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Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel coronavirus in humans, has expanded globally over the past year. COVID-19 remains an important subject of intensive research owing to its huge impact on economic and public health globally. Based on historical archives, the first coronavirus-related disease recorded was possibly animal-related, a case of feline infectious peritonitis described as early as 1912. Despite over a century of documented coronaviruses in animals, the global animal industry still suffers from outbreaks. Knowledge and experience handling animal coronaviruses provide a valuable tool to complement our understanding of the ongoing COVID-19 pandemic. In this review, we present an overview of coronaviruses, clinical signs, COVID-19 in animals, genome organization and recombination, immunopathogenesis, transmission, viral shedding, diagnosis, treatment, and prevention. By drawing parallels between COVID-19 in animals and humans, we provide perspectives on the pathophysiological mechanisms by which coronaviruses cause diseases in both animals and humans, providing a critical basis for the development of effective vaccines and therapeutics against these deadly viruses.

New variants of porcine epidemic diarrhoea virus (PEDV) causing a highly contagious intestinal disease, porcine epidemic diarrhoea virus (PED), have resulted in high mortality in suckling pigs across several countries since 2013. After 2015, the prevalence of the genogroup 2b (G2b) PEDVs decreased in a cyclical pattern with endemic seasonal outbreaks occasionally seen. To better understand the genetic diversity of PEDVs recently circulating in Taiwan, full-length spike (S) genes of 31 PEDV strains from 28 pig farms collected during 2016-2018 were sequenced. While the majority of S gene sequences (from 27/28 farms) were closely related to the previous G2b PEDV strains, increased genetic diversities leading to several nonsynonymous mutations scattering in the neutralizing epitopes of the S gene were detected in PEDVs recently circulating in Taiwan. Furthermore, novel recombinant variants, the PEDV TW/Yunlin550/2018 strains exhibiting recombinant events between a previously isolated Taiwan PEDV G2b strain and a wild-type PEDV G1a strain, were identified and further classified into a new genogroup, G1c. These results provide updated information about the genetic diversity of currently circulating PEDVs in the field and could help to develop more suitable strategies for controlling this disease., (© 2019 Blackwell Verlag GmbH.)

The porcine epidemic diarrhea virus (PEDV) that emerged and spread throughout Taiwan in 2014 triggered significant concern in the country's swine industry. Acknowledging the absence of a thorough investigation at the geographic level, we used 2014 outbreak sequence information from the Taiwan government's open access databases plus GenBank records to analyze PEDV dissemination among Taiwanese pig farms. Genetic sequences, locations, and dates of identified PEDV-positive cases were used to assess spatial, temporal, clustering, GIS, and phylogeographic factors affecting PEDV dissemination. Our conclusion is that S gene sequences from 2014 PEDV-positive clinical samples collected in Taiwan were part of the same Genogroup 2 identified in the US in 2013. According to phylogenetic and phylogeographic data, viral strains collected in different areas were generally independent of each other, with certain clusters identified across different communities. Data from GIS and multiple potential infection factors were used to pinpoint cluster dissemination in areas with large numbers of swine farms in southern Taiwan. The data indicate that the 2014 Taiwan PEDV epidemic resulted from the spread of multiple strains, with strong correlations identified with pig farm numbers and sizes (measured as animal concentrations), feed mill numbers, and the number of slaughterhouses in a specifically defined geographic area., Competing Interests: The authors have declared that no competing interests exist.

