The Impact of IgG transplacental transfer on early life immunity

Maternal transfer of oral vaccine induced anti-OspA antibodies protects Peromyscus spp. from tick-transmitted Borrelia burgdorferi

The efficacy and duration of passive immunity protection depend on maternal antibody levels and transfer efficiency. We investigated whether oral vaccination of Peromyscus leucopus dams with recombinant outer surface protein A (OspA)-expressing Escherichia coli could induce maternal transfer of anti-OspA antibodies and protect pups from Borrelia burgdorferi challenge. Dams were vaccinated until breeding pairs were created (i), until parturition (ii), and until pups were 2 weeks old (iii). Pups were challenged with nymphal Ixodes scapularis-transmitted B. burgdorferi at ~4 weeks of age. Anti-OspA IgG was quantified in dams and pups, and anti-B. burgdorferi IgG was quantified in pups. B. burgdorferi burden was assessed by flaB quantitative PCR in pups' tissues ~4 weeks after tick challenge, and viability of B. burgdorferi was assessed by culture of the heart tissue. P. leucopus pups born to dams vaccinated until breeding had low serologic anti-OspA antibody and were not protected from tick-transmitted B. burgdorferi infection. However, when dams' vaccination extended until parturition and until pups were 2 weeks old, significant anti-OspA antibody transfer and protection from B. burgdorferi infection occurred. This was evidenced by the absence of antibody to B. burgdorferi PepVF, absence of B. burgdorferi flaB DNA in heart and bladder tissues, and absence of flaB in culture from heart tissues from pups euthanized >9 weeks after birth. We show that the transfer of anti-OspA antibodies from vaccinated P. leucopus dams to offspring prevents tick transmission and infection dynamics of B. burgdorferi in the major reservoir host of this spirochete in the USA.IMPORTANCEThis study contributes to our understanding of how interventions based in reservoir-targeted outer surface protein A vaccines designed to block transmission of B. burgdorferi from infected Ixodes scapularis ticks may disrupt the enzootic cycle of this spirochete and reduce incidence of Lyme disease.

Monoclonal Antibodies for Pediatric Viral Disease Prevention and Treatment

Medical advancements over the last century have improved our ability to treat pediatric infectious diseases, significantly reducing associated morbidity and mortality worldwide. Although vaccines have been pivotal in this progress, many viral pathogens still do not currently have effective vaccines. The COVID-19 pandemic highlighted the need for rapid responses to emerging viral pathogens and introduced new tools to combat them. This review addresses human monoclonal antibodies (mAbs) as a strategy for treating and preventing viral infections in pediatric populations. We discuss previously used and currently available mAbs and advancements in mAb discovery. We address the future of mAb therapy by describing novel approaches in drug production and delivery platforms in addition to alternative antibody classes. Finally, we review the challenges and limitations of mAb therapy development for newborns and children.

Maternal Transfer of Oral Vaccine Induced Anti-OspA Antibodies Protects Peromyscus spp Pups from Tick-Transmitted Borrelia burgdorferi

The efficacy and duration of passive immunity protection depends on maternal antibody levels and transfer efficiency. We investigated whether oral vaccination of Peromyscus leucopus dams with recombinant OspA-expressing E. coli could induce maternal transfer of anti-OspA antibodies and protect pups from Borrelia burgdorferi challenge. Dams were vaccinated until breeding pairs were created (i), until parturition (ii), and until pups were 2 weeks old (iii). Pups were challenged with nymphal I. scapularis -transmitted B. burgdorferi at ∼ 4 weeks of age. Anti-OspA IgG were quantified in dams and pups, and anti -B. burgdorferi IgG were quantified in pups. B. burgdorferi burden was assessed by flaB qPCR in pups' tissues ∼ 4 weeks after tick challenge and viability of B. burgdorferi was assessed by culture of heart tissue. P. leucopus pups born to dams vaccinated until breeding had low serologic anti-OspA antibody and were not protected from tick transmitted B. burgdorferi infection. However, when dams' vaccination extended until parturition and until pups were two weeks old, significant anti-OspA antibody transfer and protection from B. burgdorferi infection occurred. This was evidenced by absence of antibody to B. burgdorferi PepVF, absence of B. burgdorferi flaB DNA in heart and bladder tissues, and absence of flaB in culture from heart tissues from pups euthanized >9 weeks after birth. We show that transfer of anti-OspA antibodies from vaccinated P. leucopus dams to offspring prevents tick transmission and infection dynamics of B. burgdorferi in the major reservoir host of this spirochete in the United States.

Importance

This study contributes to our understanding of how interventions based in reservoir targeted OspA vaccines designed to block transmission of B. burgdorferi from infected I. scapularis ticks may disrupt the enzootic cycle of this spirochete and reduce incidence of Lyme disease.

Knowledge, Attitudes, and Practices Regarding Influenza and Pertussis Immunization During Pregnancy in Greece

BACKGROUND/OBJECTIVES

Vaccination against influenza and pertussis in pregnant women protects the mother and child through the transfer of protective antibodies across the placenta. However, pregnant women's vaccine hesitancy is a major barrier to achieve satisfactory vaccination coverage in many developed countries.

METHODS

Greek pregnant women's vaccination knowledge, attitudes, and practices were recorded. Structured questionnaires were administered to mothers of infants under the age of 12 months through their pediatricians. Sampling across the country's districts was applied to achieve geographic representativeness.

RESULTS

Questionnaires from 474 mothers were collected. Their mean age was 34 (±5) years. Vaccination uptake was 16.8% and 45.7%, for pertussis and influenza, respectively. During their recent pregnancy, 68.9% and 27.1% of the responders had been informed by their gynecologists regarding influenza and pertussis maternal immunization, respectively, indicating that gynecologists miss out on informing a significant rate of pregnant women. According to multiple logistic regression, women who gave birth during spring (OR: 2.29 vs. winter delivery, p = 0.042) and those with an MSc or PhD (OR: 2.93 vs. school graduates, p = 0.015) were more likely to receive influenza vaccination. Factors favoring influenza vaccination included doctor's recommendation (OR: 18.86, p < 0.001), being not/somewhat afraid of potential vaccine side effects during pregnancy (OR: 2.09, p = 0.012), considering the flu as relatively/very dangerous during pregnancy (OR: 8.05, p < 0.001), and considering the flu vaccine as relatively/completely safe (OR: 4.37, p < 0.001). Doctor's recommendation (OR: 29.55, p < 0.001) and considering pertussis a relatively/very serious risk to the mother's health during pregnancy (OR: 6.00, p = 0.002) were factors associated with pertussis vaccination during pregnancy.

CONCLUSIONS

The education of both expectant mothers and obstetricians is urgently needed in order to increase immunization coverage during pregnancy. The low influenza vaccination coverage among women delivering during winter and low pertussis immunization rates, in combination with low recommendation rates for both vaccines, strongly indicate that Greek obstetricians focus on maternal health alone. Their perspectives play an instrumental role in vaccine acceptance during pregnancy, shaping the immunization inclusion maps.

Transplacental Antibodies: Role of Maternal Vaccines and Immunity

Transplacental transfer of maternal antibody in utero is a key component of neonatal immunity. This transfer of maternal antibody across the placenta provides temporary protection from bacterial and viral pathogens that threaten newborn health. Maternal vaccination before and during pregnancy may be used to boost maternal immunity and optimize neonatal protection from infection and serious illness.

Low levels of pertussis- and measles-specific IgG antibodies in 6-week-old HIV-exposed and -unexposed Malawian infants: implications for vaccination strategies and role of long term HIV therapy

Serological studies in infants can provide valuable information on the degree of protection conferred by IgG maternal passive transfer during early life. If infant levels are inadequate, protection may be incomplete, increasing the risk of life-threatening diseases such as pertussis and measles, before immunization completion. In addition, HIV infection, -highly prevalent in African countries like Malawi-may impair transplacental antibody transfer. We determined anti-Pertussis Toxin (PT) and anti-measles IgG in 86 6-week-old infants, born to mothers living with HIV (HIV-exposed uninfected, HEU, n = 58) and to HIV-negative mothers (HIV-unexposed uninfected, HUU, n = 28). The HEU group was divided into two subgroups: Infants born to mothers who initiated antiretroviral therapy (ART) during pregnancy (Short-ART, SA-HEU group, n = 29) or already in stable ART (Long-term ART, LA-HEU group, n = 29). The mean anti-PT and anti-measles IgG levels (1.97 IU/ml and 32.9 mIU/ml, respectively) were comparable between the HUU and HEU infants. Overall, only 12.8% and 18.6% of all infants had IgG levels above the protective thresholds for pertussis and measles, respectively. The duration of ART significantly influenced the infant's serological profile, with SA-HEU infants showing significantly lower IgG levels compared to both HUU and LA-HEU infants. Protecting infants during early life remains a significant health challenge in many middle and low-income countries. Achieving better early serological protection requires the implementation of diverse vaccination strategies. This study emphasizes the crucial importance for women living with HIV to be on stable ART before pregnancy.

