Maternal antibodies: clinical significance, mechanism of interference with immune responses, and possible vaccination strategies

Resistance against Trichinella spiralis infection in pups delivered by T. spiralis-infected dam

Maternal antibody transmission via placenta and breastmilk are known to confer protection in infants. In this study, we investigated the maternal immunity transmission in pups delivered by rats infected with Trichinella spiralis and assessed the resulting resistance against subsequent parasitic infection. Our results revealed that parasite-specific IgG, IgG1 and IgG2a antibodies were present in pups prior to breastmilk ingestion (pre-milk), in which IgG and IgG1 antibodies persisted until week 8 after birth while parasite-specific IgG2a antibodies only lasted until week 4. After weaning on week 3, pups delivered by T. spiralis-infected dam and subsequently challenge-infected (immune-challenge) were found to possess higher mucosal IgG antibodies than control groups, whereas mucosal IgA levels were not significantly different across all groups. T. spiralis excretory-secretory antigen was discovered to react with pup sera until week 8, correlating with the resistance against parasitic infection which is represented by lessened worm burden. Upon T. spiralis infection at weeks 3 and 8, lower levels of eosinophil responses were detected in immune-challenge pups compared to naïve-challenge pups, indicating correlates of resistances in which ADCC may be involved. Findings from the present study demonstrate that resistances against T. spiralis infection in pups can be acquired by maternally-derived IgG, IgG1 and IgG2a antibody transmission through the placenta and breastmilk from T. spiralis-infected dam, which lasts until week 8.

Immunogenicity and safety of a liquid Pentavalent (DTwP-Hb-Hib) combination vaccine manufactured by Human Biologicals Institute in 6-8 weeks old healthy infants: A phase III, randomized, single blind, non-inferiority study

BACKGROUND

A liquid Pentavalent (DTwP-Hb-Hib) combination vaccine, developed by Human Biologicals Institute, underwent a Phase III clinical study in India. In this randomized, single blind, non-inferiority study, the immunogenicity and safety of this Investigational vaccine was compared with Pentavac SD® vaccine in 6-8 weeks old healthy infants.

METHODS

A total of 405 healthy infants aged 6-8 weeks old were randomized in 2:1 ratio to receive three doses of either the Investigational liquid Pentavalent (DTwP-Hb-Hib) combination vaccine or Pentavac SD® vaccine at four to six weeks interval. Immunogenicity was compared by estimation of antibody titers before the first dose and 4-6 weeks after the third dose of vaccination. Safety of each vaccine was assessed and compared by collection of data on solicited and unsolicited adverse events throughout the study period.

RESULTS

Out of a total of 405 enrolled subjects, 387 subjects completed the study. The seroconversion rates, seroprotection rates and geometric mean titres of the Investigational liquid Pentavalent (DTwP-Hb-Hib) combination vaccine group were found to be comparable and non-inferior to the Pentavac SD® vaccine group at 4-6 weeks after the third dose of vaccination. Pain, erythema and swelling at the site of injection were found to be the most common local adverse events whereas fever, irritability and unusual crying were found to be the most common systemic adverse events in both the vaccine groups. No vaccine related serious adverse event was reported. In this study, both the Investigational vaccine as well as the Comparator vaccine were found to be immunogenic and well tolerated.

CONCLUSION

After assessment of the results of the study it was concluded that the Investigational liquid Pentavalent (DTwP-Hb-Hib) combination vaccine developed by Human Biologicals Institute was immunogenic and safe when administered to infants aged 6-8 weeks and was non-inferior in immunogenicity and safety to Pentavac SD® vaccine. Clinical Trial Registry of India Identifier: CTRI/2016/01/006541.

Mucosal Vaccination via the Respiratory Tract

Vaccine delivery via mucosal surfaces is an interesting alternative to parenteral vaccine administration, as it avoids the use of a needle and syringe. Mucosal vaccine administration also targets the mucosal immune system, which is the largest lymphoid tissue in the human body. The mucosal immune response involves systemic, antigen-specific humoral and cellular immune response in addition to a local response which is characterised by a predominantly cytotoxic T cell response in combination with secreted IgA. This antibody facilitates pathogen recognition and deletion prior to entrance into the body. Hence, administration via the respiratory mucosa can be favoured for all pathogens which use the respiratory tract as entry to the body, such as influenza and for all diseases directly affecting the respiratory tract such as pneumonia. Additionally, the different mucosal tissues of the human body are interconnected via the so-called “common mucosal immune system”, which allows induction of an antigen-specific immune response in distant mucosal sites. Finally, mucosal administration is also interesting in the area of therapeutic vaccination, in which a predominant cellular immune response is required, as this can efficiently be induced by this route of delivery. The review gives an introduction to respiratory vaccination, formulation approaches and application strategies.

The Effect of Maternal Immunisation During Pregnancy on Infant Vaccine Responses

INTRODUCTION

Immunisation during pregnancy to protect infants against tetanus, pertussis and influenza is recommended in many countries. However, maternal antibodies can interfere with infant vaccine responses. We investigated the effect of antenatal diphtheria-tetanus-acellular pertussis (dTpa) and trivalent inactivated influenza (TIV) immunisation on specific and heterologous antibody responses to routine immunisations given in the first year of life.

METHODS

In total, 471 healthy infants were included. At 7 and 13 months of age, antibodies to the primary course of routine vaccines given at 6 weeks, 4 and 6 months of age (pertussis (pertussis toxin (PT), filamentous haemagglutinin (FHA), pertactin (PRN)), polio (type 1, 2, 3), Haemophilus influenzae type b (Hib), pneumococcus (serotype 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, 23F)) were measured, and at 13 months of age, antibodies to the 12-month routine vaccines (Hib, meningococcus C, measles, mumps and rubella). The seroprotection rates for each vaccine and the geometric mean concentrations (GMC) of antibodies were compared between infants whose mothers did or did not receive dTpa or TIV immunisation during pregnancy.

RESULTS

A total of 369 infants were included in the final analysis. Maternal dTpa immunisation was associated with reduced antibody responses to both specific (diphtheria and pertussis) and heterologous (polio and pneumococcus) vaccine antigens. This effect was stronger for persistence of antibodies at 13 months of age than it was at 7 months of age. At 7 months of age, adjusted average antibody concentrations were significantly lower for diphtheria, pertussis (PT, FHA, PRN) and polio type 2, and at 13 months of age, for diphtheria, pertussis (PT, FHA, PRN), polio type 1-3 and pneumococcal serotypes 1, 4, 5, 6A, 6B, 7F, 18C and 23F. Additionally, at 13 months of age, seroprotection rates for diphtheria, PT, pneumococcal serotype 1, 6A and 6B were significantly lower in infants after maternal dTpa immunisation. In contrast, for Hib, in infants with maternal dTpa immunisation, the adjusted average antibody concentration and the seroprotection rate were higher, particularly at 7 months of age. Maternal TIV immunisation had minimal effect on infant vaccine responses.

CONCLUSION

Whilst maternal immunisation protects infants in the first few months of life, it might interfere with both specific and heterologous (unrelated) vaccines responses in infants.

RESEARCH IN CONTEXT

Evidence before this study: Maternal immunisation during pregnancy helps to protect infants during the period before they complete their primary immunisations. It has been proven to be safe and beneficial. However, pre-existing maternal antibodies can influence antibody responses following infant immunisation, an effect called 'blunting'. Previous studies have investigated the influence of dTpa but not influenza immunisation during pregnancy on infant vaccine responses. The majority of studies investigated antibody concentrations only to the specific vaccine antigens included in the maternal immunisation, and there is scarce data available on heterologous vaccine responses, particularly pneumococcal responses.Added value of this study: In this study, we have shown that maternal dTpa immunisation during pregnancy is associated with reduced antibody responses to both specific (diphtheria and pertussis) and heterologous (polio and pneumococcus) vaccine antigens. This effect is stronger for persistence of antibodies at 13 months of age than after primary immunisation at 7 months of age. In contrast, for Hib, in infants with maternal dTpa immunisation, antibody concentrations are higher, particularly at 7 months of age. Maternal TIV immunisation has minimal effect on infant vaccine responses.Implications of all the available evidence: Whilst maternal immunisation protects infants in the first few months of life, it might interfere with both specific and heterologous (unrelated) vaccines responses in infants. As most vaccines induce very high antibody responses, small differences in antibody concentrations may not be of clinical significance. However, since maternal immunisation during pregnancy also influences seroprotection rates, strategies, such as additional booster doses in the second year of life, particularly for pertussis and pneumococcus, might need to be considered to address this.

