Porcine circovirus type 2 (PCV2) infection in Hebei Province from 2016 to 2019: a retrospective study.

Porcine circovirus type 2 (PCV2) is the primary causative agent of porcine circovirus-associated diseases in swine, the most common of which are postweaning multisystemic wasting syndrome (PMWS) and porcine dermatitis and nephropathy syndrome (PDNS). To investigate the prevalence and genetic diversity of PCV2 in Hebei Province, Northern China, from 2016 to 2019, a total of 448 suspected cases of PCV2 infection were studied, and 179 samples were positive for PCV2. A pathological and histopathological examination suggested PCV2 to be cause of the observed lesions. Phylogenetic analysis showed that four genotypes were prevalent in Hebei Province: PCV2a, 2b, 2d, and 2e. Analysis of PCV2 strains using RDP4 and SimPlot showed that there were genetic recombination events among PCV2 strains in Hebei Province. A total of 3284 serum samples were screened by ELISA, and the positive rate of PCV2 antibodies was 73.9% (2428/3284). This study provides a scientific reference for the prevention and treatment of PCV2 in Hebei Province.

Short hairpin RNAs targeting M and N genes reduce replication of porcine deltacoronavirus in ST cells.

Porcine deltacoronavirus (PDCoV) is a recently identified coronavirus that causes intestinal diseases in neonatal piglets with diarrhea, vomiting, dehydration, and post-infection mortality of 50-100%. Currently, there are no effective treatments or vaccines available to control PDCoV. To study the potential of RNA interference (RNAi) as a strategy against PDCoV infection, two short hairpin RNA (shRNA)-expressing plasmids (pGenesil-M and pGenesil-N) that targeted the M and N genes of PDCoV were constructed and transfected separately into swine testicular (ST) cells, which were then infected with PDCoV strain HB-BD. The potential of the plasmids to inhibit PDCoV replication was evaluated by cytopathic effect, virus titers, and real-time quantitative RT-PCR assay. The cytopathogenicity assays demonstrated that pGenesil-M and pGenesil-N protected ST cells against pathological changes with high specificity and efficacy. The 50% tissue culture infective dose showed that the PDCoV titers in ST cells treated with pGenesil-M and pGenesil-N were reduced 13.2- and 32.4-fold, respectively. Real-time quantitative RT-PCR also confirmed that the amount of viral RNA in cell cultures pre-transfected with pGenesil-M and pGenesil-N was reduced by 45.8 and 56.1%, respectively. This is believed to be the first report to show that shRNAs targeting the M and N genes of PDCoV exert antiviral effects in vitro, which suggests that RNAi is a promising new strategy against PDCoV infection.

Seroprevalence of porcine bocavirus in pigs in north-central China using a recombinant-NP1-protein-based indirect ELISA.

Porcine bocavirus (PBoV), which belongs the genus Bocaparvovirus, has been identified throughout the world. However, serological methods for detecting anti-PBoV antibodies are presently limited. In the present study, an indirect enzyme-linked immunosorbent assay (PBoV-rNP1 ELISA) based on a recombinant form of nucleoprotein 1 (NP1) of PBoV was established for investigating the seroprevalence of PBoV in 2025 serum specimens collected in north-central China from 2016 to 2018, and 42.3% of the samples tested positive for anti-PBoV IgG antibodies, indicating that the seroprevalence of PBoV is high in pig populations in China.