Evidence of porcine epidemic diarrhea virus (PEDV) shedding in semen from infected specific pathogen-free boars

Immunological defense mechanisms of ejaculates and the spread of viral infectious diseases through pig semen

This review focuses on the mechanisms of immune tolerance and antimicrobial defense in the male genital tract of the pig. Sperm cells are foreign to the immune system and, therefore, they must be protected from the immune system. The blood-testis-barrier is mediated by a physical barrier between adjacent Sertoli cells, several cell types within the testis, and interactions between immunomodulatory molecules. The blood-epididymal-barrier is composed of a physical barrier that is lined with principal cells having a network of junctional complexes in their apical lateral membrane and completed by specific transporters. The seminal plasma (SP) contains many signaling agents involved in establishing a state of immune tolerance in the female genital tract, which is essential for successful fertilization. Specific SP-proteins, however, also have pro-inflammatory capacities contributing to transient uterine inflammation, supporting the removal of foreign cells, possible pathogens, and excessive spermatozoa. While many different proteins and other substances present in semen can damage sperm cells, they may also protect them against viral infections. A delicate balance of these substances, therefore, needs to be maintained. Related to this, recent studies have shown the importance of extracellular vesicles (EVs), as they contain these substances and convey immune signals. Yet, viruses may use EVs to interact with the male genital tract and circumvent immune responses. For this reason, further research needs to explore the role of EVs in the male reproductive tract, as it might contribute to elucidating the pathogenesis of viral infections that might be transmitted via semen and to developing better vaccines.

Comparative Review of the State of the Art in Research on the Porcine Epidemic Diarrhea Virus and SARS-CoV-2, Scope of Knowledge between Coronaviruses

This review presents comparative information corresponding to the progress in knowledge of some aspects of infection by the porcine epidemic diarrhea virus (PEDV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) coronaviruses. PEDV is an alphacoronavirus of great economic importance due to the million-dollar losses it generates in the pig industry. PEDV has many similarities to the SARS-CoV-2 betacoronavirus that causes COVID-19 disease. This review presents possible scenarios for SARS-CoV-2 based on the collected literature on PEDV and the tools or strategies currently developed for SARS-CoV-2 that would be useful in PEDV research. The speed of the study of SARS-CoV-2 and the generation of strategies to control the pandemic was possible due to the knowledge derived from infections caused by other human coronaviruses such as severe acute respiratory syndrome (SARS) and middle east respiratory syndrome (MERS). Therefore, from the information obtained from several coronaviruses, the current and future behavior of SARS-CoV-2 could be inferred and, with the large amount of information on the virus that causes COVID-19, the study of PEDV could be improved and probably that of new emerging and re-emerging coronaviruses.

Porcine Epidemic Diarrhea Virus: Etiology, Epidemiology, Antigenicity, and Control Strategies in China

Porcine epidemic diarrhea virus (PEDV) is a porcine enteric coronavirus, which is one of the main causative agents of porcine epidemic diarrhea (PED), with 100% morbidity and 80-100% mortality in neonatal piglets. Since 2010, large-scale PED caused by highly pathogenic variants of PEDV has occurred successively in China and other countries in the world, posing a great threat to the global pig industry. It has been demonstrated in many investigations that the classic attenuated vaccine strain, PEDV CV777, is insufficient to fully protect against the PEDV variants. Moreover, the maternally derived antibodies elicited by inactivated vaccines also cannot completely protect piglets from infection. In addition, feedback feeding poses a risk of periodic PEDV recurrence in pig farms, making it challenging to successfully limit the spread of PEDV in China. This review focuses on the etiology, epidemiology, antigenicity, and control strategies of PEDV in China and provides information for the formulation of effective control measures.

