Inhibition of in vitro reconstitution of rotavirus transcriptionally active particles by anti-VP6 monoclonal antibodies

International audience; Six monoclonal antibodies specific for the major capsid protein of rotavirus, VP6, previously characterized, were tested in a biological assay for their capacity to block the transcriptase activity associated with the single-shelled particles. The results showed that two MAbs (RV-50 and RV-133), specific for distinct antigenic sites, were able to block the transcription when they were incubated with a purified baculovirus-expressed group A VP6, prior to the reconstitution of the single-shelled particles from the cores, suggesting that at least two domains are involved in active single-shelled particle reconstitution. The results obtained previously from immunochemist…

Increase in viral gastroenteritis outbreaks in Europe and epidemic spread of new norovirus variant.

Background Highly publicised outbreaks of norovirus gastroenteritis in hospitals in the UK and Ireland and cruise ships in the USA sparked speculation about whether this reported activity was unusual. Methods We analysed data collected through a collaborative research and surveillance network of viral gastroenteritis in ten European countries (England and Wales were analysed as one region). We compiled data on total number of outbreaks by month, and compared genetic sequences from the isolated viruses. Data were compared with historic data from a systematic retrospective review of surveillance systems and with a central database of viral sequences. Findings Three regions (England and Wales,…

Predominance of G9P[8] Rotavirus Strains throughout France, 2014-2017

International audience; 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 predomi…

Data quality of 5 years of central norovirus outbreak reporting in the European Network for food-borne viruses

ABSTRACT Background The food-borne viruses in Europe (FBVE) network database was established in 1999 to monitor trends in outbreaks of gastroenteritisdue to noroviruses (NoVs), to identify major transmission routes of NoV infections within and between participating countries and to detectdiffuse international food-borne outbreaks.Methods We reviewed the total of 9430 NoVoutbreak reports from 13 countries with date of onset between 1 January 2002 and 1 January2007 for representativeness, completeness and timeliness against these objectives.Results Rates of reporting ranged from a yearly average of 1.8 in 2003 to 11.6 in 2006. Completeness of reporting of an agreed minimumdataset improved ove…

Recombinant virus-like particles of a norovirus (genogroup II strain) administered intranasally and orally with mucosal adjuvants LT and LT(R192G) in BALB/c mice induce specific humoral and cellular Th1/Th2-like immune responses

We investigated the immune response induced by mucosal immunization of BALB/c mice with virus-like particles (VLPs) of a genogroup II norovirus, Dijon171/96 virus, produced in the baculovirus system. VLPs administered alone by the intranasal route induced a high serum antibody response as well as fecal IgA, which were enhanced when the heat-labile Escherichia coli toxin or its non toxic mutant LT(R192G) was coadministered. In these conditions, the oral route was also efficient. Cytokine production by cells from different lymphoid tissues was then assessed after in vitro restimulation. A Th1/Th2-like response was observed in cervical lymph node and Peyer's patch (PP) cell cultures from mice …

Analysis of integrated virological and epidemiological reports of norovirus outbreaks collected within the Foodborne Viruses in Europe network from 1 July 2001 to 30 June 2006.

ABSTRACT The Foodborne Viruses in Europe network has developed integrated epidemiological and virological outbreak reporting with aggregation and sharing of data through a joint database. We analyzed data from reported outbreaks of norovirus (NoV)-caused gastroenteritis from 13 European countries (July 2001 to July 2006) for trends in time and indications of different epidemiology of genotypes and variants. Of the 13 countries participating in this surveillance network, 11 were capable of collecting integrated epidemiological and virological surveillance data and 10 countries reported outbreaks throughout the entire period. Large differences in the numbers and rates of reported outbreaks pe…

Virus diversity in a winter epidemic of acute diarrhea in France.