Functional antibodies as immunological endpoints to evaluate protective immunity against Shigella

The development, clinical advancement and licensure of vaccines, and monitoring of vaccine effectiveness could be expedited and simplified by the ability to measure immunological endpoints that can predict a favorable clinical outcome. Antigen-specific and functional antibodies have been described in the context of naturally acquired immunity and vaccination against Shigella, and their presence in serum has been associated with reduced risk of disease in human subjects. The relevance of these antibodies as correlates of protective immunity, their mechanistic contribution to protection (e.g. target antigens, interference with pathogenesis, and participation in microbial clearance), and factors that influence their magnitude and makeup (e.g. host age, health condition, and environment) are important considerations that need to be explored. In addition to facilitating vaccine evaluation, immunological correlates of protection could be useful for identifying groups at risk and advancing immune therapies. Herein we discuss the precedent and value of functional antibodies as immunological endpoints to predict vaccine efficacy and the relevance of functional antibody activity to evaluate protective immunity against shigellosis.

Neonatal vaccine effectiveness and the role of adjuvants

Introduction: Neonates are less responsive to vaccines than adults, making it harder to protect newborns against infection. Neonatal differences in antigen-presenting cell, B and T cell function, all likely contribute. A key question is whether novel adjuvants might be able to make neonatal vaccines more effective. Areas covered: This review addresses the issues of how to improve neonatal vaccines, which we have defined as vaccines given in the first 4 weeks of life in a human infant or the first week of life in a mouse. A search was performed using keywords including 'neonatal immunity', 'neonatal immunisation', 'vaccine' and 'adjuvant' of PubMed articles published between 1960 and 2018. Expert opinion: Sugar-like structures have recently been shown to prime the infant adaptive immune system to respond to vaccines, being potentially more effective than traditional adjuvants. Sugar-based compounds with beneficial adjuvant effects in neonatal vaccine models include delta inulin (Advax), curdlan, and trehalose 6,6'-dibehenate. Such compounds make interesting neonatal adjuvant candidates, either used alone or in combination with traditional innate immune adjuvants.

Antenatal Influenza A-Specific IgA, IgM, and IgG Antibodies in Mother's Own Breast Milk and Donor Breast Milk, and Gastric Contents and Stools from Preterm Infants

Antenatal milk anti-influenza antibodies may provide additional protection to newborns until they are able to produce their own antibodies. To evaluate the relative abundance of milk, we studied the antibodies specific to influenza A in feeds and gastric contents and stools from preterm infants fed mother’s own breast milk (MBM) and donor breast milk (DBM). Feed (MBM or DBM) and gastric contents (MBM or DBM at 1 h post-ingestion) and stool samples (MBM/DBM at 24 h post-ingestion) were collected, respectively, from 20 preterm (26–36 weeks gestational age) mother-infant pairs at 8–9 days and 21–22 days of postnatal age. Samples were analyzed via ELISA for anti-H1N1 hemagglutinin (anti-H1N1 HA) and anti-H3N2 neuraminidase (anti-H3N2 NA) specificity across immunoglobulin A (IgA), immunoglobulin M (IgM), and immunoglobulin G (IgG) isotypes. The relative abundance of influenza A-specific IgA in feeds and gastric contents were higher in MBM than DBM at 8–9 days of postnatal age but did not differ at 21–22 days. Anti-influenza A-specific IgM was higher in MBM than in DBM at both postnatal times in feed and gastric samples. At both postnatal times, anti-influenza A-specific IgG was higher in MBM than DBM but did not differ in gastric contents. Gastric digestion reduced anti-H3N2 NA IgG from MBM at 21–22 days and from DBM at 8–9 days of lactation, whereas other anti-influenza A antibodies were not digested at either postnatal times. Supplementation of anti-influenza A-specific antibodies in DBM may help reduce the risk of influenza virus infection. However, the effective antibody dose required to induce a significant protective effect remains unknown.

Impact of maternally derived antibodies to Plasmodium falciparum Schizont Egress Antigen-1 on the endogenous production of anti-PfSEA-1 in offspring

Background

We evaluated whether maternally-derived antibodies to a malarial vaccine candidate, Plasmodium falciparum Schizont Egress Antigen-1 (PfSEA-1), in cord blood interfered with the development of infant anti-PfSEA-1 antibodies in response to natural exposure.

Methods

We followed 630 Tanzanian infants who were measured their antibodies against PfSEA-1 (aa 810-1023; PfSEA-1A) at birth and 6, 12, 18, and 24 months of age, and examined the changes in anti-PfSEA-1A antibody levels in response to parasitemia, and evaluated whether maternally-derived anti-PfSEA-1A antibodies in cord blood modified infant anti-PfSEA-1A immune responses.

Results

Infants who experienced parasitemia during the first 6 months of life had significantly higher anti-PfSEA-1A antibodies at 6 and 12 months of age compared to uninfected infants. Maternally-derived anti-PfSEA-1A antibodies in cord blood significantly modified this effect during the first 6 months. During this period, infant anti-PfSEA-1A antibody levels were significantly associated with their P. falciparum exposure when they were born with low, but not higher, maternally-derived anti-PfSEA-1A antibody levels in cord blood. Nevertheless, during the first 6 months of life, maternally-derived anti-PfSEA-1A antibodies in cord blood did not abrogate the parasitemia driven development of infant anti-PfSEA-1A: parasitemia were significantly correlated with anti-PfSEA-1A antibody levels at 6 months of age in the infants born with low maternally-derived anti-PfSEA-1A antibody levels in cord blood and borderline significantly correlated in those infants born with middle and high levels.

Conclusions

Maternal vaccination with PfSEA-1A is unlikely to interfere with the development of naturally acquired anti-PfSEA-1A immune responses following exposure during infancy.

Extended delivery of vaccines to the skin improves immune responses

Vaccines prevent 2-3 million childhood deaths annually; however, low vaccine efficacy and the resulting need for booster doses create gaps in immunization coverage. In this translational study, we explore the benefits of extended release of licensed vaccine antigens into skin to increase immune responses after a single dose in order to design improved vaccine delivery systems. By administering daily intradermal injections of inactivated polio vaccine according to six different delivery profiles, zeroth-order release over 28 days resulted in neutralizing antibody titers equivalent to two bolus vaccinations administered one month apart. Vaccinations following this profile also improved immune responses to tetanus toxoid and subunit influenza vaccine but not a live-attenuated viral vaccine, measles vaccine. Finally, using subunit influenza vaccine, we demonstrated that daily vaccination by microneedle patch induced a potent, balanced humoral immunity with an increased memory response compared to bolus vaccination. We conclude that extended presentation of antigen in skin via intradermal injection or microneedle patch can enhance immune responses and reduce the number of vaccine doses, thereby enabling increased vaccination efficacy.

The indications and safety of polyvalent immunoglobulin for post-exposure prophylaxis of hepatitis A, rubella and measles

Derived from pooled blood donations, polyvalent immunoglobulins are used for post-exposure prophylaxis as one aspect of the public health management of hepatitis A, rubella and measles. This review summarizes the safety profile of these blood products and the current recommendations for their use for the prevention of hepatitis A, rubella and measles among people who have been exposed to these diseases. The current recommendations are drawn from the most recent publicly available national guidelines of the United States, Australia, New Zealand, Canada and the United Kingdom as accessed in February 2019.