Porcine epidemic diarrhea virus: an update overview of virus epidemiology, vaccines, and control strategies in South Korea

Porcine epidemic diarrhea virus (PEDV) has posed significant financial threats to the domestic pig industry over the last three decades in South Korea. PEDV infection will mostly result in endemic persistence in the affected farrow-to-finish (FTF) herds, leading to endemic porcine epidemic diarrhea (PED) followed by year-round recurrent outbreaks. This review aims to encourage collaboration among swine producers, veterinarians, and researchers to offer answers that strengthen our understanding of PEDV in efforts to prevent and control endemic PED and to prepare for the next epidemics or pandemics. We found that collaboratively implementing a PED risk assessment and customized four-pillar-based control measures is vital to interrupt the chain of endemic PED in affected herds: the former can identify on-farm risk factors while the latter aims to compensate for or improve weaknesses via herd immunity stabilization and virus elimination. Under endemic PED, long-term virus survival in slurry and asymptomatically infected gilts ("Trojan Pigs") that can transmit the virus to farrowing houses are key challenges for PEDV eradication in FTF farms and highlight the necessity for active monitoring and surveillance of the virus in herds and their environments. This paper underlines the current knowledge of molecular epidemiology and commercially available vaccines, as well as the risk assessment and customized strategies to control PEDV. The intervention measures for stabilizing herd immunity and eliminating virus circulation may be the cornerstone of establishing regional or national PED eradication programs.

Insights and progress on epidemic characteristics, genotyping, and preventive measures of PEDV in China: A review

Porcine Epidemic Diarrhoea (PED) is an acute, extremely infectious intestinal disease of pigs caused by the Porcine Epidemic Diarrhoea Virus (PEDV). The virus can affect pigs of all breeds and age groups and shows varying degrees of symptoms, with piglets, in particular, being infected with mortality rates of up to 100%. PEDV was first identified in China in the 1980s and in October 2010 a large-scale PED outbreak caused by a variant of PEDV occurred in China, resulting in huge economic losses. Initially, vaccination can effectively prevent the classical strain, but since December 2010, the PEDV variant has caused "persistent diarrhoea" with severe vomiting, watery diarrhoea, and high morbidity and mortality in newborn piglets as the dominant clinical features, with a significant increase in morbidity and mortality. This indicates that PEDV strains have mutated during evolution and that traditional vaccines no longer provide effective cross-immune protection, so it is necessary to optimize immunization programs and find effective treatments through epidemiological surveys of PEDV to reduce the economic losses caused by infections with mutated strains. This article reviews the progress of research on the aetiology, epidemiological characteristics, genotyping, pathogenesis, transmission routes, and comprehensive control of PEDV infection in China.

Porcine Epidemic Diarrhea Virus Replication in Human Intestinal Cells Reveals Potential Susceptibility to Cross-Species Infection

Various coronaviruses have emerged as a result of cross-species transmission among humans and domestic animals. Porcine epidemic diarrhea virus (PEDV; family Coronaviridae, genus Alphacoronavirus) causes acute diarrhea, vomiting, dehydration, and high mortality in neonatal piglets. Porcine small intestinal epithelial cells (IPEC-J2 cells) can be used as target cells for PEDV infection. However, the origin of PEDV in pigs, the host range, and cross-species infection of PEDV remain unclear. To determine whether PEDV has the ability to infect human cells in vitro, human small intestinal epithelial cells (FHs 74 Int cells) were inoculated with PEDV LJX and PEDV CV777 strains. The results indicated that PEDV LJX, but not PEDV CV777, could infect FHs 74 Int cells. Furthermore, we observed M gene mRNA transcripts and N protein expression in infected FHs 74 Int cells. A one-step growth curve showed that the highest viral titer of PEDV occurred at 12 h post infection. Viral particles in vacuoles were observed in FHs 74 Int cells at 24 h post infection. The results proved that human small intestinal epithelial cells are susceptible to PEDV infection, suggesting the possibility of cross-species transmission of PEDV.

Porcine Epidemic Diarrhea Virus: An Updated Overview of Virus Epidemiology, Virulence Variation Patterns and Virus-Host Interactions

The porcine epidemic diarrhea virus (PEDV) is a member of the coronavirus family, causing deadly watery diarrhea in newborn piglets. The global pandemic of PEDV, with significant morbidity and mortality, poses a huge threat to the swine industry. The currently developed vaccines and drugs are only effective against the classic GI strains that were prevalent before 2010, while there is no effective control against the GII variant strains that are currently a global pandemic. In this review, we summarize the latest progress in the biology of PEDV, including its transmission and origin, structure and function, evolution, and virus-host interaction, in an attempt to find the potential virulence factors influencing PEDV pathogenesis. We conclude with the mechanism by which PEDV components antagonize the immune responses of the virus, and the role of host factors in virus infection. Essentially, this review serves as a valuable reference for the development of attenuated virus vaccines and the potential of host factors as antiviral targets for the prevention and control of PEDV infection.

