A critical review on a globally-licensed, live, orally-administrable, monovalent human rotavirus vaccine: Rotarix

Absolute quantification of bovine lactadherin to screen the anti-rotavirus activity of dairy ingredients

The anti-rotavirus components in breast milk and infant formulas play an important role in the prevention of rotavirus infection. The present study examined whether the levels of phospholipids and bovine lactadherin, which are the major components and proteins of the milk fat globule membrane complex, are useful indices of the anti-rotavirus activity of dairy ingredients used in infant formulas. We compared the anti-rotavirus activity of 2 types of dairy ingredients enriched in the milk fat globule membrane complex: high-fat whey protein concentrate (high-fat WPC) and butter milk powder (BMP), using 50% inhibition concentration (IC₅₀) and linear inhibition activity to determine levels of solid contents, total proteins, phospholipids, and bovine lactadherin. Here, we developed a quantification method using full-length isotope-labeled proteins to measure bovine lactadherin levels in these dairy ingredients. The evaluation of anti-rotavirus activity showed that the difference in IC₅₀ was the smallest when the 2 dairy ingredients were compared at the bovine lactadherin level, among other indices in this study. Additionally, no significant difference was observed between the inhibition linearity of 2 dairy ingredients when evaluating only bovine lactadherin levels. These results indicated that the level of bovine lactadherin was more strongly associated with anti-rotavirus activity than the level of phospholipids. Our results suggest that bovine lactadherin levels can be used to estimate the anti-rotavirus activity of dairy ingredients and can be a criterion used in selecting ingredients for infant formulas.

Mucosal vaccine delivery: A focus on the breakthrough of specific barriers

Mucosal vaccines can effectively induce an immune response at the mucosal site and form the first line of defense against microbial invasion. The induced mucosal immunity includes the proliferation of effector T cells and the production of IgG and IgA antibodies, thereby effectively blocking microbial infection and transmission. However, after a long period of development, the transformation of mucosal vaccines into clinical use is still relatively slow. To date, fewer than ten mucosal vaccines have been approved. Only seven mucosal vaccines against coronavirus disease 2019 (COVID-19) are under investigation in clinical trials. A representative vaccine is the adenovirus type-5 vectored COVID-19 vaccine (Ad5-nCoV) developed by Chen and coworkers, which is currently in phase III clinical trials. The reason for the limited progress of mucosal vaccines may be the complicated mucosal barriers. Therefore, this review summarizes the characteristics of mucosal barriers and highlights strategies to overcome these barriers for effective mucosal vaccine delivery.

Rotavirus A infection in pre- and post-vaccine period: Risk factors, genotypes distribution by vaccination status and age of children in Nampula Province, Northern Mozambique (2015-2019)

Mozambique introduced the monovalent rotavirus vaccine (Rotarix^®, GSK Biologicals, Rixensart, Belgium) in September 2015. Previous analysis, showed that Nampula province continues reporting a high frequency of Rotavirus A (RVA) infection and the emergence of G9P[6], G9P[4] and G3P[4] genotypes. This analysis aimed to determine the RVA frequency; risk factors; genotype distribution by vaccination status and age between pre- and post-vaccine periods in children under-five years old with diarrhea in Nampula. A cross-sectional, hospital-based surveillance study was conducted in the Hospital Central de Nampula in Mozambique. Socio-demographic and clinical data were collected to assess factors related to RVA infection in both periods. Stool specimens were screened to detect RVA by ELISA, and positive samples were genotyped. Between 2015 (pre-vaccine period) and 2016–2019 (post-vaccine period), 614 stool specimens were collected and tested for RVA in which 34.9% (67/192) were positive in pre-vaccine period and 21.8% (92/422) in post-vaccine (p = 0.001). In the post-vaccine period, age, year, and contact with different animal species (chicken, duck, or multiple animals) were associated with RVA infection. RVA infection was higher in children partially vaccinated (40.7%, 11/27) followed by the fully vaccinated (29.3%, 56/191) and the unvaccinated (15.3%, 21/137) (p = 0.002). G1P[8] and G9P[4] were common in vaccinated children less than 12 months. The present analysis showed that RVA infection reduced slightly in the post-vaccine period, with a high proportion of infection and genotype diversity in children, under 12 months of age, vaccinated. Further research on factors associated with RVA infection on vaccinated compared to unvaccinated children and vaccination optimization should be done.