The Humoral Immune Response to BCG Vaccination

Bacillus Calmette Guérin (BCG) is the only currently available vaccine against tuberculosis (TB), but it confers incomplete and variable protection against pulmonary TB in humans and bovine TB (bTB) in cattle. Insights into the immune response induced by BCG offer an underexploited opportunity to gain knowledge that may inform the design of a more efficacious vaccine, which is urgently needed to control these major global epidemics. Humoral immunity in TB and bTB has been neglected, but recent studies supporting a role for antibodies in protection against TB has driven a growing interest in determining their relevance to vaccine development. In this manuscript we review what is known about the humoral immune response to BCG vaccination and re-vaccination across species, including evidence for the induction of specific B cells and antibodies; and how these may relate to protection from TB or bTB. We discuss potential explanations for often conflicting findings and consider how factors such as BCG strain, manufacturing methodology and route of administration influence the humoral response. As novel vaccination strategies include BCG prime-boost regimens, the literature regarding off-target immunomodulatory effects of BCG vaccination on non-specific humoral immunity is also reviewed. Overall, reported outcomes to date are inconsistent, but indicate that humoral responses are heterogeneous and may play different roles in different species, populations, or individual hosts. Further study is warranted to determine whether a new TB vaccine could benefit from the targeting of humoral as well as cell-mediated immunity.

Maternal Transfer of Natural (Auto-) Antibodies in Chickens

The presence and relative levels (titers) of IgM and IgG natural antibodies (NAb) binding keyhole limpet hemocyanin (KLH), and natural (auto-) antibodies (N(A)Ab) binding salmon double-stranded DNA (dsDNA), (oxidated-) phosphatidyl (phosphoryl) choline-conjugated bovine serum albumin (PC-BSA), PC-conjugated ovalbumin (PC-OVA), and OVA, respectively, were studied in adult hen plasma, egg yolk, egg albumen, plasma of their hatchlings, and in 8-day-old chick plasma. Birds and eggs were from 2 lines divergently selected for high or low NAb levels binding KLH. This study aimed to determine 1) correlated phenotypic responses of selection for NAb to KLH, 2) transfer of maternal NAb and N(A)Ab via egg compartments, 3) levels of likely maternal NAb and N(A)Ab in hatchlings and 8-day-old chicks, and 4) whether a composite trait: IgM anti-PC-BSA/IgG anti-dsDNA ratio in the compartments could be used as a parameter for health or immune status. NAb and N(A)Ab to all tested antigens were found in adult hens, but low or no levels were found for IgM in yolk and IgG in albumen. Depending on the antigen, NAb and N(A)Ab were found in hatchlings and day 8 birds. Divergent selection and breeding based on NAb binding KLH affected antibody titers of almost all antigens in almost all compartments, in a similar way. Maternal transfer of NAb and N(A)Ab from the adult hen to offspring was via specific routes for specific antigens and isotypes, especially for IgG as suggested by cluster analyses and significant correlations. There was little indication of production of new NAb and N(A)Ab to the studied antigens in either the egg compartments or the hatchlings. A composite trait of IgM PC-BSA/IgG dsDNA ratio was as yet not indicative for immune status, as no significant differences were found between the lines for all compartments. In conclusion, hens provide neonatal chickens with natural (self-) binding IgG antibodies that have been proposed to perform homeostatic functions during the period in which neonates do not produce these antibodies themselves.

Acquisition of specific antibodies and their influence on cell-mediated immune response in neonatal cord blood after maternal pertussis vaccination during pregnancy

Maternal immunization with pertussis acellular vaccine (Tdap) is an intervention that provides protection to newborns. However, it has been reported that high maternal antibody levels may adversely affect the immune response of infants after active immunization. In this study, we evaluated neonatal passive acquisition of pertussis-specific antibodies and their influence on the neonatal cell-mediated immune response. Pregnant women were either vaccinated with Tdap vaccine (case group, n = 66) or received no vaccine (control group, n = 101). Whole-cell Bordetella pertussis (Bp), pertussis toxin (PT), filamentous hemagglutinin (FHA) and pertactin (PRN)-specific serum IgG were quantified in paired maternal-cord sera, and Bp- and PT-specific IgA were evaluated in colostrum by ELISA. Ex vivo neonatal blood lymphocyte responsiveness after Bp stimulation was assessed in case (n = 17) and control (n = 15) groups using flow cytometry to detect proliferation, cytokine production and activation phenotype of lymphocytes in the context of high specific IgG acquired after maternal vaccination. Anti-Bp, PT, FHA and PRN IgG concentrations in maternal and cord sera from case group were higher than those in control group with positive correlation indexes in both groups for all pertussis antigens. The control group presented higher placental transfer ratios of specific antibodies and, in the case group, vaccination between 26 and 31 gestation weeks was associated with the best placental transfer ratios. Specific IgA concentrations in colostrum were not affected by vaccine status. Whole blood assays revealed that newborns responded to Bp stimulation with higher expression of CD40L, CD69 and CD4⁺ T cell proliferation compared to unstimulated cells, and a lower Th1 response, while a preserved Th2 response compared to adults, but there were no differences between the neonatal groups for any of the studied parameters. Our results indicate that higher pertussis-specific IgG levels in newborn sera after maternal vaccination do not affect the neonatal ex vivo cell-mediated immune response.

Measles Virus Bearing Measles Inclusion Body Encephalitis-Derived Fusion Protein Is Pathogenic after Infection via the Respiratory Route

A clinical isolate of measles virus (MeV) bearing a single amino acid alteration in the viral fusion protein (F; L454W) was previously identified in two patients with lethal sequelae of MeV central nervous system (CNS) infection. The mutation dysregulated the viral fusion machinery so that the mutated F protein mediated cell fusion in the absence of known MeV cellular receptors. While this virus could feasibly have arisen via intrahost evolution of the wild-type (wt) virus, it was recently shown that the same mutation emerged under the selective pressure of small-molecule antiviral treatment. Under these conditions, a potentially neuropathogenic variant emerged outside the CNS. While CNS adaptation of MeV was thought to generate viruses that are less fit for interhost spread, we show that two animal models can be readily infected with CNS-adapted MeV via the respiratory route. Despite bearing a fusion protein that is less stable at 37°C than the wt MeV F, this virus infects and replicates in cotton rat lung tissue more efficiently than the wt virus and is lethal in a suckling mouse model of MeV encephalitis even with a lower inoculum. Thus, either during lethal MeV CNS infection or during antiviral treatment in vitro, neuropathogenic MeV can emerge, can infect new hosts via the respiratory route, and is more pathogenic (at least in these animal models) than wt MeV.IMPORTANCE Measles virus (MeV) infection can be severe in immunocompromised individuals and lead to complications, including measles inclusion body encephalitis (MIBE). In some cases, MeV persistence and subacute sclerosing panencephalitis (SSPE) occur even in the face of an intact immune response. While they are relatively rare complications of MeV infection, MIBE and SSPE are lethal. This work addresses the hypothesis that despite a dysregulated viral fusion complex, central nervous system (CNS)-adapted measles virus can spread outside the CNS within an infected host.

Effects of management practices, animal transport and barn climate on animal health and antimicrobial use in Swiss veal calf operations

To assess the effects of transport, management factors and barn climate on calf health, 43 Swiss veal farms (11 large farms fattening ≥100 calves and 32 small farms fattening >20 but <100 calves per year) were monitored in a prospective cohort study over a period of one year. Detailed questionnaires on farm structure, management, housing system and animal health were filled out with the farmers during bimonthly visits, and barn temperature, humidity, ammonia and CO₂ concentrations were measured. Temperature and humidity were also measured continuously over 72 h once each in winter and summer. In addition, calf purchase and transport from birth farm to fattening unit were documented by the farmers, and the study team accompanied one transport per farm whenever possible. Antimicrobial treatment incidence was calculated from the used daily dose (TI_UDD). Risk factors for mortality, average daily weight gain (ADG) and antimicrobial use, as well as factors related to transport and barn climate measures were evaluated with mixed regression models. The overall mortality rate was 5.1% (6.2% in large herds and 3.1% in small ones). Identified risk factors for mortality >3% included a lower number of calves fattened per year and a good hygiene of the feeder. This surprising result was likely due to the fact that the threshold of 3% mortality was rather exceeded in smaller farms. Furthemore, higher temperature variation (range between maximal and minimal temperature over 3 measurement days) in the calf pen was associated with mortality >3% in the univariable analysis. The overall mean ADG was 1.40 ± 0.16 kg. Calf purchase was significantly associated with decreased ADG. The median overall TI_UDD was eight daily doses per calf and year (2.1 in small farms and 26 in large farms, respectively); the main indication for treatment was respiratory disease (81.1%). Risk factors for increased TI were no quarantine upon arrival, access to an outside pen, higher numbers of calves per drinking nipple, mechanical ventilation, vaccination against bovine respiratory disease, and a maximum ammonia value >10 ppm in the calf pen. In addition, a higher number of birth farms and calf purchase from markets were associated with increased TI in the univariable analysis. The identified risk factors associated with increased TI and mortality and with decreased ADG should be addressed in priority in veal calf operations to improve calf health and reduce antimicrobial use.

