Absence of genetic differences among G10P[11] rotaviruses associated with asymptomatic and symptomatic neonatal infections in Vellore, India

Whole-genome characterization of common rotavirus strains circulating in Vellore, India from 2002 to 2017: emergence of non-classical genomic constellations

Rotaviruses (RVs) are the most common etiological agent of acute gastroenteritis among young children, even after vaccine introduction in low-income countries. A whole-genome classification representing the 11 RV genes, was introduced for surveillance and characterization of RVs. This study characterized the common circulating strains in Vellore, India from 2002 to 2017 to understand rotavirus strain diversity and evolution using Whole genome sequencing (WGS) carried out on Illumina MiSeq. The 89% (92% of Wa-like, 86% of DS-1-like) of strains had classical constellations, while reassortant constellations were seen in 11% (8% of Wa-like, 14% of DS-1-like) of the strains. The rare E6-NSP4 in combination with DS-1 like G1P[8] and the emergence of the OP-354 subtype of P[8] were identified. Phylogenetics of RV strains revealed multiple subtypes circulating in the past 15 years, with strong evidence of animal to human gene transmission among several strains.

A Pseudovirus Nanoparticle-Based Trivalent Rotavirus Vaccine Candidate Elicits High and Cross P Type Immune Response

Rotavirus infection continues to cause significant morbidity and mortality globally. In this study, we further developed the S60-VP8* pseudovirus nanoparticles (PVNPs) displaying the glycan receptor binding VP8* domains of rotavirus spike proteins as a parenteral vaccine candidate. First, we established a scalable method for the large production of tag-free S60-VP8* PVNPs representing four rotavirus P types, P[8], P[4], P[6], and P[11]. The approach consists of two major steps: selective precipitation of the S-VP8* proteins from bacterial lysates using ammonium sulfate, followed by anion exchange chromatography to further purify the target proteins to a high purity. The purified soluble proteins self-assembled into S60-VP8* PVNPs. Importantly, after intramuscular injections, the trivalent vaccine consisting of three PVNPs covering VP8* antigens of P[8], P[4], and P[6] rotaviruses elicited high and broad immunogenicity in mice toward the three predominant P-type rotaviruses. Specifically, the trivalent vaccine-immunized mouse sera showed (1) high and balanced IgG and IgA antibody titers toward all three VP8* types, (2) high blocking titer against the VP8*-glycan receptor interaction, and (3) high and broad neutralizing titers against replications of all P[8], P[4], and P[6] rotaviruses. Therefore, trivalent S60-VP8* PVNPs are a promising non-replicating, parenteral vaccine candidate against the most prevalent rotaviruses worldwide.

Salivirus infection: Systematic review and meta-analysis of association with gastrointestinal symptoms in children

Salivirus (SaV) is a newly described member of the family Picornaviridae that has been associated with gastrointestinal (GI) symptoms, particularly in children. The aim of the present study was to evaluate the prevalence of SaV in symptomatic children and its potential association with GI complications. A systematic search was conducted from 01 December 2009 to 10 December 2020, in three major English databases, including Scopus, PubMed and Web of Science as well as Google scholar search engine. Random effect model-based overall prevalence and odds ratio (OR) were assessed in cross-sectional and case-control studies by STATA 14.1. The random effect model-based pooled prevalence of SaV was 1.6% (95% CI, 0.010-0.022%) and overall OR for all eight case-control studies indicated an association (3.19 with 95% confidence interval 1.35-7.57) that was not statistically significant, due to the small number of studies available. More comprehensive case-control studies in multiple geographies should be conducted on the prevalence of SaV in children.

Asymptomatic Rotavirus infections among children in Maiduguri, Borno state, Northeast, Nigeria

Background:

Rotavirus remains one of the main causative agents of gastroenteritis in young children. This happens, especially in countries (e.g., Nigeria) that have not yet introduced the vaccine into the national immunization program. A significant prevalence of Rotavirus infection both in children and adults without major symptoms has earlier been reported. This study aimed at defining the prevalence of asymptomatic Rotavirus infection from apparently healthy children in Maiduguri, Borno State, Northeastern Nigeria.

Methods:

A total of 269 stool samples were randomly collected from apparently healthy children <15 years of age from July 2017 to June 2018. All samples were screened using a commercially available enzyme-linked immunosorbent assay kit for the presence of Rotavirus antigen. The Rotavirus-positive samples were further subjected to polyacrylamide gel electrophoresis (PAGE) to determine their RNA electropherotypes.

Results:

A total of 59 stool samples (19.9%) were Rotavirus positive with peaks observed in the cold dry season, among male children, and 6–10 years of age group. A total of 50 randomly selected Rotavirus-positive samples were subjected to PAGE, and none of the samples showed either long or short profiles.

Conclusion:

This study shows that Rotavirus can be shed into environments without any signs and symptoms. In view of this, the Rotavirus vaccine should be considered a priority and be introduced in the existing national immunization program in Nigeria, particularly in Borno State.

