Maternal Immunization Research Articles

Transplacental transmission of SARS-CoV-2 immunoglobulin G antibody to infants from maternal COVID-19 vaccine immunization before pregnancy.

The coronavirus disease 2019 (COVID-19) vaccine generates functional antibodies in maternal circulation that are detectable in infants, while the information is restricted to the usage of COVID-19 vaccine during pregnancy. In this study, we aimed to evaluate the effect of maternal COVID-19 vaccines before pregnancy.Infants were included from mothers with no inactivated COVID-19 vaccine, 1-, 2-, and 3-dose before pregnancy, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunoglobulin G (IgG) antibodies were tested. Comparative analysis was done between the groups.A total of 130 infants were enrolled in the study. Significantly higher levels of SARS-CoV-2 IgG antibodies in infants born to mothers with 3-dose COVID-19 vaccine before pregnancy compared with 1- and 2-dose groups (p < 0.0001). The levels of antibodies decreased significantly with age in infants born to mothers with the 3-dose COVID-19 vaccine before pregnancy (r = -0.338, p = 0.035), and it was still higher than that 2-dose COVID-19 vaccine group.The maternal SARS-CoV-2 antibodies produced from the inactivated COVID-19 vaccine before pregnancy can be transferred to newborns via the placenta. Maternal immunization with 3-dose of the COVID-19 vaccine before pregnancy could be more beneficial for both mothers and infants.

Protecting the Offspring, the Gift of Maternal Immunization: Current Status and Future Perspectives.

Pregnancy is characterized by immunological alterations in pregnant women that permit the growth of a semi-allogenic fetus, resulting in greater susceptibility of childbearing women to infections. Furthermore, due to the immaturity of the immune system of neonates, a protection gap is present in early life, leaving neonates and infants vulnerable to infectious diseases with increased morbidity and mortality. Maternal immunization against influenza, pertussis, and, in the context of the COVID-19 pandemic, SARS-CoV-2 has been implemented in several countries, with beneficial effects on both the mother and the offspring. The main protective mechanism of vaccination during pregnancy is transplacental transfer of maternal antibodies. However, recent evidence has implied that the fetal immune system may be influenced beyond passive immunity. This review sheds light on the current status of the routinely administered vaccinations during pregnancy, focusing on the impact of maternal immunization on the priming of the fetal immune system and suggesting future perspectives for the optimization of vaccination strategies.

Cost-Utility Analysis of Universal Maternal Pertussis Immunisation in Thailand: A Comparison of Two Model Structures.

This study aimed to assess the cost-effectiveness of introducing universal maternal pertussis immunisation under the national vaccine programme in Thailand. We conducted a cost-utility analysis from a societal perspective to compare maternal vaccination with (1) TdaP vaccine, (2) Td vaccine and aP vaccine, and (3) Td vaccine only. We constructed two decision-tree models with Markov elements, each following a different clinical pathway, to allow us to examine structural uncertainty. Costs were converted to 2021 Thai Baht (THB) and a discount rate of 3% was applied to health and cost outcomes, with sensitivity analysis at 0% and 6%. Parameter uncertainty was investigated through deterministic and probabilistic sensitivity analysis, with expected value of perfect information analysis. Maternal pertussis vaccination would avert 27 cases and up to one death per year. The incremental cost-effectiveness ratio (ICER) for adding aP to the maternal immunisation schedule is 2,184,025 THB/QALY and the ICER for replacing maternal Td vaccination with TdaP is 3,198,101 THB/QALY. Maternal pertussis vaccination only becomes favourable in the probabilistic sensitivity analysis at cost-effectiveness thresholds above 6,000,000 THB/QALY, far above the Thai threshold of 160,000 THB/QALY. If incidence is less than 397 cases per 100,000, maternal pertussis vaccination will not be cost-effective in Thailand, within the plausible range for vaccine effectiveness and probability of hospitalisation. Budget impact is dominated by vaccination costs, which represent 12% and 18% of the 2021 national vaccine programme budget for introducing aP vaccine or for switching Td with TdaP vaccine, respectively. We have found that maternal pertussis immunisation is not cost-effective in Thailand. Although there may be substantial under-reporting of pertussis cases, comparison with hospital data suggests that most under-reported cases are not hospitalised and therefore have negligible impact on our results. However, considerations such as affordability and local manufacturing may also be important for national immunisation programme decision-making.