Interventions to improve oral vaccine performance: a systematic review and meta-analysis

BACKGROUND

Oral vaccines underperform in low-income and middle-income countries compared with in high-income countries. Whether interventions can improve oral vaccine performance is uncertain.

METHODS

We did a systematic review and meta-analysis of interventions designed to increase oral vaccine efficacy or immunogenicity. We searched Ovid-MEDLINE and Embase for trials published until Oct 23, 2017. Inclusion criteria for meta-analysis were two or more studies per intervention category and available seroconversion data. We did random-effects meta-analyses to produce summary relative risk (RR) estimates. This study is registered with PROSPERO (CRD42017060608).

FINDINGS

Of 2843 studies identified, 87 were eligible for qualitative synthesis and 66 for meta-analysis. 22 different interventions were assessed for oral poliovirus vaccine (OPV), oral rotavirus vaccine (RVV), oral cholera vaccine (OCV), and oral typhoid vaccines. There was generally high heterogeneity. Seroconversion to RVV was significantly increased by delaying the first RVV dose by 4 weeks (RR 1·37, 95% CI 1·16-1·62) and OPV seroconversion was increased with monovalent or bivalent OPV compared with trivalent OPV (RR 1·51, 95% CI 1·20-1·91). There was some evidence that separating RVV and OPV increased RVV seroconversion (RR 1·21, 95% CI 1·00-1·47) and that higher vaccine inoculum improved OCV seroconversion (RR 1·12, 95% CI 1·00-1·26). There was no evidence of effect for anthelmintics, antibiotics, probiotics, zinc, vitamin A, withholding breastfeeding, extra doses, or vaccine buffering.

INTERPRETATION

Most strategies did not improve oral vaccine performance. Delaying RVV and reducing OPV valence should be considered within immunisation programmes to reduce global enteric disease. New strategies to address the gap in oral vaccine efficacy are urgently required.

FUNDING

Wellcome Trust, Bill & Melinda Gates Foundation, UK Medical Research Council, and WHO Polio Research Committee.

Comparison of the immunogenicity and safety of 3 inactivated hepatitis A vaccines in Korean children aged 12 to 18 months: An open-label, randomized, prospective, multicenter study

Several approved inactivated hepatitis A (HA) vaccines are available in Korea. These have been shown to be immunogenic and safe in European children; however, their immunogenicity and safety have not been investigated among Korean children. We aimed to compare the immunogenicity and safety of the most commonly used HA vaccines in ethnic Korean children aged 12 to 18 months.In this open-label, randomized, prospective, multicenter study, 108 children were enrolled and randomized to receive a pediatric form of Avaxim, Epaxal, or Havrix. The 2nd dose was administered after an interval of 6 months. Anti-HA virus (HAV) immunoglobulin (Ig) G was measured to assess geometric mean concentrations (GMCs) and seropositvity rates (≥20 mIU/mL anti-HAV IgG). To assess safety, local solicited adverse events (AEs), systemic solicited AEs, unsolicited AEs, and serious AEs (SAEs) were graded.Among the 108 participants enrolled, 37, 34, and 37 received Avaxim, Epaxal, and Havrix, respectively. After administration of 2 doses, the seropositivity rates in the Avaxim, Epaxal, and Havrix groups were all 100% (95% confidence intervals [CIs]: 99.0-100, 98.9-100, and 99.0-100, respectively; P < .001). The anti-HAV GMCs in the Avaxim, Epaxal, and Havrix groups were 5868.4 (95% CI: 4237.2-8126.6), 1962.1 (95% CI: 1298.0-2965.9), and 2232.9 mIU/mL (95% CI: 1428.4-3490.4), respectively, after administration of 2 doses (P < .001). There were no significant differences in the proportions of participants reporting local solicited AEs, systemic solicited AEs, unsolicited AEs, and SAEs among the 3 vaccine groups after the 1st and 2nd doses. All local solicited and unsolicited AEs were grade 1 or 2. Grade 3 systemic solicited AE occurred in 5.4% and 2.9% of the participants in the Havrix group after the 1st and 2nd doses, respectively. SAEs after the 1st and 2nd doses were reported in 2 participants and 1 participant, respectively, but none was assessed as being related to vaccination.The results indicate that these vaccines were safe and immunogenic in ethnic Korean children. The results have contributed to the establishing of an HA vaccination policy in Korea and will be informative to countries that plan to initiate vaccination programs against HAV.

The Immune System Computes the State of the Body: Crowd Wisdom, Machine Learning, and Immune Cell Reference Repertoires Help Manage Inflammation

Here, we outline an overview of the mammalian immune system that updates and extends the classical clonal selection paradigm. Rather than focusing on strict self-not-self discrimination, we propose that the system orchestrates variable inflammatory responses that maintain the body and its symbiosis with the microbiome while eliminating the threat from pathogenic infectious agents and from tumors. The paper makes four points:

The immune system classifies healthy and pathologic states of the body—including both self and foreign elements—by deploying individual lymphocytes as cellular computing machines; immune cells transform input signals from the body into an output of specific immune reactions.

Rather than independent clonal responses, groups of individually activated immune-system cells co-react in lymphoid organs to make collective decisions through a type of self-organizing swarm intelligence or crowd wisdom.

Collective choices by swarms of immune cells, like those of schools of fish, are modified by relatively small numbers of individual regulators responding to shifting conditions—such collective inflammatory responses are dynamically responsive.

Self-reactive autoantibody and T-cell receptor (TCR) repertoires shared by healthy individuals function in a biological version of experience-based supervised machine learning. Immune system decisions are primed by formative experience with training sets of self-antigens encountered during lymphocyte development; these initially trained T cell and B cell repertoires form a Wellness Profile that then guides immune responses to test sets of antigens encountered later. This experience-based machine learning strategy is analogous to that deployed by supervised machine-learning algorithms.

We propose experiments to test these ideas. This overview of the immune system bears clinical implications for monitoring wellness and for treating autoimmune disease, cancer, and allograft reactions.

Effect of strain-specific maternally-derived antibodies on influenza A virus infection dynamics in nursery pigs

Reducing the number of influenza A virus (IAV) infected pigs at weaning is critical to minimize IAV spread to other farms. Sow vaccination is a common measure to reduce influenza levels at weaning. However, the impact of maternally-derived antibodies on IAV infection dynamics in growing pigs is poorly understood. We evaluated the effect of maternally-derived antibodies at weaning on IAV prevalence at weaning, time of influenza infection, number of weeks that pigs tested IAV positive, and estimated quantity of IAV in nursery pigs. We evaluated 301 pigs within 10 cohorts for their influenza serological (seroprevalence estimated by hemagglutination inhibition (HI) test) and virological (prevalence) status. Nasal swabs were collected weekly and pigs were bled 3 times throughout the nursery period. There was significant variability in influenza seroprevalence, HI titers and influenza prevalence after weaning. Increase in influenza seroprevalence at weaning was associated with low influenza prevalence at weaning and delayed time to IAV infection throughout the nursery. Piglets with IAV HI titers of 40 or higher at weaning were also less likely to test IAV positive at weaning, took longer to become infected, tested IAV RT-PCR positive for fewer weeks, and had higher IAV RT-PCR cycle threshold values compared to piglets with HI titers less than 40. Our findings suggest that sow vaccination or infection status that results in high levels of IAV strain-specific maternally-derived antibodies may help to reduce IAV circulation in both suckling and nursery pigs.