An Effective Platform for Exploring Rotavirus Receptors by Bacterial Surface Display System

Rotavirus (RV) is a major foodborne pathogen. For RV prevention and control, it is a key to uncover the interaction mechanism between virus and its receptors. However, it is hard to specially purify the viral receptors, including histo-blood group antigens (HBGAs). Previously, the protruding domain protein (P protein) of human norovirus (genotype II.4) was displayed on the surface of Escherichia coli, and it specifically recognized and captured the viral ligands. In order to further verify the feasibility of the system, P protein was replaced by VP8* of RV (G9P[8]) in this study. In the system, VP8* could be correctly released by thrombin treatment with antigenicity retaining, which was confirmed by Western blot and Enzyme-Linked Immunosorbent Assays. Type A HBGAs from porcine gastric mucin (PGM) were recognized and captured by this system. From saliva mixture, the captured viral receptor bound with displayed VP8* was confirmed positive with monoclonal antibody against type A HBGAs. It indicated that the target ligands could be easily separated from the complex matrix. These results demonstrate that the bacterial surface display system will be an effective platform to explore viral receptors/ligands from cell lines or food matrix.

Enteritis with pneumatosis intestinalis following rotavirus immunisation in an infant with short bowel syndrome

Rotavirus vaccines now form part of the national immunisation schedule in many countries. Contraindications to its use are few but do not currently include infants with short bowel syndrome (SBS). We present a nearly 3-month-old boy with SBS who developed enteritis with pneumatosis intestinalis following administration of the Rotarix vaccine.

Sustained Decrease in Gastroenteritis-related Deaths and Hospitalizations in Children Less Than 5 Years of Age After the Introduction of Rotavirus Vaccination: A Time-Trend Analysis in Brazil (2001-2010)

BACKGROUND

Rotavirus (RV) vaccine, Rotarix, was introduced into the Brazil national immunization program in 2006. To estimate population-level vaccine effect, we conducted a time-trend analysis on all-cause gastroenteritis (GE)-related death certificate-reported deaths (DCRDs), hospital deaths (HDs) and hospitalizations trends in <5-year-olds before and after RV vaccine introduction.

METHODS

National level all-cause GE-related death certificate [Mortality Information System] and admission (Hospital Information System) data were aggregated and analyzed. Negative-binomial regression models (adjusting for age, year and region) compared DCRDs, HDs and hospitalization trends in <5-year-olds between baseline (2001-2005) and postvaccine introduction periods (Mortality Information System: 2007-2009 and Hospital Information System: 2007-2010). Negative-binomial regression models were fitted to data for each outcome before 2006, and the predicted annual frequencies of each outcome were plotted against corresponding observed annual frequencies.

RESULTS

During the postvaccine introduction period, there was an overall age-independent GE-related DCRDs reduction (20.9%, P = 0.04) observed in children <5 years of age; a reduction was also seen in infants <1 year of age (20.8%, P = 0.003). Age-independent GE-related HDs and hospitalizations reductions (57.1%, P < 0.0001 and 26.6%, P < 0.0001, respectively) were observed in <5-year-olds; HDs reductions were also observed for each age group (<1-year-olds: 55.0%, P < 0.0001 and 1- to <5-year-olds: 59.5%, P < 0.0001). Observed annual frequencies of GE-related DCRDs, HDs and hospitalizations were lower than the predicted value in each age group in all years after 2006.

CONCLUSIONS

GE-related DCRDs, HDs and hospitalizations were significantly reduced in <1 and in 1- to <5-year-old Brazilian children after Rotarix introduction, which provides additional evidence of the direct and indirect population-level effect of RV vaccination on GE-related mortality and morbidity in children.

