Yongke Sun

Endogenous hydrogen sulfide formation mediates the liver damage in endotoxemic rats

BACKGROUND Hydrogen sulfide (H2S) is a naturally occurring gaseous transmitter and may play important roles in normal physiology and liver disease. AIMS To investigate the relationships between the formation of liver H2S and liver damage in endotoxemic rats caused by lipopolysaccharide (LPS). METHODS Male SD rats were sacrificed to acute endotoxemia and pretreated with H2S donor sodium hydrogen sulfide (NaHS) or H2S inhibitor dl-propargylglycine (PAG). Liver H2S concentration, liver cystathionine-γ-lyase (CSE) mRNA, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) level, liver histopathological alteration in different time after treatment were determined. RESULTS Endotoxemia resulted in an increase in serum levels of ALT and AST. In the liver, endotoxemia induced a significant increase in the H2S concentration, and in the expression of the H2S-synthesizing enzymes CSE. Pretreatment with NaHS promoted the increase the liver H2S concentration and aggravated the LPS-induced liver damage, However, administration of PAG abolished the increase the liver H2S concentration and reduced the liver injury caused by endotoxemia. CONCLUSIONS These findings support the view that an enhanced formation of H2S contributes to the liver injury in endotoxemia. We propose that inhibition of H2S synthesis may be a useful therapeutic strategy against the liver injury associated with endotoxemia.

High hepatitis E virus antibody positive rates in dogs and humans exposed to dogs in the south‐west of China

Hepatitis E (HE) is a zoonotic viral disease caused by hepatitis E virus (HEV). The objective of this study was to investigate the prevalence of HEV infection among dogs and humans exposed to dogs in the south‐west region of China. A total of 4,490 dog serum samples and 2,206 relative practitioner serum samples were collected from 18 pet hospitals and dog farms in Yunnan, Sichuan and Guizhou province, and the anti‐HEV IgG antibodies were detected by ELISA. The results showed that the total positive rate of anti‐HEV antibodies was 36.55% with the highest rate in city stray dogs, and the differences in distinct species and growth phases were significant. The positive rate of anti‐HEV antibody in veterinarian and farm staff‐related practitioners was significantly higher than the general population. The finding of the present survey suggested that high HEV seroprevalence in dogs and humans exposed to dogs in the south‐west area of China poses a significant public health concern. It is urgent to improve integrated strategies to detect, prevent and control HEV infection in dogs and humans exposed to dogs in this area.

Molecular characteristics of the MHC‐DRA genes from yak (Bos grunniens) and Chinese yakow (Bos grunniens × Bos taurus)

Two full‐length cDNAs (762 bp) of the DRA gene from yak and Chinese yakow were isolated and analysed to identify structural and functional variations. The sequences for DRA in yak (Bogr‐DRA) and Chinese yakow (Bogr × BoLA‐DRA) were essentially identical to those for cattle (99%) and buffalo (97%). Except for two substitutions in the amino acids comprising the domain for signal peptide (SP) in yak, the additional residues were highly conserved across the species investigated. Peptide‐binding site (PBS) of Bogr‐DRA and Bogr × BoLA‐DRA was highly reserved in the α1 domain among all species investigated. The lack of mutation in Bogr‐DRA is consistent with the conception that the gene is highly conserved among all mammalian species. The very high conservation of the DRA gene among ruminants, including yak, may be due to its recent evolutionary detachment.

Genetic characterization of MHC class II DQB exon 2 variants in gayal (Bos frontalis)

In the present study, exon 2 of major histocompatibility complex (MHC) class II DQB gene from 39 gayals (Bos frontalis) was isolated, characterized and compared with previously reported patterns for other bovidae. It was revealed by sequence analyses that there are 36 DQB exon 2 variants among 39 gayals. These variants exhibited a high degree of nucleotide and amino acid substitutions with most amino acid variations occurring at positions forming the peptide-binding sites (PBS). The DQB loci were analysed for patterns of synonymous (dS) and non-synonymous (dN) substitution. The gayals were observed to be under strong balancing selection in the DQB exon 2 PBS (dN = 0.094, P = 0.001). It appears that this variability among gayals could confer the ability to mount immune responses to a wide variety of peptides or pathogens.

Induction of ROS generation and NF-κB activation in MARC-145 cells by a novel porcine reproductive and respiratory syndrome virus in Southwest of China isolate

BackgroundPorcine reproductive and respiratory syndrome virus (PRRSV) is the cause of an economically important swine disease that has devastated the swine industry since the late 1980s. The aim of the present study was to investigate the interaction between reactive oxygen species (ROS) and NF-κB by PRRSV infection.ResultsWe isolated the local strain of PRRSV from southwest China, designated YN-2011, then sequenced and analyzed the genome. YN-2011 was then used to evaluate the interaction of ROS and NF-κB. In PRRSV infected MARC-145 cells, there was a time-dependent increase in ROS and Maleic Dialdehyde (MDA). Accordingly, NF-κB activation was also increased as PRRSV infection progressed. Degradation of IκB mRNA was detected late in PRRSV infection, and overexpression of the dominant negative form of IκBα significantly suppressed NF-κB induced by PRRSV.ConclusionsThe results indicate that the generation of ROS is involved in PRRSV replication and this progression is associated with the alteration in NF-κB activity induced by ROS. These results should extend our better understanding the interaction between PRRSV and host MARC-145 cells.

