Akkermansia muciniphila, a major gut microorganism, has garnered significant attention for its involvement in the regulation of glucose and lipid metabolism. Glucose and lipid metabolic disorders, characterized by hyperglycemia and dyslipidemia, are caused by multiple factors. These disorders are not only prevalent globally but also increasingly common among young people in China, representing a major public health concern. This review systematically elaboratesthe research progress in A. muciniphila and glucose and lipid metabolism from the perspective of its mechanisms of action. Specifically, the review summarizes the regulatory pathways through which A. muciniphila influence glucose and lipid metabolism, assesses how pharmaceuticals that enhance A. muciniphila abundance affect metabolic parameters, and discusses advances in the bioengineering of A. muciniphila. By synthesizing current research findings, this review aims to provide valuable insights for understanding glucose and lipid metabolic disorders and developing novel therapeutic approaches for related diseases.

[Objective] To prepare secretory IgA (sIgA) antibody against foot-and-mouth disease virus (FMDV) and provide a new idea and basis for the comprehensive prevention and control of foot-and-mouth disease (FMD). [Methods] We constructed an eukaryotic expression plasmid harboring the heavy chain of IgA antibody by replacing the constant region gene of heavy chain of IgG with the codon-optimized corresponding region of IgA based on POA-8, a previously screened IgG neutralizing antibody capable of neutralizing both type O and type A FMDV. At the same time, the eukaryotic expression plasmids harboring the J chain and secretory component (SC) of pigs as well as the eukaryotic expression plasmid containing heavy chain, light chain, and J chain genes were constructed respectively. CHO-S cells were transiently co-transfected with 4 plasmids (heavy, light, J, and SC) or 2 plasmids (heavy+light+J and SC) for assembling and expression of sIgA antibody. sIgA antibody was purified and identified by SDS-PAGE and Western blotting. The binding activity and neutralizing activity of sIgA antibody against FMDV were evaluated by indirect ELISA and virus neutralization assay. [Results] sIgA antibody against FMDV could be successfully assembled and expressed after transfection of CHO-S cells with 4 or 2 plasmids. The binding and neutralizing abilities of sIgA against type O and type A FMDV were stronger than those of IgG. [Conclusion] This study established an efficient expression system for sIgA against FMDV, laying a foundation for the development of mucosal vaccines and antiviral drugs against FMDV in the future.

[Objective] To investigate the antimicrobial resistance phenotypes and genomic characteristics of Salmonella Wandsworth isolates from fecal and bedding samples across four dairy farms in Jiangsu. [Methods] Serotyping was reconfirmed by the slide agglutination method, and antimicrobial susceptibility was determined via the Kirby-Bauer disk diffusion assay. Whole-genome sequencing was performed, followed by bioinformatics analysis to characterize multilocus sequence typing (MLST) profiles, antimicrobial resistance genes, and virulence genes. A phylogenetic tree was built based on core genome single nucleotide polymorphisms (SNPs) to assess genetic homology among strains and elucidate population evolutionary relationships between prevalent strains from diverse sources. [Results] Seven Salmonella Wandsworth isolates were identified, all exhibiting susceptibility to 14 tested antimicrobials. The isolates were identified as ST1498 by MLST, harboring the aminoglycoside resistance gene aac(6')-Iaa and 106 virulence genes spanning eight functional categories. The analysis of SNPs revealed high genetic homogeneity, with six isolates clustering closely and three isolates showing a difference of zero in SNPs. [Conclusion] This study isolated a rare ST1498-type Salmonella Wandsworth from dairy farms in Jiangsu. The isolates demonstrate susceptibility to all tested antimicrobials while harboring a resistance gene and multiple virulence genes. These findings highlight the necessity of enhanced Salmonella surveillance in dairy farms to mitigate potential epidemiological risks.

[Objective] To investigate the role of lmo2300 in oxidative stress resistance and infection of Listeria monocytogenes. [Methods] With L. monocytogenes 1/2 a serotype EGD-e as the parent strain, the lmo2300-deleted strain and complementary strain were constructed by homologous recombination. The growth, motility, oxidative stress resistance, minimum inhibitory concentration and reductase activity of Δlmo2300 were evaluated. The adhesion, invasion, proliferation, and intercellular migration abilities of the Δlmo2300 strain was assessed using cell models. The transcriptional levels of thioredoxin-related genes and major virulence genes in Δlmo2300 were detected with RT-qPCR. [Results] PCR identification and DNA sequencing confirmed the successful construction of Δlmo2300 and CΔlmo2300. Deletion of lmo2300 did not affect the bacterial growth, motility, antibiotic susceptibility, adhesion, invasion or intracellular proliferation. However, the Lmo2300 protein possesses reductase activity, and the transcriptional levels of the thioredoxin gene lmo1903 and grx are significantly upregulated in the Δlmo2300 mutant. And markedly improved resistance to oxidative substances, including H₂O₂, diamide, CdCl₂, and MnSO₄ compared with the wild type. The Δlmo2300 mutation significantly enhanced intercellular migration ability, accompanied by an approximately 8-fold upregulation of the actA gene transcription, which is consistent with the enhanced intercellular migration ability. [Conclusion] This study demonstrates that lmo2300 plays a critical role in modulating the oxidative stress resistance and intercellular migration of L. monocytogenes, providing novel insights into the infection biology and adaptive responses of L. monocytogenes to host-derived oxidative challenges.