Motivational interviewing for maternal Immunizations: Intervention development

Background and ObjectiveVaccine uptake during pregnancy remains low. Our objectives were to describe 1) development and adaptation of a clinician communication training intervention for maternal immunizations and 2) obstetrics and gynecology (ob-gyn) clinician and staff perspectives on the intervention and fit for the prenatal care context. MethodsDesign of the Motivational Interviewing for Maternal Immunizations (MI4MI) intervention was based on similar communication training interventions for pediatric settings and included presumptive initiation of vaccine recommendations (“You’re due for two vaccines today”) combined with motivational interviewing (MI) for hesitant patients. Interviews and focus group discussions were conducted with ob-gyn clinicians and staff in five Colorado clinics including settings with obstetric physicians, certified nurse midwives (CNMs), and clinician-trainees. Participants were asked about adapting training to the ob-gyn setting and their implementation experiences. Feedback was incorporated through iterative changes to training components. ResultsInterview and focus group discussion results from participants before (n = 3), during (n = 11) and after (n = 25) implementation guided intervention development and adaptation. Three virtual, asynchronous training components were created: a video and two interactive modules. This virtual format was favored due to challenges attending group meetings; however, participants noted opportunities to practice skills through role-play were lacking. Training modules were adapted to include common challenging vaccine conversations and live-action videos. Participants liked interactive training components and use of adult learning strategies. Some participants initially resisted the presumptive approach but later found it useful after applying it in their practices. Overall, participants reported that MI4MI training fit well with the prenatal context and recommended more inclusion of non-clinician staff. ConclusionsMI4MI training was viewed as relevant and useful for ob-gyn clinicians and staff. Suggestions included making training more interactive, and including more complex scenarios and non-clinician staff.

A sustained decrease in serum CD83 in pregnant women

Maternal immunity regulates tolerance to the semi-allogeneic fetus during pregnancy via modulation of immune regulatory factors. The serum factor CD83 is known to undergo changes during gestation in mice. Here we characterize serum levels of CD83 in women for the first time, revealing a consistent decline as pregnancy progresses and recovery to non-pregnant levels in miscarriage. Serum CD83 levels correlated negatively with rising progesterone (Pearson coefficient r = −0.489, ****p < 0.0001) and estradiol (r = −0.419, ***p = 0.0003). This result suggests that the regulation of soluble CD83 levels possibly depend on pregnancy hormones and on other yet unknown factors.

In the presence of non-neutralising maternally derived antibodies, intradermal and intramuscular vaccination with a modified live vaccine against porcine reproductive and respiratory syndrome virus 1 (PRRSV-1) induce similar levels of neutralising antibodies or interferon-gamma secreting cells

The purpose of this study was to compare the immune response generated by the intramuscular and the intradermal vaccination route against the porcine reproductive and respiratory syndrome virus (PRRSV). Piglets from a seronegative and a seropositive farm were selected (n = 28 piglets per farm), and each group was divided into two groups and vaccinated after weaning with modified live vaccine Unistrain® PRRS (Laboratorios Hipra Amer, Spain) by the intramuscular (IM) or the intradermic (ID) route. For the following 6 weeks, animals were weekly bled to assess the humoral response by PRRSV-specific antibody ELISA and viral neutralisation test. At 0-, 3-, 4- and 6 weeks post-vaccination, peripheral mononuclear blood cells (PBMC) from eight animals per group were recovered to analyse cellular response by IFN-γ ELISPOT and lymphoproliferation. Serum IL-12 was also quantified by ELISA. Seroconversion was first detected 14 days post-vaccination (dpv) for both IM and ID routes, and peaked at 35 dpv (both IM groups and ID seropositive) or 42 dpv (ID seronegative). At 3 weeks after vaccination, 6/27 (22.22%) animals from negative origin had not seroconverted, and neutralising titres were significantly lower at 35 dpv compared to the seropositive origin (mean log2 titres of 1.36 and 4.25 respectively) Also, it was 10 times more probable for them to have high levels of IL-12 a week after vaccination than for animals of seropositive origin. Cellular immune response analysed by lymphoproliferation and IFN-γ ELISPOT was already present at 21 dpv and until 42 dpv, with no significant differences between groups except for a higher lymphoproliferation at 35 dpv in the IM seropositive group (Kruskal-Wallis, p < 0.05). These results indicate that the intradermal route induces an immune response equivalent to the classical intramuscular route even in presence of non-neutralising maternal immunity, which in this study has proven to facilitate seroconversion after vaccination with an heterologous strain.

