Interaction between norovirus and Histo-Blood Group Antigens: A key to understanding virus transmission and inactivation through treatments?

Human noroviruses (HuNoVs) are a main cause of acute gastroenteritis worldwide. They are frequently involved in foodborne and waterborne outbreaks. Environmental transmission of the virus depends on two main factors: the ability of viral particles to remain infectious and their adhesion capacity onto different surfaces. Until recently, adhesion of viral particles to food matrices was mainly investigated by considering non-specific interactions (e.g. electrostatic, hydrophobic) and there was only limited information about infectious HuNoVs because of the absence of a reliable in vitro HuNoV cultivation system. Many HuNoV strains have now been described as having specific binding interactions with human Histo-Blood Group Antigens (HBGAs) and non-HBGA ligands found in food and the environment. Relevant approaches to the in vitro replication of HuNoVs were also proposed recently. On the basis of the available literature data, this review discusses the opportunities to use this new knowledge to obtain a better understanding of HuNoV transmission to human populations and better evaluate the hazard posed by HuNoVs in foodstuffs and the environment.

Predominance of G9P[8] rotavirus strains throughout France, 2014-2017.

OBJECTIVES: Group A rotavirus is a major cause of acute gastroenteritis in young children worldwide. A prospective surveillance network has been set up in France to investigate rotavirus infections and to detect the emergence of potentially epidemic strains. METHODS: From 2014 to 2017, rotavirus-positive stool samples were collected from 2394 children under 5 years old attending the paediatric emergency units of 13 large hospitals. Rotaviruses were genotyped by RT-PCR with regard to their outer capsid proteins VP4 and VP7. RESULTS: Genotyping of 2421 rotaviruses showed that after a marked increase in G9P[8] (32.1%) during the 2014-2015 season, G9P[8] became the predominant genotype during the 2015-2016 and 2016-2017 seasons with detection rates of 64.1% and 77.3%, respectively, whereas G1P[8] were detected at low rates of 16.8% and 6.6%, respectively. Phylogenetic analysis of the partial rotavirus VP7 and VP4 coding genes revealed that all of these G9P [8] strains belonged to the lineage III and the P [8]-3 lineage, respectively, and shared the same genetic background (G9-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1) as did most of previously detected G9P[8] strains and particularly the emerging G9P[8] strains from the 2004-2005 season in France. CONCLUSIONS: G9P[8] rotaviruses have become the predominant circulating genotype for the first time since their emergence a decade ago. In the absence of rotavirus immunization programmes in France, our data give an insight into the natural fluctuation of rotavirus genotypes in a non-vaccinated population and provide a base line for a better interpretation of data in European countries with routine rotavirus vaccination.

Clinical severity and molecular characteristics of circulating and emerging rotaviruses in young children attending hospital emergency departments in France.

Group A rotavirus (RVA) is the leading cause of acute gastroenteritis in young children worldwide. A prospective surveillance network has been set up to investigate the virological and clinical features of RVA infections and to detect the emergence of potentially epidemic strains in France. From 2009 to 2014, RVA-positive stool samples were collected from 4800 children <5 years old attending the paediatric emergency units of 16 large hospitals. Rotaviruses were then genotyped by RT-PCR with regard to their outer capsid proteins VP4 and VP7. Genotyping of 4708 RVA showed that G1P[8] strains (62.2%) were predominant. The incidence of G9P[8] (11.5%), G3P[8] (10.4%) and G2P[4] (6.6%) strains varied considerably, whereas G4P[8] (2.7%) strains were circulating mostly locally. Of note, G12P[8] (1.6%) strains emerged during the seasons 2011-12 and 2012-13 with 4.1% and 3.0% prevalence, respectively. Overall, 40 possible zoonotic reassortants, such as G6 (33.3%) and G8 (15.4%) strains, were detected, and were mostly associated with P[6] (67.5%). Analysis of clinical records of 624 hospitalized children and severity scores from 282 of them showed no difference in clinical manifestations or severity in relation to the genotype. The relative stability of RVA genotypes currently co-circulating and the large predominance of P[8] type strains may ensure vaccine effectiveness in France. The surveillance will continue to monitor the emergence of new reassortants that might not respond to current vaccines, all the more so as all genotypes can cause severe infections in infants.

Relationship between GII.3 norovirus infections and blood group antigens in young children in Tunisia.

Noroviruses (NoVs) constitute a major cause of gastroenteritis in Tunisia. One hundred and fourteen matched saliva and stool samples were collected from children (n = 114) suffering from acute gastroenteritis at the hospital of Monastir during the winter season 2011-2012. For 98 of 114 children, blood samples were collected for secretor genotyping. NoVs were associated with 36.8% (n = 42/114) of the gastroenteritis cases. The GII.3 genotype was the most common (69% of all NoVs). For patients who were phenotyped (n = 114) for human blood group antigens (HBGAs), the secretor and non-secretor phenotypes represented 79% and 21%, respectively. Of the NoV infections, 83% were detected in all ABO groups. Five GII.3 isolates, one GII.1 isolate and one GII.7 isolate were detected in Lewis-positive non-secretors, confirmed by genotyping of the FUT2 gene. Even though our data showed that GII.3 NoVs could infect non-secretors, no binding was observed with saliva and GII.3 baculovirus-expressed virus-like particles from the same symptomatic non-secretor individual. This suggests that other factors might also participate in NoV attachment in children and newborns.