The gut microbiota plays a pivotal role in regulating animal health, and its structure and function can be significantly modulated by fermented feed. However, the lack of cross-species comparative studies has hindered a comprehensive understanding of the universal mechanisms underlying fermented feed-mediated microbial regulation. [Objective] To integrate multi-species data for deciphering cross-species regulatory patterns of fermented feed on gut microbiota and elucidating universal functional optimization and host-specific mechanisms. [Methods] We aggregated 464 gut microbiome datasets from pigs, cattle, chickens, and geese. The alpha/beta diversity analyses, linear discriminant analysis effect size (LEfSe), BugBase, and network analyses were employed to assess the diversity, differentially enriched genera, pathogenicity, and interactions of the gut microbiota. [Results] Fermented feed markedly reduced the alpha diversity of gut microbiota in monogastric animals (pigs, chickens, and geese) but not in ruminants (cattle). Although the beta diversity of gut microbiota remained statistically stable in different animals, fermented feed enriched probiotics (e.g., Lactobacillus and Faecalibacterium) while suppressing pathogens (e.g., Campylobacter and Brachyspira) to significantly diminish the pathogenic potential. Network analysis revealed enhanced connectivity, increased network density, reduced modularity, and improved community synergy in fermented feed groups. Host-specific responses were identified: Lactobacillus dominated in pigs, Akkermansia in cattle, and Flavonifractor in chickens. [Conclusion] Fermented feed modulates gut microbiota through a pattern coupling consistent response optimization with host-specific responses, selectively enriching keystone taxa to improve the specific function and reduce the pathogenicity. This study provides theoretical foundations for developing host-tailored fermented feed strategies.

DNA methylation is an important way of epigenetic regulation in bacteria. Alphaproteobacteria methylate DNA by using the cell cycle-regulated DNA methyltransferase (CcrM). CcrM does not contain a functional unit of restriction endonuclease, thus belonging to an orphan methyltransferase. By methylating adenine in DNA sequences, CcrM influences the interaction between DNA and proteins, regulates the expression of numerous genes, and is crucial for the regulation of processes such as the cell cycle of Alphaproteobacteria. We reviewed the function, structure, and epigenetic regulation of CcrM, clarified the mechanisms of CcrM in DNA recognition, catalysis, and activity regulation, summarized the mechanism by which the global cell-cycle regulator (GcrA) utilizes the methylation signals produced by CcrM to regulate gene expression, and provided an outlook on the potential future research directions of CcrM, providing a reference for further in-depth study of the epigenetic regulation mechanisms in bacteria.

Saline-alkali soil is extensively distributed in the Songnen Plain of Northeast China, posing a major constraint on the grain yield. It has been demonstrated that endophytic bacteria of plants could promote plant growth and enhance plant tolerance to environmental stress. Agastache rugosa had been experimentally verified to exhibit strong salt tolerance. [Objective] To isolate and screen salt-alkali-tolerant endophytic bacteria from A. rugosa grown under high-salinity conditions and explore microbial resources for promoting plant growth under stress. [Methods] A. rugosa seedlings surviving under 200 mmol/L NaCl were selected to isolate endophytic bacteria by the tissue culture method. Salt-alkali tolerance of the endophytic bacteria was assessed by plate assays, and the plant growth-promoting and antimicrobial properties were also evaluated. [Results] A total of 95 endophytic bacterial strains were isolated from the leaves, stems, and roots of A. rugosa seedlings, of which 20 strains tolerated 15% NaCl and 14 strains could grow at pH 10.0. The selected elite salt-tolerant strains possessed plant growth-promoting properties such as indole-3-acetic acid (IAA) synthesis, siderophore production, and nitrogen fixation. Additionally, 18 strains showed resistance against three plant pathogens. The principal component analysis on plant growth-promoting properties, salt tolerance, and antimicrobial properties screened out strains YL-14, YS-35, and YR-18, which were molecularly identified as Bacillus sp. Under different salt stress conditions, three bacterial strains demonstrated significant growth-promoting effects on A. rugosa seedlings. Specifically, under 100 mmol/L salt stress, YL-14, YS-35, and YR-18 increased the seed germination rate by 5.5%, 8.5%, and 7.0% and the fresh root weight by 34.9%, 124.0%, and 127.0%, respectively. Strains YS-35 and YR-18 increased the main root length by 40.9% and 49.5%, respectively. [Conclusion] Endophytic bacterial strains YL-14, YS-35, and YR-18 with strong saline-alkali tolerance and plant growth-promoting properties were isolated from A. rugosa. These strains show great potential for development as bioinoculants and application in other crops to enhance crop stress resistance and growth, serving as new microbial resources for the utilization of saline-alkali soil.