Rotavirus genotypes circulating in Ontario, Canada, before and after implementation of the rotavirus immunization program

BACKGROUND AND OBJECTIVES

Ontario introduced a universal publicly-funded group A rotavirus (RVA) immunization program in August 2011, using monovalent vaccine. RVA immunization programs have decreased the incidence of RVA acute gastroenteritis in many countries but it is unclear if it will contribute to the emergence of certain genotypes. We monitored RVA trends and genotypes in Ontario before and after implementation of the publicly-funded immunization program.

METHODS

RVA detection was conducted at Public Health Ontario Laboratories from January 2009 to December 2011 (pre-program period) and January 2012 to October 2015 (publicly-funded RVA immunization program period) and number of RVA-positive specimens and percent positivity were analysed. A convenience sample of RVA-positive stool specimens, from September 2010 to December 2011 (pre-program period) and January 2012 to June 2013 (program period), were genotyped using heminested PCR. A literature review on the burden of illness from emergent genotype was performed.

RESULTS

Stool specimens showed a significant decrease in RVA percent positivity from the 36 month pre-program period (14.4%; 1537/10700) to the 46 month program period (6.1%; 548/9019). An increase in the proportion of RVA G10 among genotyped specimens, associated with five different P genotypes, from the pre-program (6.3%; 13/205) to the program (31.5%; 40/127) period was observed. Our literature review identified approximately 200 G10-positive human stool specimens from 16 different countries.

CONCLUSIONS

This study documented a decrease in the number of RVA-positive specimens and percent positivity after implementation of the immunization program. An unexpected increase in the proportion of RVA G10 was detected following program introduction. Ongoing RVA surveillance is important in evaluating both the long-term impact of immunization and emergence of RVA genotypes.

Histo-blood group antigens as receptors for rotavirus, new understanding on rotavirus epidemiology and vaccine strategy

The success of the two rotavirus (RV) vaccines (Rotarix and RotaTeq) in many countries endorses a live attenuated vaccine approach against RVs. However, the lower efficacies of both vaccines in many low- and middle-income countries indicate a need to improve the current RV vaccines. The recent discovery that RVs recognize histo-blood group antigens (HBGAs) as potential receptors has significantly advanced our understanding of RV diversity, evolution and epidemiology, providing important new insights into the performances of current RV vaccines in different populations and emphasizing a P-type-based vaccine approach. New understanding of RV diversity and evolution also raises a fundamental question about the ‘Jennerian' approach, which needs to be addressed for future development of live attenuated RV vaccines. Alternative approaches to develop safer and more cost-effective subunit vaccines against RVs are also discussed.

Saliviruses-the first knowledge about a newly discovered human picornavirus

The salivirus, first discovered in the year 2009, is a member of the large and growing family Picornaviridae. At present, the genus Salivirus contains 1 species Salivirus A and 2 genotypes, Salivirus A1 and Salivirus A2. Salivirus has been identified in humans and chimpanzees and may cause acute gastroenteritis in humans, having been detected in 0% to 8.7% of fecal samples collected from gastroenteritis in different human populations. Salivirus is ubiquitous in wastewater of human origin and river water specimens worldwide and represents a potential indicator human RNA virus for monitoring of environmental samples. This review summarizes the current knowledge on saliviruses including discovery, taxonomy, genome structure, and genetic diversity; covers all aspects of infection including epidemiology, molecular epidemiology, clinical feature, host species, environmental characteristics, and laboratory diagnosis; and gives a summary of possible future perspectives.

Clinico-epidemiology and genetic diversity of Salivirus in acute gastroenteritis cases from Pune, Western India: 2007-2011

Acute gastroenteritis is a leading cause of mortality in children from developing countries. Recently, Salivirus has been frequently detected in acute gastroenteritis patients, suggesting its possible aetiological role. Conflicting reports available on disease association of Salivirus have made it difficult to ascertain their causative role. The overall epidemiology and clinical features of Salivirus infections are poorly understood. The present five year study was undertaken to investigate the presence and genetic diversity of Salivirus in acute gastroenteritis cases from Pune, Western India and to determine the clinico-epidemiological features of Salivirus infections. A total of 985 faecal samples (778 acute gastroenteritis and 207 asymptomatic controls), collected from three local hospitals (Jan2007-Dec2011) were examined for the presence of Salivirus by RT-PCR. Molecular characterization was performed by PCR amplification of the 3D and VP regions. Frequency of Salivirus detection in cases (2.6%) and controls (1.93%) was not significantly different (p = 0.57). Co-infection with other enteric viruses was seen in 50% of the cases. Comparison of clinical features between Salivirus mono and mixed infections revealed that Salivirus alone did not exacerbate gastroenteritis. The frequency of diarrhoea and overall clinical severity of mixed infections was significantly greater than mono infections (p = 0.02). Based on clinical findings, our study suggests that Salivirus does not cause severe gastroenteritis. Phylogenetic analysis indicated that study strains belonged to Salivirus A1 and formed 2 distinct clusters which shared nucleotide identities of 94.1-96.2% and 88.9-93.8% between themselves in 3D and VP regions, respectively. Interestingly, the more divergent Cluster2 strains shared a low nucleotide identity with the closest reference strain in both regions (~95% in 3D and ~92% in VP) suggesting that they could represent a variant type of Salivirus A1. The genetic diversity in strains detected from study region, emphasizes the need for Salivirus surveillance from other regions of India.