Assessment of within and between-pen transmission of porcine epidemic diarrhea virus InDel strain

International audienc

Porcine Epidemic Diarrhea Virus, Surrogate for Coronavirus Decay Measurement in French Coastal Waters and Contribution to Coronavirus Risk Evaluation

ABSTRACT Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in infected patients mainly displays pulmonary and oronasal tropism; however, the presence of the virus has also been demonstrated in the stools of patients and consequently in wastewater treatment plant effluents, raising the question of the potential risk of environmental contamination (such as seawater contamination) through inadequately treated wastewater spillover into surface or coastal waters even if the environmental detection of viral RNA alone does not substantiate risk of infection. Therefore, here, we decided to experimentally evaluate the persistence of the porcine epidemic diarrhea virus (PEDv), considered as a coronavirus representative model, in the coastal environment of France. Coastal seawater was collected, sterile-filtered, and inoculated with PEDv before incubation for 0 to 4 weeks at four temperatures representative of those measured along the French coasts throughout the year (4, 8, 15, and 24°C). The decay rate of PEDv was determined using mathematical modeling and was used to determine the half-life of the virus along the French coast in accordance with temperatures from 2000 to 2021. We experimentally observed an inverse correlation between seawater temperature and the persistence of infectious viruses in seawater and confirm that the risk of transmission of infectious viruses from contaminated stool in wastewater to seawater during recreational practices is very limited. The present work represents a good model to assess the persistence of coronaviruses in coastal environments and contributes to risk evaluation, not only for SARS-CoV-2 persistence, but also for other coronaviruses, specifically enteric coronaviruses from livestock. IMPORTANCE The present work addresses the question of the persistence of coronavirus in marine environments because SARS-CoV-2 is regularly detected in wastewater treatment plants, and the coastal environment, subjected to increasing anthropogenic pressure and the final receiver of surface waters and sometimes insufficiently depurated wastewater, is particularly at risk. The problem also arises in the possibility of soil contamination by CoV from animals, especially livestock, during manure application, where, by soil impregnation and runoff, these viruses can end up in seawater. Our findings are of interest to researchers and authorities seeking to monitor coronaviruses in the environment, either in tourist areas or in regions of the world where centralized systems for wastewater treatment are not implemented, and more broadly, to the scientific community involved in “One Health” approaches

Utilisation des organoïdes intestinaux porcins pour l’étude du virus de la gastro-entérite transmissible

Remerciements : Institut CARNOT AgriFoodTransitionNational audienceTo date, host-virus interactions have been studied mainly in cell cultures and/or animal models. These approaches come up against two problems: i) methodological, usually related to using immortalized cell lines, which can differ greatly from the target cells of the virus, and ii) ethical, related to experimenting with animals, which can induce varying degrees of symptoms and cause suffering and death. The recent development of organoids has made it possible to develop ex vivo models whose experimental conditions are significantly closer to physiological conditions. Using organoids makes it possible to plan to decrease animal experimentation greatly, in line with the 3Rs principle (Reduction, Refinement, Replacement), and each animal can potentially produce thousands of organoids from different tissues. The Viral Genetics and Biosafety Unit applies the porcine organoid system developed locally as part of the PigOrg project (of INRAE, ANSES and INSERM, funded by the Carnot Agrifood Transition Institute) to models of enteric coronavirosis in piglets, which has a strong impact on the pig industry. Here, we used the porcine transmissible gastroenteritis virus (TGEv) as a model, for which several strains of varying virulence exist and which can be cultivated on immortalized cells, to establish protocols of infections of different organoids(jejunum, duodenum, and ileum). Infections seem more effective for the jejunum than for the duodenum or ileum, and for viruses isolated on cells than on organ homogenate. This organoid system, which connects in vitro and in vivo conditions, will open novel and original perspectives into understanding the physiopathology of virus infections, especially deciphering host-pathogen interactions, without always needing to rely on extensive animal experiments

Lessons learnt from a porcine epidemic diarrhea (PED) case in France in 2014: Descriptive epidemiology and control measures implemented