Genome-wide association study for response to vaccination in Angus calves1

Background

Bovine respiratory disease complex (BRDC) is one of the most important sources of loss within the beef cattle industry in the USA. Steps have been taken to reduce the incidence of BRDC through vaccination. Despite the effectiveness of vaccines, large proportions of cattle still experience morbidity and mortality. Identification of genomic regions that are associated with variation in response to vaccination would allow for the selection of individuals genetically predisposed to respond to vaccination based on specific markers, while heritability and accuracy estimates would help facilitate genomic selection. This in turn may lead to selection for beef cattle herds that may have lower incidence rate of BRDC after vaccination. This study utilizes an Angus herd of more than 2000 head of cattle to identify these regions of association.

Results

Genome wide association studies were performed for viral neutralization antibody level and response to vaccination traits against four different viruses associated with BRDC: bovine viral diarrhea virus 1 and 2 (BVDV1 and BVDV2), bovine respiratory syncytial virus (BRSV), and bovine herpesvirus (BHV1). A total of six 1-Mb windows were associated with greater than 1% of the genetic variance for the analyzed vaccination response traits. Heritabilities ranged from 0.08 to 0.21 and prediction accuracy ranged from 0.01 to 0.33 across 7 different vaccination traits.

Conclusions

Although six 1-Mb windows were identified as associated with 1% or greater genetic variance for viral neutralization antibody level and response to vaccination traits, few genes around these windows could readily be considered candidates. This indicates the need for further functional genomic annotation, as these regions appear to be gene deserts. Traits ranged from lowly to moderately heritable, which indicated the potential for selection of individuals that are genetically pre-disposed to respond to vaccination. The relatively low amount of genetic variance accounted for by any 1-Mb window indicated that viral neutralization antibody level and response to vaccination traits are polygenic in nature. Selection for these traits is possible, but likely to be slow due to the low heritabilities and absence of markers with high genetic variation associated with them.

Pertussis: Identification, Prevention and Control

Pertussis is a vaccine-preventable disease. Despite the high vaccination coverage among children, pertussis is considered a re-emerging disease for which identification, prevention and control strategies need to be improved. To control pertussis it is important to maintain a high vaccination coverage to protect the age groups considered at high risk for the disease. Laboratory confirmation of Bordetella pertussis infection together with a differential diagnostic test for other Bordetellae are prerequisite for a correct and timely diagnosis of pertussis. Moreover, investigations of antimicrobial susceptibility and whole genome sequencing may permit to monitor the circulation of antimicrobials resistant and/or vaccine-escape strains. Finally, the preventive framework should no longer consider pertussis exclusively as a childhood infectious disease, since adults may play a role in transmission events.

Colostrum Antibodies, Egg Antibodies and Monoclonal Antibodies Providing Passive Immunity for Animals

Passive immunity can be provided to animals by several sources of antibodies including from colostrum, avian eggs, and monoclonal sources. These antibodies have been shown protect production and companion animals from a number of pathogens. This chapter reviews the immune system for the principles of immune response to antigens and the synthesis of immunoglobulins of the five classes of antibodies in the body. Colostrum antibodies are described for passive immunity protection in animals such as calves. Chicken egg antibodies are another source of antibodies for passive immunity. Therapeutic monoclonal antibodies are also used to provide passive immunity in the veterinary field.

The molecular mechanism of pH-regulating C3d-CR2 interactions: Insights from molecular dynamics simulation

The interactions of complement receptor 2 (CR2) and the degradation fragment C3d of complement component C3 mediate the innate and adaptive immune systems. Due to the importance of C3d-CR2 interaction in the design of vaccines, many studies have indicated the interactions are pH-dependent. Moreover, C3d-CR2 interactions at pH 5.0 are unknown. To investigate the molecular mechanism of pH-regulating C3d-CR2 interaction, molecular dynamics simulations for C3d-CR2 complex in different pH are performed. Our results revealed that the protonation of His9 in C3d at pH 6.0 slightly weakens C3d-CR2 association as reducing pH from 7.4 to 6.0, initiated from a key hydrogen bond formed between Gly270 and His9 in C3d at pH 6.0. When reducing pH from 6.0 to 5.0, the protonation of His33 in C3d weakens C3d-SCR1 association by changing the hydrogen-bond network of Asp36, Glu37, and Glu39 in C3d with Arg13 in CR2. In addition, the protonation of His90 significantly enhances C3d-SCR2 association. This is because the enhanced hydrogen-bond interactions of His90 with Glu63 and Ser69 of the linker change the conformations of the linker, Cys112-Asn116 and Pro87-Gly91 regions. This study uncovers the molecular mechanism of the mediation of pH on C3d-CR2 interaction, which is valuable for vaccine design.

The impact of timing of maternal influenza immunization on infant antibody levels at birth

Pregnant women and infants are at an increased risk of severe disease after influenza infection. Maternal immunization is a potent tool to protect both these at-risk groups. While the primary aim of maternal influenza vaccination is to protect the mother, a secondary benefit is the transfer of protective antibodies to the infant. A recent study using the tetanus, diphtheria and acellular pertussis (Tdap) vaccine indicated that children born to mothers immunized in the second trimester of pregnancy had the highest antibody titres compared to children immunized in the third trimester. The aim of the current study was to investigate how the timing of maternal influenza immunization impacts infant antibody levels at birth. Antibody titres were assessed in maternal and cord blood samples by both immunoglobulin (Ig)G-binding enzyme-linked immunosorbent assay (ELISA) and haemagglutination inhibition assay (HAI). Antibody titres to the H1N1 component were significantly higher in infants born to mothers vaccinated in either the second or third trimesters than infants born to unvaccinated mothers. HAI levels in the infant were significantly lower when maternal immunization was performed less than 4 weeks before birth. These studies confirm that immunization during pregnancy increases the antibody titre in infants. Importantly, antibody levels in cord blood were significantly higher when the mother was vaccinated in either trimesters 2 or 3, although titres were significantly lower if the mother was immunized less than 4 weeks before birth. Based on these data, seasonal influenza vaccination should continue to be given in pregnancy as soon as it becomes available.

The association between continuous antibiotic prophylaxis and UTI from birth until initial postnatal imaging evaluation among newborns with antenatal hydronephrosis

INTRODUCTION

There is a lack of consensus regarding the use of continuous antibiotic prophylaxis (CAP) during the interval between birth and initial postnatal imaging in infants with a history of antenatal urinary tract dilation (AUTD).

OBJECTIVE

To determine the incidence of urinary tract infection (UTI), and the association between CAP use and UTI during the interval between birth and the first postnatal renal ultrasound (RUS) in infants with AUTD.

STUDY DESIGN

A single-institution, retrospective cohort study of newborns with a history of AUTD. Infants undergoing RUS within 3 months of birth for an indication of 'hydronephrosis' between 2012 and 2014 were identified. A random sample of 500 infants was selected; six were excluded for concomitant congenital anomalies. Baseline patient (sex, race, insurance) and clinical characteristics (circumcision status, UTD risk score, receipt of CAP, UTI prior to RUS, age at UTI, and age at RUS) were collected via retrospective chart review. Descriptive statistics were calculated. To adjust for receipt of CAP, propensity score adjusted univariate logistic regression for UTI based on CAP status was performed.

RESULTS

Among the 494 infants with AUTD, 157 (32%) received CAP. Infants with normal/low-risk UTD scores were less likely to receive CAP than those with medium/high-risk UTD (23% vs 77%; P < 0.001). There was no difference in CAP based on sex, insurance, or circumcision status (among 260/365 males with known circumcision status). Overall, seven infants (1.4%) developed UTI prior to imaging: six (1.8%) without CAP vs one (0.64%) with CAP (P = 0.44). The median age at UTI was 59 days (range 2-84); among those with UTI, initial imaging occurred significantly later (66 vs 28 days; P = 0.001). The propensity score adjusted odds of developing UTI with CAP (vs without) was 0.93 (95% CI 0.10-8.32; P = 0.95). The Summary Figure describes the infants with UTI.

CONCLUSION

The incidence of UTI prior to initial neonatal imaging in newborns with AUTD was low. Use of CAP was not associated with UTI incidence after adjusting for UTD severity. Routine use of CAP in newborns with AUTD prior to initial imaging may be of limited benefit in most patients.