Lifelong partners: Gut microbiota-immune cell interactions from infancy to old age

Our immune system and gut microbiota are intricately coupled from birth, both going through maturation during early life and senescence during aging almost in a synchronized fashion. The symbiotic relationship between the human host and microbiota is critically dependent on a healthy immune system to keep our microbiota in check, while the microbiota provides essential functions to promote the development and fitness of our immune system. The partnership between our immune system and microbiota is particularly important during early life, when microbial ligands and metabolites shape the development of the immune cells and immune tolerance; during aging, having sufficient beneficial gut bacteria is critical for the maintenance of intact mucosal barriers, immune metabolic fitness, and strong immunity against pathogens. The immune system during childhood is programmed, with the support of the microbiota, to develop robust immune tolerance, and limit autoimmunity and metabolic dysregulation, which are prevalent during aging. This review comprehensively explores the mechanistic underpinnings of gut microbiota-immune cell interactions during infancy and old age, with the goal to gain a better understanding of potential strategies to leverage the gut microbiota to combat age-related immune decline.

Cord blood IgG for respiratory syncytial virus and subsequent infection during the COVID-19 pandemic

The resurgence of respiratory syncytial virus (RSV) infection among Japanese infants during the coronavirus disease 2019 pandemic might be due to a decrease in cord blood anti-RSV immunoglobulin G (IgG) positivity resulting from reduced maternal RSV exposure. This study examined changes in the positivity before and during the pandemic to clarify the relationship between this positivity and infantile/severe RSV infections. Data from a prospective cohort study conducted in Tokyo, Japan, involving mother-child pairs of infants born between February 2019 and August 2022 were reanalyzed. Cord blood anti-RSV IgG levels measured by enzyme-linked immunosorbent assay were classified as positive, gray zone, and negative. We examined the relationship between antibody positivity and infantile (≤12 months old) and/or severe RSV infections as diagnosed by pediatricians. A total of 319 families participated. There was a significant decrease in cord blood anti-RSV IgG positivity from 65.1% in 2019 to 50.9% in 2022 (P = .02). Among infants followed up until their 2nd birthday, 43 (33.1%) were diagnosed with RSV infections. Of these cases, 5 were infantile/severe and occurred among the 50 infants classified as negative or gray zone, while none were observed among the 80 infants classified as positive (P = .004). Infantile/severe RSV infection was identified in 4 (16.7%) born during the pandemic, representing a significantly higher rate than 1 (0.9%) born before the pandemic (P < .001). This study revealed an association between lower cord blood anti-RSV IgG positivity during the coronavirus disease 2019 pandemic compared to before the pandemic, and an increased risk of subsequent infant/severe RSV infections.

B Cell Responses to the Placenta and Fetus

Pregnancy has fascinated immunologists ever since Peter Medawar's observation that reproduction runs contrary to the founding tenets of immunology. During healthy pregnancy, maternal B cells interact with antigens of the foreign conceptus (placenta and fetus) yet do not elicit rejection. Instead, robust and redundant fetomaternal tolerance pathways generally prevent maternal B cells and antibodies from harming the placenta and fetus. Fetomaternal tolerance is not absolute, and unfortunately there exist several pregnancy complications that arise from breaks therein. Here, important historic and recent developments in the field of fetomaternal tolerance pertaining to maternal B cells and antibodies are reviewed. General rules from which to conceptualize humoral tolerance to the placenta and fetus are proposed. Significant but underexplored ideas are highlighted and topics for future research are suggested, findings from which are predicted to provide insight into the fundamental nature of tolerance and bolster efforts to combat immune-mediated pregnancy complications.

Safety, Efficacy, and Effectiveness of Maternal Vaccination against Respiratory Infections in Young Infants

Lower respiratory tract infection (LRTI) is a major cause of neonatal morbidity and mortality worldwide. Maternal vaccination is an effective strategy in protecting young infants from LRTI, particularly in the first few months after birth when infant is most vulnerable, and most primary childhood vaccinations have not been administered. Additionally, maternal vaccination protects the mother from illness during pregnancy and the postnatal period, and the developing fetus from adverse outcomes such as stillbirth and prematurity. In this paper, we review the safety, efficacy, and effectiveness of maternal vaccines against LRTIs, such as pertussis, influenza, coronavirus disease 2019, and respiratory syncytial virus.

Serum Immunoglobulin G Antibodies to Human Papillomavirus Type 6 L1, E2, E4, E6, and E7 Proteins Among Children Prospectively Followed up for 3 Years

BACKGROUND

Current knowledge implicates that human papillomavirus (HPV) infection can be acquired at an early age. However, the role of HPV-specific passive immunization from mother to neonate is nearly unexplored, especially against the HPV early proteins. We analyzed immunoglobulin G (IgG) antibodies against HPV-6 early (E2, E4, E6, E7) and late (L1) proteins in children prospectively followed up for 3 years.

METHODS

A total of 272 children and their mothers from the Finnish Family HPV Study were included in these analyses. Serum samples were obtained from pregnant mothers at their third trimester and from newborn/infants at 1-, 2-, 6-, 12-, 24-, and 36-month visits after birth. Antibodies were analyzed by multiplex serology based on glutathione S-transferase fusion protein capture to fluorescent beads.

RESULTS

Maternal antibodies to all tested HPV-6 proteins were transferred to neonates, concordance between maternal and neonates' antibody levels being highly significant (P < .001). Seropositivity of HPV-6 L1 in the neonates declined during the first 6 months of life, whereas changes in the E protein antibodies were less obvious. After the maternal antibodies had vanished, seroconversion to HPV-6 L1 at 12 months (median) and to the HPV-6 E proteins between 23 and 35 months was observed.

CONCLUSIONS

IgG antibodies against HPV-6 E and L proteins are transferred from mothers to their children. Seroconversion against HPV-6 L1, E2, E4, E6, and E7 does occur in early childhood, as a sign of acquired HPV-6 infection by vertical or horizontal transmission starting at 12 months of age.

Maternal and neonatal IgG against Klebsiella pneumoniae are associated with lower risk of neonatal sepsis: A case-control study of hospitalized neonates in Botswana

Sepsis is the leading postnatal cause of neonatal mortality worldwide. Globally Klebsiella pneumoniae is the leading cause of sepsis in hospitalized neonates. This study reports the development and evaluation of an ELISA for anti-Klebsiella IgG using dried blood spot (DBS) samples and evaluates the association of anti-Klebsiella IgG (anti-Kleb IgG) antibodies in maternal and neonatal samples with the risk of neonatal sepsis. Neonates and their mothers were enrolled at 0-96 hours of life in the neonatal unit of a tertiary referral hospital in Gaborone, Botswana and followed until death or discharge to assess for episodes of blood culture-confirmed neonatal sepsis. Neonates with sepsis had significantly lower levels of Kleb-IgG compared to neonates who did not develop sepsis (Mann-Whitney U, p = 0.012). Similarly, samples from mothers of neonates who developed sepsis tended to have less Kleb-IgG compared to mothers of controls. The inverse correlation between Kleb-IgG levels and all-cause bacteremia suggests that maternal Kleb-IgG may be protective through cross-reactivity with common bacterial epitopes. These data support the continued use of immunoglobulin assays using DBS samples to explore the role of passive immunity on neonatal sepsis risk and reaffirm the critical need for research supporting the development of maternal vaccines for neonatal sepsis.

Nonhuman primate models of pediatric viral diseases

Infectious diseases are the leading cause of death in infants and children under 5 years of age. In utero exposure to viruses can lead to spontaneous abortion, preterm birth, congenital abnormalities or other developmental defects, often resulting in lifelong health sequalae. The underlying biological mechanisms are difficult to study in humans due to ethical concerns and limited sample access. Nonhuman primates (NHP) are closely related to humans, and pregnancy and immune ontogeny in infants are very similar to humans. Therefore, NHP are a highly relevant model for understanding fetal and postnatal virus-host interactions and to define immune mechanisms associated with increased morbidity and mortality in infants. We will discuss NHP models of viruses causing congenital infections, respiratory diseases in early life, and HIV. Cytomegalovirus (CMV) remains the most common cause of congenital defects worldwide. Measles is a vaccine-preventable disease, yet measles cases are resurging. Zika is an example of an emerging arbovirus with devastating consequences for the developing fetus and the surviving infant. Among the respiratory viruses, we will discuss influenza and Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). We will finish with HIV as an example of a lifelong infection without a cure or vaccine. The review will highlight (i) the impact of viral infections on fetal and infant immune development, (ii) how differences in infant and adult immune responses to infection alter disease outcome, and emphasize the invaluable contribution of pediatric NHP infection models to the design of effective treatment and prevention strategies, including vaccines, for human infants.