Epidemiological and clinical studies of rotavirus-induced diarrhea in China from 1994-2013

Group A rotavirus infections cause diarrhea in infants and primarily occur in winter. These viruses are characterized by the viral structural proteins VP7 (G subtypes) and VP4 (P subtypes). Current treatments employ vaccines combined with symptomatic treatments. Through a review of published papers from 2003-2013, which included articles, theses, dissertations and academic conference proceedings in PubMed and CNKI (China National Knowledge Infrastructure), we examined the epidemiological and clinical studies conducted in the 7 regional administrative geographical divisions of the People's Republic of China. Binning of the clinical studies provided a quantitative synthesis of the published incidences of rotavirus-positive numbers, the infection rates and the distributions of different subtypes in the provinces. In an investigation of the 32 provincial administrative regions from 1994-2013, the number of positive infections in children, primarily ≤5 years of age, was highest in Guangdong (187,000 cases), Zhejiang (133,000 cases) and Hubei (11,000 cases) Provinces; the provinces that displayed the highest positive rates were Henan (75.20%), Jilin (64.94%) and the Ningxia Hui Autonomous Region (60.16%). Furthermore, the virus, which causes diarrhea, can also infect adults. Statistics regarding the rotavirus subtypes indicated that the top 3 G-subtypes reported were G3 (8,509 cases), G1 (6,490 cases) and G2 (1,601 cases); the top 3 P-subtypes reported were P[8] (8,483 cases), P[4] (2,017 cases) and P[6] (740 cases). The majority of clinical treatments for these infections comprised a combination of Chinese traditional and Western medicines, together with nursing and the administration of a variety of oral liquids to relieve symptoms. The top 3 positive rates were identified in provinces at higher latitude, which confirms increases in humidity and ambient temperature reduce the rotavirus infection rate and the number of rotavirus infections tends to be highest under cool, dry conditions. However, the presence of rotavirus in low-latitude provinces likely indicates living habits, living environments, and education level influencethe precautions and vaccine utilization rate. The traditional subtypes are the rotavirus G- and P-subtypes, thus allowing for the development of vaccines. In China, the treatments that are primarily used to combat the infection are integrative medicines combining a variety of nursing and adjuvant therapies.

Oral delivery of nanoparticle-based vaccines

Most infectious diseases are caused by pathogenic infiltrations from the mucosal tract. Therefore, vaccines delivered to the mucosal tissues can mimic natural infections and provide protection at the first site of infection. Thus, mucosal, especially, oral delivery is becoming the most preferred mode of vaccination. However, oral vaccines have to overcome several barriers such as the extremely low pH of the stomach, the presence of proteolytic enzymes and bile salts as well as low permeability in the intestine. Several formulations based on nanoparticle strategies are currently being explored to prepare stable oral vaccine formulations. This review briefly discusses several molecular mechanisms involved in intestinal immune cell activation and various aspects of oral nanoparticle-based vaccine design that should be considered for improved mucosal and systemic immune responses.

Rotavirus infections: mechanisms, prevention and treatment

Rotavirus is an important gastrointestinal pathogen which can cause severe diarrhea in young animals and infants. Although rotavirus infections are usually latent, large-scale outbreak may occur if environmental factors change or the immune defense of hosts decreases. As rotavirus is a pathogen of zoonotic diseases, studies on rotavirus infections are of great importance in public health and clinical application. This article provides an overview of the progress in research on viral pathogen, clinical manifestations, as well as drug and vaccine research, with an aim to provide a reference for the prevention and treatment of rotavirus infections.

Multiple-dose therapy with bovine colostrum confers significant protection against diarrhea in a mouse model of human rotavirus-induced gastrointestinal disease

