Impact of rotavirus vaccination on rotavirus genotype distribution and diversity in England, September 2006 to August 2016.

Introduction Rotavirus vaccination with the live-attenuated monovalent (a G1P[8] human rotavirus strain) two-dose Rotarix vaccine was introduced in England in July 2013. Since then, there have been significant reductions in rotavirus gastroenteritis incidence. Aim We assessed the vaccine's impact on rotavirus genotype distribution and diversity 3 years post-vaccine introduction. Methods Epidemiological and microbiological data on genotyped rotavirus-positive samples between September 2006 and August 2016 were supplied by EuroRotaNet and Public Health England. Multinomial multivariable logistic regression adjusting for year, season and age was used to quantify changes in genotype prevalence in the vaccine period. Genotype diversity was measured using the Shannon's index (H') and Simpson's index of diversity (D). Results We analysed genotypes from 8,044 faecal samples. In the pre-vaccine era, G1P[8] was most prevalent, ranging from 39% (411/1,057) to 74% (527/709) per year. In the vaccine era, G1P[8] prevalence declined each season (35%, 231/654; 12%, 154/1,257; 5%, 34/726) and genotype diversity increased significantly in 6-59 months old children (H' p < 0.001: D p < 0.001). In multinomial analysis, G2P[4] (adjusted multinomial odds ratio (aMOR): 9.51; 95% confidence interval (CI): 7.02-12.90), G3P[8] (aMOR: 2.83; 95% CI: 2.17-3.81), G12P[8] (aMOR: 2.46; 95% CI: 1.62-3.73) and G4P[8] (aMOR: 1.42; 95% CI: 1.02-1.96) significantly increased relative to G1P[8]. Conclusions In the context of reduced rotavirus disease incidence, genotype diversity has increased, with a relative change in the dominant genotype from G1P[8] to G2P[4] after vaccine introduction. These changes will need continued surveillance as the number and age of vaccinated birth cohorts increase in the future

Molecular evolution of GII-4 Norovirus strains.

BACKGROUND: Human Noroviruses (NoV) are the major cause of acute nonbacterial gastroenteritis and the leading cause of outbreaks of gastroenteritis worldwide. Genotype II-4 (GII-4) NoV has been shown to spread rapidly and is the most commonly detected strain worldwide, particularly in association with outbreaks. Previously, we have shown that circulating GII-4 NoV strains exist as populations of selectively neutral variants, and that the emergence of epidemic GII-4 NoV strains correlated with mutations in at least two key sites (Sites A and B) within the P2 domain of the surface exposed major capsid protein (VP1). METHODOLOGY: We developed a rapid pyrosequencing method for screening of the two Sites A and B and a homology based modelling system was used to predict the effects of amino acid substitutions at these sites on the antigenic properties of the virus (defined as surface motif types). PRINCIPLE FINDING/CONCLUSION: Here, we describe the characterisation of amino acid diversity at Sites A and B for 1062 GII-4 NoV strains from clinical specimen associated with outbreak of gastroenteritis (2000-2011) and 250 GII-4 NoV sequences from Genbank. Our data identified a high diversity of different Site A and B site combinations at amino acid level and amino acid diversity was higher at Site B than Site A. Site A motifs could be grouped into 3 clusters based on similar surface motif types. We predict that Site A is a major epitope on the virus surface, responsible for defining the antigenic profile, and a more subtle role for Site B, maintaining minor antigenic variation within the virus population

Human bocaviruses are not significantly associated with gastroenteritis: results of retesting archive DNA from a case control study in the UK.

Gastroenteritis is a common illness causing considerable morbidity and mortality worldwide. Despite improvements in detection methods, a significant diagnostic gap still remains. Human bocavirus (HBoV)s, which are associated with respiratory infections, have also frequently been detected in stool samples in cases of gastroenteritis, and a tentative association between HBoVs, and in particular type-2 HBoVs, and gastroenteritis has previously been made. The aim of this study was to determine the role of HBoVs in gastroenteritis, using archived DNA samples from the case-control Infectious Intestinal Disease Study (IID). DNA extracted from stool samples from 2,256 cases and 2,124 controls were tested for the presence of HBoV DNA. All samples were screened in a real time PCR pan-HBoV assay, and positive samples were then tested in genotype 1 to 3-specific assays. HBoV was detected in 7.4% but no significantly different prevalence was observed between cases and controls. In the genotype-specific assays 106 of the 324 HBoV-positive samples were genotyped, with HBoV-1 predominantly found in controls whilst HBoV-2 was more frequently associated with cases of gastroenteritis (p<0.01). A significant proportion of HBoV positives could not be typed using the type specific assays, 67% of the total positives, and this was most likely due to low viral loads being present in the samples. However, the distribution of the untyped HBoV strains was no different between cases and controls. In conclusion, HBoVs, including HBoV-2 do not appear to be a significant cause of gastroenteritis in the UK population

Antibodies against Lewis antigens inhibit the binding of human norovirus GII.4 virus-like particles to saliva but not to intestinal Caco-2 cells.

