Acanthopanax senticosus cultures fermented by Lactobacillus rhamnosus enhanced immune response through improvement of antioxidant activity and inflammation in crucian carp (Carassius auratus).

Lactic acid bacteria (LAB) have been recognized as safe microorganism that improve micro-flora disturbances and enhance immune response. A well-know traditional herbal medicine, Acanthopanax senticosus (As) was extensively utilized in aquaculture to improve growth performance and disease resistance. Particularly, the septicemia, skin wound and gastroenteritis caused by Aeromonas hydrophila threaten the health of aquatic animals and human. However, the effects of probiotic fermented with A. senticosus product on the immune regulation and pathogen prevention in fish remain unclear. Here, the aim of the present study was to elucidate whether the A. senticosus fermentation by Lactobacillus rhamnosus improve immune barrier function. The crucian carp were fed with basal diet supplemented with L. rhamnosus fermented A. senticosus cultures at 2 %, 4 %, 6 % and 8 % bacterial inoculum for 8 weeks. After trials, the weight gain rate (WGR), specific growth rate (SGR) were significantly increased, especially in LGG-6 group. The results confirmed that the level of the CAT, GSH-PX, SOD, lysozyme, and MDA was enhanced in fish received with probiotic fermented product. Moreover, the L. rhamnosus fermented A. senticosus cultures could trigger innate and adaptive immunity, including the up-regulation of the C3, C4, and IgM concentration. The results of qRT-PCR revealed that stronger mRNA transcription of IL-1ß, IL-10, IFN-γ, TNF-α, and MyD88 genes in the liver, spleen, kidney, intestine and gills tissues of fish treated with probiotic fermented with A. senticosus product. After infected with A. hydrophila, the survival rate of the LGG-2 (40 %), LGG-4 (50 %), LGG-6 (60 %), LGG-8 (50 %) groups was higher than the control group. Meanwhile, the pathological damage of the liver, spleen, head-kidney, and intestine tissues of probiotic fermentation-fed fish could be alleviated after pathogen infection. Therefore, the present work indicated that L. rhamnosus fermented A. senticosus could be regard as a potential intestine-target therapy strategy to protecting fish from pathogenic bacteria infection.

Detection of changes in biological characteristics of Aeromonas veronii TH0426 after deletion of lsrB gene by homologous recombination.

Aeromonas veronii is a widespread pathogenic microorganism that can infect humans, animals, and a variety of aquatilia, at the same time, can cause diseases, mainly sepsis and ulcer syndrome. In this research, we first deleted the gene of lsrB's nucleotide sequences by homologous recombination. The results showed that the median lethal dose (LD50) of the mutant strain (ΔlsrB) for zebrafish was 1.28-times higher than that of the TH0426 strain. The toxicity of TH0426 to epithelioma papulosum cyprini (EPC) cells was 1.15-times and 1.64-times higher than that of ΔlsrB, 1 and 2 h after infection. The production ability of the biofilm of ΔlsrB decreased by 1.38-times, and the adhesion ability of ΔlsrB to EPC cells greatly decreased by 1.96-times than the TH0426. The result of motility detection pointed out that the swimming ability of ΔlsrB was down by 1.67-times. The results indicated that almost all of them lost their flagella after deleting the lsrB gene. In general, the virulence of TH0426 was reduced after deleting the lsrB gene. The final results point out that the lsrB gene of TH0426 is related to motility, biofilm formation, adhesion, and virulence.

Transcriptomic insights into the immune response of the intestine to Aeromonas veronii infection in northern snakehead (Channa argus).