Molecular characterization of porcine epidemic diarrhoea virus (PEDV) in Poland reveals the presence of swine enteric coronavirus (SeCoV) sequence in S gene

Porcine epidemic diarrhoea (PED) is a highly contagious enteric viral disease of pigs with a high morbidity and mortality rate, which ultimately results in huge economic losses in the pig production sector. The etiological agent of this disease is the porcine epidemic diarrhoea virus (PEDV) which is an enveloped, positive single-stranded RNA virus. The aim of this study was to perform molecular characterization of PEDV to identify the strains circulating in Poland. In this study, 662 faecal samples from 2015 to 2021 were tested with reverse transcription quantitative real-time PCR (RT-qPCR) and the results showed that 3.8% of the tested samples revealed a positive result for PEDV. A phylogenetic analysis of the complete genome and complete S gene sequences showed that Polish PEDV strains belonged to the G1b (S-INDEL) subgroup and were closely related to the European PEDV strains isolated from 2014 to 2019. Furthermore, RDP4 analysis revealed that the Polish PEDV strains harboured a recombinant fragment of ~400 nt in the 5' end of S gene with PEDV and swine enteric coronavirus (SeCoV) being the major and minor parents, respectively. Antigenic analysis showed that the aa sequences of neutralizing epitopes were conserved among the Polish PEDV strains. Only one strain, #0100/5P, had a unique substitution in the COE epitope. However, Polish PEDV strains showed several substitutions, especially in the COE antigen, as compared to the classical strain CV777. To the best of our knowledge, this is the first report concerning the molecular characterization of porcine epidemic diarrhoea virus strains, as well as the first phylogenetic analysis for PEDV in Poland.

Impact of N-Acetylcysteine on the Gut Microbiota in the Piglets Infected With Porcine Epidemic Diarrhea Virus

This study was to investigate the impact of N-acetylcysteine (NAC) on the gut microbiota in the healthy piglets and the piglets infected with porcine epidemic diarrhea virus (PEDV). Forty seven-day-old piglets were allocated into four groups: control group, NAC group (supplemented with 50 mg/kg body weight NAC), PEDV group (inoculated with 10^4.5 TCID₅₀ PEDV), and PEDV+NAC group (PEDV infection + NAC supplementation). The intestinal content was collected for DNA extraction and Illumina sequencing. The PEDV-infected piglets displayed distinct bacterial communities compared to the healthy piglets. PEDV infection decreased the abundance of Shigella and increased the abundance of Lactobacillus, Odoribacter, Anaerovibrio, Helicobacter, unclassified Lachnospiraceae, and Sutterella; affected several functions associated with metabolism, barrier, and immune. NAC supplementation decreased the abundance of unclassified Rikenellaceae and increased the abundance of Lactobacillus, Streptococcus, and Enterococcus in the healthy piglets, decreased the abundance of Oscillospira and Prevotella and increased the abundance of Lactobacillus in the PEDV-infected piglets; altered multiple functions involving in amino acid metabolism, cell signaling, cellular community, disease-related pathways, endocrine, and excretory system. In conclusion, PEDV infection caused severe dysbiosis of gut microbiome, whereas NAC supplementation played a positive role in regulating the gut microbiome during PEDV infection. Therefore, substances that can regulate gut microbiota could be ideal candidates to prevent or treat PEDV infection.

Viruses in the reproductive tract: On their way to the germ line?

Studies of vertebrate genomes have indicated that all species contain in their chromosomes stretches of DNA with sequence similarity to viral genomes. How such 'endogenous' viral elements (EVEs) ended up in host genomes is usually explained in general terms such as 'they entered the germ line at some point during evolution'. This seems a correct statement, but is also rather imprecise. The vast number of endogenous viral sequences suggest that common routes to the 'germ line' may exist, as relying on chance alone may not easily explain the abundance of EVEs in modern mammalian genomes. An increasing number of virus types have been detected in human semen and a growing number of studies have reported on viral infections that cause male infertility or subfertility and on viral infections that threaten in vitro fertilisation practices. Thus, it is timely to survey the pathway(s) that viruses can use to gain access to the human germ line. Embryo transfer and semen quality studies in livestock form another source of relevant information because virus infection during reproduction is clearly unwanted, as is the case for the human situation. In this review, studies on viruses in the male and female reproductive tract and in the early embryo will be discussed to propose a plausible viral route to the mammalian germ line.