Outbreaks and epidemics of RNA viruses represent a serious threat to human health. The retinoic acid-inducible gene-I (RIG-I)-like receptors (RLRs) signaling pathway plays a pivotal role in host resistance to viral infections. RLRs recognize the RNA produced after viral invasion, initiating the activation of the RLR signaling pathway to combat viral infection. Abnormal activation of this pathway is linked to the development of chronic inflammation, damage to immune organs, and autoimmune diseases. To prevent the disruption of RLR signaling pathway activation, the body has established a comprehensive regulatory system with the objective of stabilizing the RLR signaling pathway. Protein methylation represents a significant post-translational modification of proteins, playing a pivotal role in numerous biological processes. The methylation of molecules in the RLR signaling pathway has been demonstrated to be indispensable for the body to regulate the RLR signaling pathway. This paper presents a comprehensive review of the latest research findings on the role of protein methylation in regulation of the RLR signaling pathway, offering novel insights into the host regulation of the RLR signaling pathway in combatting viral infection.

Foot-and-mouth disease (FMD) is a highly contagious disease caused by foot-and-mouth disease virus (FMDV) in cloven-hoofed animals. FMDV is a single-stranded positive-sense non-enveloped RNA virus with icosahedral symmetry. FMDV can cause innate and adaptive immunity of the host, and it has evolved a variety of immune escape ways. The FMDV infection is a complicated process involving various host proteins. However, the related mechanisms remain largely unknown. Voltage dependent anion-selective channel 2 (VDAC2) is a mitochondrial channel protein, and the specific mechanism by which VDAC2 regulates FMDV replication remains unclear. [Objective] To confirm the regulatory effects between VDAC2 and FMDV and reveal the molecular mechanism by which VDAC2 inhibits FMDV replication. [Methods] The subcellular localization of VDAC2 was determined by the indirect immunofluorescence assay. The effects of FMDV on the translation and transcription levels of VDAC2 were determined by Western blotting and qPCR, respectively. The effect of VDAC2 overexpression on FMDV replication in BHK-21 cells was measured based on the virus titer. The effects of VDAC2 overexpression and knockdown on the levels of IL-1β, ISG15, OAS1, mtDNA, and gDNA during FMDV infection were evaluated by qPCR. [Results] VDAC2 was localized in the cytoplasm. FMDV infection down-regulated the expression of VDAC2. The overexpression of VDAC2 inhibited FMDV replication in a dose-dependent manner, while the knockdown of VDAC2 promoted FMDV replication. The overexpression of VDAC2 enhanced FMDV-induced interferon-I (IFN-I) response, while the knockdown of VDAC2 inhibited FMDV-induced IFN-I response. In addition, the overexpression of VDAC2 increased the release of mtDNA. [Conclusion] FMDV infection can downregulate the transcription and translation of VDAC2, as VDAC2 can exert antiviral effects by regulating mtDNA release and promoting the expression of antiviral factors such as IL-1β, ISG15, and OAS1. This study indicates that upon FMDV infection, host cells can regulate the virus replication by enhancing IFN-I response via VDAC2 to exert antiviral effects.

Legionnaires’ disease, a serious pulmonary infection caused by Legionella, requires early diagnosis for effective treatment and favorable outcomes. Laboratory diagnostic methods primarily encompass isolation and culture, antigen detection, nucleic acid detection, and serological testing. Although isolation and culture are considered the gold standard, it is characterized by low sensitivity and extended culture duration. Antigen detection offers simple and fast operation but necessitates improved specificity. Nucleic acid detection, although being highly sensitive, has complex operation and high costs. Serological testing provides limited value for early diagnosis. Urine antigen detection, extensively employed globally, is limited to the detection of Legionella pneumophila serogroup I. Novel nucleic acid detection technologies, including digital PCR, isothermal amplification, and next-generation sequencing, present promising applications. Future research should aim to develop more streamlined, rapid, and sensitive detection methods to enhance the early diagnostic rate of Legionnaires’ disease.