Intestinal inflammation is a protective response that is implicated in bacterial enteritis triggered by gastrointestinal infection. The immune mechanisms elicited in teleost against the infection of Aeromonas veronii are largely unknown. In this study, we performed a de novo northern snakehead (Channa argus) transcriptome assembly using Illumina sequencing platform. On this basis we performed a comparative transcriptomic analysis of northern snakehead intestine from A. veronii-challenge and phosphate buffer solution (PBS)-challenge fish, and 2076 genes were up-regulated and 1598 genes were down-regulated in the intestines infected with A. veronii. The Gene Ontology (GO) enrichment analysis indicated that the differentially expressed genes (DEGs) were enriched to 27, 21 and 20 GO terms in biological process, cellular component, and molecular function, respectively. A Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that 420 DEGs were involved in 194 pathways. Moreover, 33 DEGs were selected for quantitative real-time PCR analysis to validate the RNA-seq data. The results reflected the consistency of the expression levels between qRT-PCR and RNA-seq data. In addition, a time-course analysis of the mRNA expression of 33 immune-related genes further indicated that the intestinal inflammation to A. veronii infection simultaneously regulated gene expression alterations. The present study provides transcriptome data of the teleost intestine, allowing us to understand the mechanisms of intestinal inflammation triggered by bacterial pathogens. DATA AVAILABILITY STATEMENT: All data supporting the findings of this study are available within the article and Supplementary files. The RNA-seq raw sequence data are available in NCBI short read archive (SRA) database under accession number PRJNA615958.

A phage cocktail in controlling phage resistance development in multidrug resistant Aeromonas hydrophila with great therapeutic potential.

Aeromonas hydrophila (A. hydrophila) is an opportunistic pathogen of fish-human-livestock, which poses a threat to the development of aquaculture. Lytic phage has long been considered as an effective bactericidal agent. However, the rapid development of phage resistance seriously hinders the continuous application of lytic phages. In our study, a new bacteriophage vB_ AhaP_PZL-Ah8 was isolated from sewage and its characteristics and genome were investigated. Phage vB_ AhaP_PZL-Ah8 has been classified as the member of the Podoviridae family, which exhibited the latent period was about 30 min. As revealed from the genomic sequence analysis, vB_ AhaP_PZL-Ah8 covered a double-stranded genome of 40,855 bp (exhibiting 51.89% G + C content), with encoding 52 predicted open reading frames (ORFs). The results suggested that the combination of vB_ AhaP_PZL-Ah8 and another A. hydrophila phage vB_ AhaP_PZL-Ah1 could improve the therapeutic efficacy both in vitro and in vivo. The resistance mutation frequency of A. hydrophila cells infected with the mixture phage (vB_ AhaP_PZL-Ah8+ vB_ AhaP_PZL-Ah1) was significantly lower than cells treated with single phage (P <0.01). Phage therapy in vivo showed that the survival rate in the mixture phage treatment group was significantly higher than that in single phage treatment group.

Immune enhancement effects of inactivated vaccine against extracellular products of Aeromonas caviae AC-CY on crucian carp.

Aeromonas caviae is a zoonotic pathogen that can cause disease in aquatic organisms and mammals, including humans, and it is widespread in nature, especially in freshwater environments. Previous research has reported that extracellular products (ECPs) secreted by pathogens during growth are effective protective antigens that can induce the host immune response and protect the host from pathogens. However, little is known about how ECPs enhance immunity. Here, we prepared extracellular products by the cellophane plate method, determined the total protein concentration, and analysed the protein composition of the extracellular products by SDS-PAGE. Subsequently, their enzyme activity and pathogenicity were evaluated separately. Crucian carp were randomly divided into four groups to receive formalin-inactivated A. caviae vaccine (FKC), ECPs mixed with the same amount of Freund's complete adjuvant, the same amount of ECPs mixed with an equal volume of A. caviae inactivated vaccine (FKC + ECPs), sterile PBS alone via intraperitoneal injection. On Days 7, 14, 21, and 28 after immunization, the expression levels of IgM, SOD, and CAT and the lysozyme (LYS) activity in the serum were detected by ELISA, and the relative expression levels of the TNF-α, IFN-γ, IL-1ß, and IL-10 genes in the liver, kidney, spleen, intestine, and gills were measured by qPCR. The extracellular products generated five clearly visible protein bands and exhibited lipase, protease, amylase, DNase and lysozyme but no urease or lecithinase activities. In addition, the median lethal doses of A. caviae and ECPs to crucian carp were 411.64 µg/fish and 1.6 × 105 CFU/mL, respectively. Compared with those of the control group, the IgM, SOD, and CAT contents and serum LYS activity were significantly increased in the experimental groups, and the qRT-PCR results showed that the relative expression levels of TNF-α, IFN-γ, IL-1ß, and IL-10 genes in the liver, kidney, spleen, and intestine were significantly increased after injection immunization. In addition, the relative immune protection rates of the three experimental groups were 60%, 65%, and 45%, all of which were significantly higher than those of the control group. Collectively, our findings show that the extracellular products of A. caviae can be used as a vaccine to significantly improve the immune level of crucian carp and have obvious anti-infection ability. This may represent a promising approach to prevent and control infection by A. caviae and provides strong theoretical support for the development of new inactivated vaccines.

