Michel Pépin

Detection and genetic characterization of Seoul virus from commensal brown rats in France.

BackgroundHantaviruses are single-stranded RNA viruses, which are transmitted to humans primarily via inhalation of aerosolised virus in contaminated rodent urine and faeces. Whilst infected reservoir hosts are asymptomatic, human infections can lead to two clinical manifestations, haemorrhagic fever with renal syndrome (HFRS) and hantavirus cardiopulmonary syndrome (HCPS), with varying degrees of clinical severity. The incidence of rodent and human cases of Seoul virus (SEOV) in Europe has been considered to be low, and speculated to be driven by the sporadic introduction of infected brown rats (Rattus norvegicus) via ports.MethodsBetween October 2010 and March 2012, 128 brown rats were caught at sites across the Lyon region in France.ResultsSEOV RNA was detected in the lungs of 14% (95% CI 8.01 – 20.11) of brown rats tested using a nested pan-hantavirus RT-PCR (polymerase gene). Phylogenetic analysis supports the inclusion of the Lyon SEOV within Lineage 7 with SEOV strains originating from SE Asia and the previously reported French & Belgian SEOV strains. Sequence data obtained from the recent human SEOV case (Replonges) was most similar to that obtained from one brown rat trapped in a public park in Lyon city centre. We obtained significantly improved recovery of virus genome sequence directly from SEOV infected lung material using a simple viral enrichment approach and NGS technology.ConclusionsThe detection of SEOV in two wild caught brown rats in the UK and the multiple detection of SEOV infected brown rats in the Lyon region of France, suggests that SEOV is circulating in European brown rats. Under-reporting and difficulties in identifying the hantaviruses associated with HFRS may mask the public health impact of SEOV in Europe.

Detection of rat hepatitis E virus in wild Norway rats (Rattus norvegicus) and Black rats (Rattus rattus) from 11 European countries

Rat hepatitis E virus (HEV) is genetically only distantly related to hepeviruses found in other mammalian reservoirs and in humans. It was initially detected in Norway rats (Rattus norvegicus) from Germany, and subsequently in rats from Vietnam, the USA, Indonesia, China, Denmark and France. Here, we report on a molecular survey of Norway rats and Black rats (Rattus rattus) from 12 European countries for ratHEV and human pathogenic hepeviruses. RatHEV-specific real-time and conventional RT-PCR investigations revealed the presence of ratHEV in 63 of 508 (12.4%) rats at the majority of sites in 11 of 12 countries. In contrast, a real-time RT-PCR specific for human pathogenic HEV genotypes 1-4 and a nested broad-spectrum (NBS) RT-PCR with subsequent sequence determination did not detect any infections with these genotypes. Only in a single Norway rat from Belgium a rabbit HEV-like genotype 3 sequence was detected. Phylogenetic analysis indicated a clustering of all other novel Norway and Black rat-derived sequences with ratHEV sequences from Europe, the USA and a Black rat-derived sequence from Indonesia within the proposed ratHEV genotype 1. No difference in infection status was detected related to age, sex, rat species or density of human settlements and zoological gardens. In conclusion, our investigation shows a broad geographical distribution of ratHEV in Norway and Black rats from Europe and its presence in all settlement types investigated.

The Nonstructural Protein NSs Induces a Variable Antibody Response in Domestic Ruminants Naturally Infected with Rift Valley Fever Virus

ABSTRACT Rift Valley fever (RVF) is an emerging zoonosis in Africa which has spread to Egypt, the Arabian Peninsula, Madagascar, and Comoros. RVF virus (RVFV) (Bunyaviridae family, Phlebovirus genus) causes a wide range of symptoms in humans, from benign fever to fatal hemorrhagic fever. Ruminants are severely affected by the disease, which leads to a high rate of mortality in young animals and to abortions and teratogenesis in pregnant females. Diagnostic tests include virus isolation and genome or antibody detection. During RVFV infection, the nucleoprotein encapsidating the tripartite RNA genome is expressed in large amounts and raises a robust antibody response, while the envelope glycoproteins elicit neutralizing antibodies which play a major role in protection. Much less is known about the antigenicity/immunogenicity of the nonstructural protein NSs, which is a major virulence factor. Here we have developed a competitive enzyme-linked immunosorbent assay (ELISA) enabling detection of low levels of NSs-specific antibodies in naturally infected or vaccinated ruminants. Detection of the NSs antibodies was validated by Western blotting. Altogether, our data showed that the NSs antibodies were detected in only 55% of animals naturally infected by RVFV, indicating that NSs does not induce a consistently high immune response. These results are discussed in light of differentiation between infected and vaccinated animals (DIVA) tests distinguishing naturally infected animals and those vaccinated with NSs-defective vaccines.