In the present study, we investigated the roles of interactions among the poly(A) tail, coronavirus nucleocapsid (N) protein, and poly(A)-binding protein (PABP) in the regulation of coronavirus gene expression. Through dissociation constant ( K d ) comparison, we found that the coronavirus N protein can bind to the poly(A) tail with high affinity, establishing N protein as a PABP. A subsequent analysis with UV cross-linking and immunoprecipitation revealed that the N protein is able to bind to the poly(A) tail in infected cells. Further examination demonstrated that poly(A) tail binding by the N protein negatively regulates translation of coronaviral RNA and host mRNA both in vitro and in cells. Although the N protein can interact with PABP and eukaryotic initiation factor 4G (eIF4G), the poor interaction efficiency between the poly(A)-bound N protein and eIF4E may explain the observed decreased translation efficiency. In addition to interaction with translation factor eIF4G, the N protein is able to interact with coronavirus nonstructural protein 9 (nsp9), a replicase protein required for replication. The study demonstrates interactions among the poly(A) tail, N protein, and PABP both in vitro and in infected cells. Of the interactions, binding of the poly(A) tail to N protein decreases the interaction efficiency between the poly(A) tail and eIF4E, leading to translation inhibition. The poly(A)-dependent translation inhibition by N protein has not been previously demonstrated and thus extends our understanding of coronavirus gene expression. IMPORTANCE Gene expression in coronavirus is a complicated and dynamic process. In this study, we demonstrated that coronavirus N protein is able to bind to the poly(A) tail with high affinity, establishing N protein as a PABP. We also show how the interplay between coronavirus 3' poly(A) tail, PABP, and N protein regulates gene expression of the coronavirus and host cell. Of the interactions, poly(A) tail binding by the N protein negatively regulates translation, and to our knowledge, this inhibition of translation by binding of the N protein to poly(A) tail has not been previously studied. Accordingly, the study provides fundamental molecular details regarding coronavirus infection and expands our knowledge of coronavirus gene expression., (Copyright © 2018 American Society for Microbiology.)

Similar to eukaryotic mRNA, the positive-strand coronavirus genome of ~30 kilobases is 5'-capped and 3'-polyadenylated. It has been demonstrated that the length of the coronaviral poly(A) tail is not static but regulated during infection; however, little is known regarding the factors involved in coronaviral polyadenylation and its regulation. Here, we show that during infection, the level of coronavirus poly(A) tail lengthening depends on the initial length upon infection and that the minimum length to initiate lengthening may lie between 5 and 9 nucleotides. By mutagenesis analysis, it was found that (i) the hexamer AGUAAA and poly(A) tail are two important elements responsible for synthesis of the coronavirus poly(A) tail and may function in concert to accomplish polyadenylation and (ii) the function of the hexamer AGUAAA in coronaviral polyadenylation is position dependent. Based on these findings, we propose a process for how the coronaviral poly(A) tail is synthesized and undergoes variation. Our results provide the first genetic evidence to gain insight into coronaviral polyadenylation., Competing Interests: The authors have declared that no competing interests exist.

Porcine epidemic diarrhea virus (PEDV) is an important pathogen that has a significant economic impact on the swine industry by imposing a high rate of mortality in suckling piglets. However, limited information on the productivity values of gilts and sows infected with PEDV is available. Here, we evaluate the productivity index in gilts and sows during the 1-year period before (19 January 2013 to 18 January 2014) and after (19 January 2014 to 18 January 2015) a PEDV outbreak from a 2000-sow breeding herd in Taiwan. The farrowing rate (FR), return rate (RR), total pigs born per litter (TB), pigs born alive per litter (BA), weaning pigs per litter (WPL), pre-weaning mortality, percentage of sows mated by 7 days after weaning, weaning to first service interval (WFSI), mated female nonproductive days (NPDs), replacement rate of sows and sow culling rate were compared using productive records. The FR (-9.6%), RR (+9.8%), TB (-1.6), BA (-1.1), WPL (-1.1), sows mated by 7 days after weaning (-6.9%), WFSI (+0.8 days), NPDs (+6.9 days) and sow culling rate (+7.2%) were significantly different between the 1-year pre-PEDV outbreak period and the post-PEDV outbreak period. Impacts of the PEDV infection on the reproductive performance were more severe in pregnant gilts than in sows. In conclusion, these findings indicate that the outbreak of PEDV caused an increase in the rate of NPDs in breeding herds.

Since late 2013, several outbreaks of porcine epidemic diarrhea virus (PEDV) infection have emerged in Taiwan. Suckling piglets under 2 weeks of age showed severe vomiting and watery yellowish diarrhea with morbidity and mortality ranging from 80 to 100% and 90 to 100%, respectively. A total of 68 samples from 25 pig farms were confirmed as positive for PEDV and negative for rotavirus and transmissible gastroenteritis virus by reverse transcription PCR, and the partial S gene of PEDV was analyzed. Phylogenetic analysis places all 18 Taiwanese PEDV isolates collected during this outbreak in the same clade as the US strains of PEDV. This novel PEDV is prevailing and currently causing severe outbreaks in Taiwan.