Characterization and genome analysis of two new Aeromonas hydrophila phages, PZL-Ah1and PZL-Ah8.

Aeromonas hydrophila (A. hydrophila) is an opportunistic pathogen of fish, humans, and livestock, and has a severe negative impact on aquaculture development. Phage therapy is considered an alternative strategy for controlling bacterial infections and contamination. In this study, we isolated and characterized the genomes of two A. hydrophila-specific phages, PZL-Ah1 and PZL-Ah8, which, based on transmission electron microscopy, were identified as members of the family Podoviridae. Both of these phages had a relatively narrow host range, with lytic activity against Aeromonas spp. strains. Whole-genome sequence analysis revealed that PZL-Ah1 and PZL-Ah8 have a double-stranded DNA genome of 38,641 bp and 40,855 bp in length, with a GC content of 53.68% and 51.89%, respectively. Forty-four open reading frames (ORFs) were predicted in PZL-Ah1, and 52 were predicted in PZL-Ah8. Twenty-eight (63.6%) ORFs in PZL-Ah1 and 29 (55.8%) ORFs in PZL-Ah8 were predicted to encode functional proteins with homologs in the NCBI database, while the remaining ORFs were classified as encoding hypothetical proteins with unknown functions. A comparison with known phage genes suggested that ORF 02, ORF 29, and ORF 04 of PZL-Ah1 and ORF 2 and ORF 4 of PZL-Ah8 are involved in host cell lysis. This study expands the phage genome database and provides good candidates for phage typing applications.

Toxoplasma gondii infection in pet cats and their owners in northeastern China:an important public health concern.

BACKGROUND: Limited information about Toxoplasma gondii infection in pet cats and their owners is available in China. METHODS: In this study, blood samples were randomly collected from 306 pet cats and 397 corresponding pet owners in Jilin province, northeastern China. Sera from the pet cats and the pet owners were tested for anti-T. gondii antibodies using an modified agglutination test (MAT) and an enzyme-linked immunosorbent assay (ELISA), respectively. Moreover, the risk factors for T. gondii infection in pet cats and corresponding pet owners were explored. RESULT: In total, 62 sera out of 306 examined pet cats (20.3%) and 18.1% (72/397) pet cat owners were seropositive for T. gondii, respectively. The results of statistical analysis showed that both pet cats and their owners from rural area had significantly higher T. gondii seroprevalence than those from urban area (p < 0.001). Moreover, owners of pet cas who have the knowledge of zoonotic protozoan diseases had a significantly lower T. gondii seroprevalence than those without the knowledge of zoonotic protozoan diseases (p < 0.001). CONCLUSIONS: The present results revealed that the seroprevalence of T. gondii infection are widespread in pet cats and their owners in Jilin province, northeastern China. Residence area and understanding knowledge of zoonotic protozoan diseases are considered to be raleted to the T. gondii infection. Hence, it is necessary to highlight the dangers and protection methods of zoonotic protozoan diseases caused by pet cats, especially in rural area.

Essential role of ascO for virulence of Aeromonas veronii and inducing apoptosis.