Porcine epidemic diarrhea virus (PEDV): An update on etiology, transmission, pathogenesis, and prevention and control

Porcine epidemic diarrhea virus (PEDV), a member of the genus Alphacoronavirus in the family Coronaviridae, causes acute diarrhea and/or vomiting, dehydration and high mortality in neonatal piglets. Two different genogroups of PEDV, S INDEL [PEDV variant containing multiple deletions and insertions in the S1 subunit of the spike (S) protein, G1b] and non-S INDEL (G2b) strains were detected during the diarrheal disease outbreak in US swine in 2013-2014. Similar viruses are also circulating globally. Continuous improvement and update of biosecurity and vaccine strains and protocols are still needed to control and prevent PEDV infections worldwide. Although the non-S INDEL PEDV was highly virulent and the S INDEL PEDV caused milder disease, the latter has the capacity to cause illness in a high number of piglets on farms with low biosecurity and herd immunity. The main PEDV transmission route is fecal-oral, but airborne transmission via the fecal-nasal route may play a role in pig-to-pig and farm-to-farm spread. PEDV infection of neonatal pigs causes fecal virus shedding (alongside frequent detection of PEDV RNA in the nasal cavity), acute viremia, severe atrophic enteritis (mainly jejunum and ileum), and increased pro-inflammatory and innate immune responses. PEDV-specific IgA effector and memory B cells in orally primed sows play a critical role in sow lactogenic immunity and passive protection of piglets. This review focuses on the etiology, transmission, pathogenesis, and prevention and control of PEDV infection.

Porcine epidemic diarrhea virus: Viral RNA detection and quantification using a validated one-step real time RT-PCR

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Development and complete validation of a one-step RT-qPCR method for the detection and quantification of PEDV.

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Broad range detection of S-INDEL and S-non-INDEL strains.

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Optimization of Primer concentrations reduce primer dimer formation.

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Addition of a proteinase K treatment allow good reproducibility.

Since 2014, porcine epidemic diarrhea virus (PEDV) has reemerged in Europe. RT-PCR methods have been described for the detection of PEDV, but none have been validated according to a norm. In this study we described the development and validation of a SYBR™ Green one-step RT-qPCR according to the French norm NF U47-600, for the detection and quantification of PEDV viral RNA. The method was validated from sample preparation (feces or jejunum) through to nucleic acid extraction and RT-qPCR detection. Specificity and sensitivity, limit of detection (LoD), limit of quantification (LQ), linearity, intra and inter assay variability were evaluated using transcribed RNA and fecal and jejunum matrices spiked with virus. The analytical and diagnostic specificities and sensitivities of this RT-qPCR were 100% in this study. A LoD of 50 genome copies/5 μl of extract from fecal matrices spiked with virus or RNA transcript and 100 genome copies/5 μl of extract from jejunum matrices spiked with virus were obtained. The Lower LQ (LLQ) was 100 genome copies/5 μl and the Upper LQ (ULQ) 10⁸ copies/5 μl. This method is the first, validated according a norm for PEDV and may serve as a global reference method to harmonize detection and quantification of PEDV viral RNA in both field and experimental settings.

From Ancient to Emerging Infections: The Odyssey of Viruses in the Male Genital Tract

The male genital tract (MGT) is the target of a number of viral infections that can have deleterious consequences at the individual, offspring, and population levels. These consequences include infertility, cancers of male organs, transmission to the embryo/fetal development abnormalities, and sexual dissemination of major viral pathogens such as human immunodeficiency virus (HIV) and hepatitis B virus. Lately, two emerging viruses, Zika and Ebola, have additionally revealed that the human MGT can constitute a reservoir for viruses cleared from peripheral circulation by the immune system, leading to their sexual transmission by cured men. This represents a concern for future epidemics and further underlines the need for a better understanding of the interplay between viruses and the MGT. We review here how viruses, from ancient viruses that integrated the germline during evolution through old viruses (e.g., papillomaviruses originating from Neanderthals) and more modern sexually transmitted infections (e.g., simian zoonotic HIV) to emerging viruses (e.g., Ebola and Zika) take advantage of genital tract colonization for horizontal dissemination, viral persistence, vertical transmission, and endogenization. The MGT immune responses to viruses and the impact of these infections are discussed. We summarize the latest data regarding the sources of viruses in semen and the complex role of this body fluid in sexual transmission. Finally, we introduce key animal findings that are relevant for our understanding of viral infection and persistence in the human MGT and suggest future research directions.

