High Prevalence, Genetic Diversity, and Recombination of Porcine Sapelovirus in Pig Farms in Fujian, Southern China.

Porcine sapelovirus (PSV) is a ubiquitous virus in farmed pigs that is associated with SMEDI syndrome, polioencephalomyelitis, and diarrhea. However, there are few reports on the prevalence and molecular characterization of PSV in Fujian Province, Southern China. In this study, the prevalence of PSV and a poetical combinative strain PSV2020 were characterized using real-time PCR, sequencing, and bioinformatics analysis. As a result, an overall sample prevalence of 30.8% was detected in 260 fecal samples, and a farm prevalence of 76.7% was observed in 30 Fujian pig farms, from 2020 to 2022. Noteably, a high rate of PSV was found in sucking pigs. Bioinformatics analysis showed that the full-length genome of PSV2020 was 7550 bp, and the genetic evolution of its ORF region was closest to the G1 subgroup, which was isolated from Asia and America; the similarity of nucleotides and amino acids to other PSVs was 59.5~88.7% and 51.7~97.0%, respectively. However, VP1 genetic evolution analysis showed a distinct phylogenetic topology from the ORF region; PSV2020 VP1 was closer to the DIAPD5469-10 strain isolated from Italy than strains isolated from Asia and America, which comprise the G1 subgroup based on the ORF region. Amino acid discrepancy analysis illustrated that the PSV2020 VP1 gene inserted twelve additional nucleotides, corresponding to four additional amino acids (STAE) at positions 898-902 AAs. Moreover, a potential recombination signal was observed in the 2A coding region, near the 3' end of VP1, owing to recombination analysis. Additionally, 3D genetic evolutionary analysis showed that all reference strains demonstrated, to some degree, regional conservation. These results suggested that PSV was highly prevalent in Fujian pig farms, and PSV2020, a PSV-1 genotype strain, showed gene diversity and recombination in evolutionary progress. This study also laid a scientific foundation for the investigation of PSV epidemiology, molecular genetic characteristics, and vaccine development.

Effects of Toxin-Antitoxin System HicAB on Biofilm Formation by Extraintestinal Pathogenic E. coli.

The type II toxin-antitoxin (T-A) HicAB system is abundant in several bacteria and archaea, such as Escherichia coli, Burkholderia Pseudomallei, Yersinia pestis, Pseudomonas aeruginosa, and Streptococcus pneumoniae. This system engages in stress response, virulence, and bacterial persistence. This study showed that the biofilm-forming ability of the hicAB deletion mutant was significantly decreased to moderate ability compared to the extra-intestinal pathogenic Escherichia coli (ExPEC) parent strain and the complemented strain, which are strong biofilm producers. Congo red assay showed that the hicAB mutant maintained the ability to form curli fimbriae. Using RNA-seq and comparative real-time quantitative RT-PCR, we observed the difference in gene expression between the hicAB mutant and the parent strain, which was associated with biofilm formation. Our data indicate that the HicAB type II T-A system has a key role in biofilm formation by ExPEC, which may be associated with outer membrane protein (OMP) gene expression. Collectively, our results indicate that the hicAB type II T-A system is involved in ExPEC biofilm formation.

The Immune Efficacy of Inactivated Pseudorabies Vaccine Prepared from FJ-2012ΔgE/gI Strain.

An emerging pseudorabies virus (PRV) variant has been reported on Bartha-K61-vaccinated farms since 2011, causing great economic losses to China's swine-feeding industry. In this study, two vaccines, FJ-2012ΔgE/gI-GEL02 and FJ-2012ΔgE/gI-206VG, were administered to piglets for immune efficacy investigation. Humoral immunity response, clinical signs, survival rate, tissue viral load, and pathology were assessed in piglets. The results showed that both vaccines were effective against the PRV FJ-2012 challenge, the piglets all survived while developing a high level of gB-specific antibody and neutralizing antibody, the virus load in tissue was alleviated, and no clinical PR signs or pathological lesions were displayed. In the unimmunized challenged group, typical clinical signs of pseudorabies were observed, and the piglets all died at 7 days post-challenge. Compared with commercial vaccines, the Bartha-K61 vaccine group could not provide full protection, which might be due to a lower vaccine dose; the inactivated vaccine vPRV* group piglets survived, displaying mild clinical signs. The asterisk denotes inactivation. These results indicate that FJ-2012ΔgE/gI-GEL02 and FJ-2012ΔgE/gI-206VG were effective and could be promising vaccines to control or eradicate the new PRV epidemic in China.