ABSTRACT In France, an epidemic peak of acute diarrhea is observed each winter. Previous results suggested a viral etiology for these winter epidemics. We investigated the role of enteric viruses in acute diarrhea and their molecular diversity. One hundred sixty-one patients with acute diarrhea and 45 healthy patients (controls) from the general population were given a standardized questionnaire between December 1998 and May 1999. Stool specimens were screened for group A and C rotaviruses, human caliciviruses, astroviruses, and adenovirus types 40 and 41 by reverse transcription-PCR and/or enzyme immunoassay. Virologic analysis was positive for 63 cases (39%). Caliciviruses and group A rot…

A Biocatalytic Nanomaterial for the Label-Free Detection of Virus-Like Particles

International audience; The design of nanomaterials that are capable of specific and sensitive biomolecular recognition is an on-going challenge in the chemical and biochemical sciences. A number of sophisticated artificial systems have been designed to specifically recognize a variety of targets. However, methods based on natural biomolecular detection systems using antibodies are often superior. Besides greater affinity and selectivity, antibodies can be easily coupled to enzymatic systems that act as signal amplifiers, thus permitting impressively low detection limits. The possibility to translate this concept to artificial recognition systems remains limited due to design incompatibilit…

Cosavirus, Salivirus and Bufavirus in Diarrheal Tunisian Infants

International audience; Three newly discovered viruses have been recently described in diarrheal patients: Cosa-virus (CosV) and Salivirus (SalV), two picornaviruses, and Bufavirus (BuV), a parvovirus. The detection rate and the role of these viruses remain to be established in acute gastroen-teritis (AGE) in diarrheal Tunisian infants. From October 2010 through March 2012, stool samples were collected from 203 children <5 years-old suffering from AGE and attending the Children's Hospital in Monastir, Tunisia. All samples were screened for CosV, SalV and BuV as well as for norovirus (NoV) and group A rotavirus (RVA) by molecular biology. Positive samples for the three screened viruses were …

Diversity and zoonotic potential of rotaviruses in swine and cattle across Europe.

Group A rotaviruses can infect both humans and animals. Individual rotavirus strains can occasionally cross species barriers and might hereby contribute to the emergence of new genotypes in heterologous hosts. The incidence and impact of zoonotic rotavirus are not well defined, and one reason for this is a lack of data about strains circulating in suspected reservoir animal hosts. In this study we report the incidence, genetic diversity, and molecular epidemiology of rotaviruses detected in domestic cattle and swine in 6 European countries. From 2003 to 2007, 1101 and more than 2000 faecal specimens were collected from swine and cattle, both healthy and diarrhoeic, and tested for rotaviruse…

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

International audience; 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 …

Oral delivery of homologous and heterologous strains of rotavirus to BALB/c mice induces the same profile of cytokine production by spleen cells.

Abstract In this work, we wanted to clarify if differences in antibody (Ab) and particularly in secretory immunoglobulin A (IgA) responses following homologous or heterologous rotavirus infection could be explained by different priming of specific T helper (Th) cells. We compared the Ab responses from suckling BALB/c mice orally inoculated with either a heterologous simian (SA11) or bovine (RF) rotavirus or a homologous murine rotavirus (EHP w ), as well as the profile of cytokines produced by spleen cells after in vitro restimulation. Oral inoculation of EHP w and SA11 induced a similar pattern of Ab with mucosal and serum IgA associated with serum IgG with equal levels of IgG1 and IgG2a, …

Antibody inhibition of the transcriptase activity of the rotavirus DLP: a structural view.

On entering the host cell the rotavirus virion loses its outer shell to become a double-layered particle (DLP). The DLP then transcribes the 11 segments of its dsRNA genome using its own transcriptase complex, and the mature mRNA emerges along the 5-fold axis. In order to better understand the transcription mechanism and the role of VP6 in transcription we have studied three monoclonal antibodies against VP6: RV-238 which inhibits the transcriptase activity of the DLP; and RV-133 and RV-138 which have no effect on transcription. The structures obtained by cryo-electron microscopy of the DLP/Fab complexes and by X-ray crystallography of the VP6 trimer and the VP6/Fab-238 complex have been co…

Cover Picture: A Biocatalytic Nanomaterial for the Label-Free Detection of Virus-Like Particles (ChemBioChem 11/2017)

Norovirus disease today.