Qualitative and quantitative analysis of the binding of GII.4 norovirus variants onto human blood group antigens.

Noroviruses (NoVs) are one of the leading causes of gastroenteritis in children and adults. For the last 2 decades, genogroup II genotype 4 (GII.4) NoVs have been circulating worldwide. GII.4 NoVs can be divided into variants, and since 2002 they have circulated in the population before being replaced every 2 or 3 years, which raises questions about the role of their histo-blood group antigen (HBGA) ligands in their evolution. To shed light on these questions, we performed an analysis of the interaction between representative GII.4 variants and HBGAs, and we determined the role of selected amino acids in the binding profiles. By mutagenesis, we showed that there was a strict structural requirement for the amino acids, directly implicated in interactions with HBGAs. However, the ablation of the threonine residue at position 395 (ΔT395), an epidemiological feature of the post-2002 variants, was not deleterious to the binding of the virus-like particle (VLP) to the H antigen, while binding to A and B antigens was severely hampered. Nevertheless, the ΔT395 VLPs gained the capacity to bind to the Lewis x and sialyl-Lewis x antigens in comparison with the wild-type VLP, demonstrating that amino acid residues outside the HBGA binding site can modify the binding properties of NoVs. We also analyzed the attachment of baculovirus-expressed VLPs from six variants (Bristol, US95/96, Hunter, Yerseke, Den Haag, and Osaka) that were isolated from 1987 to 2007 to phenotyped saliva samples and synthetic HBGAs. We showed that the six variants could all attach to saliva of secretors irrespective of the ABO phenotype and to oligosaccharides characteristic of the secretor phenotype. Interestingly, Den Haag and Osaka variants additionally bound to carbohydrates present in the saliva of Lewis-positive nonsecretors. The carbohydrate binding profile and the genetic and mutagenesis analysis suggested that GII.4 binding to Lewis x and sialyl-Lewis x antigens might be a by-product of the genetic variation of the amino acids located in the vicinity of the binding site. Analysis of the binding properties for the six variants by surface plasmon resonance showed that only post-2002 variants (i.e., Hunter, Yerseke, Den Haag, and Osaka) presented strong binding to A and B antigens, suggesting that the GII.4 evolution could be related to an increased affinity for HBGAs for the post-2002 variants. The combination of increased affinity for ABH antigens and of a newly acquired ability to recognize glycans from Lewis-positive nonsecretors could have contributed to the epidemiological importance of strains such as the Den Haag GII.4 subtype.

Rotavirus genotypes co-circulating in Europe between 2006 and 2009 as determined by EuroRotaNet, a pan-European collaborative strain surveillance network.

EuroRotaNet, a laboratory network, was established in order to determine the diversity of co-circulating rotavirus strains in Europe over three or more rotavirus seasons from 2006/2007 and currently includes 16 countries. This report highlights the tremendous diversity of rotavirus strains co-circulating in the European population during three years of surveillance since 2006/2007 and points to the possible origins of these strains including genetic reassortment and interspecies transmission. Furthermore, the ability of the network to identify strains circulating with an incidence of ≥1% allowed the identification of possible emerging strains such as G8 and G12 since the beginning of the study; analysis of recent data indicates their increased incidence. The introduction of universal rotavirus vaccination in at least two of the participating countries, and partial vaccine coverage in some others may provide data on diversity driven by vaccine introduction and possible strain replacement in Europe.

[Epidemics of gastroenteritis caused by norovirus in Parisian children]. / Épidémies parisiennes de gastro-entérites à norovirus.

During the months of October and November 2006-2008, norovirus was detected in the stools of 14 children hospitalized with acute diarrhea (no sapovirus). Nine of these noroviruses belonged to a unique GGII4 strain, which produced severe clinical symptoms, present only in 2007 and 2008 and absent in 2006. This strain, identified in Europe mainly in the elderly, seems to be on the rise in children in the Paris area over the past few years.

Rotavirus surveillance in europe, 2005-2008: web-enabled reporting and real-time analysis of genotyping and epidemiological data.