Rotavirus is the most important etiologic agent of severe gastroenteritis. Previously, we reported that skimmed and concentrated bovine late colostrum (SCBLC) obtained from normal unimmunized cows at 6 to 7d after parturition effectively prevented against human rotavirus (HRV)-induced severe gastroenteritis in vivo, when administered as a single dose 60 min before viral inoculation. In the present study, we examined the efficacy of multiple administrations of SCBLC at smaller dosages after viral inoculation in vivo. We demonstrate that multiple administrations within 24h after virus inoculation resulted in earlier recovery from diarrheal symptoms, in an administration frequency-dependent manner. Furthermore, we investigated whether isolated IgG anti-HRV activity in SCBLC was equivalent to that of IgG isolated from bovine mature milk as measured by in vitro activity assays. We found that IgG-containing fractions from SCBLC and mature milk exhibited approximately the same level of anti-HRV activity. We concluded that the SCBLC contains a high level of IgG against HRV-induced severe gastroenteritis, which will be possible to use in protective effects in immunocompromised hosts, such as children and the elderly. Multiple doses of SCBLC during the early stages of infection or lower dosage of SCBLC given as a single dose both resulted in relief of diarrheal symptoms.

A dose-escalation safety and immunogenicity study of a new live attenuated human rotavirus vaccine (Rotavin-M1) in Vietnamese children

We tested a candidate live, oral, rotavirus vaccine (Rotavin-M1™) derived from an attenuated G1P [8] strain (KH0118-2003) isolated from a child in Vietnam. The vaccine was tested first for safety in 29 healthy adults. When deemed safe, it was further tested for safety and immunogenicity in 160 infants (4 groups) aged 6-12 weeks in a dose and schedule ranging study. The vaccine was administered in low titer (10(6.0)FFU/dose) on a 2-dose schedule given 2 months apart (Group 2L) and on a 3-dose schedule given 1 month apart (Group 3L) and in high titer (10(6.3)FFU/dose) in 2 doses 2 months apart (Group 2H) and in 3 doses 1 month apart (Group 3H). For comparison, 40 children (group Rotarix™) were given 2 doses of the lyophilized Rotarix™ vaccine (10(6.5)CCID(50)/dose) 1 month apart. All infants were followed for 30 days after each dose for clinical adverse events including diarrhea, vomiting, fever, abdominal pain, irritability and intussusception. Immunogenicity was assessed by IgA seroconversion and viral shedding was monitored for 7 days after administration of each dose. Two doses of Rotavin-M1 (10(6.3)FFU/dose) were well tolerated in adults. Among infants (average 8 weeks of age at enrollment), administration of Rotavin-M1 was safe and did not lead to an increased rate of fever, diarrhea, vomiting or irritability compared to Rotarix™, indicating that the candidate vaccine virus had been fully attenuated by serial passages. No elevation of levels of serum transaminase, blood urea, or blood cell counts were observed. The highest rotavirus IgA seroconversion rate (73%, 95%CI (58-88%)) was achieved in group 2H (2 doses--10(6.3)FFU/dose, 2 months apart). The 2 dose schedules performed slightly better than the 3 dose schedules and the higher titer doses performed slightly better than the lower titer doses. These rates of seroconversion were similar to that of the Rotarix™ group (58%, 95%CI (42-73%)). However more infants who received Rotarix™ (65%) shed virus in their stool after the first dose than those who received Rotavin-M1 (44-48%) (p<0.05) and the percent shedding decreased after subsequent doses of either vaccine. Rotavin-M1 vaccine is safe and immunogenic in Vietnamese infants. A trial in progress will assess the safety, immunogenicity and efficacy of Rotavin-M1 (2 doses at 10(6.3)FFU/dose) in a larger number of infants. The trial registration numbers are NCT01375907 and NCT01377571.

The unpredictable diversity of co-circulating rotavirus types in Europe and the possible impact of universal mass vaccination programmes on rotavirus genotype incidence

This article reviews the incidence of group A rotavirus (RV) types isolated from children with acute gastroenteritis (AGE) in European countries during the last 5-10 years, with the aim of establishing an overview of RV diversity before the introduction of universal mass vaccination (UMV) programmes against RV disease in most European countries. Consistent with findings from previous surveys, a high degree of diversity of co-circulating RV types exists in different locations of Europe, and over different RV seasons. Whilst RV UMV can potentially change the diversity of co-circulating genotypes, there are at present insufficient data for Europe to come to firm conclusions. Even in countries outside Europe, with several years of RV surveillance following the introduction of RV UMV (Brazil, Australia, USA), it is not clear whether changes observed in the diversity of particular RV types are due to natural fluctuations or immunological pressure exerted by RV UMVs. Consequently, it will be very difficult for European countries that have RV UMVs to conclude whether incidence changes of RV types in children with AGE are driven by immune pressures from vaccination or simply reflect natural temporal and spatial fluctuations. Whilst the monitoring of co-circulating RV strains should be continued, it should be acknowledged that the licensed monovalent and pentavalent RV vaccines are similarly effective in developed countries and that levels of RV type-specific neutralising antibodies after RV vaccination are only partially correlated with the degree of protection achieved; therefore, the significance of RV diversity for RV vaccination may be less important than is often assumed.

