Breastfeeding linked to the reduction of both rotavirus shedding and IgA levels after Rotarix® immunization in Mexican infants

Select Gut Microbiota Impede Rotavirus Vaccine Efficacy

BACKGROUND & AIMS

The protection provided by rotavirus (RV) vaccines is highly heterogeneous among individuals. We hypothesized that microbiota composition might influence RV vaccine efficacy.

METHODS

First, we examined the potential of segmented filamentous bacteria (SFB) colonization to influence RV vaccine efficacy in mice. Next, we probed the influence of human microbiomes on RV vaccination via administering mice fecal microbial transplants (FMTs) from children with robust or minimal RV vaccine responsiveness. Post-FMT, mice were subjected to RV vaccination followed by RV challenge.

RESULTS

SFB colonization induced a phenotype that was reminiscent of RV vaccine failure (ie, failure to generate RV antigens and, consequently, anti-RV antibodies following RV vaccination resulting in proneness to RV challenge after SFB levels diminished). FMTs from children to mice recapitulated donor vaccination phenotype. Specifically, mice receiving FMTs from high-responsive vaccinees copiously shed RV antigens and robustly generated anti-RV antibodies following RV vaccination. Concomitantly, such mice were impervious to RV challenge. In contrast, mice receiving FMTs from children who had not responded to RV vaccination exhibited only modest responses to RV vaccination and, concomitantly, remained prone to RV challenge. Microbiome analysis ruled out a role for SFB but suggested involvement of Clostridium perfringens. Oral administration of cultured C. perfringens to gnotobiotic mice partially recapitulated the RV vaccine non-responder phenotype. Analysis of published microbiome data found C. perfringens abundance in children modestly associated with RV vaccine failure.

CONCLUSION

Microbiota composition influences RV vaccine efficacy with C. perfringens being one, perhaps of many, potential contributing taxa.

Gut-resident C. perfringens impedes rotavirus vaccine efficacy

Background & Aims

The extent to which live orally-administered rotavirus (RV) vaccines elicit protective immunity is highly heterogeneous. We hypothesized microbiota composition might influence vaccine efficacy.

Methods

We tested this concept by examining extent to which colonizing mice with segmented filamentous bacteria (SFB) influenced RV vaccine efficacy.Influence of human microbiomes on RV vaccination was studied via administering germ-free mice fecal microbial transplants (FMT) from children with robust or minimal RV vaccine responsiveness. Post-FMT, mice were subjected to vaccination and challenge doses of RV.

Results

SFB administration resulted in a phenotype reminiscent of RV vaccine failure, i.e. minimal generation of RV antigens and, consequently, lack of anti-RV antibodies resulting in proneness to RV challenge once SFB levels diminished. Transplant of microbiomes from children to mice recapitulated donor vaccination phenotype. Specifically, mice receiving FMT from high-responding children exhibited high levels of fecal RV antigen shedding and RV antibodies in response to RV vaccination and, concomitantly, were impervious to RV challenge. In contrast, mice receiving FMT from children who had not responded to RV vaccination exhibited only modest responses to RV challenge and, accordingly, remained prone to RV challenge. Microbiome analysis ruled out a role for SFB but suggested that RV vaccine failure might involve Clostridium perfringens . Oral administration of cultured C. perfringens to gnotobiotic mice partially recapitulated the RV vaccine non-responder phenotype. Analysis of previously-reported microbiome data found C. perfringens abundance in children associated with RV vaccine failure.

Conclusion

Microbiota composition influences RV vaccine virus infection and, consequently, protective immunity. C. perfringens may be one, perhaps of many, bacterial species harbored in the intestine of RV-vaccine non-responders that influences RV vaccine outcomes.