Characterization of 26 isolates of Staphylococcus aureus, predominantly from dairy sheep, using four different techniques of molecular epidemiology.

Little information is available regarding the molecular epidemiology of Staphylococcus aureus–induced mastitis in dairy sheep. In this study, 4 different typing techniques were compared in typing 26 S. aureus isolates, predominantly from cases of subclinical mastitis in dairy ewes. The 4 techniques were pulsed-field gel electrophoresis (PFGE), restriction fragment length polymorphism (RFLP) on 2 genes (coagulase and clumping factor B), randomly amplified polymorphic DNA–polymerase chain reaction (PCR) (RAPD-PCR), and multilocus sequence typing (MLST). On the basis of discriminatory power as the key parameter of typing systems, MLST and PFGE were found to be the most powerful techniques. The MLST and PFGE could contribute to epidemiological surveillance and evaluation of mastitis control programs, by documenting prevalence and dissemination of endemic clones in infected populations. The results of this study show that a single clone of S. aureus is widely distributed in infected ewe mammary glands.

Experimental conjunctival-route infection with Mycoplasma agalactiae in lambs

Abstract Contagious agalactia caused by Mycoplasma agalactiae is a major cause of mastitis in ewes and goats. To explore the first stages of infection, an experimental infection in lambs has been developed, using the strain P89 of M. agalactiae . Lambs were inoculated by the conjunctival route with various doses of viable bacteria. Following necropsy at regular intervals, enumeration of viable bacteria was performed on various organs including the lymph nodes (LNs) draining the conjunctiva. A rapid colonization of LNs from Day 7 (Group 10 9 colony-forming units [CFU]) or from Day 14 (Group 10 7 CFU) post-inoculation (p.i.) was observed and was associated with a transient infection of the spleen suggesting a bacteriemic phase. In a second experiment, lambs were inoculated with the 10 7 dose which had induced a regular infection on Day 14 p.i. in the first experiment. The lambs were necropsied on Days 14 or 56 p.i. The bacteriological examinations of the group necropsied on Day 14 p.i. confirmed the previous results. On Day 56 p.i., the infection decreased but all head LNs remained infected and M. agalactiae was still present at the inoculation site in one lamb, suggesting that M. agalactiae can persist for a long time in its host. This experimental model, using lambs inoculated by the conjunctival route and slaughtered 14 days after inoculation, was simple and easily reproducible, in comparison with a model using lactating ewes. This model can be used to compare virulence of field strains and to test protection following immunization of lambs with attenuated strains of M. agalactiae or with antigens.

DE L’IMPORTANCE CROISSANTE DES BUNYAVIRIDAE EN SANTÉ PUBLIQUE ET VÉTÉRINAIRE, ILLUSTRÉE AVEC LES HANTAVIRUS ET LES VIRUS DE SCHMALLENBERG ET DE LA FIÈVRE DE LA VALLÉE DU RIFT

The virus family of Bunyaviridae is very important in terms of public health and veterinary medicine. With over 350 viruses identified to date, it includes viruses mainly transmitted by arthropods (arboviruses) or rodents (roboviruses), infecting mammals and plants for the genus Tospovirus. Humans can be infected by around 60 bunyaviruses sometime with very serious or even fatal consequences. The examples of Schmallenberg and Rift Valley fever viruses and hantavirus genus illustrate perfectly the many questions surrounding the Bunyaviridae family’s capacity to emerge, widely variable pathogenicity for different hosts, and capacity to persist in different vectors such as arthropods or rodents and more recently the soricomorph species (insectivores)