No abstract

Since 2010, the variant porcine epidemic diarrhea virus (PEDV) has been the etiological agent responsible for the outbreak of porcine epidemic diarrhea (PED) worldwide. In this study, a variant PEDV strain YN1 was isolated, serially propagated on the Vero cells and was characterized for 200 passages. To better elucidate the molecular basis of Vero cell adaptation of variant PEDV strains, we sequenced, compared, and analyzed the full-genome sequences of parental YN1 and passages 15, 30, 60, 90, 144, and 200. The results showed that the variations increased with the viral passage. The nucleotides sequences of non-structural protein (NSP)2, NSP4-7, NSP10, NSP12 and NSP13 genes did not change during the Vero cell adaptation process. After comparison of the variation characteristic of classical, variant virulent/attenuated strains, it was found that attenuation of PEDV virus was associated with 9−26 amino acid (aa) changes in open reading frames (ORF) 1a/b and S protein, early termination in ORF3, 1–3 aa changes in E, M and N protein and some nucleotide sequences’ synonymous mutations. The aa deletion at about 144 aa of S protein could be the attenuation marker for the PEDV. The pig study showed that the early termination in ORF3 was more important for virus cell adaptation than virus attenuation.

Bacterial diseases of swine are a kind of multifactorial and uncontrollable diseases that commonly exist in pig farms all over the world and will lead to huge economic losses every year. In this study, a detailed and overall survey was carried out to better understand the prevalence and antimicrobial susceptibilities of bacterial diseases from 2013 to 2017 in China. A total of 19673 bacterial strains were isolated from 44175 samples collected from 9661 pig farms that distributed in 16 Chinese major pig breeding provinces. The results showed that the average isolation rates of Streptococcus suis (SS), Haemophilus parasuis (HPS), Escherichia coli ( E. coli ), Pasteurella multocida (Pm), Actinobacillus pleuropneumoniae (APP), Brodetella bronchiseptica (Bb), Salmonella enteria (SE), Erysipelothrix rhusiopathiae (E. rhusiopathiae) were 16.9%, 9.7%, 6.3%, 3.4%, 0.3%, 1.5%, 2.3% and 0.9%, respectively. The isolate rates of E. coli , APP and SE showed an increasing trend from 2013 to 2017. The seasonal prevalence characteristics of SS, HPS and Pm were obviously higher from April to August for first two bacteria and higher at February, March, April, and October for Pm. The dominant serotypes for SS, HPS were serotype 2 and serotype 5 (changed from serotype 4), respectively. The SS, HPS, and Pm showed very high antibiotic resistance rates to almost 8 common antibiotics (β-lactam, aminoglycoside, macrolides, lincomycin, tetracycline, quinolone, polymyxin, and sulfonamide) and an obvious increasing trend of antibiotic resistance rates from 2013 to 2017. In conclusion, the study provides detailed information on the prevalence and antimicrobial susceptibilities of different bacterial pathogens of swine from 2013 to 2017 in China. These data can provide a foundation for monitoring epidemiological patterns of bacterial diseases in the Chinese swine herds, as well as provide insight into potential antibiotic resistance profiles in these pathogens.

The epidemiology and genetic diversity of transmissible gastroenteritis virus (TGEV) in the United States (US) was investigated by testing clinical cases for TGEV by real time RT-PCR between January 2008 and November 2016. Prevalence of TGEV ranged between 3.8–6.8% and peaked during cold months until March 2013, in which prevalence decreased to < 0.1%. Nineteen complete TGEV genomes and a single strain of porcine respiratory coronavirus (PRCV) from the US were generated and compared to historical strains to investigate the evolution of these endemic coronaviruses. Sixteen of our TGEV strains share 8 unique deletions and 119 distinct amino acid changes, which might greatly affect the biological characteristics of the variant TGEV, and resulted in a “variant” genotype of TGEV. The “variant” genotype shared similar unique deletions and amino acid changes with the recent PRCV strain identified in this study, suggesting a recombination event occurred between the ‘‘variant’’ TGEV and PRCV. Moreover, the results indicate the “variant” genotype is the dominant genotype circulating in the US. Therefore, this study provides insight into the occurrence, origin, genetic characteristics, and evolution of TGEV and PRCV circulating in the US.

A porcine deltacoronavirus (PDCoV) was identified in the Chinese mainland and found to be closely related to Hong Kong strain HKU15-155 but differed from PDCoV strains in the United States and South Korea. The complete genome of PDCoV strain CH/SXD1/201 was sequenced and analyzed to further characterize PDCoV in Chinese swine.