In utero human cytomegalovirus infection expands NK-like FcγRIII+CD8+ T cells that mediate Fc antibody functions

Human cytomegalovirus (HCMV) profoundly impacts host T and NK cells across the lifespan, yet how this common congenital infection modulates developing fetal immune cell compartments remains underexplored. Using cord blood from neonates with and without congenital HCMV (cCMV) infection, we identify an expansion of Fcγ receptor III-expressing (FcγRIII-expressing) CD8+ T cells following HCMV exposure in utero. Most FcγRIII+CD8+ T cells express the canonical αβ T cell receptor (TCR), but a proportion express noncanonical γδ TCR. FcγRIII+CD8+ T cells are highly differentiated and have increased expression of NK cell markers and cytolytic molecules. Transcriptional analysis reveals FcγRIII+CD8+ T cells upregulate T-bet and downregulate BCL11B, known transcription factors that govern T/NK cell fate. We show that FcγRIII+CD8+ T cells mediate antibody-dependent IFN-γ production and degranulation against IgG-opsonized target cells, similar to NK cell antibody-dependent cellular cytotoxicity (ADCC). FcγRIII+CD8+ T cell Fc effector functions were further enhanced by IL-15, as has been observed in neonatal NK cells. Our study reveals that FcγRIII+CD8+ T cells elicited in utero by HCMV infection can execute Fc-mediated effector functions bridging cellular and humoral immunity and may be a promising target for antibody-based therapeutics and vaccination in early life.

Maternal influences on offspring food allergy

The prevalence of allergies has been globally escalating. While allergies could appear at any age, they often develop in early life. However, the significant knowledge gap in the field is the mechanisms by which allergies affect certain people but not others. Investigating early factors and events in neonatal life that have a lasting impact on determining the susceptibilities of children to develop allergies is a significant area of the investigation as it promotes the understanding of neonatal immune system that mediates tolerance versus allergies. This review focuses on the research over the recent 10 years regarding the potential maternal factors that influence offspring allergies with a view to food allergy, a potentially life-threatening cause of anaphylaxis. The role of breast milk, maternal diet, maternal antibodies, and microbiota that have been suggested as key maternal factors regulating offspring allergies are discussed here. We also suggest future research area to expand our knowledge of maternal-offspring interactions on the pathogenesis of food allergy.

Disease modifying treatment guidelines for multiple sclerosis in the United Arab Emirates

The newly constituted National Multiple Sclerosis (MS) Society (NMSS)of the United Arab Emirates (UAE), set up a scientific committee to create a MS disease modifying treatment (DMT) guideline for UAE. The committee considered several unique features of the MS community in UAE including large number of expatriate population, wide variations in health insurance coverage, physician and patient preferences for DMT. The overall goal of the treatment guideline is to facilitate the most appropriate DMT to the widest number of patients. To this end it has adapted recommendations from various health systems and regulatory authorities into a pragmatic amalgamation of best practices from across the world. Importantly where data is unavailable or controversial, a common sense approach is taken rather than leave physicians and patients in limbo. The committee classifies MS into subcategories and suggests appropriate treatment choices. It recommends treatment of RIS and CIS with poor prognostic factors. It largely equates the efficacy and safety of DMT with similar mechanisms of action or drug classes e.g. ocrelizumab is similar to rituximab. It allows early switching of treatment for unambiguous disease activity and those with progression independent of relapses. Autologous hematopoietic stem cell transplantation can be offered to patients who fail one high efficacy DMT. Pragmatic guidance on switching and stopping DMT, DMT choices in pregnancy, lactation and pediatric MS have been included. It is expected that these guidelines will be updated periodically as new data becomes available.

Analysis of the immune response using FTIR spectroscopy in mothers and their newborns with different vaccination schemes for COVID-19

The SARS-CoV-2 outbreak has provoked more than 6 million deaths worldwide. The scarcity of effective treatments and its virulence converted the vaccines into an essential tool to face it. The most used vaccines were the mRNA, adenovirus vector, and inactivated whole-virus. However, nowadays, infants aged < 6 months are not eligible for any vaccines against COVID-19, and their immunization relies on passive immunity. In this research, we investigated the humoral and cellular immune response generated on newborns of SARS-CoV-2 vaccinated mothers with mRNA or viral vector (VV) vaccine employing Fourier transformed infrared (FTIR) spectroscopy in saliva samples. For this purpose, saliva samples of newborns and their mothers were collected; the population was divided into two groups, VV and mRNA, which were subdivided into three subgroups: before pregnancy (BP), at the first (FTP) and second (STP) trimesters of pregnancy. The samples were analyzed using FTIR spectroscopy, and the bands associated with the humoral and cellular immune responses, such as IgG, IgA, and IFN-γ were analyzed. The integrated areas were calculated and compared to elucidate the quantity of those immunoglobins and the cytokine. Likewise, the correlation of the humoral and cellular immune response between the newborns and their mothers and the correlation between cellular and humoral immune response was also evaluated. The VV vaccine produced a significant humoral and cellular immune response in newborns and their mothers when they received it at the STP compared with the mRNA vaccine, evidencing statistical significance. However, no correlation was observed between newborns and their mothers when the vaccine was applied in this trimester of pregnancy. When administered BP, the mRNA vaccine generated more humoral immunity in newborns and their mothers. Nevertheless, compared with the VV vaccine, it only showed statistical significance in the mothers, highlighting that IgG showed a moderate positive correlation between the newborns and their mothers.

Differences in maternal-newborn ABO blood groups and risk of serious infant infection

BACKGROUND

During pregnancy, various maternal IgG antibodies are transferred to the developing fetus, some of which may protect the newborn against infection. If a mother and her fetus have different A, B or O (ABO) blood groups, then transferred maternal antibodies may plausibly protect the infant against infection.

AIM

To determine if maternal-newborn ABO blood group incongruence vs. congruence is associated with a lower risk of serious infection in the infant.

DESIGN

Retrospective population-based cohort.

METHODS

We used linked patient-level datasets for all singleton hospital livebirths from 2008 to 2022 in Ontario, Canada, with known maternal and newborn ABO blood groups. We used a dichotomous exposure state, either ABO blood group congruent (N = 114 507) or incongruent (N = 43 074). The main outcome of interest was the risk of serious infant infection within 27 days, and from 28 to 365 days, after birth. Cox proportional hazard models generated hazard ratios and 95% confidence intervals, and were adjusted for maternal age, world region of origin, residential income quintile and gestational age at birth.

RESULTS

Relative to maternal-newborn congruency, incongruent ABO blood group was associated with an adjusted hazard ratio of 0.88 (95% CI: 0.80-0.97) for serious neonatal infection within 27 days of birth, and 0.93 (95% CI: 0.90-0.96) for serious infection between 28 and 365 days after birth.

CONCLUSIONS

Maternal-newborn ABO incongruence may be associated with a lower relative risk of a serious infant infection within 27 days, and from 28 to 365 days, after birth.

Evaluation of mRNA-LNP and adjuvanted protein SARS-CoV-2 vaccines in a maternal antibody mouse model

Maternal antibodies (matAbs) protect against a myriad of pathogens early in life; however, these antibodies can also inhibit de novo immune responses against some vaccine platforms. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) matAbs are efficiently transferred during pregnancy and protect infants against subsequent SARS-CoV-2 infections. It is unknown if matAbs inhibit immune responses elicited by different types of SARS-CoV-2 vaccines. Here, we established a mouse model to determine if SARS-CoV-2 spike-specific matAbs inhibit immune responses elicited by recombinant protein and nucleoside-modified mRNA-lipid nanoparticle (mRNA-LNP) vaccines. We found that SARS-CoV-2 mRNA-LNP vaccines elicited robust de novo antibody responses in mouse pups in the presence of matAbs. Recombinant protein vaccines were also able to circumvent the inhibitory effects of matAbs when adjuvants were co-administered. While additional studies need to be completed in humans, our studies raise the possibility that mRNA-LNP-based and adjuvanted protein-based SARS-CoV-2 vaccines have the potential to be effective when delivered very early in life.

Predictors of mortality among low birth weight neonates after hospital discharge in a low-resource setting: A case study in Uganda

BACKGROUND

Most neonatal deaths occur among low birth weight infants. However, in resource-limited settings, these infants are commonly discharged early which further exposes them to mortality. Previous studies on morbidity and mortality among low birth weight infants after early discharge mainly focused on very low birth weight infants, and none described post-discharge neonatal mortality. This study aimed to determine the proportion and predictors of mortality among low birth weight neonates discharged from the Special Care Baby Unit at Mulago National Referral Hospital in Uganda.

METHODS

This was a prospective cohort study of 220 low birth weight neonates discharged from the Special Care Baby Unit at Mulago National Referral Hospital. These were followed up to 28 completed days of life, or death, whichever occurred first. Proportions were used to express mortality. To determine the predictors of mortality, Cox hazards regression was performed.

RESULTS

Of the 220 enrolled participants, 216 (98.1%) completed the follow-up. The mean gestational age of study participants was 34 ±3 weeks. The median weight at discharge was 1,650g (IQR: 1,315g -1,922g) and 46.1% were small for gestational age. During follow-up, 14/216 (6.5%) of neonates died. Mortality was highest (7/34, 20.6%) among neonates with discharge weights less than 1,200g. The causes of death included presumed neonatal sepsis (10/14, 71.4%), suspected aspiration pneumonia (2/14, 14.3%), and suspected cot death (2/14, 14.3%). The median time to death after discharge was 11 days (range 3-16 days). The predictors of mortality were a discharge weight of less than 1,200g (adj HR: 23.47, p <0.001), a 5-minute Apgar score of less than 7 (adj HR: 4.25, p = 0.016), and a diagnosis of neonatal sepsis during admission (adj HR: 7.93, p = 0.009).