Burden and typing of rotavirus group A in Latin America and the Caribbean: systematic review and meta-analysis

The efficacy of licensed rotavirus vaccines has only been shown against certain rotavirus group A (RV-A) types. It is critical to understand the burden of rotavirus gastroenteritis (RVGE) and its prevalent types to assess the potential impact of these vaccines in Latin America and the Caribbean (LA&C). We performed a systematic review and meta-analyses of all the available evidence reported from 1990 to 2009 on the burden of rotavirus disease and strains circulating in LA&C. Eligible studies--185 country-level reports, 174 951 faecal samples--were selected from MEDLINE, Cochrane Library, EMBASE, LILACS, regional Ministries of Health, PAHO, regional proceedings, doctoral theses, reference lists of included studies and consulting experts. Arc-sine transformations and DerSimonian-Laird random-effects model were used for meta-analyses. The proportion of gastroenteritis cases due to rotavirus was 24.3% (95%CI 22.3-26.4) and the incidence of RVGE was 170 per 1000 children-years (95%CI 130-210). We estimated a global annual mortality for 22 countries of 88.2 (95%CI 79.3-97.1) deaths per 100 000 under 5 years (47 000 deaths).The most common G type detected was G1 (34.2%), followed by G9 (14.6%), and G2 (14.4%). The most common P types detected were P[8] (56.2%), P[4] (22.1%) and P[1] 5.4%, and the most prevalent P-G type associations were P[8]G1 17.9%, P[4]G2 9.1% and P[8]G9 8.8%. In the last 10 years, G9 circulation increased remarkably and G5 almost disappeared. More recently, G12 appeared and P[4]G2 re-emerged. To our knowledge, this is the first meta-analysis of rotavirus infection and burden of disease in LA&C.

Rotarix in Japan: Expectations and Concerns

A live-attenuated, orally-administered, monovalent, human rotavirus vaccine, Rotarix® (GlaxoSmithKline Biologicals, Rixensart, Belgium), was licensed and launched in 2011 as the first rotavirus vaccine in Japan. The rotavirus causes a substantial disease burden with an estimated 790,000 outpatient visits, 27,000–78,000 hospitalizations, and approximately 10 deaths each year in Japan. Since a recent clinical trial showed that Rotarix was as efficacious in Japan as in other industrialized countries, it is expected that the annual number of rotavirus hospitalizations will be reduced to between 1000–3000, and that outpatient visits will be reduced to 200,000. The universal rotavirus immunization program with Rotarix was calculated to be at the threshold of being cost-effective, even from the healthcare perspective, and it was highly cost-effective from the societal perspective, assuming that Rotarix is co-administered with other childhood vaccines. While Rotarix contains only a single G1P[8] human rotavirus, the postlicensure studies in Brazil showed that Rotarix provided a 75%–85% protective efficacy against severe dehydrating diarrhea or hospitalizations due to fully-heterotypic G2P[4] strains. While postlicensure studies detected a small and finite risk of intussusception associated with the administration of Rotarix, the authors conclude that Rotarix is safe to administer to infants between 6-12 weeks of age for the first dose and by 24 weeks of age for the second dose. However, the authors strongly discourage the delayed administration of the first dose between 13-20 weeks of age, which is allowed without any warning. Given the high incidence of naturally-occurring intussusception in Japan (185 cases per 100,000 children/year among children less than 1 year of age), this should prevent pediatricians and parents from having ill-perceptions of Rotarix being associated with an increased number of temporally-associated intussusception, and fully appreciate the benefit of the rotavirus vaccine.