Maternal immune protection against infectious diseases

The maternal immune system protects developing offspring against pathogens before birth via transplacental transfer and after birth through secreted milk. This transferred maternal immunity influences each generation's susceptibility to infections and responsiveness to immunization. Thus, boosting immunity in the maternal-neonatal dyad is a potentially valuable public health strategy. Additionally, at critical times during fetal and postnatal development, environmental factors and immune stimuli influence immune development. These "windows of opportunity" offer a chance to identify both risk and protective factors that promote long-term health and limit disease. Here, we review pre- and postpartum maternal immune factors that protect against infectious agents in offspring and how they may shape the infant's immune landscape over time. Additionally, we discuss the influence of maternal immunity on the responsiveness to immunization in early life. Lastly, when maternal factors are insufficient to prevent neonatal infectious diseases, we discuss pre- and postnatal therapeutic strategies for the maternal-neonatal dyad.

Update on rotavirus vaccine underperformance in low- to middle-income countries and next-generation vaccines

In the decade since oral rotavirus vaccines (ORV) were recommended by the World Health Organization for universal inclusion in all national immunization programs, significant yet incomplete progress has been made toward reducing the burden of rotavirus in low- to middle-income countries (LMIC). ORVs continue to demonstrate effectiveness and impact in LMIC, yet numerous factors hinder optimal performance and evaluation of these vaccines. This review will provide an update on ORV performance in LMIC, the increasing body of literature regarding factors that affect ORV response, and the status of newer and next-generation rotavirus vaccines as of early 2020. Fully closing the gap in rotavirus prevention between LMIC and high-income countries will likely require a multifaceted approach accounting for biological and methodological challenges and evaluation and roll-out of newer and next-generation vaccines.

Rotavirus vaccination in the neonatal intensive care units: where are we? A rapid review of recent evidence

PURPOSE OF REVIEW

Rotavirus is a leading cause of viral acute gastroenteritis in infants. Neonates hospitalized in neonatal intensive care units (NICUs) are at risk of rotavirus infections with severe outcomes. The administration of rotavirus vaccines is only recommended, in the United States and Canada, upon discharge from the NICU despite rotavirus vaccines being proven well tolerated and effective in these populations, because of risks of live-attenuated vaccine administration in immunocompromised patients and theoretical risks of rotavirus vaccine strains shedding and transmission.We aimed to summarize recent evidence regarding rotavirus vaccine administration in the NICU setting and safety of rotavirus vaccines in preterm infants.

METHODS

We conducted a rapid review of the literature from the past 10 years, searching Medline and Embase, including all study types except reviews, reporting on rotavirus vaccines 1 and 5; NICU setting; shedding or transmission; safety in preterm. One reviewer performed data extraction and quality assessment.

RECENT FINDINGS

Thirty-one articles were analyzed. Vaccine-derived virus shedding following rotavirus vaccines existed for nearly all infants, mostly during the first week after dose 1, but with rare transmission only described in the household setting. No case of transmission in the NICU was reported. Adverse events were mild to moderate, occurring in 10-60% of vaccinated infants. Extreme premature infants or those with underlying gastrointestinal failure requiring surgery presented with more severe adverse events.

SUMMARY

Recommendations regarding rotavirus vaccine administration in the NICU should be reassessed in light of the relative safety and absence of transmission of rotavirus vaccine strains in the NICU.

Shedding of oral pentavalent bovine-human reassortant rotavirus vaccine indicates high uptake rate of vaccine and prominence of G-type G1

BACKGROUND

Live oral pentavalent bovine-human reassortant rotavirus (RV) vaccine, RotaTeq®, contains bovine rotaviruses reassorted with human G-types G1, G2, G3 and G4, and P-type P[8]. Shedding of RotaTeq® vaccine, as studied by RT-PCR, has been shown to be more common than initially reported, and may include formation of vaccine-derived double-reassortant G1P[8] RVs. We studied the extent and duration of RotaTeq® vaccine virus shedding, genotypes shed, and clinical symptoms associated with shedding.