CONCLUSION

Post-discharge mortality among low birth weight neonates at Mulago National Referral Hospital is high. A discharge weight of less than 1,200g may be considered unsafe among neonates. Caregiver education about neonatal danger signs, and measures to prevent sepsis, aspiration, and cot death should be emphasized before discharge and during follow-up visits.

Maternal and neonatal IgG against Klebsiella pneumoniae are associated with broad protection from neonatal sepsis: a case-control study of hospitalized neonates in Botswana

Sepsis is the leading postnatal cause of neonatal mortality worldwide. Globally Klebsiella pneumoniae is the leading cause of sepsis in hospitalized neonates. This study reports development and evaluation of ELISA for anti-Klebsiella IgG using dried blood spot samples and evaluates the association of anti-Klebsiella IgG (anti-Kleb IgG) antibodies in maternal and neonatal samples and the risk of neonatal sepsis. Neonates and their mothers were enrolled at 0-96 hours of life in the neonatal unit of a tertiary referral hospital in Gaborone, Botswana and followed until death or discharge to assess for episodes of blood culture-confirmed neonatal sepsis. Neonates with sepsis had significantly lower levels of Kleb-IgG compared to neonates who did not develop sepsis (Mann-Whitney U, p=0.012). Similarly, samples from mothers of neonates who developed sepsis tended to have less Kleb-IgG compared to mothers of controls (p=0.06). The inverse correlation between Kleb-IgG levels and all-cause bacteremia suggests that maternal Kleb-IgG is broadly protective through cross-reactivity with common bacterial epitopes. These data support the continued use of immunoglobulin assays using DBS samples to explore the role of passive immunity on neonatal sepsis risk and reaffirm the critical need for research supporting the development of maternal vaccines for neonatal sepsis.

Comparison of Anti-SARS-CoV-2-Specific Antibody Signatures in Maternal and Infant Blood after COVID-19 Infection versus COVID-19 Vaccination during Pregnancy

OBJECTIVE

 The Advisory Committee on Immunization Practices and The American College of Obstetricians and Gynecologists recommend coronavirus disease 2019 (COVID-19) vaccine for pregnant persons to prevent severe illness and death. The objective was to examine levels of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgG, IgM, and IgA against spike protein receptor binding domain (RBD) and nucleocapsid protein (NCP) in maternal and infant/cord blood at delivery after COVID 19 vaccination compared with SARS-CoV-2 infection at in mother-infant dyads at specified time points.

STUDY DESIGN

 Mothers with SARS-CoV-2 infection (n = 31) or COVID-19 vaccination (n = 25) during pregnancy were enrolled between July 2020 and November 2021. Samples were collected at delivery and IgG, IgM, and IgA to RBD of spike and NCPs compared in the infected and vaccinated groups. Timing of infection/vaccination prior to delivery and correlation with antibody levels was performed.

RESULTS

 The majority of participants received vaccination within 90 days of delivery and over half received the Pfizer BioNTech vaccine. There were no significant correlations between antibody levels and timing of infection or vaccination. Infant IgG levels to the RBD domain of spike protein were higher in the vaccinated group (n = 25) as compared with the infants born to mothers with infection (n = 31). Vaccination against COVID-19 during pregnancy was associated with detectable maternal and infant anti-RBD IgG levels at delivery irrespective of the timing of vaccination.

CONCLUSION

 Timing of vaccination had no correlation to the antibody levels suggesting that the timing of maternal vaccination in the cohort did not matter. There was no IgM detected in infants from vaccinated mothers. Infants from vaccinated mothers had robust IgG titers to RBD, which have a lasting protective effect in infants.

KEY POINTS

· COVID-19 vaccination during pregnancy had detectable antibody.. · No correlation between antibody levels and timing of vaccination.. · Infants from vaccinated mothers had robust IgG titers to RBD..

Life-threatening infections in human newborns: Reconciling age-specific vulnerability and interindividual variability

In humans, the interindividual variability of clinical outcome following exposure to a microorganism is immense, ranging from silent infection to life-threatening disease. Age-specific immune responses partially account for the high incidence of infection during the first 28 days of life and the related high mortality at population level. However, the occurrence of life-threatening disease in individual newborns remains unexplained. By contrast, inborn errors of immunity and their immune phenocopies are increasingly being discovered in children and adults with life-threatening viral, bacterial, mycobacterial and fungal infections. There is a need for convergence between the fields of neonatal immunology, with its in-depth population-wide characterization of newborn-specific immune responses, and clinical immunology, with its investigations of infections in patients at the cellular and molecular levels, to facilitate identification of the mechanisms of susceptibility to infection in individual newborns and the design of novel preventive and therapeutic strategies.

Disturbances in the IgG Antibody Profile in HIV-Exposed Uninfected Infants Associated with Maternal Factors

Over the last 20 years, the incidence of vertical HIV transmission has decreased from 25%-42% to less than 1%. Although there are no signs of infection, the health of HIV-exposed uninfected (HEU) infants is notoriously affected during the first months of life, with opportunistic infections being the most common disease. Some studies have reported effects on the vertical transfer of antibodies, but little is known about the subclass distribution of these antibodies. We proposed to evaluate the total IgG concentration and its subclasses in HIV+ mothers and HEU pairs and to determine which maternal factors condition their levels. In this study, plasma from 69 HEU newborns, their mothers, and 71 control pairs was quantified via immunoassays for each IgG isotype. Furthermore, we followed the antibody profile of HEUs throughout the first year of life. We showed that mothers present an antibody profile characterized by high concentrations of IgG1 and IgG3 but reduced IgG2, and HEU infants are born with an IgG subclass profile similar to that of their maternal pair. Interestingly, this passively transferred profile could remain influenced even during their own antibody production in HEU infants, depending on maternal conditions such as CD4+ T-cell counts and maternal antiretroviral treatment. Our findings indicate that HEU infants exhibit an altered IgG subclass profile influenced by maternal factors, potentially contributing to their increased susceptibility to infections.

Monocyte and neutrophil to lymphocyte ratios in hospitalized children with RSV bronchiolitis

OBJECTIVE

Acute bronchiolitis is the most common cause of hospitalization in young children. Data on monocyte-to-lymphocyte-ratio (MLR) and neutrophil-to-lymphocyte-ratio (NLR) as biomarkers are limited. We aim to evaluate these ratios in children hospitalized with respiratory syncytial virus (RSV) bronchiolitis and their value as biomarkers for severe clinical outcomes.

STUDY DESIGN

A single-center retrospective cohort study of children aged <2 years hospitalized due to RSV bronchiolitis, between January 2018 and March 2022, with a complete blood count upon admission. We divided the cohort into quartiles based on MLR and NLR values. We examined associations between quartiles and four clinical severity outcomes.

RESULTS

A total of 2038 children (median age: 4.4 months, IQR: 1.9-9.8) were included in the study. The median MLR and NLR values for quartiles 1-4 were 0.14, 0.22, 0.30, 0.47, and 0.37, 0.70, 1.16, 2.29, respectively. Children with higher MLR had higher hospitalization rates to the pediatric intensive care unit (PICU) (Q1 2.4%, Q4 9.4%, p < .001), extended hospital stays (Q1 19.4%, Q4 32%, p < .001), and lower minimal oxygen saturation (Q1 90%, Q4 87%, p < .001). Cut-off values of 0.34 for MLR and 0.67 for NLR optimally identified PICU admissions. In a model accounting for age and sex, the fourth MLR quartile had an RR of 3.4 (95% CI: 1.76-7.22) and successfully predicted PICU admissions (area under the curve = 0.73; 95% CI: 0.681-0.789).

CONCLUSIONS

MLR and NLR are potential biomarkers for identifying children with RSV bronchiolitis at a higher risk for severe outcomes, specifically PICU admission.

Maternal vaccination against RSV can substantially reduce childhood mortality in low-income and middle-income countries: A mathematical modeling study

Background

Respiratory syncytial virus (RSV) is a leading cause of childhood mortality in infants below 6 months of age. In low-income and middle-income countries (LMICs), the public health burden is substantial and resources are limited. It is critical to inform decision makers about effectiveness of new interventions.

Methods

We developed a mathematical model where individual RSV subtype A (RSV-A) and B (RSV-B) maternally derived neutralizing titers were predicted at time of birth after maternal vaccination with the RSV prefusion F protein-based vaccine. We estimated the subsequent duration of vaccine-induced immunity and compared this to the age at time of death distribution in the RSV GOLD Mortality Database to predict the potential impact of maternal vaccination on RSV-related childhood mortality. We used country-specific timing of antenatal care visits distributions and mortality estimates to make country-specific predictions for number of cases averted.