Porcine Epidemic Diarrhea Altered Colonic Microbiota Communities in Suckling Piglets

Porcine epidemic diarrhea (PED) is a major gastrointestinal disease afflicting suckling pigs that causes huge industrial economic losses. In this study, we investigated microbiota from the colonic mucosa and content in healthy and PED piglets. High-throughput 16S rRNA gene sequencing was performed to identify inter-group differences. Firmicutes, Fusobacteria, Proteobacteria, and Bacteroidetes were the top four affected phyla. The proportion of Proteobacteria was higher in infected than in healthy piglets, and the opposite was observed for Bacteroidetes (more than four-fold higher in the healthy group). In the infected group, Fusobacterium accounted for 36.56% and 21.61% in the colonic mucosa and contents, respectively, while in the healthy group, they comprised 22.53% and 12.67%, respectively. The percentage of Lactobacillus in healthy colons (15.63%) was considerably higher than that in the disease group (<10%). In both the colonic mucosa and contents, functional enrichment differed significantly between healthy and diseased groups. Overall, infection with the PED virus increased the proportion of harmful bacteria and decreased the proportion of beneficial bacteria in the colons of piglets. Targeting intestinal microbiota could be a promising method for PED prevention, thus opening new avenues for future research.

Upregulation of CD4+CD8+ memory cells in the piglet intestine following oral administration of Bacillus subtilis spores combined with PEDV whole inactivated virus

Oral immunization is a commonly employed route for inducing local immunity. However, the application of oral immunization is limited by the short-term persistence of immunity, particularly for inactivated viruses. The ultimate goal for mucosal vaccination is to stimulate protective immunological memory. In the intestine, long-term persistence of immunity is related to CD4⁺CD8⁺ memory T-cells. In this study, piglets were orally immunized with Bacillus subtilis spores (B.s) plus whole inactivated porcine epidemic diarrhea virus (PEDV WIV), followed by booster oral immunization. Initially, the results showed that B.s plus PEDV WIV enhanced the anti-PEDV capability on mucosal surfaces, as evidenced by plaque reduction neutralization tests in serum and intestinal fluid. Elevated antigen-specific IgG titers in the serum and IgA titers in saliva, feces and nasal washing liquid were also observed. Meanwhile, B.s plus PEDV WIV increased the area of Peyer's patches and the number of intraepithelial lymphocytes in the ileum of piglets. Similarly, the percentage of CD4⁺CD8⁺ memory T-cells were upregulated and proliferation ability of antigen-specific memory T-cell was strengthened in intestinal mucosal-associated lymphocytes, which was accompanied with increased expression of CCR9 after oral immunization with B.s plus PEDV WIV. In addition, the activation of memory T-cells is correlated with the increased mRNA expression of Toll-like receptor 2 and 4, as well as interleukin-6 and induced by B.s. Collectively, the study provided further insight into the potential immunopotentiator ability of B.s to assist PEDV WIV in the potentiation of immunity by upregulating memory CD4⁺CD8⁺ T cells via oral immunization.

Isolation and characterisation of porcine epidemic diarrhoea virus in Hungary - Short communication

Porcine epidemic diarrhoea virus (PEDV) is an emerging enteropathogen, causing great economic losses in the pig industry. After many years of quiescence, PEDV was detected in Hungary in 2016 with a recombination in its S gene. In order to determine the extent of this change, an attempt was made to isolate the recombinant PEDV. This study was extended with a variety of samples collected from three separate farms with newly identified PEDV in 2018. The recombinant PEDV from 2016 was isolated successfully along with three viruses from 2018, and one isolate from the new cases was used for whole genome determination. Whole genome sequence alignment revealed the highest identity with recombinant Hungarian and Slovenian PEDV within the low-pathogenic European viruses. This suggests that these recombinant PEDV are circulating in this area and may spread to other parts of the continent.