Rotavirus 2/6 virus-like particles administered intranasally in mice, with or without the mucosal adjuvants cholera toxin and Escherichia coli heat-labile toxin, induce a Th1/Th2-like immune response

ABSTRACTWe investigated the rotavirus-specific lymphocyte responses induced by intranasal immunization of adult BALB/c mice with rotavirus 2/6 virus-like particles (2/6-VLPs) of the bovine RF strain, by assessing the profile of cytokines produced after in vitro restimulation and serum and fecal antibody responses. The cytokines produced by splenic cells were first evaluated. Intranasal immunization with 50 μg of 2/6-VLPs induced a high serum antibody response, including immunoglobulin G1 (IgG1) and IgG2a, a weak fecal antibody response, and a mixed Th1/Th2-like profile of cytokines characterized by gamma interferon and interleukin 10 (IL-10) production and very low levels of IL-2, IL-4, and…

Intrarectal immunization with rotavirus 2/6 virus-like particles induces an antirotavirus immune response localized in the intestinal mucosa and protects against rotavirus infection in mice.

ABSTRACTRotavirus (RV) is the main etiological agent of severe gastroenteritis in infants, and vaccination seems the most effective way to control the disease. Recombinant rotavirus-like particles composed of the viral protein 6 (VP6) and VP2 (2/6-VLPs) have been reported to induce protective immunity in mice when administered by the intranasal (i.n.) route. In this study, we show that administration of 2/6-VLPs by the intrarectal (i.r.) route together with either cholera toxin (CT) or a CpG-containing oligodeoxynucleotide as the adjuvant protects adult mice against RV infection. Moreover, when CT is used, RV shedding in animals immunized by the i.r. route is even reduced in comparison with…

[Norovirus infections: an overview]

National audience; Noroviruses belong to the Caliciviridae family. They are a major cause of sporadic cases and outbreaks of gastroenteritis in all age groups, and are responsible for a considerable disease burden in industrialized countries. Noroviruses are single-stranded RNA viruses, and show great genetic diversity making their detection difficult. Noroviruses can be divided into 5 genogroups, which themselves are subdivided into genotypes. Besides chance mutations that occur during viral replication, the great heterogeneity observed among noroviruses is also due to intra and inter-genotypic recombination events between strains. Some of these new variants or new recombinants are frequen…

Crystallization and Preliminary X-Ray Analysis of Rotavirus Protein VP6

ABSTRACT As a first step to gain insight into the structure of the rotavirus virion at atomic resolution, we report here the expression, purification, and crystallization of recombinant rotavirus protein VP6. This protein has the property of polymerizing in the form of tubular structures in solution which have hindered crystallization thus far. Using a combination of electron microscopy and small-angle X-ray scattering, we found that addition of Ca 2+ at concentrations higher than 100 mM results in depolymerization of the tubes, leading to an essentially monodisperse solution of trimeric VP6 even at high protein concentrations (higher than 10 mg/ml), thereby enabling us to search for crysta…

Rapid and sensitive detection of metapneumovirus in clinical specimens by indirect fluorescence assay using a monoclonal antibody.

Human metapneumovirus, with two known genotypes named A and B, is associated with mild respiratory symptoms to severe LRTI in children, high-risk adults and the elderly. Rapid and reliable methods of hMPV detection in clinical samples are essential to implement appropriate care, to better understand the pathology of hMPV and to determine its epidemiology. Respiratory samples from 1,386 patients collected during 2 consecutive years were screened for hMPV using indirect immunofluorescence (IFA) assay with a monoclonal antibody. Forty-three patients tested positive for hMPV by the IFA method. In parallel, the samples were examined with RT-PCR on the F gene. Of these, 41 specimens were RT-PCR p…

Prevalence and genetic diversity of Aichi virus strains in stool samples from community and hospitalized patients.