Aeromonas veronii is a significant pathogen that is capable of infecting humans, animals, and aquatic animals. The type III secretion system (T3SS) is intimately associated with bacterial pathogenicity. The ascO gene is an important core component of T3SS in A. veronii, but its function is still unclear. The ascO gene of A. veronii TH0426 was deleted by using the pRE112 suicide plasmid to study its function. The study results showed that the ability of ∆ascO to adhere and invade EPC cells was significantly reduced by 1.28 times. The toxicity of the mutant strain ΔascO to EPC cells was consistently significantly lower than wild-type strain TH0426 at 1, 2, and 4 h. The LD50 values of ∆ascO against zebrafish and Carassius auratus (C. auratus) were 53 and 15 times that of the wild-type strain. In addition, the bacterial load of the mutant strain ΔascO in blood, heart, liver, and spleen was lower than wild-type strain TH0426. The Hoechst staining showed that the apoptotic degree of EPC cells induced by the mutant strain ΔascO was lower than that of the wild-type strain TH0426. Furthermore, real-time quantitative PCR (RT-qPCR) analysis revealed lower expression levels of pro-apoptotic genes (including cytC, cas3, cas9, TNF-α, and IL-1ß) in C. auratus tissues infected with the mutant strain ΔascO compared to the wild-type strain TH0426. The results of in vivo and in vitro experiments have shown that ascO gene mutation can reduce the adhesion and toxicity of A. veronii to EPC and reduce the level of apoptosis induced by A. veronii. As a result, these insights will help further elucidate the function of the ascO gene and thus contribute to understanding the pathogenesis of A. veronii.

Functional analysis of fis in Aeromonas veronii TH0426 reveals a key role in the regulation of virulence.

Aeromonas veronii is a comorbid pathogen that can infect humans, and animals including various aquatic organisms. In recent years, an increasing number of cases of A. veronii infection has been reported, indicating serious risks. This bacterium not only threatens public health and safety but also causes considerable economic loss in the aquaculture industry. Currently, some understanding of the pathogenic mechanism of A. veronii has been obtained. In this study, we first constructed the A. veronii TH0426 fis gene deletion strain Δfis and the complementation strain C-fis through homologous recombination technology. The results showed that the adhesion and invasion ability of the Δfis strain towards Epithelioma papulosum cyprini (EPC) cells and the cytotoxicity were 3.8-fold and 1.38-fold lower, respectively, than those of the wild-type strain. In the zebrafish infection model, the lethality of the deleted strain is 3-fold that of the wild strain. In addition, the bacterial load of the deletion strain Δfis in crucian carp was significantly lower than the wild-type strain, and the load decreased with time. In summary, deletion of the fis gene led to a decrease in the virulence of A. veronii. Our research results showed that the deletion of the fis gene significantly reduces the virulence and adhesion ability of A. veronii TH0426. Therefore, the fis gene plays a vital role in the pathogenesis of A. veronii TH0426. This preliminary study of the function of the fis gene in A. veronii will help researchers further understand the pathogenic mechanism of A. veronii.

First detection of anti-Toxoplasma gondii antibodies in domestic goat's serum and milk during lactation in China.

Goat milk is considered as one of the most suitable substitute for human milk, especially for children, the aged and those with cow milk allergies. Consumption of raw or unpasteurized goat milk has been known to be a potential route of Toxoplasma gondii infection for human beings. However, no studies have been carried out to detect T. gondii in goat milk in China. Thus, this stuy was firstly carried out to detect T. gondii IgG antibody in domestic goat's serum and milk during lactation by a commercial validated ELISA kit in China. In total, 10.49% (66/629) serum samples and 9.70% (61/629) milk samples randomly collected from Shandong and Jilin provinces were seropositive for anti-T. gondii IgG, respectively. A high correlation of S/P% value was obtained between serum and milk samples (Spearman's coefficient = 0.891, p-value <0.001 and Kendall's tau = 0.724, p-value < 0.001). Statistical analysis showed that history of abortion, source of water and source of fodder were considered to be highly related to the T. gondii infection in the investigated domestic goats. The present results provide important information for the control and prevention of toxoplasmosis in goats and human beings in China.

Comparative genomic analysis of different virulence strains reveals reasons for the increased virulence of Aeromonas veronii.

