Shareholder)Luna Biologics (Consultant)Meissa Vaccines (Advisor or Review Panel member)Takeda Vaccines (Grant/Research Support) Kathryn M. Edwards, MD, Bionet (Individual(s) Involved: Self): Consultant; CDC (Individual(s) Involved: Self): Research Grant or Support; IBM (Individual(s) Involved: Self): Consultant; Merck (Individual(s) Involved: Self): member DSMC, Other Financial or Material Support; Moderna (Individual(s) Involved: Self): member DSMC, Other Financial or Material Support; NIH (Individual(s) Involved: Self): Research Grant or Support; Pfizer (Individual(s) Involved: Self): member DSMC, Other Financial or Material Support; Roche (Individual(s) Involved: Self): member of DSMB, Other Financial or Material Support; Sanofi Pasteur (Individual(s) Involved: Self): member DSMB, Other Financial or Material Support; Sequiras (Individual(s) Involved: Self): Member DSMB, Other Financial or Material Support; X4 Pharmaceuticals (Individual(s) Involved: Self): Consultant Buddy Creech, MD, MPH, Altimmune (Consultant)Astellas (Other Financial or Material Support, Data and Safety Monitoring Committee)Diotheris (Consultant)GSK (Consultant)Horizon (Consultant)Merck (Scientific Research Study Investigator)Premier Healthcare (Advisor or Review Panel member)Vir (Consultant)

Determination of Maternal and Infant Immune Responses to Pertussis Vaccination in Pregnancy.

The Bordetella pertussis bacterium is the causative agent of whooping cough (pertussis disease). Following recent outbreaks of pertussis, disproportionately affecting young infants, several countries have introduced maternal pertussis vaccination strategies, aimed at boosting transplacental transfer of protective antibodies during pregnancy. Given historical associations between high maternal antibody and blunted infant responses to vaccination, subsequent research studies have investigated the impact of maternal pertussis vaccine on infant humoral responses. However, far less is known about the potential impact of the vaccine on innate immunity. Here, we describe methods to detect in vitro cellular responses to B. pertussis in mothers and their infants using a B. pertussis stimulation assay and multiplex cytokine assays to address this research question.

Modification of innate immune responses to Bordetella pertussis in babies from pertussis vaccinated pregnancies.

BackgroundTetanus, diphtheria, acellular pertussis, inactivated polio (Tdap-IPV) vaccines administered during pregnancy protect young infants from Bordetella pertussis (B. pertussis) infection. Whilst the impact of maternal Tdap-IPV vaccination on infants’ humoral response to subsequent pertussis immunisation has been investigated, little is known about any impact on innate responses.MethodsWe investigated the immune response to B. pertussis in mothers and infants from Tdap-IPV-vaccinated and unvaccinated pregnancies, utilising a whole blood assay and flow cytometric phenotyping of neonatal natural killer (NK) cells, monocytes and dendritic cells. Blood was collected from mother and umbilical cord at birth, and from infants at seven weeks (one week pre-primary pertussis immunisation) and five months of age (one month post-primary pertussis immunisation). 21 mothers and 67 infants were studied.FindingsVaccinated women had elevated pro-inflammatory cytokine responses to B. pertussis. At birth, babies of vaccinated women had elevated IL-2 and IL-12 responses, elevated classical monocyte proportions, and reduced monocyte and NK cell cytokine responses. The elevated IL-2 response persisted to seven weeks-of-age, when lower IL-10 and IL-13 responses were also seen. One-month post-primary pertussis vaccination, infants from vaccinated pregnancies still had lower IL-10 responses to B. pertussis, as well as lower IL-4.InterpretationThis study suggests that pertussis vaccination during pregnancy impacts infant cellular immune responses, potentially contributing to the modification of antibody responses already reported following primary immunisation against B. pertussis.FundingNational Institute for Health Research Imperial Biomedical Research Centre and IMmunising PRegnant women and INfants neTwork (funded by the GCRF Networks in Vaccines R&D).

Analysis of multivariate longitudinal immuno-epidemiological data using a pairwise joint modelling approach

BackgroundImmuno-epidemiologists are often faced with multivariate outcomes, measured repeatedly over time. Such data are characterised by complex inter- and intra-outcome relationships which must be accounted for during analysis. Scientific questions of interest might include determining the effect of a treatment on the evolution of all outcomes together, or grouping outcomes that change in the same way. Modelling the different outcomes separately may not be appropriate because it ignores the underlying relationships between outcomes. In such situations, a joint modelling strategy is necessary. This paper describes a pairwise joint modelling approach and discusses its benefits over more simple statistical analysis approaches, with application to data from a study of the response to BCG vaccination in the first year of life, conducted in Entebbe, Uganda.MethodsThe study aimed to determine the effect of maternal latent Mycobacterium tuberculosis infection (LTBI) on infant immune response (TNF, IFN-γ, IL-13, IL-10, IL-5, IL-17A and IL-2 responses to PPD), following immunisation with BCG. A simple analysis ignoring the correlation structure of multivariate longitudinal data is first shown. Univariate linear mixed models are then used to describe longitudinal profiles of each outcome, and are then combined into a multivariate mixed model, specifying a joint distribution for the random effects to account for correlations between the multiple outcomes. A pairwise joint modelling approach, where all possible pairs of bivariate mixed models are fitted, is then used to obtain parameter estimates.ResultsUnivariate and pairwise longitudinal analysis approaches are consistent in finding that LTBI had no impact on the evolution of cytokine responses to PPD. Estimates from the pairwise joint modelling approach were more precise. Major advantages of the pairwise approach include the opportunity to test for the effect of LTBI on the joint evolution of all, or groups of, outcomes and the ability to estimate association structures of the outcomes.ConclusionsThe pairwise joint modelling approach reduces the complexity of analysis of high-dimensional multivariate repeated measures, allows for proper accounting for association structures and can improve our understanding and interpretation of longitudinal immuno-epidemiological data.

