Phylogenetic Classification of Global Porcine Deltacoronavirus (PDCoV) Reference Strains and Molecular Characterization of PDCoV in Taiwan.

Porcine deltacoronavirus (PDCoV), a highly transmissible intestinal pathogen, causes mild to severe clinical symptoms, such as anorexia, vomiting and watery diarrhea, in piglets and/or sows. Since the first report of PDCoV infection in Hong Kong in 2012, the virus has readily disseminated to North America and several countries in Asia. However, to date, no unified phylogenetic classification system has been developed. To fill this gap, we classified historical PDCoV reference strains into two major genogroups (G-I and G-II) and three subgroups (G-II-a, G-II-b and G-II-c). In addition, no genetic research on the whole PDCoV genome or spike gene has been conducted on isolates from Taiwan so far. To delineate the genetic characteristics of Taiwanese PDCoV, we performed whole-genome sequencing to decode the viral sequence. The PDCoV/104-553/TW-2015 strain is closely related to the G-II-b group, which is mainly composed of PDCoV variants from China. Additionally, various mutations in the Taiwanese PDCoV (104-553/TW-2015) strain might be linked to the probability of recombination with other genogroups of PDCoVs or other porcine coronaviruses. These results represent a pioneering phylogenetic characterization of the whole genome of a PDCoV strain isolated in Taiwan in 2015 and will potentially facilitate the development of applicable preventive strategies against this problematic virus.

Genotypic analyses and virulence characterization of Glaesserella parasuis isolates from Taiwan.

BACKGROUND: Glaesserella (Haemophilus) parasuis (G. parasuis) causes severe economic losses in the swine industry. Multiple G. parasuis strains can exist in single animals. Typing techniques are required for identifying G. parasuis isolates. Different strains within a serovar display varying virulence. Enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) can assess the heterogeneity. The group 1 virulence-associated trimeric autotransporters (vtaA) gene is an indicator of virulence. The aim of this study was to characterize Taiwanese G. parasuis isolates via molecular serotyping, vtaA PCR and ERIC-PCR. METHODS: One hundred and forty-five strains were collected between November 2013 and March 2017 in Taiwan and further examined by molecular serotyping, vtaA PCR and ERIC-PCR. RESULTS: The dendrogram revealed heterogeneous genetic diversity within many clusters. Partial correlation between the ERIC-PCR clusters of different strains, serovars and lesion patterns was observed. Twelve herds (8.3%) infected with more than one strain. Group 1 vtaA positive rate reached 98.6%. DISCUSSION: This study showed the high genetic diversity of G. parasuis in Taiwan by a high discriminatory capability of ERIC-PCR. Group 1 vtaA commonly exists in G. parasuis isolates and may play important roles in the pathogenesis of Taiwanese G. parasuis isolates.

Emergence of a virulent porcine reproductive and respiratory syndrome virus in Taiwan in 2018.

In March 2018, an abortion storm caused by porcine reproductive and respiratory syndrome virus was confirmed in a farrow-to-finish pig herd in Taiwan. Open reading frame 5 and non-structural protein 2 of the virus confirmed that the virus is closely related to the virulent strains circulating in the United States.

Molecular serotyping of Haemophilus parasuis isolated from diseased pigs and the relationship between serovars and pathological patterns in Taiwan.

BACKGROUND: Haemophilus parasuis is the etiological agent of Glässer's disease, and causes severe economic losses in the swine industry. Serovar classification is intended as an indicator of virulence and pathotype and is also crucial for vaccination programs and vaccine development. According to a polysaccharide biosynthesis locus analysis, H. parasuis isolates could be classified by a molecular serotyping assay except serovars 5 and 12 detected by the same primer pair. The aim of this study was to identify H. parasuis isolates from diseased pigs in Taiwan by using a molecular serotyping assay and to analyze the relationship between serovars and pathological patterns. METHODS: From August 2013 to February 2017, a total of 133 isolates from 277 lesions on 155 diseased animals from 124 infected herds serotyped by multiplex PCR and analyzed with pathological data. RESULTS: The dominant serovars of H. parasuis in Taiwan were serovars 5/12 (37.6%), 4 (27.8%) and 13 (15%) followed by molecular serotyping non-typable (MSNT) isolates (13.5%). Nevertheless, the serovar-specific amplicons were not precisely the same sizes as previously indicated in the original publication, and MSNT isolates appeared with unexpected amplicons or lacked serovar-specific amplicons. Most H. parasuis isolates were isolated from nursery pigs infected with porcine reproductive and respiratory syndrome virus. The percentage of lung lesions (30.4%) showing H. parasuis infection was significantly higher than that of serosal lesions. DISCUSSION: Collectively, the distribution of serovars in Taiwan is similar to that found in other countries, but MSNT isolates remain due to genetic variations. Furthermore, pulmonary lesions may be optimum sites for H. parasuis isolation, the diagnosis of Glässer's disease, and may also serve as points of origin for systemic H. parasuis infections in hosts.