Aeromonas veronii is an important zoonotic and aquatic agent. More and more cases have shown that it has caused huge economic losses in the aquaculture industry in addition to threatening human health. But the reasons for the increasing virulence of A. veronii are still unclear. In order to further understand the reasons for the increased virulence of A. veronii, we conducted a comparative analysis of the genomes of A. veronii with different virulence. The analysis revealed that there are multiple virulence factors, such as those related to fimbriae, flagella, toxins, iron ion uptake systems and type II, type III and type VI secretion systems in the virulent strain TH0426 genome. And comparative analysis showed that there were two complete type III secretion systems (API1 and API2), of which the API2 and iron ion transport system were unique to the TH0426 strain. In addition, TH0426 strain also has unique functional gene clusters, which may play important roles in terms of resisting infection, adapting to different environments and genetic evolution. These particular virulence factors and gene clusters may be the important reasons for the increased virulence. These insights will provide a reference for the study of the pathogenesis of A. veronii.

Inactivation of the T6SS inner membrane protein DotU results in severe attenuation and decreased pathogenicity of Aeromonas veronii TH0426.

BACKGROUND: The inner membrane protein DotU of Aeromonas veronii is an important component of the minimal core conserved membrane proteome required for the formation of an envelope-transmembrane complex. This protein functions in a type VI secretion system (T6SS), and the role of this T6SS during the pathogenic process has not been clearly described. RESULTS: A recombinant A. veronii with a partial disruption of the dotU gene (720 bp of the in-frame sequence) (defined as ∆dotU) was constructed by two conjugate exchanges. We found that the mutant ∆dotU allele can be stably inherited for more than 50 generations. Inactivation of the A. veronii dotU gene resulted in no significant changes in growth or resistance to various environmental changes. However, compared with the wild-type strain colony, the mutant ∆dotU colony had a rough surface morphology. In addition, the biofilm formation ability of the mutant ∆dotU was significantly enhanced by 2.1-fold. Conversely, the deletion of the dotU gene resulted in a significant decrease in pathogenicity and infectivity compared to those of the A. veronii wild-type strain. CONCLUSIONS: Our findings indicated that the dotU gene was an essential participant in the pathogenicity and invasiveness of A. veronii TH0426, which provides a novel perspective on the pathogenesis of TH0426 and lays the foundation for discovering potential T6SS effectors.

Cadaverine reverse transporter (CadB protein) contributes to the virulence of Aeromonas veronii TH0426.

Aeromonas veronii is one of the main pathogens causing sepsis and ulcer syndrome in freshwater fish. Analysis of the results of epidemiological investigations in recent years has revealed that the virulence of A. veronii and its tolerance to drugs have been increasing year by year. Currently, most of the research on A. veronii focuses on its isolation, identification, and drug susceptibility, whereas research on its virulence factors and pathogenesis mechanisms is relatively rare. In this study, we identified and obtained the highly expressed TH0426 cadaverine reverse transporter (CadB) of A. veronii. We used efficient suicide plasmid-mediated homologous recombination to delete the cadB gene in TH0426 and constructed a cadB deletion strain. The LD50 of ΔcadB was 93.2 times higher than that of TH0426 in zebrafish, the toxicity of ΔcadB was 9.5 times less than that of TH0426 in EPC cells, and the biofilm formation ability of ΔcadB was 5.6-fold greater than that of TH0426. In addition, motility detection results indicated that ΔcadB had lost its swimming ability. The results of flagellar staining and TEM demonstrated that ΔcadB shed the flagella. In summary, the virulence and adhesion of A. veronii TH0426 were significantly decreased by the deletion of cadB, which might provide a theoretical basis for research into A. veronii virulence factors.

An iTRAQ-Based Comparative Proteomics Analysis of the Biofilm and Planktonic States of Aeromonas veronii TH0426.