Nucleotide sequence and polymorphism of MHC class II DQB exon 2 alleles in Chinese yakow ( Bos grunniens × Bos taurus )

The objective of this study is to describe the gene characteristics of the bovine lymphocyte antigen (BoLA)‐DQB exon 2 locus in Chinese yakow (Bos grunniens × Bos taurus) and to compare it with previously reported patterns in other bovidae species to investigate genetic factors for disease resistance. The exon 2 of the MHC class II DQB gene was cloned and sequenced. It was revealed by sequence analyses that there are 36 DQB exon 2 alleles among 44 Chinese yakow. These alleles exhibited a high degree of nucleotide and amino acid polymorphism with most amino acid variations occurring at positions forming the peptide‐binding sites (PBS). The DQB loci were analysed for patterns of synonymous (dS) and nonsynonymous (dN) substitution. The Chinese yakow was observed to be under strong positive selection in the DQB exon 2 peptide‐binding sites (dN = 0.147, P < 0.01). It appears that this variability among Chinese yakow confers the ability to mount immune responses to a wide variety of peptides or pathogens.

Complete Genome Sequence of a Novel Natural Recombinant Porcine Reproductive and Respiratory Syndrome Virus Isolated from a Pig Farm in Yunnan Province, Southwest China

ABSTRACT YN-2011 is a highly pathogenic North American porcine reproductive and respiratory syndrome virus (PRRSV). Unlike previously described PRRSVs, which contained a 30-amino-acid deletion in NS2, YN-2011 had no amino acid deletions or insertions but had several new mutations in NS2. Here, we announce the complete genome sequence of YN-2011.

Isolation and cDNA characteristics of MHC-DRA genes from gayal (Bos frontalis) and gaytle (Bos frontalis × Bos taurus).

The mammalian major histocompatibility complex (MHC) plays important roles in pathogen recognition and disease resistance. In the present study, the coding sequence and the 5′- and 3′-untranslated regions of MHC class II DR alpha chain (the DRA gene) from rare gayal and gaytle were cloned and analyzed to dissect structural and functional variations. The nucleotide and amino acid sequences for the DRA genes in gayal (Bofr-DRA) and gaytle (Bofr × BoLA-DRA) were almost identical to those for cattle and yak (99%). Compared to yak, two amino acids substitutions in the signal peptide (SP) domain for gayal were found within all Bos animals. Except for only one replacement in the amino acid within the α2 domain of the DRA protein in gayal, the additional residues were highly conserved across the species investigated. The 20 peptide-binding sites (PBS) of Bofr-DRA and Bofr × BoLA-DRA were essentially reserved in the α1 domain among all species investigated. The lesser degree of substitution in Bofr-DRA is concordant with the concept that the DRA gene is highly conserved among all mammals. The very high degree of conservativity of the DRA gene among ruminants, including gayal, suggests its recent evolutionary separation.

CDNA Cloning, Sequence Identification and Tissue Expression Distribution of Three Novel Genes: DFP, ITM2B and PQLC1 from Black-Boned Sheep (Ovis Aries)

ABSTRACT The complete coding sequences of three of Black-boned sheep (Ovis aries) genes DFP, ITM2B and PQLC1 were amplified using the reverse transcriptase polymerase chain reaction (RT-PCR) according to the conserved sequence information of the cattle or other mammals and known highly homologous sheep ESTs. Black-boned sheep DFP gene encodes a protein of 213 amino acids which contains the conserved putative DNA/pantothenate metabolism flavoprotein domain and has high homology with the DFP proteins of four species: cattle (99%), dog (91%), human (88%) and zebrafish (53%). Black-boned sheep ITM2B gene encodes a protein of 266 amino acids that contains the conserved putative BRICHOS domain and has high similarity with the ITM2B proteins of five species: cattle (98%), human (95%), mouse (94%), rat (94%) and pig (94%). Black-boned sheep PQLC1 gene encodes a protein of 253 amino acids that contains the conserved putative PQ-loop repeat domain and has high homology with the PQLC1 proteins of four species: cattle (99%), human (91%), mouse (90%) and rat (84%). The phylogenetic tree analysis demonstrated that Black-boned sheeps DFP, ITM2B andPQLC1 proteins have a close relationship with cattle. The tissue expression analysis indicated that Black-boned sheep DFP, ITM2B and PQLC1 genes were expressed in a range of tissues including leg muscle, kidney, skin, longissimus dorsi muscle, spleen, heart and liver. Our experiment is the first to provide the primary foundation for further insight into these three sheep genes.

The irp2 Genes in High Pathogenicity Islands are Involved in the ROS Generation and Increases Antioxidase Levels in the PMNs Caused by Porcine Pathogenic Escherichia coli

Polymorphonuclear leukocytes (PMNs) release large quantities of reactive oxygen species (ROS) to kill pathogens. Escherichia coli (E. coli) strains containing a Yersinia high-pathogenicity island (HPI) display increased virulence that is attributable to increased iron scavenging activity, which enhances bacterial growth and limits the availability of iron for use by innate immune cells. ROS generation requires the catalysis of iron. The irp2 gene has been confirmed to be the main gene involved in the synthesis of HPI. In the present study, the effect of pathogenic HPI-positive Yunnandominant (O152) E. coli strains on the respiratory oxidative stress response from PMNs in Yunnan Saba pigs were not explored. The results showed that E. coli containing the HPI can reduce ROS generation by competitively consuming iron in the surrounding environment, while inducing high levels of antioxidases in PMNs. We discovered a novel mechanism by which the HPI protects E.coli from ROS and enhances its virulence in PMNs. These results increase our understanding of the interaction between pathogenic E. coli and host PMNs in Saba pigs.