The Long-Term Healthcare Utilization and Economic Burden of RSV Infection in Children ≤5 Years in Japan: Propensity Score Matched Cohort Study.

The objective of this study was to estimate the long-term healthcare utilization and cost burden of RSV by chronological age of diagnosis (Year 1, Year 2 and Years 3-5 cohorts) as well as by gestational age at birth in Japan. The JMDC database was used to retrospectively identify RSV and control patients between February 1, 2011 and January 31, 2016 and follow them through December 31, 2017. Infants with RSV infection (n = 9028 in Year 1; n = 4929 in Year 2; n = 2004 in Years 3-5) were matched to controls (n = 17,886; n = 9351; n = 3655, respectively) based on gestational age and year and quarter of birth; controls were assigned the index date (ie, diagnosis) of their respective match. Covariate-balancing propensity score weights were employed adjusting for remaining imbalances between cohorts. The main outcomes were average cumulative rates for all-cause, asthma/wheezing, and respiratory-related hospitalizations, physician and urgent care/emergency visits and associated costs (reported as 2018 ¥JPY) over 36-months of follow-up since index. Healthcare utilization was significantly higher among RSV cases for most comparisons. All-cause average differential cost burden was higher for RSV, compared to controls, among the following cohorts: Year 1 full-term (¥277,727); Year 2 preterm (¥530,302), late preterm (¥270,797), full-term (¥238,832); Years 3-5 preterm (¥110,057), late preterm (¥486,670), full-term (¥289,986). While all-cause costs were similar for preterm and late preterm children in the Year 1 cohort, respiratory- and asthma/wheezing-related attributable costs were substantially higher for RSV. RSV infection had a significant long-term health and economic burden among children infected during their first year of life and later in life. Study findings have import for prevention strategies, currently directed at maternal immunization and monoclonal antibodies for preventing primary RSV infections in the first six months of life and beyond but also for older age not targeted currently.

Emergence of Vaccine-Preventable Diseases: The Perfect Storm of Hesitancy, Refusal, a Pandemic, and War.

The landscape of pediatric vaccination has changed dramatically due to changing attitudes toward immunizations and recent world events. The rise of vaccine hesitancy and refusal related to the concurrent rise of social media and anti-vaccination messages with misinformation campaigns have led to populations of children being unimmunized or under-immunized. These populations have been left vulnerable to the rapid spread of vaccine-preventable infection. Additionally, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the clinical syndrome known as coronavirus disease 2019 (COVID-19) resulted in the emergence of a worldwide pandemic. Control measures to mitigate the spread of COVID-19 resulted in numerous reports of children missing routine vaccines along with the stopping of many public health immunization programs. Finally, armed conflicts and war have led to large family migrations from their homelands to various countries and regions leading to increased risk for missed maternal and child immunization as well as difficulty in keeping vaccination records. [Pediatr Ann. 2022;51(11):e426-e430.].

A socio-ecological exploration to identify factors influencing the COVID-19 vaccine decision-making process among pregnant and lactating women: Findings from Kenya