Mucosal immune responses induced by oral administration recombinant Bacillus subtilis expressing the COE antigen of PEDV in newborn piglets

Porcine epidemic diarrhea (PED) is a highly contagious disease in newborn piglets and causes substantial economic losses in the world. PED virus (PEDV) spreads by fecal–oral contact and can be prevented by oral immunization. Therefore, it is necessary to develop an effective oral vaccine against PEDV infection. Currently, Bacillus subtilis as recombinant vaccine carrier has been used for antigen delivery and proved well in immune effect and safety. The present study evaluated the immunogenicity of recombinant Bacillus subtilis (B. subtilis-RC) in piglets via oral administration. After oral immunization in piglets, B. subtilis-RC significantly increased the local mucosal immune responses. Oral administration with B. subtilis-RC significantly improved the level of specific mucosal immunoglobulin A (IgA) antibodies against PEDV infection, through enlarging the area of Peyer’s patches (PPs) and increasing the number of ileum IgA⁺ secreting (SIgA) cells. In the meantime, B. subtilis-RC remarkably increased the number of intraepithelial lymphocytes (IELs). We also observed that oral administration of B. subtilis-RC significantly increased CD3⁺T lymphocytes’ numbers and up-regulated the ratio of CD4⁺/CD8⁺ T cells. Furthermore, high titers of specific serum immunoglobulin G (IgG) revealed satisfactory systemic immune response against PEDV infection. In summary, our study demonstrated that oral administration of B. subtilis-RC could trigger a high level of local and systemic immune responses and would be a promising candidate vaccine against PEDV infection in piglets.

Dynamic Change of Gut Microbiota During Porcine Epidemic Diarrhea Virus Infection in Suckling Piglets

Porcine epidemic diarrhea (PED) is a disease that has a devastating effect on livestock. Currently, most studies are focused on comparing gut microbiota of healthy piglets and piglets with PED, resulting in gut microbial populations related to dynamic change in diarrheal piglets being poorly understood. The current study analyzed the characteristics of gut microbiota in porcine epidemic diarrhea virus (PEDV)-infected piglets during the suckling transition stage. Fresh fecal samples were collected from 1 to 3-week-old healthy piglets (n = 20) and PEDV infected piglets (n = 18) from the same swine farm. Total DNA was extracted from each sample and the V3-V4 hypervariable region of the 16S rRNA gene was amplified and sequenced using the Illumina MiSeq platform. Statistically significant differences were observed in bacterial diversity and richness between the healthy and diarrheal piglets. Principal coordinates analysis (PCoA) showed structural segregation between diseased and healthy groups, as well as among 3 different age groups. The abundance of Escherichia-Shigella, Enterococcus, Fusobacterium, and Veillonella increased due to dysbiosis induced by PEDV infection. Notably, there was a remarkable age-related increase in Fusobacterium and Veillonella in diarrheal piglets. Certain SCFA-producing bacteria, such as Ruminococcaceae_UCG-002, Butyricimonas, and Alistipes, were shared by all healthy piglets, but were not identified in various age groups of diarrheal piglets. In addition, significant differences were observed between clusters of orthologous groups (COG) functional categories of healthy and PEDV-infected piglets. Our findings demonstrated that PEDV infection caused severe perturbations in porcine gut microbiota. Therefore, regulating gut microbiota in an age-related manner may be a promising method for the prevention or treatment of PEDV.

No evidence of PEDV infection in French artificial insemination centers in 2015

Pigs infected by porcine epidemic diarrhea virus (PEDV) are affected by severe diarrhea, vomiting and dehydration. The severity of clinical signs depends on the virus strain. Two genetically different PEDV strains are known to infect pigs, the PEDV S-InDel strains which circulate on all continents and the highly virulent PEDV S-non-InDel strains found in Asia and in America. We have previously demonstrated the presence of PEDV RNA in semen from boars experimentally infected with an S-non-InDel PEDV strain. If naturally infected boars may shed PEDV in semen, this would have important consequences for the breeding sector. Thus we sought to determine whether PEDV has been circulating in populations of breeding boars from French artificial insemination (AI) centers. The current study reports on a serological survey conducted on one hundred and twenty boars from six AI centers, representing 18.6% of the total population of breeding boars in French AI centers in 2015. All of them were found negative for PEDV antibodies, showing no evidence of PEDV circulation in French AI centers at that time.