Isolation of a Reassortant H1N2 Swine Flu Strain of Type "Swine-Human-Avian" and Its Genetic Variability Analysis.

We isolated an influenza strain named A/Swine/Fujian/F1/2010 (H1N2) from a pig suspected to be infected with swine flu. The results of electron microscopy, hemagglutination (HA) assay, hemagglutination inhibition (HI) assay, and whole genome sequencing analysis suggest that it was a reassortant virus of swine (H1N1 subtype), human (H3N2 subtype), and avian influenza viruses. To further study the genetic evolution of A/Swine/Fujian/F1/2010 (H1N2), we cloned its whole genome fragments using RT-PCR and performed phylogenetic analysis on the eight genes. As a result, the nucleotide sequences of HA, NA, PB1, PA, PB2, NP, M, and NS gene are similar to those of A/Swine/Shanghai/1/2007(H1N2) with identity of 98.9%, 98.9%, 99.0%, 98.6%, 99.0%, 98.9%, 99.3%, and 99.3%, respectively. Similar to A/Swine/Shanghai/1/2007(H1N2), we inferred that the HA, NP, M, and NS gene fragments of A/Swine/Fujian/F1/2010 (H1N2) strain were derived from classical swine influenza H3N2 subtype, NA and PB1 were derived from human swine influenza H3N2 subtype, and PB2 and PA genes were derived from avian influenza virus. This further validates the role of swine as a "mixer" for influenza viruses.

Pathogenicity and Whole Genome Sequence Analysis of a Pseudorabies Virus Strain FJ-2012 Isolated from Fujian, Southern China.

The outbreaks of pseudorabies have been frequently reported in Bartha-K61-vaccinated farms in China since 2011. To study the pathogenicity and evolution of the circulating pseudorabies viruses in Fujian Province, mainland China, we isolated and sequenced the whole genome of a wild-type pseudorabies virus strain named "FJ-2012." We then conducted a few downstream bioinformatics analyses including phylogenetic analysis and pathogenic analysis and used the virus to infect 6 pseudorabies virus-free piglets. FJ-2012-infected piglets developed symptoms like high body temperature and central nervous system disorders and had high mortality rate. In addition, we identified typical micropathological changes such as multiple gross lesions in infected piglets through pathological analysis and conclude that the FJ-2012 genome is significantly different from known pseudorabies viruses, in which insertions, deletions, and substitutions are observed in multiple immune and virulence genes. In summary, this study shed lights on the molecular basis of the prevalence and pathology of the pseudorabies virus strain FJ-2012. The genome of FJ-2012 could be used as a reference to study the evolution of pseudorabies viruses, which is critical to the vaccine development of new emerging pseudorabies viruses.

Down-regulation of eIF5A-2 prevents epithelial-mesenchymal transition in non-small-cell lung cancer cells.

BACKGROUND: Epithelial-mesenchymal transition (EMT) is believed to be the critical process in malignant tumor invasion and metastases, and has a great influence on improving the survival rate in non-small-cell lung cancer (NSCLC) patients. Recent studies suggested that eukaryotic initiation factor 5A-2 (eIF5A-2) might serve as an adverse prognostic marker of survival. We detected eIF5A-2 in NSCLC A549 cells, and found that the invasive capability correlates with the eIF5A-2 expression. METHODS: Transforming growth factor (TGF)-ß1 was used to induce EMT in A549 cells. Western blotting, immunofluorescence, wound healing assay, and transwell-matrigel invasion chambers were used to identify phenotype changes. Western blotting was also used to observe changes of the expression of eIF5A-2. We down-regulated the eIF5A-2 expression using an eIF5A-2 siRNA and identified the phenotype changes by western blotting and immunofluorescence. We tested the change of migration and invasion capabilities of A549 cells by the wound healing assay and transwell-matrigel invasion chambers. RESULTS: After stimulating with TGF-ß1, almost all A549 cells changed to the mesenchymal phenotype and acquired more migration and invasion capabilities. These cells also had higher eIF5A-2 protein expression. Down-regulation of eIF5A-2 expression with eIF5A-2 siRNA transfection could change the cells from mesenchymal to epithelial phenotype and decrease tumor cell migration and invasive capabilities significantly. CONCLUSIONS: The expression of eIF5A-2 was up-regulated following EMT phenotype changes in A549 cells, which correlated with enhanced tumor invasion and metastatic capabilities. Furthermore, in the A549 cell line, the process of EMT phenotype change could be reversed by eIF5A-2 siRNA, with a consequent weakening of both invasive and metastatic capabilities.