MATERIAL AND METHODS

We enrolled a total of 301 infants who received RotaTeq® vaccine according to Finnish schedule at 2, 3 and 5 months of age. Stool samples were collected 5-10 days after the first and 0-7 days before the third dose of the vaccine. Additional stool samples 6 and 12 weeks later were collected if the second stool sample was positive. All stools were studied with RT-PCR for RV VP7, VP4 and VP6. Parents filled a symptom diary for a week after each vaccine dose.

RESULTS

We found that 93% of the vaccinees shed vaccine related viral particles in one sample taken 5-10 days after the first dose, indicating that stool shedding is very common and may be regarded as a marker of successful vaccination. Genotype G1 was the predominant genotype in shedding, often in association with P[8], and the only genotype found in long-term shedding. Also G4 was commonly detected whereas other vaccine G-types and bovine-type P[5] were not.

CONCLUSIONS

Shedding of RotaTeq® vaccine-derived viruses is a sign for successful vaccination. Intense shedding of G1 with or without P[8]reflects effective multiplication and may be an important factor in the induction of protective immunity. Shedding of G1 containing vaccine viruses may be prolonged up to 8 months of age. These results suggest that the pentavalent vaccine functions largely like a monovalent G1 vaccine. Eudra-CT: 2014-004252-60.

The effect of increased inoculum on oral rotavirus vaccine take among infants in Dhaka, Bangladesh: A double-blind, parallel group, randomized, controlled trial

BACKGROUND

Oral, live-attenuated rotavirus vaccines suffer from impaired immunogenicity and efficacy in low-income countries. Increasing the inoculum of vaccine might improve vaccine response, but this approach has been inadequately explored in low-income countries.

METHODS

We performed a double-blind, parallel group, randomized controlled trial from June 2017 through June 2018 in the urban Mirpur slum of Dhaka, Bangladesh to compare vaccine take (primary outcome) among healthy infants randomized to receive either the standard dose or double the standard dose of oral Rotarix (GlaxoSmithKline) vaccine at 6 and 10 weeks of life. Infants with congenital malformations, birth or enrollment weight <2000 gm, known immunocompromising condition, enrollment in another vaccine trial, or other household member enrolled in the study were excluded. Infants were randomized using random permuted blocks. Vaccine take was defined as detection of post-vaccination fecal vaccine shedding by real-time reverse transcription polymerase chain reaction with sequence confirmation or plasma rotavirus-specific immunoglobulin A (RV-IgA) seroconversion 4 weeks following the second dose.

RESULTS

220 infants were enrolled and randomized (110 per group). 97 standard-dose and 92 high-dose infants completed the study per-protocol. For the primary outcome, no significant difference was observed between groups: vaccine take occurred in 62 (67%) high-dose infants versus 69 (71%) standard-dose infants (RR 0.92, 95% CI 0.67-1.24). However, in post-hoc analysis, children with confirmed vaccine replication had significantly increased RV-IgA responses, independent of the intervention. No significant adverse events related to study participation were detected.

CONCLUSIONS

Administration of double the standard dose of an oral, live-attenuated rotavirus vaccine (Rotarix) did not improve vaccine take among infants in urban Dhaka, Bangladesh. However, improved immunogenicity in children with vaccine replication irrespective of initial inoculum provides further evidence for the need to promote in-host replication and improved gut health to improve oral vaccine response in low-income settings. ClinicalTrials.gov: NCT02992197.

Monitoring Shedding of Five Genotypes of RotaTeq Vaccine Viruses by Genotype-Specific Real-Time Reverse Transcription-PCR Assays