Aeromonas veronii is a virulent fish pathogen that causes extensive economic losses in the aquaculture industry worldwide. In this study, a virulent strain of A. veronii TH0426 was used to establish an in vitro biofilm model. The results show that the biofilm-forming abilities of A. veronii TH0426 were similar in different media, peaking under conditions of 20 °C and pH 6. Further, isobaric tags for relative and absolute quantitation (iTRAQ)-based quantitative proteomics methods were used to compare the differential expression of A. veronii between the biofilm and planktonic cells. The results show alterations in 277 proteins, with 130 being upregulated and 147 downregulated. Pathway analysis and GO (Gene Ontology) annotations indicated that these proteins are mainly involved in metabolic pathways and the biosynthesis of secondary metabolites and antibiotics. These proteins are the main factors affecting the adaptability of A. veronii to its external environment. MRM (multiple reaction 27 monitoring) and qPCR (qPCR) were used to verify the differential proteins of the selected A. veronii. This is the first report on the biofilm and planktonic cells of A. veronii, thus contributing to studying the infection and pathogenesis of A. veronii.

Herd-level prevalence and associated risk factors for Toxoplasma gondii, Neospora caninum, Chlamydia abortus and bovine viral diarrhoea virus in commercial dairy and beef cattle in eastern, northern and northeastern China.

Although the seroprevalence of Toxoplasma gondii, Neospora caninum, Chlamydia abortus and bovine viral diarrhea virus infection in cattle have been reported in some areas in China, most of them were conducted with small number of cattle samples and very limited districts and neglected the assessment of herd management factors associated with herd-level prevalence of these pathogen infections. Thus, from September 2013 to December 2014, a large-scale seroprevalence study was conducted to determine the animal-level and herd-level seroprevalence and identify herd-level risk factors associated with these pathogen infections in 4487 cattle from 134 herds in five provinces (Heilongjiang, Jilin, Liaoning, Shandong, Hebei) and Inner Mongolia Autonomous Region of China. At animal level, the true prevalence of antibodies against T. gondii, N. caninum, C. abortus and bovine viral diarrhoea virus (BVDV) was 10.48, 17.14, 11.92 and 50.10%, respectively. At herd level, the true prevalence of antibodies against T. gondii, N. caninum, C. abortus and BVDV was 27.16, 29.10, 37.31 and 40.30%, respectively. Multivariate analysis of these characteristics showed that source of water and presence of felids were significantly associated with T. gondii infection in the studied cattle herds. Source of water was significantly associated with N. caninum infection in the studied cattle herds. While herd size and management system were significantly associated with BVDV infection in the studied cattle herds, this is the first report of herd-level prevalence and associated risk factors of T. gondii, N. caninum, C. abortus and BVDV infection in cattle in China.

Seroprevalence and risk factors associated with hepatitis E virus infection in three species of pet birds in northwest China.

Hepatitis E virus (HEV), the causative agent of hepatitis E, has been reported in a wide variety of animals, including birds, but little is known of HEV infection in pet birds in northwest China. The objective of the present investigation was to examine HEV seroprevalence in three species of pet birds, namely, Eurasian siskin, Oriental skylark, and black-tailed grosbeak from Gansu. Serum samples collected from 685 pet birds from August 2011 to September 2012 were examined independently for the presence of antibodies against HEV. A total of 59 (8.31%) pet birds were tested positive for HEV antibodies by the commercially available enzyme immunoassay kits. Of these, the seroprevalence was diverse in different species pet birds; the most frequent level was 10.83% (39/360) in Eurasian siskin, followed by 6.57% (19/289) in Oriental skylark, and 2.29% (1/36) in black-tailed grosbeak. Age and collecting region of pet birds were the main risk factors associated with HEV infection. The present study firstly revealed the seroprevalence of HEV infection in three species of pet birds in northwest China, which provided the baseline data for taking comprehensive countermeasures and measures for effectively preventing and controlling HEV infection in birds.

Effect of high-pathogenicity island (HPI) on TGF-ß1/Smad3 pathway in mouse model of E. coli strains causing diarrhea in calf.