Findings

The model predicts that on average a neonate born at 40 weeks gestational age will be protected between 6 and 7 months from RSV-A and approximately 5 months from RSV-B related mortality. We estimated the potential impact of RSV-related mortality for in-hospital and out-of-hospital cases in LMICs and predicted that in 51 GAVI-eligible countries maternal vaccination could avert between 55% and 63% of the RSV-related in-hospital mortality cases below 6 months of age.

Interpretation

We show that maternal vaccination could substantially decrease RSV-A and RSV-B related in-hospital and out-of-hospital mortality in LMICs in the first 6 months of life.

Neonatal Outcomes of Premature Infants Born to Women with the Novel Coronavirus (SARS-CoV-2) Infection: A Case Control Study

OBJECTIVE

Novel coronavirus disease 2019 (COVID-19) is a disease associated with atypical pneumonia caused by the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). The first cases of COVID-19 were reported in Wuhan at the end of 2019. Transmission usually occurs via infected droplets and close personal contact; the possibility of vertical transmission is still under debate. This retrospective study aimed to analyze clinical characteristics of premature infants born to mothers with symptomatic COVID-19 disease.

STUDY DESIGN

This case control study compared the clinical and laboratory data of 20 premature infants born to mothers infected with SARS-CoV-2 with sex and gestational age-matched historical controls.

RESULTS

The median gestational age and birth weight in both groups were similar. Respiratory distress developed in 11 (55.5%) infants in study group and 19 (47.5%) infants in control group. Mechanical ventilation and endotracheal surfactant administration rates were similar. Median duration of hospitalization was 8.5 (2-76) days in study group and 12 days in historical controls. Real-time reverse-transcription polymerase chain reaction tests (RT-PCR) of nasopharyngeal swab samples for SARS-CoV-2 were found to be negative twice, in the first 24 hours and later at 24 to 48 hours of life. No neutropenia or thrombocytopenia was detected in the study group. Patent ductus arteriosus, bronchopulmonary dysplasia, and necrotizing enterocolitis rates were similar between groups. No mortality was observed in both groups.

CONCLUSION

To the best of our knowledge, this is one of the few studies evaluating the clinical outcomes of premature infants born to SARS-CoV-2 infected mothers. There was no evidence of vertical transmission of SARS-CoV-2 from symptomatic SARS-CoV-2-infected women to the neonate in our cohort. The neonatal outcomes also seem to be favorable with no mortality in preterm infants.

KEY POINTS

· SARS-CoV-2 pandemic is a challenge for pregnant women.. · Neonatal outcomes of premature infants born to mothers infected with SARS-CoV-2 not well defined.. · SARS-CoV-2 infection seems to have no adverse effect on mortality and morbidity in premature infants..

Advances in proteomics: characterization of the innate immune system after birth and during inflammation

Proteomics is the characterization of the protein composition, the proteome, of a biological sample. It involves the large-scale identification and quantification of proteins, peptides, and post-translational modifications. This review focuses on recent developments in mass spectrometry-based proteomics and provides an overview of available methods for sample preparation to study the innate immune system. Recent advancements in the proteomics workflows, including sample preparation, have significantly improved the sensitivity and proteome coverage of biological samples including the technically difficult blood plasma. Proteomics is often applied in immunology and has been used to characterize the levels of innate immune system components after perturbations such as birth or during chronic inflammatory diseases like rheumatoid arthritis (RA) and inflammatory bowel disease (IBD). In cancers, the tumor microenvironment may generate chronic inflammation and release cytokines to the circulation. In these situations, the innate immune system undergoes profound and long-lasting changes, the large-scale characterization of which may increase our biological understanding and help identify components with translational potential for guiding diagnosis and treatment decisions. With the ongoing technical development, proteomics will likely continue to provide increasing insights into complex biological processes and their implications for health and disease. Integrating proteomics with other omics data and utilizing multi-omics approaches have been demonstrated to give additional valuable insights into biological systems.

Maternal antibody transfer rate of vaccination against SARS-CoV-2 before or during early pregnancy and its protective effectiveness on offspring

This study focuses on maternal antibody transfer following vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) before or during early pregnancy and its potential protective effects on infants, providing scientific evidence for vaccination strategies. This prospective study tested the samples for SARS-CoV-2 IgG antibody titers and neutralizing capacity and tracked the infections after birth. Perform multivariate analysis of factors influencing antibody transfer rate, newborn antibody titers, and infant infection. Total 87.1% (122/140) women received coronavirus disease 2019 (COVID-19) vaccine before or during early pregnancy, and 28 of them had breakthrough infection. The maternal and neonatal IgG positive rates at delivery were 60.7% (85/140) and 60.8% (87/143), respectively. A positive correlation was found between neonatal and maternal IgG antibody titers. Compared with the median IgG antibody transfer rate of infected pregnant women, that of vaccinated but not infected pregnant women was higher (1.21 versus: 1.53 [two doses], 1.71 [three doses]). However, neonatal IgG antibodies were relatively low (174.91 versus: 0.99 [two doses], 8.18 [three doses]), and their neutralizing capacity was weak. The overall effectiveness of maternal vaccination in preventing infant infection was 27.0%, and three doses had higher effectiveness than two doses (64.3% vs. 19.6%). Multivariate analysises showed that in vaccination group women receiving three doses or in infection group women with longer interval between infection and delivery had a higher antibody transfer rate and neonatal IgG antibody titer. More than half of women vaccinated before or during early pregnancy can achieve effective antibody transfer to newborns. However, the neonatal IgG antibody titer is low and has a weak neutralizing capacity, providing limited protection to infants.

Fetal Secretory IgA Delivery via Transamniotic Fetal Immunotherapy (TRAFIT) in a Rodent Model

PURPOSE

We sought to determine the feasibility and routing kinetics of transamniotic fetal delivery of secretory immunoglobulin-A (SIgA), in a rodent model.

METHODS

Fetuses (n = 94) from seven time-dated pregnant dams received intra-amniotic injections on gestational day 17 (E17, term = E21-22) of either saline (n = 15) or a solution of 1 mg/mL of ≥95% homogeneous human SIgA (n = 79). Animals were euthanized daily at E18-E21 for quantification of the IgA component by ELISA at gestational membranes, placenta, and select fetal anatomical sites against saline controls procured at term. Statistical analysis was by Mann-Whitney U-test.

RESULTS

None of the saline-injected animals had detectable human IgA. SIgA-injected fetuses showed human IgA in the stomach aspirate, intestinal wall, lungs, liver, and serum at all time points. IgA levels were significantly higher in the gastric aspirate and in the intestine than in all other sites (p < 0.001 for both), with intestinal levels remaining stable through E18-E21 (p = 0.09-0.62 pairwise). Serum and placental levels were consistently low throughout, reaching near zero levels by E21.

CONCLUSIONS

The chronology of exogenous secretory-IgA kinetics after intra-amniotic injection is suggestive of fetal uptake by ingestion, leading to consistent levels in the gastrointestinal tract. Transamniotic fetal immunotherapy (TRAFIT) with secretory-IgA may become a novel strategy for enhancing early mucosal immunity.

LEVEL OF EVIDENCE

N/A (animal and laboratory study).

TYPE OF STUDY

Animal and laboratory study.

Are high avidity antibodies to Plasmodium falciparum antigens preferentially transferred across the placenta of premature and term babies?

INTRODUCTION

Transplacental transport of maternal IgG via the neonatal Fc receptor (FcRn) provides babies with passive immunity. Several factors are reported to influence transport, including the avidity of antibodies (Abs) for their cognate antigens. Unfortunately, information on the role of antibody (Ab) avidity is limited. This study investigated if i) antibodies (Abs) with high avidity for 6 Plasmodium falciparum antigens and tetanus toxoid (TTx) were preferentially transferred to premature and term Cameroonian babies and ii) if Ab avidity was increased in babies whose mothers had placental malaria (PM), implicating the involvement of immune complexes.

METHODS

Total IgG (mg/ml) and Abs to malarial antigens (AMA1, EBA-175, MSP1-42, MSP2, MSP3, DBL5 of VAR2CSA) and TTx were measured in paired mother-cord samples obtained from premature and term deliveries in Cameroon. Half the women had PM at delivery. Avidity Indices (AIs) were determined by treating antigen-bound-Abs with different molar concentrations of NH4SCN and calculating 50% endpoints.

RESULTS

Total IgG and antigen-specific Abs increased in cord blood with gestational age; however, AIs did not. AIs in paired maternal-cord blood samples were strongly associated for all antigens (r = 0.77-0.96). However, no significant different in AIs was found between paired mother-cord blood samples for any of the antigens (p values > 0.05). Similarly, Ab avidity was not increased in cord blood of babies whose mothers had PM or hypergammaglobulinemia.

DISCUSSION

Overall, there was no evidence that higher avidity Abs to any of the malarial antigens or TTx were preferentially transferred to Cameroonian babies.