Porcine epidemic diarrhea virus (PEDV) is a porcine enteropathogenic coronavirus that has received increasing attention since the emergence of a PEDV variant worldwide. Previous studies have shown that PEDV ORF3 encodes an ion channel protein. However, its influence on cell cycle and subcellular structure still require more research. In this study, we developed a Vero cell line that stably expresses PEDV ORF3 gene. Subcellular localization and influences of PEDV ORF3 on host cells were investigated. We further verified whether or not this gene enhances virus production. The results showed that PEDV ORF3 protein localizes in the cytoplasm and affects cell cycle progression by prolonging the S phase. In addition, the ORF3-expressing Vero cells had more vesicles than the host Vero cells. Furthermore, the attenuated PEDV rather than virulent PEDV could grow better in ORF3-expressing Vero cells. The expression level of the PEDV nucleocapsid protein also increased. These results provided information on the function of PEDV ORF3 and were helpful in understanding the mechanisms of PEDV replication.

Haemophilus parasuis (H. parasuis) is a kind of opportunistic pathogen of the upper respiratory tract of piglets. Under certain circumstances, virulent strains can breach the mucosal barrier and enter the bloodstream, causing severe Glässer's disease. Many virulence factors are found to be related to the pathogenicity of H. parasuis strain, but the pathogenic mechanism remains unclear. LuxS/AI-2, as a kind of very important quorum sensing system, affects the growth characteristics, biofilm formation, antibiotic production, virulence, and metabolism of different strains. In order to investigate the effect of luxS/AI-2 quorum sensing system on the virulence of H. parasuis, a deletion mutant strain (ΔluxS) and complemented strain (C-luxS) were constructed and characterized. The results showed that the luxS gene participated in regulating and controlling stress resistance, biofilm formation and virulence. Compared with wild-type strain, ΔluxS strain decreased the production of AI-2 molecules and the tolerance toward oxidative stress and heat shock, and it reduced the abilities of autoagglutination, hemagglutination, and adherence, whereas it increased the abilities to form biofilm in vitro. In vivo experiments showed that ΔluxS strain attenuated its virulence about 10-folds and significantly decreased its tissue burden of bacteria in mice, compared with the wild-type strain. Taken together, the luxS/AI-2 quorum sensing system in H. parasuis not only plays an important role in growth and biofilm formation, but also affects the pathogenicity of H. parasuis.

Alzheimer’s disease (AD) is a chronic neurodegenerative disease that often occurs at a slow pace yet deteriorates with time. MicroRNAs (miRs) have been demonstrated to offer novel therapeutic hope for disease treatment. The aim of the present study was to investigate the effect of miR-98 on amyloid β (Aβ)-protein production, oxidative stress and mitochondrial dysfunction through the Notch signaling pathway by targeting hairy and enhancer of split (Hes)-related with YRPW motif protein 2 (HEY2) in mice with AD. A total of 70 Kunming mice were obtained and subjected to behavioral assessment. The levels of oxidative stress-related proteins glutathione peroxidase, reduced glutathione, super-oxide dismutase, malondialdehyde, acetylcholinesterase and Na+-K+-ATP were measured. Morphological changes in brain tissue, HEY2-positivity levels, neuronal apoptotic index (AI) and neuron mitochondrial DNA (mtDNA) levels were also determined. Subsequently, the levels of miR-98 and the mRNA and protein levels of HEY2, Jagged1, Notch1, Hes1, Hes5, β-amyloid precursor protein, B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein in tissues and hippocampal neurons were determined by reverse transcription-quantitative polymerase chain reaction and western blot analyses, respectively. Finally, hippocampal neuron viability and apoptosis were determined using an MTT assay and flow cytometry, respectively. The levels of miR-98-targeted HEY2 and miR-98 were low and the levels of HEY2 were high in the AD mice. The AD mice exhibited poorer learning and memory abilities, oxidative stress function, and morphological changes of pyramidal cells in the hippocampal CA1 region. Furthermore, the AD mice exhibited increased protein levels of HEY2 and AI in the CA1 region of brain tissues with reduced mtDNA levels and dysfunctional neuronal mitochondria. miR-98 suppressed hippocampal neuron apoptosis and promoted hippocampal neuron viability by inactivating the Notch signaling pathway via the inhibition of HEY2. In conclusion, the results demonstrated that miR-98 reduced the production of Aβ and improved oxidative stress and mitochondrial dysfunction through activation of the Notch signaling pathway by binding to HEY2 in AD mice.