The vaccine decision-making process of pregnant and lactating women is complex. Regarding COVID-19, pregnant women are at increased risk for severe disease and poor health outcomes. While pregnant and lactating women were excluded from COVID-19 vaccine trials, available evidence suggests that COVID-19 vaccines are safe and protective during pregnancy. In this study, we used a socio-ecological approach to explore factors influencing the decision-making process for COVID-19 vaccines in pregnant and lactating women in Kenya, for the purpose of informing demand generation strategies. As pregnant and lactating women are influenced by many factors, we conducted 84 in-depth interviews with a variety of stakeholders, including 31 pregnant or lactating women, 20 healthcare workers such as nurses, midwives, doctors, and frontline workers, 25 male family members of pregnant or lactating women, and 8 gatekeepers such as community leaders and faith-based leaders. These individuals were recruited from six communities in Kenya: three urban, and three rural. We applied a grounded theory approach to identify emerging themes and organized emerging themes using the SAGE Vaccine Hesitancy model, which includes three categories of determinants of vaccine acceptance, including contextual influences, individual and group influences, and vaccine and vaccination specific issues. Myths, interpersonal norms, and religion emerged as themes related to contextual influences. Safety, risk perception, and the role of the healthcare worker emerged as themes related to individual and group influences. For vaccine and vaccination specific issues, emerging themes included availability, accessibility, and eligibility. While maternal immunization can substantially reduce the effect of infectious diseases in mothers and infants, vaccine acceptance is critical. However, vaccines do not save lives; vaccination does. We hope the results of this study can be used to tailor communication efforts to increase vaccine demand among pregnant and lactating women.

Continuum of care of mothers and immunization status of their children: A secondary analysis of 2015–2016 Myanmar Demographic and Health Survey

ObjectiveTo assess the association between the continuum of care of mothers and the immunization status of their 12–23 months old children. Study designA secondary data analysis using the Myanmar Demographic and Health Survey (2015–16) data, a cross-sectional, household-based, nationally representative survey conducted during 2015–2016. MethodsWe included 1669 pairs of mothers and their children in this analysis. We categorized the children into fully immunized and no/not fully immunized children and define a continuum of care (CoC) of the mother if women received antenatal care ≥ four times, delivered with skilled birth attendances, and received postnatal care within 48 h after delivery. We used the multivariable binary logistics regression using STATA version 15.1 with the survey command (svy) and reported the results by adjusted odds ratios (aORs) with 95% confidence intervals (CIs). ResultsThe mother's CoC prevalence was 42.5%, and that of fully immunized children was 33.5%. However, only one-fifth of mothers and their children received the continuum of care services altogether. The children of mothers who received CoC were more likely to be fully vaccinated than those who did not (aOR = 1.60, 95%CI: 1.21, 2.13, P < 0.001). The child's birth order, employment status, and wealth status of the households are independent predictors of the full immunization of children. ConclusionsWe concluded that receiving the CoC in mothers influenced their children's vaccination status. Hence, integrating maternal health programs and immunization programs is essential to achieving sustainable development goals in Myanmar.

Protection of hatchlings against coccidiosis by maternal antibodies to four recombinant proteins of Eimeria tenella, Eimeria acervulina and Eimeria maxima

Maternally derived IgG antibodies to protective Eimeria antigens have great potential to control chicken coccidiosis and multivalent vaccines are more practical to resist against co-infection with several species of Eimeria under natural conditions. In this study, five good protective antigens of Eimeria species were combined into two combinations based on previous studies, namely C1(EtROPK-Eten5-A, EtGAM22, Ea3–1E and EmGAM56) and C2(EtM2AP and EtGAM22, Ea3–1E and EmGAM56). Then, five antigens were expressed in the Escherichia coli system and purified to inoculate breeding hens. After three times immunization, the specific antibodies could sustain for 11 and 10 weeks in hens’ plasma and egg yolk, respectively. Moreover, maternally derived antibodies against recombinant proteins could retain for 14 days in hatchlings’ serum. Then, protective efficacies of specific antibodies on hatchlings against mixed infection of E. tenella, E. acervulina and E. maxima were evaluated. The results showed that the hatchlings of the immunized hens had a higher survival rate on day 7 of hatching. Moreover, body weight gains within the hatchlings of immunized hens were higher than those of unvaccinated hens on 7 days (C1: p = 0.0744; C2: p = 0.4020) and 14 days (p < 0.0001). Moreover, hatchlings from vaccinated hens showed significantly alleviated lesion scores in the small intestine and duodenum at day 7 (p < 0.01) and day 14 (C1: p < 0.05). Particularly, the number of oocyst excretion from hatchlings of immunized hens was significantly reduced at day 7 (p < 0.0001) and day 14 (p < 0.0001). Our findings suggest that the maternal immunization with multivalent recombinant vaccines has the potential to be transmission blocking vaccines against mixed infection of Eimeria.