Colostrum Features of Active and Recovered COVID-19 Patients Revealed Using Next-Generation Proteomics Technique, SWATH-MS

Colostrum performs nutritional, anti-inflammatory and anti-infective functions and promotes immune system formation and organ development. The new coronavirus, SARS-CoV-2, has generated concerns about viral transmission through human milk, with a lack of evidence about human milk's protective effects against the infection. This study aimed at analyzing presence of the virus and at identifying the protein expression profile of human colostrum in active and COVID-19-recovered patients. Colostrum samples were collected from women with COVID-19 (n = 3), women recently recovered from the infection (n = 4), and non-infected women (n = 5). The samples were analyzed by means of RT-qPCR to determine presence of the virus and using SWATH-MS for proteomic analysis. Proteomic results were then analyzed using bioinformatic methods. The viral tests were negative for SARS-CoV-2 in the colostrum from COVID-19 patients. The proteomic analysis identified 301 common proteins in all samples analyzed. Nineteen proteins were upregulated and 7 were downregulated in the COVID-19 group versus the control samples, whereas 18 were upregulated and 7 were downregulated when comparing the COVID-19 group to the recovered group. Eleven proteins were biomarkers of active COVID-19 infection. Ten were upregulated: ACTN1, CD36, FAM3B, GPRC5B, IGHA2, IGK, PLTP, RAC1, SDCBP and SERPINF1, and one was downregulated: PSAP. These proteins are mainly related to immunity, inflammatory response and protein transport. In conclusion, the results of this study suggest that colostrum is not a vehicle for mother-to-child SARS-CoV-2 transmission. Moreover, the colostrum's proteome of active and recuperated patients indicate that it could provide immune benefits to infants.

Transplacental transfer of anti-SARS-CoV-2 neutralizing antibodies in comparison to other pathogens total antibodies

BACKGROUNDS

Due to immaturity of their immune system, passive maternal immunization is essential for newborns during their first months of life. Therefore, in the current context of intense circulation of SARS-CoV-2, identifying factors influencing the transfer ratio (TR) of neutralizing antibodies against SARS-CoV-2 (NAb) appears important.

METHODS

Our study nested in the COVIPREG cohort (NCT04355234), included mothers who had a SARS-CoV-2 PCR positive during their pregnancy and their newborns. Maternal and neonatal NAb levels were measured with the automated iFlash system.

RESULTS

For the 173 mother-infant pairs included in our study, the median gestational age (GA) at delivery was 39.4 weeks of gestation (WG), and 29.7 WG at maternal SARS-CoV-2 infection. Using a multivariate logistic model, having a NAb TR above 1 was positively associated with a longer delay from maternal positive SARS-CoV-2 PCR to delivery (aOR 1.09, 95% CI: 1.03 - 1.17) and with a later GA at delivery (aOR = 1.58, 95% CI: 1.09 - 2.52). It was negatively associated with being a male newborn (aOR 0.21, 95% CI: 0.07 - 0.59). In 3rd trimester SARS-CoV-2 infected mothers, NAb TR was inferior to VZV, toxoplasmosis, CMV, measle and rubella's TR. However, in 1st or 2nd trimester infected mothers, only measle TR was different from NAb TR.

CONCLUSION

Male newborn of mothers infected by SARS-CoV-2 during their pregnancy appear to have less protection against SARS-CoV-2 in their first months of life than female newborns. Measle TR was superior to NAb TR even in case of 1st or 2nd trimester maternal SARS-CoV-2 infection. Future studies are needed to investigate possible differences in transmission of NAb following infection vs vaccination and its impact on TR.

Fetal Alloimmune Hemolytic Anemia (AHA) as a Potential Target for Transamniotic Fetal Immunotherapy (TRAFIT)

PURPOSE

Fetal alloimmune hemolytic anemia (AHA) resulting from maternal antibodies against fetal erythrocytes may require fetal administration of immunoglobulin-G (IgG) via invasive methods. IgG can reach the fetal circulation after transamniotic fetal immunotherapy (TRAFIT). We sought to both develop a model of AHA and to test TRAFIT as a potential treatment.

METHODS

Sprague-Dawley fetuses (n = 113) received intra-amniotic injections on gestational-day 18 (E18, term = E21) of either saline (control; n = 40), anti-rat-erythrocyte antibodies (AHA; n = 37), or anti-rat-erythrocyte antibodies plus IgG (AHA + IgG; n = 36). At term, blood was procured for red blood count (RBC), hematocrit, or ELISA for inflammatory markers.

RESULTS

There was no difference in survival [95% (107/113)] across groups (p = 0.87). Both hematocrit and RBC were significantly lower in the AHA group than controls (p < 0.001). Although still significantly lower than controls (p < 0.001), both hematocrit and RBC significantly increased in AHA + IgG group compared to AHA alone (p < 0.001). Pro-inflammatory TNF-α and IL1-β were significantly elevated from controls in the AHA group, but not in AHA + IgG (p < 0.001-0.159).

CONCLUSIONS

Intra-amniotic injection of anti-rat-erythrocyte antibodies can reproduce manifestations of fetal AHA, constituting a practical model of this disease. Transamniotic fetal immunotherapy with IgG reduces anemia in this model and may emerge as a new minimally invasive means of treatment.

TYPE OF STUDY

Animal and laboratory study.

LEVEL OF EVIDENCE

N/A (animal and laboratory study).

Inflammatory and Immune Responses during SARS-CoV-2 Infection in Vaccinated and Non-Vaccinated Pregnant Women and Their Newborns

BACKGROUND

Pregnant women are more susceptible to severe disease associated with SARS-CoV-2 infection. We performed a prospective study to analyze the inflammatory and immune profile after SARS-CoV-2 infection occurring in vaccinated or non-vaccinated pregnant women and their newborns.

METHODS

Twenty-five pregnant women with SARS-CoV-2 infection were enrolled, and sixteen cord blood samples were obtained at delivery.

RESULTS

We observed that IL-1β, TNF-α, Eotaxin, MIB-1β, VEGF, IL-15, IL-2, IL-5, IL-9, IL-10 and IL-1ra levels were significantly higher in vaccinated than non-vaccinated mothers. Furthermore, the newborns of the vaccinated mothers produced higher levels of IL-7, IL-5 and IL-12 compared to the newborns of non-vaccinated mothers. Anti-Spike (S) IgG levels were significantly higher in all vaccinated mothers and their newborns compared to the non-vaccinated group. We found that 87.5% of vaccinated women and 66.6% of non-vaccinated women mounted an S-specific T-cell response quantified by ELISpot assay. Moreover, 75.0% of vaccinated mothers and 38.4% of non-vaccinated mothers showed S-specific CD4⁺ T-cell proliferative response. The T-helper subset response was restricted to CD4⁺ T_h1 in both vaccinated and non-vaccinated women.

CONCLUSION

A higher level of cytokines, IgG antibodies and memory T cells was noted in the vaccinated women. Furthermore, the maternal IgG antibody trans-placental transfer occurred more frequently in vaccinated mothers and may protect the newborn.

Evidence for the Role of a Second Fc-Binding Receptor in Placental IgG Transfer in Nonhuman Primates

Transplacental transfer of maternal antibodies provides the fetus and newborn with passive protection against infectious diseases. While the role of the highly conserved neonatal Fc receptor (FcRn) in transfer of IgG in mammals is undisputed, recent reports have suggested that a second receptor may contribute to transport in humans. We report poor transfer efficiency of plant-expressed recombinant HIV-specific antibodies, including engineered variants with high FcRn affinity, following subcutaneous infusion into rhesus macaques close to parturition. Unexpectedly, unlike those derived from mammalian tissue culture, plant-derived antibodies were essentially unable to cross macaque placentas. This defect was associated with poor Fcγ receptor binding and altered Fc glycans and was not recapitulated in mice. These results suggest that maternal-fetal transfer of IgG across the three-layer primate placenta may require a second receptor and suggest a means of providing maternal antibody treatments during pregnancy while avoiding fetal harm. IMPORTANCE This study compared the ability of several human HIV envelope-directed monoclonal antibodies produced in plants with the same antibodies produced in mammalian cells for their ability to cross monkey and mouse placentas. We found that the two types of antibodies have comparable transfer efficiencies in mice, but they are differentially transferred across macaque placentas, consistent with a two-receptor IgG transport model in primates. Importantly, plant-produced monoclonal antibodies have excellent binding characteristics for human FcRn receptors, permitting desirable pharmacokinetics in humans. The lack of efficient transfer across the primate placenta suggests that therapeutic plant-based antibody treatments against autoimmune diseases and cancer could be provided to the mother while avoiding transfer and preventing harm to the fetus.