United States rotavirus strain surveillance from 2005 to 2008: genotype prevalence before and after vaccine introduction

BACKGROUND

A live, attenuated rotavirus vaccine, RotaTeq®, was approved in 2006 for immunization of infants in the United States. To monitor the distribution of rotavirus genotypes before and after vaccine introduction, the Centers for Disease Control and Prevention conducted strain surveillance with the National Rotavirus Strain Surveillance System.

METHODS

Over 3 rotavirus seasons, 2005-2006, 2006-2007, and 2007-2008, National Rotavirus Strain Surveillance System laboratories collected rotavirus-positive stool specimens and submitted them to the Centers for Disease Control and Prevention. Rotavirus strains were G- and P-genotyped by multiplex reverse transcription-polymerase chain reaction or nucleotide sequencing.

RESULTS

During 2005-2006 and 2006-2007 seasons, G1 was the dominant G-type but in the 2007-2008 season, G3 replaced G1 as the most frequently detected strain. Four genotypes, G1P[8], G2P[4], G3P[8], and G9P[8] were detected in every season. Uncommon strains observed during the study period were G2P[8], G1P[6], G2P[6], G4P[6], G1P[4], G3P[9], G12P [6], and G12P[8]. The mean age of rotavirus cases in the 2007-2008 season increased significantly in patients less than 3 years old compared with the 2 previous seasons.

CONCLUSIONS

: The increased overall prevalence of G3P [8] strains in 2007-2008, the first rotavirus season with reasonable rotavirus vaccine coverage, was consistent with Australian reports of G3 dominance following RotaTeq introduction. However, these strain changes in both countries have occurred in the context of large declines in severe rotavirus disease and we cannot rule out that they are simply the result of naturally occurring changes in rotavirus strain prevalence. These findings underscore the need for careful monitoring of strains to assess possible vaccine pressure-induced changes and vaccine effectiveness against various rotavirus genotypes.

Update on Rotarix: an oral human rotavirus vaccine

Worldwide, rotaviruses are the single most important agents of severe gastroenteritis in infants and young children. Globally, it is estimated that every year rotavirus gastroenteritis causes more than 125 million episodes of diarrhea and nearly 527,000 deaths, mainly in developing countries. The development of new effective and safe rotavirus vaccines was recognized as the most effective intervention strategy that could yield a significant impact on the burden of rotavirus disease. Rotarix is an oral live-attenuated human rotavirus vaccine containing a single G1P[8] strain. The first oral dose may be administered as early as 6 weeks of age, with a minimum interval of 4 weeks prior to second dose; the vaccination course should be completed by the age of 24 weeks according to the manufacturer. In the USA, the upper age limit for the second dose has recently been recommended at 32 weeks of age by the Advisory Committee on Immunization Practices. The development program for Rotarix including Phase I, II and III multicenter studies involving over 100,000 infants has been established in Latin America, Europe, Asia and Africa. The vaccine proved to be well tolerated, immunogenic, efficacious, safe and not associated with intussusception. It provided 85-96% protection against severe rotavirus gastroenteritis caused by G1 and non-G1 serotypes in Latin American and European clinical trials; and of public health importance, Rotarix reduced hospitalizations of all-cause gastroenteritis by 40 and 75%, respectively. Efficacy against G2P[4] strains ranged from 41% in Latin America to 81% in Europe. In the former, Rotarix afforded sustained high protection (80.5%; 95% CI: 71.3-87.1) against severe rotavirus gastroenteritis during the first 2 years of life in a region with a changing pattern of wild-type rotavirus circulation. In a recently completed vaccine trial in South Africa and Malawi, Rotarix showed an overall efficacy of 61.2% (95% CI: 44.0-73.2) by 1 year of age. Although these rates are lower than those from developed and middle-income countries, they look promising given the lack of other effective interventions. With the expanding introduction of rotavirus vaccines into national immunization programs, postmarketing surveillance should be conducted to measure the impact of rotavirus vaccination, as well as continued monitoring of circulating rotavirus strains.