Influence of Immunological Maturity on Respiratory Syncytial Virus-Induced Morbidity in Young Children

Respiratory syncytial virus (RSV) is a very frequent viral respiratory pathogen of the young (<5 years old) with a significant portion of young toddlers having been infected before 2 years of age. Although we understand that some of the morbidity associated with RSV in neonates is due to immunological maturation that favors immunosuppression over antiviral innate and/or adaptive immune responses, the rapid development of the immune system right after birth suggests that each age group (newborn, early infant, older infant, toddler, and older) may respond to the virus in different ways. In this study, we summarize the morbidity associated with infection in young children in the context of immunological maturation of monocytes/macrophages and the ramifications for poor innate control of viral pathogenesis. We also summarize key mechanisms that contribute to the diminished antiviral innate immune responses of these young children.

Murine Norovirus Infection Induces TH1 Inflammatory Responses to Dietary Antigens

Intestinal reovirus infection can trigger T helper 1 (TH1) immunity to dietary antigen, raising the question of whether other viruses can have a similar impact. Here we show that the acute CW3 strain of murine norovirus, but not the persistent CR6 strain, induces TH1 immunity to dietary antigen. This property of CW3 is dependent on its major capsid protein, a virulence determinant. Transcriptional profiling of mesenteric lymph nodes following infection reveals an immunopathological signature that does not segregate with protective immunity but with loss of oral tolerance, in which interferon regulatory factor 1 is critical. These data show that viral capacity to trigger specific inflammatory pathways at sites where T cell responses to dietary antigens take place interferes with the development of tolerance to an oral antigen. Collectively, these data provide a foundation for the development of therapeutic strategies to prevent TH1-mediated complex immune disorders triggered by viral infections.

Impact of Maternal Antibody on the Immunogenicity of Inactivated Polio Vaccine in Infants Immunized With Bivalent Oral Polio Vaccine: Implications for the Polio Eradication Endgame

Background

Quantifying interference of maternal antibodies with immune responses to varying dose schedules of inactivated polio vaccine (IPV) is important for the polio endgame as IPV replaces oral polio vaccine (OPV).

Methods

Type 2 poliovirus humoral and intestinal responses were analyzed using pre-IPV type 2 seropositivity as proxy for maternal antibodies from 2 trials in Latin America. Infants received 1 or 2 doses of IPV in sequential IPV-bivalent oral polio vaccine (bOPV) or mixed bOPV-IPV schedules.

Results

Among infants vaccinated with bOPV at age 6, 10, and 14 weeks of age and IPV at 14 weeks, those with type 2 pre-IPV seropositivity had lower seroprotection rates than seronegative infants at 4 weeks (92.7% vs 83.8%; difference, 8.9% [95% confidence interval, 0.6%-19.9%]; n = 260) and 22 weeks (82.7% vs 60.4%; difference, 22.3 [12.8%-32.4%]; n = 481) post-IPV. A second IPV at age 36 weeks resulted in 100% seroprotection in both groups. Among infants vaccinated with 1 IPV at age 8 weeks followed by 2 doses of bOPV, pre-IPV type 2-seropositive infants had lower seroprotection at age 28 weeks than those who were seronegative (93.0% vs 73.9%; difference, 19.6% [95% confidence interval, 7.3%-29.4%]; n = 168). A second dose of IPV at 16 weeks achieved >97% seroprotection at age 24 or 28 weeks, regardless of pre-IPV status. Poliovirus shedding after challenge with monovalent OPV, serotype 2, was higher in pre-IPV seropositive infants given sequential IPV-bOPV. No differences were observed in the mixed bOPV-IPV schedule.

Conclusions

The presence of maternal antibody is associated with lower type 2 post-IPV seroprotection rates among infants who receive a single dose of IPV. This impact persists until late in infancy and is overcome by a second IPV dose.

Trends in Poliovirus Seroprevalence in Kano State, Northern Nigeria

Background

Kano state has been a protracted reservoir of poliovirus in Nigeria. Immunity trends have been monitored through seroprevalence surveys since 2011. The survey in 2015 was, in addition, intended to assess the impact of use of inactivated poliovirus vaccine (IPV).

Methods

It was a health facility based seroprevalence survey. Eligible children aged 6-9, 12-15 and 19-22 months of age brought to the paediatrics outpatient department of Murtala Mohammad Specialist Hospital between 19 October and 6 November 2015, were screened for eligibility. Eligible children were enrolled after parental consent, history taken, physical examination conducted, and a blood sample collected to test for neutralizing antibody titres against the three poliovirus serotypes.

Results

Overall, 365 results were available in the three age groups. In the 6-9-month-old age group, the seroprevalence was 73% (95% confidence interval [CI] 64-80%), 83% (95% CI 75-88%), and 66% (95% CI 57-73%) for serotypes 1, 2, and 3, respectively. In the 12-15- and 19-22-month-old age groups, seroprevalence was higher but still remained <90% across serotypes. Seroprevalence to serotypes 1 and 3 in 2015 was similar to 2014; however, for serotype 2 there was a significant improvement. IPV received in supplemental immunization activities was found to be a significant predictor of seropositivity among 6-9-month-old infants for serotypes 1 and 2.

Conclusions

Seroprevalence for serotypes 1 and 3 remains low (<80%) in 6-9-month-olds. This poses a significant risk for poliovirus spread if reintroduced into the population. Efforts to strengthen immunization coverage are imperative to secure and sustain high population immunity.

Immune suppression of food allergy by maternal IgG in murine models

BACKGROUND

Most of the patients develop food allergy early in life. The factors related to parental immune condition might be one of the conceivable causes.

METHODS

We reported murine models of food allergy and oral OVA tolerance. To investigate the influence of parental immune condition on infant food allergy, female and male mice with food allergy or oral tolerance were mated with each other.

RESULTS

Food allergy was suppressed by decreased IgE production in the offspring of mice with food allergy. On the contrary, anaphylaxis for OVA was induced in the offspring of mice with oral tolerance. The suppression of food allergy being dependent on a maternal factor was revealed in the offspring after cross-mating mice with food allergy and oral tolerance. Because OVA-specific IgG, presumed to be from the allergic mother, was detected in the serum of naïve infants from mothers allergic to food, we assumed that the suppression was dependent on a specific IgG. The serum IgG purified by a G-protein column was administered before OVA sensitization in the food allergy model, and OVA-specific IgE production was found to be diminished in the administered mice. However, OVA-specific monoclonal IgG₁ and IgG_2a administration could not suppress food allergy. Because we detected OVA-IgG immune complex in the serum of mothers allergic to food, it might be a cause of maternal immune suppression.

CONCLUSIONS

We demonstrated that maternal specific IgG conjugated food antigen is an important factor related to the development of food allergy and acquiring tolerance.

Review of vaccination in pregnancy to prevent pertussis in early infancy

Maternal pertussis vaccination has been introduced in several countries to protect infants from birth until routine infant vaccination takes place. This review assesses existing evidence on the effectiveness and safety of immunization in pregnancy. The search was finalized in April 2017 and was based on searches using several databases. The selection criteria included any experimental or observational study reporting on the immunogenicity, effectiveness or safety of vaccination with a pertussis-containing vaccine in pregnant women and their infants. Following de-duplication and exclusions, we identified 8395 studies, which were reduced to 46 for inclusion. The overall risk of bias was low, with the exception of some early studies and pharmacovigilance safety data. The evidence demonstrates efficient transplacental transfer of maternal antibodies in infants whose mothers were vaccinated with Tdap or Tdap/IPV in pregnancy, with good evidence that this protects against disease in young infants. Safety studies covering more than 150 000 women vaccinated mostly in the late second or third trimesters are generally consistent and provide reassurance of no significant increased risk of recognized maternal conditions or of adverse events (including congenital anomalies) in infants born to vaccinated women. The clinical significance of reduced seroconversion to pertussis following routine immunization is not yet clear, but no increased risk of pertussis in infants whose mothers were vaccinated in pregnancy was found following primary immunizations in North American and English studies. Most post-booster studies suggest that any blunting effect is short-lived and that longer-term protection in infants from active immunization is not compromised.