Immune Response and Transplacental Antibody Transfer in Pregnant Women after COVID-19 Vaccination

COVID-19 infection is associated with increased risk of pregnancy complications, making vaccination during pregnancy critical for mother-neonate dyads. Few data, often with an unrepresentative sample size, are available on SARS-CoV-2 vaccine-induced humoral and cell-mediated response. Here, we evaluated anti-S antibody and interferon-gamma (IFN-γ) production elicited by SARS-CoV-2 immunization in maternal and neonatal plasma. Pregnant women (n = 230) were prospectively enrolled and classified as unvaccinated (n = 103) and vaccinated (n = 127); after serological screening for previous infections, assays were performed on 126 dyads, 15 mothers and 17 newborns. Positive anti-S antibodies were found in most of the vaccinated subjects, regardless of timespan between immunization and delivery (range: 7-391 days). A total of 89 of 92 vaccinated women showed a broad response to COVID-19 immunization and highly effective placental transfer, as attested by anti-S positive rates (maternal = 96.7%, cord = 96.6%). Most of our subjects had indeterminate results in an IGRA assay, preventing a conclusive evaluation of IFN-γ production. Indeed, pregnancy-related hormonal changes may influence T-cell response with an impact on IFN-γ production. Positive pregnancy and perinatal outcomes reinforce the evidence that the anti-SARS-CoV-2 immunization is effective and well-tolerated in pregnant women and also protective for the fetus/neonate, even though it was not possible to define the related IFN-γ production and role.

Some Immune Parameters of Term Newborns at Birth Are Associated with the Concentration of Iron, Copper and Magnesium in Maternal Serum

The nutritional status of pregnant women is considered to affect fetal development and the health condition of newborns, including their immune system. We investigated the relationship between the concentrations of magnesium (Mg), calcium (Ca), zinc (Zn), iron (Fe) and copper (Cu) in maternal serum (MS) and the concentrations of IgG antibodies and antineutrophil cytoplasmatic auto-antibodies against lactoferrin (Lf-ANCA) in umbilical cord serum (UCS). IgG was considered as a promoter of immunity, and Lf-ANCA as an inhibitor. The examined group consisted of 98 pregnant women and their healthy term newborn children. The concentrations of mineral elements were measured by FAAS/FAES, while the concentrations of antibodies were determined by ELISA. Excessive MS Fe and insufficient MS Cu were related to insufficient UCS IgG and excessive UCS Lf-ANCA. The correlation analysis showed confirming results. Adequate UCS IgG and Lf-ANCA were related to MS Mg at the strictly lower limit of the reference values. The results obtained seem to suggest that an excess of Fe and a deficiency of Cu in pregnancy may adversely affect some immune parameters of newborns. Reference values for MS Mg are likely to require reconsideration. It would be advisable to monitor the nutritional status of pregnant women with minerals in order to support the immune capacity of newborns.

Transplacental transfer of SARS-CoV-2 antibodies: a cohort study

The purpose of this study was to examine the transfer rate of SARS-CoV-2 IgG antibodies in pregnancy and newborns. Two Danish labor wards screened all women for SARS-CoV-2 by PCR upon arrival. Women (n = 99) with a SARS-CoV-2 PCR-positive nasopharyngeal (NP) swab or with a household member with a positive swab at labor or any time during pregnancy, or COVID-19 symptoms upon admission (November 2020 through August 2021), were included. Mother and infant were tested by NP swabs at delivery, and maternal and infant (umbilical cord) venous blood samples were collected. We obtained clinical information including previous PCR test results from the medical records. SARS-Cov-2 IgM and quantified IgG antibodies were measured by enzyme-linked immunosorbent assay and transfer ratios of IgG. We detected IgG antibodies in 73 women and 65 cord blood sera and found a strong correlation between SARS-CoV-2 IgG concentrations in maternal and umbilical cord sera (r = 0.9; p < 0.05). Transfer ratio was > 1.0 in 51 out of 73 (69%) infants and > 1.5 in 26 (35%). We found that transfer was proportional to time from a positive SARS-CoV-2 PCR NP swab to delivery (r = 0.5; p < 0.05). Transfer ratios of SARS-CoV-2 antibodies were associated with time from infection to delivery with transfer ratios of more than 1.0 in the majority of seropositive mother-infant dyads.

Evaluation of Transplacental Antibody Transfer in Pregnant Women Immunized with Different SARS-CoV-2 Homologous or Heterologous Schemes

There is scarce information related to transplacental antibody transfer against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with different homologous and heterologous vaccination schemes. This study aimed to correlate the magnitude of transplacental transfer anti-SARS-CoV-2 antibodies in different homologous and heterologous schemes. An observational cross-sectional study was developed to identify pregnant women vaccinated against SARS-CoV-2. They were questioned about their immunization status; blood samples from the mother, umbilical cord during labor, and the newborn 72 h after birth were taken to measure anti-S1 and anti-S2 specific IgG antibodies for SARS-CoV-2. We recruited 104 women with a median age of 29 (SD 1.17). We found antibodies in all newborns with vaccinated mothers. Homologous BNT162b2 mRNA regimen had the highest mean (SD) antibody titers (AU/mL) in maternal (994.93 (3.08), p = 0.039), umbilical cord (1316.43 (2.79), p = 0.016), and newborn (1192.02 (3.55), p = 0.020) blood. The generalized linear model showed a positive effect over antibodies with at least one dose in maternal (β = -1.1, p = 0.002) and newborn (β= -0.717, p = 0.044) blood, and with two doses (β = -0.684, p = 0.026) in umbilical cord blood. In conclusion, antibodies were detected in all vaccinated women and their newborns. Transfer of antibodies was found from the first dose, and the levels increased with the number of vaccine doses. Vaccination should be encouraged in pregnant women with any available scheme.

Age-related seroprevalence trajectories of seasonal coronaviruses in children including neonates in Guangzhou, China

OBJECTIVES

Four seasonal coronaviruses, including human coronavirus (HCoV)-229E and HCoV-OC43, HCoV-NL63, and HCoV-HKU1 cause approximately 15-30% of common colds in adults. However, the full landscape of the immune trajectory to these viruses that covers the whole childhood period is still not well understood.

METHODS

We evaluated the serological responses against the four seasonal coronaviruses in 1886 children aged under 18 years by using enzyme-linked immunosorbent assay. The optical density values against each HCoV were determined from each sample. Generalized additive models were constructed to determine the relationship between age and seroprevalence throughout the whole childhood period. The specific antibody levels against the four seasonal coronaviruses were also tested from the plasma samples of 485 pairs of postpartum women and their newborn babies.

RESULTS

The immunoglobulin (Ig) G levels of the four seasonal coronaviruses in the mother and the newborn babies were highly correlated (229E: r = 0.63; OC43: r = 0.65; NL63: r = 0.69; HKU1: r = 0.63). The seroprevalences in children showed a similar trajectory in that the levels of IgG in the neonates dropped significantly and reached the lowest level after the age of around 1 year (229E: 1.18 years; OC43: 0.97 years; NL63: 1.01 years; HKU1: 1.02 years) and then resurgence in the children who aged older than 1 year. Using the lowest level from the generalized additive models as our cutoff, the seroprevalences for HCoV-229E, HCoV-OC43, HCoV-NL63, and HCoV-HKU1 were 98.11%, 96.23%, 96.23% and 94.34% at the age of 16-18 years.

CONCLUSION

Mothers share HCoV-specific IgGs with their newborn babies and the level of maternal IgGs waned at around 1 year after birth. The resurgence of the HCoV-specific IgGs was found thereafter with the increase in age suggesting repeated infection occurred in children.

Immunoglobulin G and subclasses placental transfer in fetuses and preterm newborns: a systematic review

Immunoglobulin G (IgG) and subclasses are the only class of antibodies capable of crossing placenta and providing protection against neonatal infectious diseases, especially in premature infants. This systematic review aimed to review the literature concerning the transplacental transfer of IgG and its subclasses in fetuses and preterm newborns and compare the results with data from term neonates. Eleven studies were included in the final review. Most studies demonstrated a lower transplacental passage of IgG2 than other subclasses in term and preterm newborns and a more efficient passage of total IgG and IgG1 after 37 weeks of gestational age. These results elucidate the physiology of IgG subclass transfer during pregnancy and may explain one of the reasons preterm newborns are especially susceptible to specific pathogens, such as encapsulated bacteria.

Maternal immunization with pneumococcal surface protein A provides the immune memories of offspring against pneumococcal infection

Introduction

Streptococcus pneumoniae (S. pneumoniae) is one of the most widespread pathogens in the world and one of the largest infectious causes of infant mortality. Although current vaccines have various benefits, antibiotic resistance and the inability to vaccinate infants less than one year old demands the development of new protective strategies. One strategy, 'maternal immunization', is to protect infants by passive immunity from an immunized mother, although its mechanism is still not fully understood.

Materials and methods

The current study aimed to acquire immunity against S. pneumoniae in infants by maternal immunization with pneumococcal common antigen, pneumococcal surface protein A (PspA). Four-week-old female mice were immunized with recombinant PspA intranasally twice a week for three weeks. Females were mated with age-matched males after immunization, and delivered offspring.

Results

The week-old offspring derived from and fostered by immunized mothers had more anti-PspA-specific antibody producing cells in the spleen than those derived from sham-immunized mothers. The offspring were raised up to four weeks old and were subcutaneously stimulated with recombinant PspA. The levels of anti-PspA IgG in sera after stimulation were significantly higher in the offspring derived from the immunized mothers and the induced specific antibody to PspA showed protective efficacy against systemic pneumococcal infection.