COVID-19 Pandemic and Infant Neurodevelopmental Impairment

Primary studies proposed that aberrant maternal antiviral immunity and/or giving birth in quarantine, such as during the ongoing COVID-19 pandemic, may be associated with the risk of neurodevelopmental impairment (NDI) in offspring. To evaluate the associations of birth and being raised during the COVID-19 pandemic with risk of NDI among infants and to assess the association of gestational exposure to SARS-CoV-2 with risk of NDI. PubMed, Web of Science, Scopus, Embase, and preprint servers were systematically searched from inception to March 25, 2022. Studies evaluating the neurodevelopment of infants born during the SARS-CoV-2 pandemic were included in this systematic review and meta-analysis. Studies using Ages and Stages Questionnaires, Third Edition (ASQ-3), were used for quantitative meta-analysis. Following the Preferred Reporting Items for Systematic Reviews and Meta-analyses, a random-effects model meta-analysis was used to pool the proportion and odds ratios (ORs) of overall NDI, as well as each developmental domain on ASQ-3 with the corresponding 95% CI. The primary outcome was the risk of overall NDI among infants screened during the pandemic vs prepandemic. The secondary outcome was the comparison of NDI by ASQ-3 domain among infants born to women with known gestational exposure to SARS-CoV-2 vs no exposure. A total of 8 studies were included, including 21 419 infants (11 438 screened in pandemic and 9981 in prepandemic period). NDI was present in 330 of 8992 infants (7%; 95% CI, 4%-10%) screened during the COVID-19 pandemic from January 2020 to January 2021. Among the pandemic cohort, the prevalence of NDI among infants with gestational exposure to SARS-CoV-2 was 77 of 691 (12%; 95% CI, 6%-18%). Compared with the prepandemic cohort (2015-2019), the pandemic cohort was more likely to have communication impairment (OR, 1.70; 95% CI, 1.37-2.11; P < .001), without significant differences in other ASQ-3 domains (eg, gross motor, fine motor, personal-social, and problem-solving). In contrast, maternal SARS-CoV-2 infection was not associated with significant differences in any neurodevelopment domain in offspring, except for increasing the odds of fine motor impairment (OR, 3.46; 95% CI, 1.43-8.38; P < .001). In this systematic review and meta-analysis examining the association between COVID-19 pandemic and the risk of NDI, findings suggest that overall neurodevelopment in the first year of life was not changed by either being born or raised during the SARS-CoV-2 pandemic or by gestational exposure to SARS-CoV-2. Interestingly, the first year of life during the COVID-19 pandemic, regardless of maternal infection, was significantly associated with the risk of communication delay among the offspring.

Predicted effectiveness of vaccines and extended half-life monoclonal antibodies against RSV hospitalizations in children

Several vaccines and extended half-life monoclonal antibodies (mAbs) against respiratory syncytial virus (RSV) have shown promise in clinical trials. We used age-structured transmission models to predict the possible impact of various RSV prevention strategies including maternal immunization, live-attenuated vaccines, and long-lasting mAbs. Our results suggest that maternal immunization and long-lasting mAbs are likely to be highly effective in preventing RSV hospitalizations in infants under 6 months of age, averting more than half of RSV hospitalizations in neonates. Live-attenuated vaccines could reduce RSV hospitalizations in vaccinated age groups and are also predicted to have a modest effect in unvaccinated age groups because of disruptions to transmission. Compared to year-round vaccination, a seasonal vaccination program at the country level provides at most a minor advantage regarding efficiency. Our findings highlight the substantial public health impact that upcoming RSV prevention strategies may provide.

Rotavirus A Inoculation and Oral Vitamin A Supplementation of Vitamin A Deficient Pregnant Sows Enhances Maternal Adaptive Immunity and Passive Protection of Piglets against Virulent Rotavirus A.