Safety and immunogenicity of a plant-derived rotavirus-like particle vaccine in adults, toddlers and infants

BackgroundThis study is the first clinical trial for a parenteral non-replicating rotavirus vaccine developed using virus-like particle (VLP) technology. MethodsThis open-labeled, randomized, placebo-controlled trial was conducted in two parts: Part A (a first-in-human study in Australian adults) and Part B (ascending dose and descending age in South African adults, toddlers and infants). In Part A, two cohorts of 10 adults were assigned to receive a single intramuscular injection of 1 of 2 escalating dose levels of the rotavirus VLP (Ro-VLP) vaccine (7 μg or 21 μg) or placebo. In Part B, one cohort of 10 adults was assigned to receive a single injection of the Ro-VLP vaccine (21 μg) or placebo, two cohorts of 10 toddlers were assigned to receive 2 injections of 1 of 2 escalating dose levels of the Ro-VLP vaccine (7 μg or 21 μg) or placebo 28 days apart, and three cohorts of 20 infants were assigned to receive 3 injections of 1 of 3 escalating dose levels of the Ro-VLP vaccine (2.5 μg, 7 μg or 21 μg) or placebo or 2 doses of oral Rotarix 28 days apart. Safety, reactogenicity and immunogenicity were assessed. ResultsThere were no safety or tolerability concerns after administration of the Ro-VLP vaccine. The Ro-VLP vaccine induced an anti-G1P[8] IgG response in infants 4 weeks after the second and third doses. Neutralizing antibody responses against homologous G1P[8] rotavirus were higher in all Ro-VLP infant groups than in the placebo group 4 weeks after the third dose. No heterotypic immunity was elicited by the Ro-VLP vaccine. ConclusionsThe Ro-VLP vaccine was well tolerated and induced a homotypic immune response in infants, suggesting that this technology platform is a favorable approach for a parenteral non-replicating rotavirus vaccine.Clinical Trial Registration: NCT03507738.

Immunogenicity of an oral rotavirus vaccine administered with prenatal nutritional support in Niger: A cluster randomized clinical trial.

BackgroundNutritional status may play a role in infant immune development. To identify potential boosters of immunogenicity in low-income countries where oral vaccine efficacy is low, we tested the effect of prenatal nutritional supplementation on immune response to 3 doses of a live oral rotavirus vaccine.Methods and findingsWe nested a cluster randomized trial within a double-blind, placebo-controlled randomized efficacy trial to assess the effect of 3 prenatal nutritional supplements (lipid-based nutrient supplement [LNS], multiple micronutrient supplement [MMS], or iron–folic acid [IFA]) on infant immune response (n = 53 villages and 1,525 infants with valid serology results: 794 in the vaccine group and 731 in the placebo group). From September 2015 to February 2017, participating women received prenatal nutrient supplement during pregnancy. Eligible infants were then randomized to receive 3 doses of an oral rotavirus vaccine or placebo at 6–8 weeks of age (mean age: 6.3 weeks, 50% female). Infant sera (pre-Dose 1 and 28 days post-Dose 3) were analyzed for anti-rotavirus immunoglobulin A (IgA) using enzyme-linked immunosorbent assay (ELISA). The primary immunogenicity end point, seroconversion defined as ≥3-fold increase in IgA, was compared in vaccinated infants among the 3 supplement groups and between vaccine/placebo groups using mixed model analysis of variance procedures. Seroconversion did not differ by supplementation group (41.1% (94/229) with LNS vs. 39.1% (102/261) with multiple micronutrients (MMN) vs. 38.8% (118/304) with IFA, p = 0.91). Overall, 39.6% (n = 314/794) of infants who received vaccine seroconverted, compared to 29.0% (n = 212/731) of infants who received placebo (relative risk [RR]: 1.36; 95% confidence interval [CI]: 1.18, 1.57, p < 0.001). This study was conducted in a high rotavirus transmission setting. Study limitations include the absence of an immune correlate of protection for rotavirus vaccines, with the implications of using serum anti-rotavirus IgA for the assessment of immunogenicity and efficacy in low-income countries unclear.ConclusionsThis study showed no effect of the type of prenatal nutrient supplementation on immune response in this setting. Immune response varied depending on previous exposure to rotavirus, suggesting that alternative delivery modalities and schedules may be considered to improve vaccine performance in high transmission settings.Trial registrationClinicalTrials.gov NCT02145000.

A study of the effects of age on the dynamics of RSV in animal models

Respiratory syncytial virus can cause severe illness and even death, particularly in infants. The increased severity of disease in young children is thought to be due to a lack of previous exposure to the virus as well as the limited immune response in infants. While studies have examined the clinical differences in disease between infants and adults, there has been limited examination of how the viral dynamics differ as infants develop. In this study, we apply a mathematical model to data from cotton rats and ferrets of different ages to assess how viral kinetics parameters change as the animals age. We find no clear trend in the viral decay rate, infecting time, and basic reproduction number as the animals age. We discuss possible reasons for the null result including the limited data, lack of detail of the mathematical model, and the limitations of animal models.