Haemophilus parasuis is an economically important bacterial pathogen of swine.Extensive genetic and phenotypic heterogeneity among H.parasuis strains have been observed, which hinders the deciphering of the population structure and its association with clinical virulence.In this study, two highly divergent clades were defined according to iscR-based phylogeny analysis of 148 isolates.Clear separation of serovars and potential virulence markers (PVMs) were observed between the two clades, which are indicative of independent evolution of the two lineages.Previously suggested virulence factors showed no correlation with clinical virulence, and were probably clade or serovar specific genes emerged during different stage of evolution.PVMs profiles varied widely among isolates in the same serovar.Higher strain diversity in respect of PVMs was found for isolates from multi-strain infected farms than those from single strain infected ones, which indicates that multi-strain infection in one farm may increase the frequency of gene transfer in H.parasuis.Systemic isolates were more frequently found in serovar 13 and serovar 12, while no correlation between clinical virulence and iscR-based phylogeny was observed.It shows that iscR is a reliable marker for studying population structure of H.parasuis, while other factors should be included to avoid the interference of gene exchange of iscR between isolates.The two lineages of H.parasuis may have undergone independent evolution, but show no difference in clinical virulence.Wide distribution of systemic isolates across the entire population poses new challenge for development of vaccine with better cross-protection.Our study provides new information for better deciphering the population structure of H.parasuis, which helps understanding the extreme diversity within this pathogenic bacterium.
Haemophilus parasuis is an economically important bacterial pathogen of swine.Extensive genetic and phenotypic heterogeneity among H.parasuis strains have been observed, which hinders the deciphering of the population structure and its association with clinical virulence.In this study, two highly divergent clades were defined according to iscR-based phylogeny analysis of 148 isolates.Clear separation of serovars and potential virulence markers (PVMs) were observed between the two clades, which are indicative of independent evolution of the two lineages.Previously suggested virulence factors showed no correlation with clinical virulence, and were probably clade or serovar specific genes emerged during different stage of evolution.PVMs profiles varied widely among isolates in the same serovar.Higher strain diversity in respect of PVMs was found for isolates from multi-strain infected farms than those from single strain infected ones, which indicates that multi-strain infection in one farm may increase the frequency of gene transfer in H.parasuis.Systemic isolates were more frequently found in serovar 13 and serovar 12, while no correlation between clinical virulence and iscR-based phylogeny was observed.It shows that iscR is a reliable marker for studying population structure of H.parasuis, while other factors should be included to avoid the interference of gene exchange of iscR between isolates.The two lineages of H.parasuis may have undergone independent evolution, but show no difference in clinical virulence.Wide distribution of systemic isolates across the entire population poses new challenge for development of vaccine with better cross-protection.Our study provides new information for better deciphering the population structure of H.parasuis, which helps understanding the extreme diversity within this pathogenic bacterium.
Domestic ducks are natural reservoirs of avian influenza viruses and serve as reassortant hosts for new virus subtypes. We isolated 2 novel influenza A(H5N8) viruses from domestic ducks in eastern China, sequenced their genomes, and tested their pathogenicity in chickens and mice. Circulation of these viruses may pose health risks for humans.
Porcine reproductive and respiratory syndrome virus (PRRSV) is a major pathogen that has threatened the global swine industry for almost 30 years. Because current vaccines do not provide complete protection, exploration of new preventive strategies is urgently needed. Here, we combined a heat-labile enterotoxin B subunit of Escherichia coli (LTB) and ginsenoside Rg1 to form an intranasal adjuvant and evaluated its enhancement of immune responses in mice when added to an inactivated-PRRSV vaccine. The combination adjuvant synergistically elicited higher neutralizing and non-neutralizing (immunoglobulin G and A) antibody responses in the circulatory system and respiratory tract, and enhanced T and B lymphocyte proliferation, CD4+ T-cell priming, and cytotoxic CD4+ T cell activities in mononuclear cells from spleen and lung tissues when compared to the PRRSV vaccine alone, and it resulted in balanced Th1/Th2/Th17 responses. More importantly, we observed that the combination adjuvant also up-regulated type I interferon signaling, which may contribute to improvement in adaptive immune responses. These results highlight the potential value of a combined adjuvant approach for improving the efficacy of vaccination against PRRSV. Further study is required to evaluate the efficacy of this combined adjuvant in swine.
Hemoplasmas belong to Mycoplasmataceae (Mollicutes: Mycoplasmatales) and are able to infect a broad range of mammalian species. We investigated prevalence of hemotropic mycoplasma species in pig farms in the region of Zhejiang by a PCR scheme using universal primers targeting 16S rRNA and RNase P RNA gene (rnpB). Representative positive samples from different farms were selected for sequencing of 16S rRNA and the 219bp rnpB gene fragments for phylogenetic analysis. Sequencing analysis of PCR products from first samples identified a novel hemoplasma species present in several pig farms in the region with highest nucleotide identity of 92% to Candidatus Mycoplasma turicensis. A duplex PCR assay was then designed for differential detection of the novel hemoplasma from Mycoplasma parvum/M. suis in field samples. Of 324 blood samples from clinically healthy pigs, 26.5% was positive for this novel hemoplasma species and 50% positive for M. suis/M. parvum, indicating that the novel hemotropic mycoplasma species were of considerably high prevalence in Zhejiang province, China.
We report here the complete genome sequence of porcine epidemic diarrhea virus (PEDV) strain ZJ/ZX2018-C10, isolated from infected piglets in Zhejiang Province, China. The genome sequence was highly similar to AH2012, a highly virulent Chinese PEDV strain. It will help in understanding the molecular and evolutionary characteristics of PEDV in China.
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