The aim of this study was to determine the impact of vitamin A deficiency (VAD)/supplementation (±VA) and group A RV (RVA) maternal immunization of RVA seropositive multiparous pregnant sows, on their immune responses (anamnestic response) and on passive protection of their piglets against RVA challenge. Our results showed that VAD- mock sows had increased RVA RNA shedding at 1-5 days post piglet RVA challenge, and their litters had increased RVA shedding and diarrhea frequency throughout the experiment. VAD decreased memory B cell frequencies while VA supplementation increased RVA specific IgA/IgG antibody (Ab) secreting cell (ASC) numbers in blood, milk, and tissues of RVA inoculated VAD sows. The increased numbers of RVA specific IgA/IgG ASCs in blood, milk/colostrum, intestinal contents, and tissues in VA supplemented VAD sows, suggest a role of VA in B cell immunity and trafficking to tissues. We also observed that RVA inoculated sows had the highest viral neutralizing Ab titers in serum and milk while VA supplementation of VAD sows and RVA inoculation increased IgA+ B cell frequencies in sow colostrum. In summary, we demonstrated that daily oral VA-supplementation (2nd trimester-throughout lactation) to RVA inoculated VAD sows improved the function of their gut-mammary-IgA immunological axis, reducing viral RNA shedding, diarrhea, and increasing weight gain in suckling piglets.

Understanding barriers to dTap vaccination recommendations during pregnancy among healthcare workers

Abstract Background Diphtheria, tetanus and pertussis (dTap) vaccination is heavily endorsed during pregnancy. However, maternal dTap immunization rates in Italy remain low. Lack of healthcare workers (HCWs) recommendation to get vaccinated represents one of the main barriers to immunization during pregnancy. Therefore, this study aimed to investigate what HCWs know about dTap vaccination, practices and potential barrier to recommending immunization during pregnancy. Methods This cross-sectional study was conducted among obstetricians-gynaecologists (OBs), midwives and general practitioners (GPs) in 2 regions of Southern Italy. An anonymous self-administered questionnaire was used to collect data on professional information, knowledge, risk perceptions and practices regarding dTap vaccination during pregnancy. Results Until now 94 HCWs were recruited (36.2% OBs, 35.1% GPs and 28.7% midwives). Overall, 63.8% knew that dTap vaccination has to be administered during the third trimester of gestation and 94.7% that it is able to protect newborns against pertussis before active immunization. One-third of the HCWs believed that vaccines in pregnancy were more dangerous than safe. Seven out of ten HCWs routinely recommended dTap vaccine and provided information about dTap vaccination to all pregnant women. Most frequent reported reasons for not recommending dTap vaccination during pregnancy were that it was outside the scope of their practice (72.4%), that women are more vaccine hesitant during pregnancy (42.9%), lack of time (28.6%), lack of knowledge on the topic (28.6%) and the belief that the vaccine could interfere with the development of the fetus (14,3%). Conclusions Lack of knowledge, unsatisfactory recommendation of dTap immunization during pregnancy and uncertainty over their responsibility around vaccination suggest that public health organisations should strengthen dissemination and implementation of evidence-based recommendations. Key messages • Barriers to recommending dTap immunization during pregnancy remain among healthcare workers. • Strategies (e.g. electronic reminders) to facilitate HCWs in recommending and informing on dTap immunization should be implemented and evaluated to improve vaccination coverage in pregnant women.

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.

Single-Cell Immunobiology of the Maternal-Fetal Interface.

Pregnancy success requires constant dialogue between the mother and developing conceptus. Such crosstalk is facilitated through complex interactions between maternal and fetal cells at distinct tissue sites, collectively termed the "maternal-fetal interface." The emergence of single-cell technologies has enabled a deeper understanding of the unique processes taking place at the maternal-fetal interface as well as the discovery of novel pathways and immune and nonimmune cell types. Single-cell approaches have also been applied to decipher the cellular dynamics throughout pregnancy, in parturition, and in obstetrical syndromes such as recurrent spontaneous abortion, preeclampsia, and preterm labor. Furthermore, single-cell technologies have been used during the recent COVID-19 pandemic to evaluate placental viral cell entry and the impact of SARS-CoV-2 infection on maternal and fetal immunity. In this brief review, we summarize the current knowledge of cellular immunobiology in pregnancy and its complications that has been generated through single-cell investigations of the maternal-fetal interface.