Predictors of the immune response to booster immunisation against tetanus in Czech healthy adults

An evaluation of the relationship between predictors and immune response was conducted using data obtained from a clinical trial in 200 Czech healthy adults aged 24-65 years receiving a booster dose of a monovalent tetanus vaccine in 2017. The response was determined from ELISA antibody concentrations of paired sera obtained before and 4 weeks after the immunisation. While all subjects with initial antibody levels 2.2 IU/ml. The immune response was not affected by sex, age, tetanus vaccine type, concomitant medication, related adverse events or post-vaccination period since there were no significant differences in geometric mean concentrations or seroconversion rates. The seroconversion rate of 56% in smokers was significantly lower than that of 73% achieved in non-smokers. Although the seroconversion rates did not differ between individuals with normal or higher body weight, the adjusted odds ratio (1.3; 95% Cl 1.08-1.60) revealed a positive correlation between seroconversion rate and body mass index (BMI). Although the vaccine-induced response was influenced by pre-vaccination antibody levels, smoking or BMI, the booster immunisation against tetanus produced a sufficient response regardless the predictors.

Detection of opsonizing antibodies directed against a recently circulating Bordetella pertussis strain in paired plasma samples from symptomatic and recovered pertussis patients

Correlates of protection (CoPs) against the highly contagious respiratory disease whooping cough, caused by Bordetella pertussis, remain elusive. Characterizing the antibody response to this pathogen is essential towards identifying potential CoPs. Here, we evaluate levels, avidity and functionality of B. pertussis-specific-antibodies from paired plasma samples derived from symptomatic and recovered pertussis patients, as well as controls. Natural infection is expected to induce protective immunity. IgG levels and avidity to nine B. pertussis antigens were determined using a novel multiplex panel. Furthermore, opsonophagocytosis of a B. pertussis clinical isolate by neutrophils was measured. Findings indicate that following infection, B. pertussis-specific antibody levels of (ex-) pertussis patients waned, while the avidity of antibodies directed against the majority of studied antigens increased. Opsonophagocytosis indices decreased upon recovery, but remained higher than controls. Random forest analysis of all the data revealed that 28% of the opsonophagocytosis index variances could be explained by filamentous hemagglutinin- followed by pertussis toxin-specific antibodies. We propose to further explore which other B. pertussis-specific antibodies can better predict opsonophagocytosis. Moreover, other B. pertussis-specific antibody functions as well as the possible integration of these functions in combination with other immune cell properties should be evaluated towards the identification of CoPs against pertussis.

Antibody Kinetics and Response to Routine Vaccinations in Infants Born to Women Who Received an Investigational Trivalent Group B Streptococcus Polysaccharide CRM197-Conjugate Vaccine During Pregnancy

Background

Maternal vaccination against group B Streptococcus (GBS) might provide protection against invasive GBS disease in infants. We investigated the kinetics of transplacentally transferred GBS serotype-specific capsular antibodies in the infants and their immune response to diphtheria toxoid and pneumococcal vaccination.

Methods

This phase 1b/2, observer-blind, single-center study (NCT01193920) enrolled infants born to women previously randomized (1:1:1:1) to receive either GBS vaccine at dosages of 0.5, 2.5, or 5.0 μg of each of 3 CRM₁₉₇-glycoconjugates (serotypes Ia, Ib, and III), or placebo. Infants received routine immunization: combination diphtheria vaccine (diphtheria-tetanus-acellular pertussis–inactivated poliovirus/Haemophilus influenzae type b vaccine; age 6/10/ 14 weeks) and 13-valent pneumococcal CRM₁₉₇-conjugate vaccine (PCV13; age 6/14 weeks and 9 months). Antibody levels were assessed at birth, day (D) 43, and D91 for GBS serotypes; 1 month postdose 3 (D127) for diphtheria; and 1 month postprimary (D127) and postbooster (D301) doses for pneumococcal serotypes.

Results

Of 317 infants enrolled, 295 completed the study. In infants of GBS vaccine recipients, GBS serotype-specific antibody geometric mean concentrations were significantly higher than in the placebo group at all timepoints and predictably decreased to 41%–61% and 26%–76% of birth levels by D43 and D91, respectively. Across all groups, ≥95% of infants were seroprotected against diphtheria at D127 and ≥91% of infants had seroprotective antibody levels against each PCV13 pneumococcal serotype at D301.

Conclusions

Maternal vaccination with an investigational CRM₁₉₇-glycoconjugate GBS vaccine elicited higher GBS serotype-specific antibody levels in infants until 90 days of age, compared with a placebo group, and did not affect infant immune responses to diphtheria toxoid and pneumococcal vaccination.

Clinical Trials Registration

NCT01193920.

Effect of Chronic Social Stress on Prenatal Transfer of Antitetanus Immunity in Captive Breeding Rhesus Macaques (Macaca mulatta)

Because tetanus can cause significant morbidity and mortality in NHP, colonywide vaccination with tetanus toxoid is recommended for outdoor breeding colonies of rhesus macaques, with primary immunizations commonly given to infants at 6 mo of age followed by booster vaccines every 10 y. Maternal antibodies are thought to offer protective immunity to infants younger than 6 mo. However, historical colony data from the Yerkes National Primate Research Center show a higher incidence of tetanus among infants (≤ 6 mo old) born to subordinate dams. Whether this higher incidence of infantile tetanus is due to a higher incidence of trauma among subordinate animals or is a stress-induced impairment of maternal antibody protection is unknown. Studies in other NHP species suggest that chronic exposure to social stressors interferes with the receptor-mediated transplacental transfer of IgG. Therefore, the primary aim of this study was to determine whether chronic stress associated with social subordination impairs prenatal transfer of antitetanus immunity in breeding female rhesus macaques. Subjects included 26 high- and 26 low-ranking adult female rhesus macaques that were nearly 5 or 10 y after their initial immunization and their nonimmunized infants. We hypothesized that infants born to subordinate dams that were nearly 10 y after immunization would have the lowest infant-to-dam antibody ratios and thus would be at greatest risk for infection. Results revealed no significant intergroup differences in infant antitetanus IgG levels. However, infant-to-dam IgG ratios against tetanus were significantly lower among subordinate animals compared with dominant macaques, after accounting for the number of years since the dam's initial vaccination. In addition, higher maternal hair cortisol levels predicted lower infantto-dam tetanus toxoid IgG ratios. Together, these findings suggest that chronic social stress in female rhesus macaques may hamper the prenatal transfer of antitetanus immunity to offspring.

A Microneedle Patch for Measles and Rubella Vaccination Is Immunogenic and Protective in Infant Rhesus Macaques

Background

New methods to increase measles and rubella (MR) vaccination coverage are needed to achieve global and regional MR elimination goals.

Methods

Here, we developed microneedle (MN) patches designed to administer MR vaccine by minimally trained personnel, leave no biohazardous sharps waste, remove the need for vaccine reconstitution, and provide thermostability outside the cold chain. This study evaluated the immunogenicity of MN patches delivering MR vaccine to infant rhesus macaques.

Results

Protective titers of measles neutralizing antibodies (>120 mIU/mL) were detected in 100% of macaques in the MN group and 75% of macaques in the subcutaneous (SC) injection group. Rubella neutralizing antibody titers were >10 IU/mL for all groups. All macaques in the MN group were protected from challenge with wild-type measles virus, whereas 75% were protected in the SC group. However, vaccination by the MN or SC route was unable to generate protective immune responses to measles in infant macaques pretreated with measles immunoglobulin to simulate maternal antibody.

Conclusions

These results show, for the first time, that MR vaccine delivered by MN patch generated protective titers of neutralizing antibodies to both measles and rubella in infant rhesus macaques and afforded complete protection from measles virus challenge.