ABSTRACT Aichi virus has been proposed as a causative agent of gastroenteritis. A total of 457 stool specimens from children hospitalized with acute diarrhea and 566 stool specimens from adults and children involved in 110 gastroenteritis outbreaks were screened for the presence of Aichi virus by reverse transcription-PCR (RT-PCR) amplification of the genomic region of the 3C and 3D (3CD) nonstructural proteins. Our results show a low incidence of Aichi virus in pediatric samples and the existence of mixed infections with other microbiological agents in some cases. From the outbreak survey, it appears that the presence of Aichi virus is an indicator of mixed infections causing gastroenterit…

Atomic structure of the major capsid protein of rotavirus: implications for the architecture of the virion

The structural protein VP6 of rotavirus, an important pathogen responsible for severe gastroenteritis in children, forms the middle layer in the triple-layered viral capsid. Here we present the crystal structure of VP6 determined to 2 A resolution and describe its interactions with other capsid proteins by fitting the atomic model into electron cryomicroscopic reconstructions of viral particles. VP6, which forms a tight trimer, has two distinct domains: a distal beta-barrel domain and a proximal alpha-helical domain, which interact with the outer and inner layer of the virion, respectively. The overall fold is similar to that of protein VP7 from bluetongue virus, with the subunits wrapping …

Molecular Cloning, Expression, Self-Assembly, Antigenicity, and Seroepidemiology of a Genogroup II Norovirus Isolated in France

ABSTRACT Virus-like particles of Dijon171/96 virus, a genogroup II norovirus, were expressed in a baculovirus system and were used for a seroepidemiological study of 1,078 age-stratified human sera collected in Dijon, France. The results showed a seroprevalence of 74.1%. Furthermore, we showed that murine antibodies generated against recombinant Dijon171/96 virus, and human antibodies recognized discontinuous epitopes on the particles.

Absolute Humidity Influences the Seasonal Persistence and Infectivity of Human Norovirus

ABSTRACT Norovirus (NoV) is one of the main causative agents of acute gastroenteritis worldwide. In temperate climates, outbreaks peak during the winter season. The mechanism by which climatic factors influence the occurrence of NoV outbreaks is unknown. We hypothesized that humidity is linked to NoV seasonality. Human NoV is not cultivatable, so we used cultivatable murine norovirus (MNV) as a surrogate to study its persistence when exposed to various levels of relative humidity (RH) from low (10% RH) to saturated (100% RH) conditions at 9 and 25°C. In addition, we conducted similar experiments with virus-like particles (VLPs) from the predominant GII-4 norovirus and studied changes in bin…

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

SUMMARYEuroRotaNet, 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…

In vitro reconstitution of rotavirus transcriptional activity using viral cores and recombinant baculovirus expressed VP 6

International audience; Purified baculovirus-expressed group A rotavirus VP6 polypeptide was shown to be active in the recovery of the transcriptase activity associated with the reconstitution of the single-shelled rotavirus particle. Recombinant VP6 polypeptide was able to restore the transcriptional activity in purified viral cores from both SA-11 and RF rotavirus strains. Recombinant group C VP 6 (Cowden strain) is capable of binding as a trimer to group A viral core particles but unable to restore the transcriptase activity, suggesting that the binding of the polypeptide to cores is not the only requirement to restore the transcriptase activity. The VP 6 group A polypeptide was shown to…

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

International audience; 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 …

Detection and characterization of Human caliciviruses associated with sporadic acute diarrhea in adults in Djibouti (horn of Africa).

International audience; Recent advances in molecular diagnostics have allowed us to recognize Human caliciviruses (HuCVs) as important agents of acute diarrhea in industrialized countries. Their prevalence and genetic diversity in developing countries remains unknown. We report on the characterization of HuCVs among adults presenting acute diarrheas in Djibouti; 108 stool samples collected were screened by EIA, RTPCR, or cell cultures for the group A Rotaviruses, Adenoviruses, Astroviruses, and HuCVs, which were further characterized by genotyping. Among stool samples screened for HuCVs, 25.3% were positive. The other enteric viruses were less prevalent. The 11 HuCV strains sequenced reveal…