Antibody Response to Rotavirus C Pre-Farrow Natural Planned Exposure to Gilts and Their Piglets.

A longitudinal study was conducted to investigate the dynamics of genotype-specific (G6 and P[5]) antibody response to different doses (3, 2 and 1) of rotavirus C (RVC) natural planned exposure (NPE) in gilt serum, colostrum/milk and piglet serum, and compare with antibody response to rotavirus A NPE (RVA genotypes G4, G5, P[7] and P[23]). G6 and P[5] antigens of RVC were expressed in mammalian and bacterial cells, and used to develop individual indirect ELISAs. For both antigens, group 1 with 3 doses of NPE resulted in significantly higher IgG and IgA levels in colostrum compared to other groups. In piglet serum, group 1 P[5] IgG levels were significantly higher than other study groups at day 0 and 7. Piglet serum had higher IgA levels for group 1 piglets compared to other groups for both antigens. A comparison of colostrum antibody levels to rotavirus A (RVA) and RVC revealed that colostrum RVC IgG and IgA titers were lower than RVA titers irrespective of the G and P-type. Next generation sequencing (NGS) detected same RVC genotypes (G6 and P[5]) circulating in the piglet population under the window of lactogenic immunity. We conclude that the low RVC load in NPE material (real-time PCR Ct-values 32.55, 29.32 and 30.30) failed to induce sufficient maternal immunity in gilts (low colostrum RVC antibody levels) and passively prevent piglets from natural RVC infection in the farrowing room. To the best of our knowledge, this is the first study comparing differences in antibody response to porcine RVA and RVC in a commercial setting.

Adjuvants to increase immunogenicity of SARS-CoV-2 RBD and support maternal-fetal transference of antibodies in mice.

Adjuvants are important components of vaccines, increasing immunogenicity and modulating the immune response. SARS-CoV-2 vaccines are still being developed in order to improve worldwide access to immunization. Specific populations should be addressed in these investigations, such as pregnant women-to protect both mothers and neonates. In this study, female adult mice were immunized with Receptor-binding domain (RBD) from SARS-CoV-2 adjuvanted by a mixture of DDA and Saponin and put to mating to verify the maternal transference of IgG. For comparison, other group received RBD adjuvanted by OMVs from Neisseria meningitidis and Alum. The adjuvants enhanced IgG production and neutralization. DDA/Sap contributed to increase IgG1, IgG2a, IgG2b, and IgG3 isotypes. Total IgG avidity was considered high, as well as IgG1, IgG2a, and IgG2b avidity. IgG antibodies were effectively transferred to the offspring, predominantly IgG2a, IgG2b, and IgG3. The passive transferred immunoglobulin maintained the neutralizing ability, although it lost avidity. ELISA data was confirmed in Dot-ELISA and immunoblotting assays. DDA and Saponin seem a promising adjuvant mixture to enhance the humoral response of SARS-CoV-2 antigens. Further studies considering the effects of maternal immunization in the protection of offspring are needed, regardless the platform used in COVID-19 vaccines.

A Walk through Gumboro Disease

Infectious bursal disease (IBD), caused by an Avibirnavirus, belonging to the family Birnaviridae, is an immunosuppressive disease that affects 3–6-week-old chickens, resulting in clinical or subclinical infection. Although clinical disease occurs in chickens, turkeys, ducks, guinea fowl, and ostriches can be also infected. IBD virus (IBDV) causes lymphoid depletion of the bursa, which is responsible for the severe depression of the humoral antibody response, primarily if this occurs within the first 2 weeks of life. IBD remains an issue in chicken meat production due to economic losses caused by the spread of variants or subtypes, resistant to the most common vaccines, responsible for a subclinical disease characterized by reduced growth performance and increased susceptibility to secondary infections. Very virulent strains of classical serotype 1 are also common in several countries and can cause severe disease with up to 90% mortality. This review mainly focuses on the immunosuppressive effect of the IBDV and potential vaccination strategies, capable of overcoming challenges associated with the optimal time for vaccination of offspring, which is dependent on maternal immunity and IBDV variant occurrence.