PURPOSE: This study evaluated pathogenic effect of TGF-ß1/Smad3 pathway in mouse model after infecting them with HPI+ and HPI- strains of Escherichia coli (E. coli) which were isolated from diarrhea in calves. METHODS: Kunming mice were randomly divided into 3 groups: a control group, HPI+-infection group and HPI--infection group. After intraperitoneal injection of HPI strains of E. coli (concentration: 3 × 108 cfu/mL) in mice, alanine aminotransferase (ALT) and aspartate aminotransferase (AST), tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) contents were detected at 12 h post infection. The sections of liver and kidney were obtained for histopathological observations. Propidium iodide and 4',6-diamidino-2-phenylindole (DAPI) staining was used to analyze the cell apoptosis. The immunohistochemistry staining and quantitative real time PCR (q-PCR) were performed for evaluating the protein and mRNA expression of TGF-ß1, Collagen I and Smad3. The histological change and PI staining of liver and kidney showed significant injuries. Compared with the control group, the serum ALT and AST activities and TNF-α and IL-6 contents of mice in the HPI+ and HPI- groups were increased, number of apoptotic cells and expression of TGF-ß1, Collagen Iand Smad3 were up-regulated after E. coli infection in liver and kidney, which was significantly increased in HPI+-infected compared to HPI-. CONCLUSION: The study concludes that E. coli HPI induced and enhanced the over expression of TGF-ß1/Smad3 pathway and ultimately caused pathological anomalies.

Bacteriophage Therapy as an Application for Bacterial Infection in China.

Antibiotic resistance has emerged as a significant issue to be resolved around the world. Bacteriophage (phage), in contrast to antibiotics, can only kill the target bacteria with no adverse effect on the normal bacterial flora. In this review, we described the biological characteristics of phage, and summarized the phage application in China, including in mammals, ovipara, aquatilia, and human clinical treatment. The data showed that phage had a good therapeutic effect on drug-resistant bacteria in veterinary fields, as well as in the clinical treatment of humans. However, we need to take more consideration of the narrow lysis spectrum, the immune response, the issues of storage, and the pharmacokinetics of phages. Due to the particularity of bacteriophage as a bacterial virus, there is no unified standard or regulation for the use of bacteriophage in the world at present, which hinders the application of bacteriophage as a substitute for antibiotic biological products. We aimed to highlight the rapidly advancing field of phage therapy as well as the challenges that China faces in reducing its reliance on antibiotics.

Toxoplasma gondii Antibodies in Raw Milk and Sera of Cows in China.

Toxoplasma gondii is a worldwide food-borne protozoa that has harmful influences on animal and human health. Raw milk containing T. gondii has been considered as one of the possible infectious sources for humans. Although China is one of the world's leading milk consumers, there is still no study to investigate the seroprevalence of T. gondii in raw cow milk in China; especially for cows in rural areas. Thus, we conducted this study to examine the specific anti-T. gondii IgG-antibody in the raw milk and sera of domestic cows in China. In total, 894 cows were randomly selected from rural areas in northeastern China. The positive rate of T. gondii in the milk and serum samples were 6.38% (57/894) and 7.16% (64/894), respectively. Moreover, a history of abortion (OR = 2.03, 95% CI: 1.11-3.72, p = 0.022) was identified as the only risk factor for T. gondii infection in the studied cows. This study investigated the seroprevalence of T. gondii in the raw milk and sera of cows in China; it provided timely and useful data for public health and food safety, especially in rural areas.

Functional analysis of ascP in Aeromonas veronii TH0426 reveals a key role in the regulation of virulence.

Aeromonas veronii is a pathogen which can induce diseases in humans, animals and aquatic organisms, but its pathogenic mechanism and virulence factors are still elusive. In this study, we successfully constructed a mutant strain (ΔascP) by homologous recombination. The results showed that the deletion of the ascP gene significantly down-regulated the expression of associated effector proteins in A. veronii compared to its wild type. The adhesive and invasive abilities of ΔascP to EPC cells were 0.82-fold lower in contrast to the wild strain. The toxicity of ΔascP to cells was decreased by about 2.91-fold (1 h) and 1.74-fold (2 h). Furthermore, the LD50 of the mutant strain of crucian carp was reduced by 19.94-fold, and the virulence was considerably attenuated. In contrast to the wild strain, the ΔascP content in the liver and spleen was considerably lower. The titers of serum cytokines (IL-8, TNF-α, and IL-1ß) in crucian carp after the infection of the ΔascP strain were considerably lower in contrast to the wild strain. Hence, the ascP gene is essential for the etiopathogenesis of A. veronii TH0426.