Evaluation of responses to vaccination of Angus cattle for four viruses that contribute to bovine respiratory disease complex

Although vaccination is an effective measure in reducing the risk of bovine respiratory disease complex (BRDC) in cattle, BRDC losses remain significant. Increasing the efficacy of vaccination depends on elucidating the protective immune response to different antigens included in vaccines, determining the best timing for vaccination, and understanding the impact of the age of the calf on vaccination. This study measured the serum antibodies present in calves following vaccination against 4 viruses commonly associated with BRDC: bovine viral diarrhea virus type 1 and 2 (BVDV1 and BVDV2), bovine respiratory syncytial virus (BRSV), and bovine herpesvirus 1 (BHV1). Serum antibody titers were measured in more than 1,600 calves at 3-wk intervals starting at the time of the first vaccination. This first vaccination occurred at weaning for approximately half of the individuals and 3 wk before weaning for the other half. Dam age (years), time of weaning (initial vaccination or booster vaccination), and age of calf within year-season (days within year-season) classification all were found to have a significant effect on measured traits such as the initial titer and overall response. An increased initial titer was negatively correlated with each response trait (initial, booster, and overall response). Calves that were weaned at initial vaccination had greater overall antibody response to BVDV1 and BVDV2 compared with calves weaned 3 wk before initial vaccination. In contrast, calves given their initial vaccination 3 wk before weaning had greater overall antibody response to BRSV and BHV1 compared with calves that were vaccinated at weaning. Furthermore, the circulating antibody titer at which each virus needed to be below for an individual calf to positively respond to vaccination was determined (log titer of 0.38 for BVDV1, 1.5 for BVDV2, 3.88 for BRSV, and 1.5 for BHV1). This information can be used to improve vaccination protocols to allow for a greater response rate of individuals to vaccination and, hopefully, improved protection.

Protection against neonatal enteric colibacillosis employing E. Coli-derived outer membrane vesicles in formulation and without vitamin D3

OBJECTIVE

Enterotoxigenic Escherichia Coli (ETEC) is the cause of diarrhea and even death in humans and offspring of animals. Outer membrane vesicles (OMVs) of the ETEC was prepared and its potential as a vaccine candidate against enteric colibacillosis in neonatal mice was evaluated. Dam mice intradermally injected with ETEC-derived OMVs and OMVs plus an active form of vitamin D3 (avD3). Mucosal and systemic immune responses in mice and passive immunity protection against ETEC lethality in their offspring was investigated.

RESULTS

Immunization of adult mice via ETEC-derived OMV alone and in formulation with avD3 protect offspring from ETEC-induced lethality. Nevertheless, avD3 did not indicate a positive effect on mucosal and systemic immune responses. Only the combination of OMV plus avD3 elicited a significant (P < 0.05) increase in the level of specific IgA antibodies in serum.

Maternal immunization: where are we now and how to move forward?

Pregnancy and the postpartum period are associated with elevated risks to both mother and infant from infectious disease. Vaccination of pregnant women, also called maternal immunization, has the potential to protect pregnant women, foetuses and infants from several vaccine-preventable diseases. Maternal immunoglobulin G antibodies are actively transferred through the placenta to provide passive immunity to new-borns during the first months of life, until the time for infant vaccinations or until the period of greatest susceptibility has passed. Currently, inactivated influenza, tetanus, and pertussis vaccines are recommended during pregnancy in many countries, but other vaccines may also be administered to pregnant women when risk factors are present. Several new vaccines with a specific indication for use during pregnancy are under development (e.g. respiratory syncytial virus and group B streptococcus vaccines). Years of experience suggest that maternal immunization against influenza, tetanus or pertussis has an acceptable safety profile, is well tolerated, effective and confers significant benefits to pregnant women and their infants. This review describes the principles of maternal immunization and provides an update of the recent evidence regarding the use and timing of maternal immunization. Finally, the barriers preventing wider vaccination coverage and the current limitations in addressing these are also described ( Supplementary Material ). Key messages Maternal immunization gives pregnant women greater protection against infectious diseases; induces high levels of maternal antibodies that can be transferred to the foetus; and helps protect new-borns during their first months of life, until they are old enough to be vaccinated. Pregnant women and new-borns are more vulnerable to infectious diseases than the overall population; nevertheless, vaccination rates are often low in pregnant women. This review provides an update of the recent evidence regarding the use and timing of maternal immunization and describes the barriers preventing wider vaccination uptake and the current limitations in addressing these.

Maternal Vaccination as an Essential Component of Life-Course Immunization and Its Contribution to Preventive Neonatology

Maternal immunisation schedules are increasingly coming under the spotlight as part of the development of lifetime immunisation programmes for the role that they play in improving maternal, foetal, and neonatal health. Maternally-acquired antibodies are critical in protecting infants during the first months of their lives. Maternal immunisation was previously overlooked owing to concerns regarding vaccinations in this untested and high-risk population but is now acknowledged for its potential impact on the outcomes in many domains of foetal and neonatal health, aside from its maternal benefits. This article highlights the role that maternal immunisation may play in reducing infections in preterm and term infants. It explores the barriers to antenatal vaccinations and the optimisation of the immunisation uptake. This review also probes the part that maternal immunisation may hold in the reduction of perinatal antimicrobial resistance and the prevention of non-infectious diseases. Both healthcare providers and expectant mothers should continue to be educated on the importance and safety of the appropriate immunizations during pregnancy. Maternal vaccination merits its deserved priority in a life-course immunization approach and it is perhaps the only immunization whereby two generations benefit directly from a single input. We outline the current recommendations for antenatal vaccinations and highlight the potential advances in the field contributing to “preventive neonatology”.

Seroprevalence of Human Parainfluenza Virus Types 1-4 Among Healthy Children Under 5 Years of Age in Korea

Human parainfluenza viruses (HPIVs) are among the major causes of respiratory infections in children, worldwide, including in Korea. There are four types of HPIVs, each with different epidemiological characteristics. HPIV3 is the most frequently circulating HPIV type, while the epidemiology of HPIV4 remains unclear. The aim of this study was to investigate the age-stratified seropositivity rates of HPIV types 1-4 among children in Korea. These data will be useful to determine vaccine requirements. This study included 245 participants categorized into four age groups: 6-11 months, 1 year, 2 years, and 3-5 years. Hemagglutination inhibition (HAI) assay was used to measure the antibody titers in the serum samples of the subjects. Overall, a significantly higher seropositivity rate (68%) was observed for HPIV3 (p < 0.001), indicating the predominant circulation of this type. In the 3- to 5-year-old group, 97% of the participants displayed seropositivity for HPIV3, suggesting that most Korean children acquire HPIV3 infection by the age of 5 years. The seropositivity rate for HPIV3 increased with age (p < 0.001); a prompt rise was observed between the 6-11 months age group and the 1-year age group. The seropositivity rates of HPIV1, HPIV2, and HPIV4 were found to increase with age (p < 0.001), with a marked increase recorded after the age of 2 years. HPIV1, HPIV2, and HPIV4 tended to infect children later than HPIV3. Older children showed high antibody titer ranges for HPIV3 (p < 0.001), suggesting that children experience multiple HPIV3 infections. An increasing trend of HPIV4 seropositivity rates with age was observed and this was comparable to theHPIV1 and HPIV2 seropositivity rates, indicating that its incidence may have been underestimated. To reduce HPIV infection, the administration of a HPIV3 vaccine to children 1 year of age is likely to be the most effective option.

Maternal immunization increases nestling energy expenditure, immune function, and fledging success in a passerine bird

Female birds transfer maternally derived antibodies (matAb) to their nestlings, via the egg yolk. These antibodies are thought to provide passive protection, and allow nestlings to avoid the costs associated with mounting an innate immune response. To test whether there is an energetic benefit to nestlings from receiving matAb, we challenged adult female tree swallows (Tachycineta bicolor) prior to clutch initiation with either lipopolysaccharide (LPS) or saline (Control). Following hatching, one half of each female's nestlings were immunized on day 8 post-hatch with LPS or saline, and the 4-h post-immunization nestling metabolic rate (MR) was measured. There was no difference in either LPS-reactive antibodies or total Ig levels between offspring of immunized and non-immunized mothers on day 6 or 14 post-hatch, possibly reflecting a relatively short half-life of matAbs in altricial birds. Additionally, we found no evidence that nestlings from LPS-immunized mothers could avoid the growth suppression that may result from activation of an inflammatory response. Unexpectedly, we found that control nestlings from LPS mothers had higher resting MR than control nestlings of control mothers. We attribute the increased MR to the costs associated with a general non-specific enhancement of immune function in nestlings from LPS-immunized mothers. Consistent with enhanced immune function, nestlings of immunized mothers had a more robust inflammatory response to phytohaemagglutinin and higher fledging success. Our results suggest that maternal antigen exposure pre-laying can result in increased fitness for both mothers and offspring, depending on food availability.

Summary: Exposure of female birds to a simulated pathogen prior to egg laying increases the metabolic rate, immune function, and fledging success of her nestlings.