RotaTeq (RV5) is a widely used live attenuated pentavalent rotavirus (RV) vaccine. Although fecal shedding of RV vaccine strains persists for long time periods, it is unclear how each vaccine strain replicates in intestinal tissue and is excreted in stool. To examine this issue, we established RV5 genotype-specific real-time reverse transcription-PCR (RT-PCR) assays. Five real-time RT-PCR assays were designed for the VP7 gene in genotypes G1, G2, G3, G4, and G6. All assays exhibited excellent linearity, and the detection limit was 1 infectious unit (IU)/reaction for G2, G4, and G6 and 10 IUs/reaction for G1 and G3. No cross-reactivity was observed among G genotypes. The inter- and intra-assay coefficients of variation were less than 3%. The assays were used to examine 129 stool samples collected from eight infants who received RV5. In cases 1 and 2, who received three rounds of vaccination, RV shedding decreased gradually with the number of vaccinations. G1 and G6 shedding appeared to be predominant in comparison to shedding of the other genotypes. Patterns of fecal shedding of the five genotypes of vaccine viruses differed between the eight vaccine recipients. RV5 genotype-specific real-time RT-PCR assays will be useful to study the molecular biology of RV5 replication in infants and experimental animals.

The Lewis A phenotype is a restriction factor for Rotateq and Rotarix vaccine-take in Nicaraguan children

Histo-blood group antigens (HBGAs) and the Lewis and secretor antigens are associated with susceptibility to rotavirus infection in a genotype-dependent manner. Nicaraguan children were prospectively enrolled in two cohorts vaccinated with either RotaTeq RV5 (n = 68) or Rotarix RV1 (n = 168). Lewis and secretor antigens were determined by saliva phenotyping and genotyping. Seroconversion was defined as a 4-fold increase in plasma IgA antibody titer 1 month after administration of the first dose of the vaccine. Regardless of the vaccine administered, significantly fewer of the children with Lewis A phenotype (0/14) seroconverted after receiving the first vaccine dose compared to 26% (45/175) of those with the Lewis B phenotype and 32% (15/47) of the Lewis negative individuals (P < 0.01). Furthermore, following administration of the RV1 vaccine, secretor-positive ABO blood group B children seroconverted to a significantly lesser extent (5%) compared to secretor-positive children with ABO blood groups A (26%) and O (27%) (P < 0.05). Other factors such as pre-vaccination titers, sex, breastfeeding, and calprotectin levels did not influence vaccine-take. Differences in HBGA expression appear to be a contributing factor in the discrepancy in vaccine-take and thus, in vaccine efficacy in different ethnic populations.

Development of a new enzyme immunoassay for improved detection of rotavirus in fecal specimens of vaccinated infants

BACKGROUND

Group A rotavirus is the most common cause of acute diarrhea in young children worldwide. A simple and rapid enzyme immunoassay (EIA) has been commonly used to detect rotavirus infection and evaluate rotavirus vaccines. Currently licensed commercial EIA kits have low sensitivity. A more sensitive detection of rotavirus can improve rotavirus diagnostics and vaccine efficacy studies.

OBJECTIVE

A biotin-avidin based sandwich EIA was developed and compared with commercial EIA kits for improved detection of viral shedding in fecal samples from infants who received human rotavirus vaccine Rotarix in Mexico.

STUDY DESIGN

A monoclonal antibody (mAb: 1D4) specific to human rotavirus group antigen VP6 was prepared and used to develop a biotin-avidin based sandwich EIA. This EIA was employed to test 128 fecal samples from vaccinated infants, in comparison with two commercial EIA kits using RT-PCR as a reference.

RESULTS

A new biotin-avidin based sandwich EIA showed specific reaction to group A rotaviruses, but not to other enteric viruses. This new EIA had a detection rate of 36.7% for rotavirus antigen shedding in fecal specimens, which was two times higher (16.4%, 18.0%) than those from two commercial EIA kits.

CONCLUSION

The new EIA had specificity and higher sensitivity than commercial kits. This new EIA has the potential to detect rotavirus at lower concentration in clinical specimens and thus should be further evaluated as a more sensitive kit for use in diagnostics and vaccine efficacy and effectiveness studies.

Decreased performance of live attenuated, oral rotavirus vaccines in low-income settings: causes and contributing factors

INTRODUCTION

Numerous studies have shown that the oral rotavirus vaccines are less effective in infants born in low income countries compared to those born in developed countries. Identifying the specific factors in developing countries that decrease and/or compromise the protection that rotavirus vaccines offer, could lead to a path for designing new strategies for the vaccines' improvement.