Discussion

Maternal immunization is suggested to be able to provide a sustained immune memory to offspring. The current study would be a milestone in the field of maternal immunization toward a universal pneumococcal vaccine.

Influenza subtype-specific maternal antibodies protect offspring against infection but inhibit vaccine-induced immunity and protection in mice

Following influenza A virus (IAV) infection or vaccination during pregnancy, maternal antibodies are transferred to offspring in utero and during lactation. The age and sex of offspring may differentially impact the transfer and effects of maternal immunity on offspring. To evaluate the effects of maternal IAV infection on immunity in offspring, we intranasally inoculated pregnant mice with sublethal doses of mouse-adapted (ma) H1N1, maH3N2, or media (mock) at embryonic day 10. In offspring of IAV-infected dams, maternal subtype-specific antibodies peaked at postnatal day (PND) 23, remained detectable through PND 50, and were undetectable by PND 105 in both sexes. When offspring were challenged with homologous IAV at PND 23, both male and female offspring had greater clearance of pulmonary virus and less morbidity and mortality than offspring from mock-inoculated dams. Inactivated influenza vaccination (IIV) against homologous IAV at PND 23 caused lower vaccine-induced antibody responses and protection following live virus challenge in offspring from IAV than mock-infected dams, with this effect being more pronounced among female than male offspring. At PND 105, there was no impact of maternal infection status, but vaccination induced greater antibody responses and protection against challenge in female than male offspring of both IAV-infected and mock-inoculated dams. To determine if maternal antibody or infection interfered with vaccine-induced immunity and protection in early life, offspring were vaccinated and challenged against a heterosubtypic IAV (i.e., different IAV group than dam) at PND 23 or 105. Heterosubtypic IAV maternal immunity did not affect antibody responses after IIV or protection after live IAV challenge of vaccinated offspring at either age. Subtype-specific maternal IAV antibodies, therefore, provide protection independent of offspring sex but interfere with vaccine-induced immunity and protection in offspring with more pronounced effects among females than males.

Transplacental transfer of total immunoglobulin G and antibodies to Plasmodium falciparum antigens between the 24th week of gestation and term

Full-term newborns have antibody (Ab) repertoires and levels similar to their mothers to help protect them from environmental pathogens. Unfortunately, preterm babies, especially those born < 34 weeks, have reduced levels of protective antibodies. In Africa, antibodies to Plasmodium falciparum are important in protection from malaria. This study investigated the transfer of total IgG and antibodies to 9 P. falciparum antigens and tetanus toxoid between 24 weeks and term. Paired maternal and cord samples from 166 preterm (24-37 weeks) and 154 term deliveries were used. Transfer efficiency was expressed as the ratio of Ab levels in cord to maternal plasma (CMR). At 24-25 weeks, CMR ranged from 0.31 to 0.94 for the different antigens; the rate of transfer was similar for all antigens between 24 and 40 weeks; resulting in median CMR of 0.49-0.95 at term. Babies of mothers with hypergammaglobulinemia and normal IgG levels had similar amounts of IgG, supporting data that saturation of the neonatal Fc-receptor occurs at ~ 16 mg IgG/ml. Thus, babies born prior to 34-35 weeks in Africa are likely to have reduced Ab levels to some, but not all antigens. Since IgG transfer is Fc-mediated, why differences exist in CMR among the antigens warrants further investigation.

Comparison of Maternal and Neonatal Antibody Levels After COVID-19 Vaccination vs SARS-CoV-2 Infection

Importance

Pregnant persons are at an increased risk of severe COVID-19 from SARS-CoV-2 infection, and COVID-19 vaccination is currently recommended during pregnancy.

Objective

To ascertain the association of vaccine type, time from vaccination, gestational age at delivery, and pregnancy complications with placental transfer of antibodies to SARS-CoV-2.

Design, Setting, and Participants

This cohort study was conducted in Pennsylvania Hospital in Philadelphia, Pennsylvania, and included births at the study site between August 9, 2020, and April 25, 2021. Maternal and cord blood serum samples were available for antibody level measurements for maternal-neonatal dyads.

Exposures

SARS-CoV-2 infection vs COVID-19 vaccination.

Main Outcomes and Measures

IgG antibodies to the receptor-binding domain of the SARS-CoV-2 spike protein were measured by quantitative enzyme-linked immunosorbent assay. Antibody concentrations and transplacental transfer ratios were measured after SARS-CoV-2 infection or receipt of COVID-19 vaccines.

Results

A total of 585 maternal-newborn dyads (median [IQR] maternal age, 31 [26-35] years; median [IQR] gestational age, 39 [38-40] weeks) with maternal IgG antibodies to SARS-CoV-2 detected at the time of delivery were included. IgG was detected in cord blood from 557 of 585 newborns (95.2%). Among 169 vaccinated persons without SARS-CoV-2 infection, the interval from first dose of vaccine to delivery ranged from 12 to 122 days. The geometric mean IgG level among 169 vaccine recipients was significantly higher than that measured in 408 persons after infection (33.88 [95% CI, 27.64-41.53] arbitrary U/mL vs 2.80 [95% CI, 2.50-3.13] arbitrary U/mL). Geometric mean IgG levels were higher after vaccination with the mRNA-1273 (Moderna) vaccine compared with the BNT162b2 (Pfizer/BioNTech) vaccine (53.74 [95% CI, 40.49-71.33] arbitrary U/mL vs 25.45 [95% CI, 19.17-33.79] arbitrary U/mL; P < .001). Placental transfer ratios were lower after vaccination compared with after infection (0.80 [95% CI, 0.68-0.93] vs 1.06 [95% CI, 0.98-1.14]; P < .001) but were similar between the mRNA vaccines (mRNA-1273: 0.70 [95% CI, 0.55-0.90]; BNT162b2: 0.85 [95% CI, 0.69-1.06]; P = .25). Time from infection or vaccination to delivery was associated with transfer ratio in models that included gestational age at delivery and maternal hypertensive disorders, diabetes, and obesity. Placental antibody transfer was detectable as early as 26 weeks' gestation. Transfer ratio that was higher than 1.0 was present for 48 of 51 (94.1%) births at 36 weeks' gestation or later by 8 weeks after vaccination.

Conclusions and Relevance

This study found that maternal and cord blood IgG antibody levels were higher after COVID-19 vaccination compared with after SARS-CoV-2 infection, with slightly lower placental transfer ratios after vaccination than after infection. The findings suggest that time from infection or vaccination to delivery was the most important factor in transfer efficiency.

Development of a TLR7/8 agonist adjuvant formulation to overcome early life hyporesponsiveness to DTaP vaccination

Infection is the most common cause of mortality early in life, yet the broad potential of immunization is not fully realized in this vulnerable population. Most vaccines are administered during infancy and childhood, but in some cases the full benefit of vaccination is not realized in-part. New adjuvants are cardinal to further optimize current immunization approaches for early life. However, only a few classes of adjuvants are presently incorporated in vaccines approved for human use. Recent advances in the discovery and delivery of Toll-like receptor (TLR) agonist adjuvants have provided a new toolbox for vaccinologists. Prominent among these candidate adjuvants are synthetic small molecule TLR7/8 agonists. The development of an effective infant Bordetella pertussis vaccine is urgently required because of the resurgence of pertussis in many countries, contemporaneous to the switch from whole cell to acellular vaccines. In this context, TLR7/8 adjuvant based vaccine formulation strategies may be a promising tool to enhance and accelerate early life immunity by acellular B. pertussis vaccines. In the present study, we optimized (a) the formulation delivery system, (b) structure, and (c) immunologic activity of novel small molecule imidazoquinoline TLR7/8 adjuvants towards human infant leukocytes, including dendritic cells. Upon immunization of neonatal mice, this TLR7/8 adjuvant overcame neonatal hyporesponsiveness to acellular pertussis vaccination by driving a T helper (Th)1/Th17 biased T cell- and IgG2c-skewed humoral response to a licensed acellular vaccine (DTaP). This potent immunization strategy may represent a new paradigm for effective immunization against pertussis and other pathogens in early life.

Catheter-related bloodstream infections in infants hospitalized in neonatal intensive care units: a single center study

Sepsis in neonates carries a high morbidity and mortality rate and is among the most feared complications in the neonatal intensive care unit (NICU). Catheter-related bloodstream infections (CRBSI) are a common etiology of late-onset sepsis. The aim of this study was to compare risk factors and characteristics between patients according to the type of catheter that was utilized and according to birth weight classification. The study included 51 newborns with confirmed CRBSI, which were hospitalized in our level 3 NICU between January 2017 and December 2018. The study population was stratified according to the type of venous catheter utilized (peripherally inserted central catheter, central venous catheter (CVC), and peripheral venous catheter). Infants with low birth weight and those who required prolonged parenteral nutrition were most likely to develop CRBSI in our study group. The type of venous catheter was not associated with blood culture results. Also, infants with a birth weight of < 1500 g and > 1500 g did not differ in sepsis etiology. Further research is required to assess venous catheters relative risk of causing sepsis and if the outcome can be traced back specifically to catheter type or patient characteristics.