Editorial: Emerging Swine Viruses

PERFUMO, CARLOS JUAN; PEREDA, ARIEL; JONGKAEWWATTANA, ANAN; CHEN, ZHENHAI; PEREZ, DANIEL ROBERTO; MA, JINGYUN

Frontiers in Veterinary Science

Frontiers

Año: 2020 vol. 7

Over the last 30 years, diseases caused by emerging swine viruses (ESV) have acquired great relevance, more than in other species. Diseases caused by porcine reproductive and respiratory syndrome virus (PRRSv), high pathogenicity porcine epidemic diarrhea virus (PEDv), porcine circovirus type 2 (PCV-2), and influenza virus H1N1pdm09 had great economic impact. Others, however, such as porcine enteroviruses, porcine toroviruses (PToV), porcine sapelovirus (PSV), porcine bocavirus (PBoV), porcine kobuvirus (PKBV), and porcine Torque teno sus virus (TTSuV) are mostly subclinical in swine herds. Furthermore, novel emerging viruses, such as SENECA virus, atypical porcine pestivirus (APPV), PCV-3, SADS-CoV, influenza D, and others with regional or worldwide distribution constitute a new challenge for researchers and practicing veterinarians.Emerging viruses should be considered to occur when there are changes in the relationship between the agent, the host and the enviroment. The response to how and why the ESV have emerged can be explained through several factors.First, interspecies transmission means the presence of a potentially pathogenic agent into a new host, such as between aquatic migratory birds and human beings for influenza A. Bats are the source of Nipah virus, and swine acute diarrhea syndrome (SADS coronavirus). Both have limited distribution to Asia or TGE and PED. Currently PCV-3 have been found with high homology with bats PCV-1.Secondly, changes in the virulence (mutation, reassortant, recombination) of the agents in the same host, particularly the RNA and single strand DNA viruses that have a high mutation rate (10?4/10?5 nucleotides per replication cycle), that facilitate its adaptation to the innate immune response. The absence of enzymes (transcriptase) in infected cells that correct errors in reading RNA synthesis and segmented RNA chains favor reassortant. A population of RNA viruses does not consist of a single genotype, but a ?set or cloud? of related viruses that interact with each other called ?quasispecies?. Relevant examples are HP PRRSv, influenza A H1N1pdm09 and PEDv.Next, the viruses have been present for a long period of time as subclinical infections and have been discovered with the development of metagenomic techniques [Next Generation Sequencing NGS, Lawrence Livermore Microbial Detection Array (LLMDA or virochip)], or exogenous factors as most emerging viruses do not grow in traditional culture media. Viruses such PCV-3, SADS-CoV, and LINDA virus have been characterized by the aforementioned techniques.Now we come to change in the production system. The presence of farms of good health, large size and homogeneous genetics favors the fitness, and the ability of a particular population of viruses to multiply and spread in a specific environment.Our fifth point is the recognition and sensitization of practicing veterinaries of ?abnormal? cases or syndromes through the routine postmortem monitoring of pigs that die ?unexceptionally? on the farm, as well as the syndromes surveillance at the slaughterhouse.Finally, Specialized diagnostic laboratories that offer new and accessible diagnostic tools for the diagnoses of known and unknown emerging viruses.This Research Topics comprises ten review articles are related by: Next Generation Sequencing (NGS) plus in situ Hybridization (ISH); porcine hemagglutinating encephalomyelitis coronavirus (PHE-CoV); porcine circovirus type 3 (PCV-3); classical swine fever virus (CSF); porcine torovirus (PToV); porcine respiratory reproductive syndrome virus (PRRSV); human influenza A; Nipah virus in humans and pigs swine; atypical porcine pestivirus (APPV); porcine epidemic diarrhea coronavirus (PEDV); and porcine delta coronavirus (PDCoV) pathogenesis. These subjects provide a discussion on the broad field of emerging swine viruses infections and its control.Three original research articles about phylogeny and genome composition of novel Seneca virus (SVA) isolated in China; estimation of time to porcine epidemic diarrhea coronavirus (PED-CoV) removal in Ontario herds and a longitudinal serological and RT-PCR fecal studies of hepatitis E virus (HEV) were published.