International audienceAn acute epidemic of porcine epidemic diarrhea (PED) has affected the USA since 2013 and spread all around the world. In France, the immune status of the pig population against PED virus (PEDV) was expected to be low due to the absence of circulation of the virus since the 80's and a compulsory notification of PED was set up in 2014. Here, we reported the first case of a PED outbreak in December 2014 in the North of France after a long absence of the disease, the monitoring of the excretion and the control measure implementation. The isolated strain in France in December 2014 was a PEDV "S-InDel" strain which was close to the "S-InDel" German PEDV strain isolated in May 2014. The individual shedding duration of PEDV in feces was estimated around 20 days for pigs of different ages. Biosecurity measures implemented allowed the limitation of PEDV spread to fattening and farrowing rooms without dissemination to the nursery block. Using strict biosecurity measures, direct shipment of infected fatteners to the slaughterhouse, strict decontamination protocols with a quarantine of 6 weeks for replacement gilts without voluntary contamination helped PEDV fade out within the herd and avoided the spread to other herds. PEDV presence in manure was investigated as well as the inactivation treatment of the virus present in the liquid manure. An increase to a pH 12 of liquid manure by liming led to the absence of PEDV detection by RT-PCR after seven days

Comparison of the horizontal transmission of a French InDel strain and a US non InDel strain of porcine epidemic diarrhea virus

National audienc

Promising new vaccine candidates against Campylobacter in broilers.

Campylobacter is the leading cause of human bacterial gastroenteritis in the European Union. Birds represent the main reservoir of the bacteria, and human campylobacteriosis mainly occurs after consuming and/or handling poultry meat. Reducing avian intestinal Campylobacter loads should impact the incidence of human diseases. At the primary production level, several measures have been identified to reach this goal, including vaccination of poultry. Despite many studies, however, no efficient vaccine is currently available. We have recently identified new vaccine candidates using the reverse vaccinology strategy. This study assessed the in vivo immune and protective potential of six newly-identified vaccine antigens. Among the candidates tested on Ross broiler chickens, four (YP_001000437.1, YP_001000562.1, YP_999817.1, and YP_999838.1) significantly reduced cecal Campylobacter loads by between 2 and 4.2 log10 CFU/g, with the concomitant development of a specific humoral immune response. In a second trial, cecal load reductions results were not statistically confirmed despite the induction of a strong immune response. These vaccine candidates need to be further investigated since they present promising features

Better horizontal transmission of a US non-InDel strain compared with a French InDel strain of porcine epidemic diarrhoea virus

International audienceFrom the severe porcine epidemic diarrhoea (PED) epidemics that struck in 2013 in the United States of America and other countries of North and South America, two types of porcine epidemic diarrhoea virus (PEDV) were isolated, namely the InDel and the non-InDel strains. They are differentiated by insertions/deletions in the S1 nucleotide sequence of the S gene, and differences in virulence were observed from the clinical cases. In 2014, a PED outbreak occurred in a pig farm in France, from which an InDel strain was isolated. This study aimed at comparing, under experimental conditions, the pathogenicity and the direct and indirect transmissions between a non-InDel strain isolated from a PED-affected piglet in 2014 in the USA and the French InDel strain. All infected pigs showed clinical signs with the non-InDel strain although only the inoculated and direct contact pigs showed clinical signs in the InDel strain group. Although viral RNA was detected in air samples with both strains, the indirect contact pigs remained free from infection with the InDel strain in contrast to the non-InDel group in which airborne transmission occurred in the indirect contact pigs. All infected pigs shed virus in faeces regardless of PEDV strain with 9 of 30 pigs showing intermittent faecal shedding. The transmission rate by direct contact was found to be 2.17-fold higher than the non-InDel strain compared with the InDel. In conclusion, the InDel strain was less pathogenic than the non-InDel strain in our experimental conditions. The transmission route differed between the two strains. Direct contact was the main transmission route for the InDel strain, although the non-InDel strain was transmitted through direct contact and indirectly through the air

Comparison of pathogenicity and intestinal immunity outcomes in infected pigs with French InDel and US non-InDel strains of porcine epidemic diarrhea virus

National audienc