AREAS COVERED

We accessed PubMed to identify rotavirus vaccine performance studies (i.e., efficacy, effectiveness and immunogenicity) and correlated performance with several risk factors. Here, we review the factors that might contribute to the low vaccine efficacy, including passive transfer of maternal rotavirus antibodies, rotavirus seasonality, oral polio vaccine (OPV) administered concurrently, microbiome composition and concomitant enteric pathogens, malnutrition, environmental enteropathy, HIV, and histo blood group antigens.

EXPERT COMMENTARY

We highlight two major factors that compromise rotavirus vaccines' efficacy: the passive transfer of rotavirus IgG antibodies to infants and the  co-administration of rotavirus vaccines with OPV. We also identify other potential risk factors that require further research because the data about their interference with the efficacy of rotavirus vaccines are inconclusive and at times conflicting.

Breastfeeding and the gut-brain axis: is there a role for melatonin?

The benefits of breastfeeding over formula feed are widely appreciated. However, for many mothers breastfeeding is not possible, highlighting the need for a significant improvement in the contents of formula feed. In this article, the overlooked role of melatonin and the melatonergic pathways in breast milk and in the regulation of wider breast milk components are reviewed. There is a growing appreciation that the benefits of breastfeeding are mediated by its effects in the infant gut, with consequences for the development of the gut-brain axis and the immune system. The melatonergic pathways are intimately associated with highly researched processes in the gut, gut microbiome and gut-brain axis. As the melatonergic pathways are dependent on the levels of serotonin availability as a necessary precursor, decreased melatonin is linked to depression and depression-associated disorders. The association of breastfeeding and the gut-brain axis with a host of medical conditions may be mediated by their regulation of processes that modulate depression susceptibility. The biological underpinnings of depression include increased levels of pro-inflammatory cytokines, oxidative stress, kynurenine pathway activity and dysregulation of the hypothalamic-pituitary adrenal axis, all of which can decrease melatonergic pathway activity. The inclusion of the melatonergic pathways in the biological interactions of breast milk and gut development has significant theoretical and treatment implications, as well as being important to the prevention of a host of infant-, child- and adult-onset medical conditions.

Rotavirus Vaccines: a story of success with challenges ahead

Approximately 40 years have passed since the discovery of the rotavirus and 10 years since the introduction and progressive dissemination of rotavirus vaccines worldwide. Currently, 92 countries have introduced rotavirus vaccines into national or subnational programs with evident impact in disease reduction. Two vaccines have been widely used, and four additional vaccines have been licensed and are being used in defined regions. In this context, one main issue that remains unsolved is the lower vaccine efficacy/effectiveness in low-income countries. An additional partially answered issue relates to rotavirus strain circulation in vaccinated populations. These issues are discussed in this review. The most imperative challenge ahead is to fulfill the WHO’s recommendation to introduce rotavirus vaccines in all countries.

Options for improving effectiveness of rotavirus vaccines in developing countries

Rotavirus gastroenteritis is a leading global cause of mortality and morbidity in young children due to diarrhea and dehydration. Over 85% of deaths occur in developing countries. In industrialised countries, 2 live oral rotavirus vaccines licensed in 2006 quickly demonstrated high effectiveness, dramatically reducing severe rotavirus gastroenteritis admissions in many settings by more than 90%. In contrast, the same vaccines reduced severe rotavirus gastroenteritis by only 30-60% in developing countries, but have been proven life-saving. Bridging this "efficacy gap" offers the possibility to save many more lives of children under the age of 5. The reduced efficacy of rotavirus vaccines in developing settings may be related to differences in transmission dynamics, as well as host luminal, mucosal and immune factors. This review will examine strategies currently under study to target the issue of reduced efficacy and effectiveness of oral rotavirus vaccines in developing settings.