Duck sewage source coliphage P762 can lyse STEC and APEC.

Multiple pathogenic types or serotypes restrict treatment for colibacillosis. In addition, rising antibiotic resistance has heightened public awareness to prevent and control pathogenic Escherichia coli. The bacteriophage is a viable technique to treat colibacillosis as an alternative to antibiotics. P762, a coliphage isolated from duck farm sewage, was demonstrated to cloud lyse Shiga toxin-producing Escherichia Coli serotypes O157 and non-O157 (17/39), Avian pathogenic E. coli covered serotype O78, O83, and O9 (5/19), and other pathogenic Escherichia coli (5/17). Additional fundamental biological characteristics analysis revealed that P762 is stable at pH 3 ~ 11 and temperature between 4 °C and 60 °C, and its optimum multiplicity of infection (MOI) is 0.1. The one-step curve of P762 exhibited three bursts of growth stage: two rapid and one slow stage. Furthermore, the first rapid burst size is 80 CFU/PFU, the burst size of the slow stage is 10 CFU/PFU, and the second rapid burst size is about 990 CFU/PFU. In addition, P762 can form a "halo" on a double agar plate, implying that the phage secretes depolymerase. With 95.14% identity and 90% query coverage, genome sequence analysis revealed that P762 is most closely related to Escherichia phage DY1, which belongs to the genus Kayfunavirus. After screening using RAST and VFDB, no virulence factors were discovered in P762. In vitro antibacterial tests revealed that P762 has high bactericidal activity in lettuce leaves contaminated with STEC. In conclusion, phage P762 might be employed in the future to prevent and control pathogenic Escherichia coli.

Hepatocyte-Specific Deficiency of BAP31 Amplified Acetaminophen-Induced Hepatotoxicity via Attenuating Nrf2 Signaling Activation in Mice.

Liver-specific deficiency of B-cell receptor-associated protein 31 knockout mice (BAP31-LKO) and the littermates were injected with acetaminophen (APAP), markers of liver injury, and the potential molecular mechanisms were determined. In response to APAP overdose, serum aspartate aminotransferase and alanine aminotransferase levels were increased in BAP31-LKO mice than in wild-type controls, accompanied by enhanced liver necrosis. APAP-induced apoptosis and mortality were increased. Hepatic glutathione was decreased (1.60 ± 0.31 µmol/g tissue in WT mice vs. 0.85 ± 0.14 µmol/g tissue in BAP31-LKO mice at 6 h, p < 0.05), along with reduced glutathione reductase activity and superoxide dismutase; while malondialdehyde was significantly induced (0.41 ± 0.03 nmol/mg tissue in WT mice vs. 0.50 ± 0.05 nmol/mg tissue in BAP31-LKO mice for 6 h, p < 0.05). JNK signaling activation and APAP-induced hepatic inflammation were increased in BAP31-LKO mice. The mechanism research revealed that BAP31-deficiency decreased Nrf2 mRNA stability (half-life of Nrf2 mRNA decreased from ~1.3 h to ~40 min) and miR-223 expression, led to reduced nuclear factor erythroid 2-related factor 2 (Nrf2) signaling activation and antioxidant genes induction. BAP31-deficiency decreased mitochondrial membrane potentials, reduced mitochondria-related genes expression, and resulted in mitochondrial dysfunction in the liver. Conclusions: BAP31-deficiency reduced the antioxidant response and Nrf2 signaling activation via reducing Nrf2 mRNA stabilization, enhanced JNK signaling activation, hepatic inflammation, and apoptosis, amplified APAP-induced hepatotoxicity in mice.

Genome-wide association study identifies the virulence-associated marker in Streptococcus suis serotype 2.