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

From 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.

Network analyses using case-control data to describe and characterize the initial 2014 incursion of porcine epidemic diarrhea (PED) in Canadian swine herds

The overall objective of this study was to describe the contact structure and animal movement patterns of porcine epidemic diarrhea (PED) case herds and matched control herds during the initial incursion of PEDV in Canada, and to evaluate possible mechanisms of spread during this period. Possible mechanisms of spread included transmission through a common-source, herd-to-herd transmission, and transmission due to low biosecurity. Three hypotheses were evaluated by assessing: 1) whether feed supplier, semen supplier and/or animal transportation company networks contained a higher proportion of case herds compared to randomly permuted networks, 2) whether the proportion of case herds in the giant weak component differed from randomly permuted networks, and 3) whether external herd biosecurity, defined as the number of mean contacts with other herds in a one-mode network, was different between case and control herds. The study period for recruiting case and control herds was from January 22, 2014 to March 1, 2014, and a 30-day history of each participating site was collected using a questionnaire. The study included swine herds located in central and eastern Canadian provinces. Multiple two-mode networks with swine herds and service suppliers were constructed. This included feed suppliers, animal movement, animal transportation companies, semen suppliers and a complete network with all service providers. The complete network consisted of 145 nodes. There were a total of 765 edges in the complete network and majority were between feed suppliers and primary herds 29.8% (228/765). The proportion of case herds in the largest feed supplier network was higher than what was expected using randomly permuted networks, suggesting that the likely mechanism of spread during this phase was a common-source through the feed network. A single feed supplier (FS1) had the highest out-degree and outgoing contact chain indicating its importance in disease spread throughout the feed and complete networks. Network descriptive measures, as well as the results of the hypotheses testing indicate little significance in the roles of animal movement, animal transportation companies, and semen suppliers during the initial phase of the 2014 Canadian PED outbreak.

Limited shedding of an S-InDel strain of porcine epidemic diarrhea virus (PEDV) in semen and questions regarding the infectivity of the detected virus

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The aim of this study was to determine if PEDV can be shed in semen from SPF (specific pathogens free) boars infected by a French «S-InDel» PEDV strain (PEDV/FR/001/2014) and in case of positive semen to determine the infectivity of that semen.

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Both infected boars had diarrhea after inoculation and shed virus in feces.

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In addition, PEDV genome was detected by RT-qPCR in the sperm-rich fraction of semen from the two boars infected with the «S-InDel» PEDV strain.

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The PEDV positive semen («S-non-InDel» and «S-InDel») sampled during a previous trial and in this boar trial were inoculated to six SPF weaned pigs. PEDV could be detected in intestinal tissues such as duodenum, jejunum and jejunum Peyer’s patches by RT-qPCR except for one pig.

PEDV is mainly transmitted by the oro-fecal route although PEDV shedding in semen has already been shown for an S-non-InDel PEDV strain infection. The aim of this study was to determine if PEDV can be shed in semen from SPF (specific pathogens free) boars infected by a French S-InDel PEDV strain (PEDV/FR/001/2014) and in case of positive semen to determine the infectivity of that semen. Both infected boars had diarrhea after inoculation and shed virus in feces. PEDV genome was also detected by RT-qPCR in the sperm-rich fraction of semen (6.94 × 10³ and 4.73 × 10³ genomic copies/mL) from the two boars infected with the S-InDel PEDV strain but only once at 7DPI. In addition, PEDV RNA in Peyer’s patches and in mesenteric lymph nodes was also present for the two inoculated boars. The PEDV positive semen (S-non-InDel and S-InDel) sampled during a previous trial and in this boar trial were inoculated to six SPF weaned pigs. The inoculated piglets did not seroconvert and did not shed virus throughout the duration of the study except for one pig at 18 DPI. But, PEDV could be detected in intestinal tissues such as duodenum, jejunum and jejunum Peyer’s patches by RT-qPCR except for one pig. Even if PEDV genome has been detected in semen, experimental infection of piglets with positive semen failed to conclude to the infectivity of the detected PEDV.

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

An 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.