BACKGROUND: The first European rotavirus surveillance network, EuroRotaNet, comprising 16 laboratories in 15 European countries, has been established. METHODS: Fecal samples from gastroenteritis cases positive for group A rotavirus antigen were collected from multiple European countries from 2005 to mid-2008 and were subjected to G and P genotyping. Epidemiological data collected included age, sex, geographical location, setting, dates of onset and sample collection, and clinical symptoms. RESULTS: A total of 8879 rotavirus-positive samples were characterized: 2129 cases were from the 2005-2006 season, 4030 from the 2006-2007 season, and 2720 from the ongoing 2007-2008 season. A total of 30 different G and P type combinations of strains circulated in the region from 2005 through 2008. Of these strains, 90% had genotypes commonly associated with human infections-G1P[8], G2P[4], G3P[8], G4P[8], and G9P[8]-and 1.37% represented potential zoonotic introductions. G1P[8] remained the most prevalent genotype in Europe as a whole, but the incidence of infection with G1P[8] rotavirus strains was <50% overall, and all 3 seasons were characterized by a significant diversity of cocirculating strains. The peak incidence of rotavirus infection occurred from January through May, and 81% of case patients were aged <2.5 years. Conclusions. Data gathered through EuroRotaNet will provide valuable background information on the rotavirus strain diversity in Europe before the introduction of rotavirus vaccines, and the network will provide a robust method for surveillance during vaccine implementation.

Methicillin-resistant Staphylococcus aureus among a network of French private-sector community-based-medical laboratories.

OBJECTIVE: The aim of this study was to estimate the frequency of methicillin-resistant Staphylococcus aureus (MRSA) strains in the French community and the proportion of Panton-Valentine (PVL)-MRSA. DESIGN: A cross-sectional study was made during a 3-month period in 2003 through a network of private-sector, community-based medical laboratories selected throughout France: the Labville network. Each MRSA isolate was included and characterized by French National Reference Center for Staphylococci. The total number of S. aureus isolates was also collected. RESULTS: Among the 283 patients infected or colonized by MRSA, 166 (59%) were considered as healthcare-associated, 14 (5%) as nursing-associated and 39 (14%) as community-acquired. The proportion of methicillin resistance among S. aureus was 14%. Taking into account the sampling design, the incidence of MRSA cases in French outpatients was estimated to be 0.50 [CI95%: 0.41-0.60] per 10,000 inhabitants. The molecular analysis confirmed that 80.6% belong to the Lyon clone, the most prevalent hospital MRSA clone spreading in France and 10.6% to a closely related clone. An emerging MRSA clone containing the tst1 gene was detected in six patients and the PVL-positive ST80 clone only in one, 22-year-old, patient. CONCLUSION: Most of MRSA cases diagnosed in the community in France, in 2003, were elderly with specific risk factors and harbored hospital strains. The prevalence of PVL-MRSA remained low.

[Sensitivity and specificity of the VIKIA Rota-Adeno immuno-chromatographic test (bioMérieux) and the ELISA IDEIA Rotavirus kit (Dako) compared to genotyping]. / Sensibilité et spécificité du test immuno-chromatographique VIKIA Rota-Adéno (bioMérieux) et du kit Elisa IDEIA Rotavirus (Dako) par rapport aux techniques de génotypage.

The performances of two diagnostic tests for rotavirus infection in stool samples were evaluated during a prospective study in children of less than 36 months in child-care centers of Lyon from November 2004 to May 2005. The VIKIA Rota-Adeno immuno-chromatographic test (bioMérieux) and the ELISA IDEIA Rotavirus kit (Dako) were compared with a referral method, the genotyping. Fifty-seven stool samples were collected and analyzed by RT-PCR. The virus genome was detected in 29 samples. The most frequent genotypic combinations were G9P[8] with a prevalence of 75.9%. Sensitivity and specificity of the VIKIA Rota-Adeno test and the ELISA IDEIA Rotavirus kit were strictly comparable and very good: 96.6% (83.0; 99.9) and 96.4% (81.6; 99.9), respectively. The immuno-chromatographic technique were in concordance with the ELISA tests in 93.6% of cases. Thus, the VIKIA Rota-Adeno test is a good alternative for the occasional analysis of stool samples in ambulatory practice.

Unexpected substitution of dominant rotavirus G genotypes in French hospitalized children over five consecutive seasons.

The study was designed to evaluate the circulation of group A rotaviruses in French hospitalized children, and to detect unusual strains. This prospective study was conducted from 2001 to 2006 in children consulting for acute diarrhea at the pediatric emergency department in three French University Hospitals. The rotaviruses were detected by rapid test and genotyped by RT-PCR on the basis of their outer capsid proteins VP4 (P-type) and VP7 (G-type). The stools from 757 children were analyzed. G1P[8] strains were predominant (44.0%), followed by G9P[8] (17.7%), G3P[8] 13.1%, G4P[8] (9.5%), and G2P[4] (1.8%); mixed rotavirus infections occurred in 2.3%. G9 rotaviruses emerged during the 2004-2005 season (73.4%) and remained the second most prevalent strains. Few unusual strains, G6, G8, G12 and P[6]-types, were detected. The monitoring of rotavirus infections should be maintained to document strain distribution and to assess the emergence of new reassortants that may not respond to current rotavirus vaccines.