Streptococcus suis (S. suis) has been reported to be a highly invasive pathogen in swine, which causes severe infections like meningitis, arthritis and septicemia, and also a zoonotic agent for humans. Although many putative virulence factors (VFs) have been identified, the exact and wildly accepted virulence associated marker and pathogenesis mechanism of S. suis are still unclear. To establish connection of the genotypes with virulence phenotypes, we performed an "internal standard" method based on the zebrafish model to assess the virulence phenotypes of S. suis and did the genome-wide association study (GWAS) based on the genomes of 68 S. suis isolates. Through GWAS, a total number of 172 genes were identified. Among these genes, 143 of them distribute in virulent isolates. Further VFs interaction network analysis based on protein-protein interaction database found that 71 genes identified in this study could interact with known VFs and some of them even played an important role as the bridge between known VFs or formed important hub. In addition, 12 genes were found conserved in virulent isolates and 3 genes were conserved in avirulent isolates, 8 genes of the virulent conserved genes were belonging to a srtBCD pili cluster. Considering that sbp2', a member of the srtBCD pili cluster has been reported as a virulence-associated factor, we predict that sbp2' could be a fitness virulence-associated marker of virulent isolates. Taken together, our findings contribute to the insights in S. suis pathogenesis, enhance the knowledge of the genomic evolution of S. suis and provide several novel virulence-associated candidates.

Evaluation of the immunogenicity and protective ability of a pili subunit, SBP2', of Streptococcus suis serotype 2.

Streptococcus suis is an important zoonotic pathogen that leads to huge economic losses in the swine industry. Because of the enormous genetic and phenotypic diversity within S. suis, it is necessary to develop effective vaccines to control this zoonotic pathogen. SBP2' is a major pili subunit in S. suis that belongs to an srtBCD pili cluster and has already been reported to be associated with the pathogenesis of this bacterium. In this study, we aimed to evaluate the immunogenicity and protective ability of SBP2'. The rSBP2' protein was expressed by an Escherichia coli expression system and emulsified with Montanide ISA 201 adjuvant to prepare the subunit vaccine. Through active immune assays, the results showed that rSBP2' exhibited good immunogenicity and could protect mice from a lethal dose challenge. Additionally, the qRT-PCR data showed that the transcription levels of cytokines associated with systemic symptoms caused by S. suis were decreased, indicating that immunization with rSBP2' could protect the host from cytokine storms caused by S. suis. Furthermore, the passive immune assay showed that the humoral immunity induced by rSBP2' played an important role against S. suis infection. Taken together, SBP2' could provide proper immune protection against S. suis challenge and could be a candidate for S. suis subunit vaccine. The results of this study could provide new ideas for the development of effective vaccines against S. suis.

Identification of novel fibronectin-binding proteins by 2D-far Western blot in atypical enteropathogenic Escherichia coli serotype O55:H7.

Atypical enteropathogenic Escherichia coli (aEPEC) is a subgroup of EPEC, which is one of the major pathogens responsible for fatal diarrhoea in children. Compared with typical EPEC (tEPEC), aEPEC lack an EAF (EPEC adherence factor) plasmid (pEAF), which encodes a series of virulence-associated genes. The extracellular matrix (ECM) component of human cells has been reported to be an important element in the interaction between host and bacterial pathogens. In this research, a 2D-Far Western blot method was performed to identifiy the bacterial proteins that could bind to fibronectin, one of the most common constituents of ECM. A total of 17 protein spots were identified, including 4 outer membrane proteins (OMPs), namely, OmpC, OmpD, OmpX and LamB. In vitro studies were used to determine whether these OMPs were involved in the adherence process. Through indirect immunofluorescence assays, four OMPs could be observed on the surfaces of host cells. After incubating the cells with the recombinant proteins, the adhesion rate of the O55:H7 isolate was decreased. Furthermore, the deletion of OmpX and LamB can also decrease the adhesion rate of WT. Taken together, a high-throughput screening method for host ECM-binding proteins based on 2D Far-Western blot was established, and four outer membrane proteins identified by this method were found to be involved in the adherence process.