BACKGROUND: Human noroviruses (NoVs) are the main cause of gastroenteritis worldwide. The most commonly detected NoV strains belong to the genetically diverse GII.4 genotype, with new pandemic variants emerging periodically. Despite extensive efforts, NoV investigation has been hampered by the lack of an effective in vitro cell culture system. However, NoV-derived recombinant virus-like particles (VLPs) resembling empty capsids are good surrogates for analysing NoV antigenicity and virus-ligand interactions. NoV VLPs have been reported to bind to histo-blood group antigens (HBGAs). We have analysed the ability of NoV VLPs derived from GI.1 genotype and from three GII.4 genotype variants, GII.4-1999, GII.4-2004 and GII.4-2006b, to bind to porcine gastric mucin (PGM), human saliva and differentiated human intestinal Caco-2 cells (D-Caco-2 cells). RESULTS: Distinct patterns of saliva binding with the NoV GII.4 variant VLPs were observed, although they bound to D-Caco-2 cells independently of the expression of HBGAs. Monoclonal antibodies against Lewis antigens were able to block the binding of NoV VLPs to saliva, but not to D-Caco-2 cells. Blocking HBGAs on the surface of D-Caco-2 cells with specific monoclonal antibodies did not affect NoV VLP binding to cellular membranes. Co-localisation of Lewis y (Le(y)) and H-type 2 antigens with NoV VLPs was not observed by immunofluorescence assays. CONCLUSION: Although the binding of NoV VLPs of GII.4 genotype variants to human saliva samples occur with distinct HBGA binding patterns and can be blocked by antibodies against Lewis antigens, their attachment to D-Caco-2 cells can be mediated by other receptors, which still need further investigation

Early impact of rotavirus vaccination in a large paediatric hospital in the UK.

The impact of routine rotavirus vaccination on community-acquired (CA) and healthcare-associated (HA) rotavirus gastroenteritis (RVGE) at a large paediatric hospital, UK, was investigated over a 13-year period. A total of 1644 hospitalized children aged 0-15 years tested positive for rotavirus between July 2002 and June 2015. Interrupted time-series analysis demonstrated that, post vaccine introduction (July 2013 to June 2015), CA- and HA-RVGE hospitalizations were 83% [95% confidence interval (CI): 72-90%) and 83% (95% CI: 66-92%] lower than expected, respectively. Rotavirus vaccination has rapidly reduced the hospital rotavirus disease burden among both CA- and HA-RVGE cases

Measuring transfer of human norovirus during sandwich production: Simulating the role of food, food handlers and the environment.

Foodborne outbreaks associated with transmission of norovirus are increasingly becoming a public health concern. Foods can be contaminated with faecal material at the point of production or during food preparation, in both the home and in commercial premises. Transmission of norovirus occurs through the faecal-oral route, either via person-to-person contact or through faecal-contamination of food, water, or environmental surfaces. Understanding the role and pathways of norovirus transmission - either via food handlers' hands, contaminated foods or the environment - remains a key public health priority to reduce the burden of norovirus-associated gastroenteritis. However the proportion of norovirus that is typically transferred remains unknown. Understanding this is necessary to estimate the risk of infection and the burden of gastroenteritis caused by norovirus. In this paper we present a novel method of capture, concentration and molecular detection of norovirus from a wider range of complex food matrices than those demonstrated in existing published methods. We demonstrate that this method can be used as a tool to detect and quantify norovirus from naturally contaminated food, and for monitoring norovirus transfer between food handlers' gloved hands, food or the environment. We measure the effect of introducing contamination at different food production process stages, to the final food product, to determine whether this could cause infection and disease. Between 5.9 and 6.3 Log10 cDNA copies/?l of norovirus GII were inoculated onto food handlers' gloved hands, food or the environment and 1.1-7.4% of norovirus contamination was recovered from all samples tested. When interpreted quantitatively, this percentage equates to levels predicted to be sufficient to cause infection and disease through consumption of the final food product, demonstrating a public health risk. Overall detection and quantification of norovirus from foods, food handlers' gloved hands and the environment, when suspected to be implicated in foodborne transmissions, is paramount for appropriate outbreak investigation

Assignment of the group A rotavirus NSP4 gene into genotypes using a hemi-nested multiplex PCR assay: a rapid and reproducible assay for strain surveillance studies

The rotavirus non-structural protein NSP4 has been implicated in a number of biological functions during the rotavirus cellular cycle and pathogenesis, and has been addressed as a target for vaccine development. The NSP4 gene has been classified into six genotypes (A-F). A semi-nested triplex PCR was developed for genotyping the major human NSP4 genotypes (A-C), which are common in human rotavirus strains but are also shared among most mammalian rotavirus strains. A total of 192 previously characterized human strains representing numerous G and P type specificities (such as G1P[8], G1P[4], G2P[4], G3P[3], G3P[8], G3P[9], G4P[6], G4P[8], G6P[4], G6P[9], G6P[14], G8P[10], G8P[14], G9P[8], G9P[11], G10P[11], G12P[6] and G12P[8]) were tested for NSP4 specificity by the collaborating laboratories. An additional 35 animal strains, including the reference laboratory strains SA11 (simian, G3P[2]), NCDV (bovine, G6P[1]), K9 and CU-1 (canine, G3P[3]), together with 31 field isolates (canine, G3P[3]; feline, G3P[9]; porcine, G2P[23], G3P[6], G4P[6], G5P[6], G5P[7], G5P[26], G5P[27], G9P[6] and G9P[7]) were also successfully NSP4-typed. Four human G3P[9] strains and one feline G3P[9] strain were found to possess an NSP4 A genotype, instead of NSP4 C, suggesting a reassortment event between heterologous strains. Routine NSP4 genotyping may help to determine the genomic constellation of rotaviruses of man and livestock, and identify interspecies transmission of heterologous strain