Mycothiol is the major low-molecular-mass thiol in M. tuberculosis, which plays an important role in maintaining redox homeostasis. Mycothiol acetyltransferase (MshD) finishes the synthesis process by transferring the acetyl group of Acetyl-CoA to the mycothiol precursor. In order to explore the role of MshD in M. tuberculosis, we constructed a MshD knockout strain with a phage vector-based homologous recombination technology. Compared with the wild strain H37Ra, the knockout had smaller colonies, slower growth rate, decreased biofilm, and was more sensitive to chemical challengers by 5 mmol/L H₂O₂, 0.05% SDS, 50 ℃ heat shock and hypoxic conditions. The above results indicated that the mshD gene played an important role in M. tuberculosis. This study laid the foundation for further revealing the function and mechanism of the gene.

Objective　To investigate the role of Hepatitis B surface antigen (HBsAg) in the immune escape of innate immunity by Hepatitis B virus (HBV).　Methods After treated with PMA, THP-1 was differentiated into macrophage- like cells. Macrophage- like cells were treated further with LPS and the pam3csk4 in the presence or absence of HBsAg. Cytokine IL-10 , IL-12 protein, IL-10, IL-12 mRNA levels , NF-κB p65 protein nuclear translocation as well as IκB-α degradation and ERK protein phosphorylation were detected to monitor the activation of the TLR signaling pathway. Results LPS and the pam3csk4 induced production of cytokine IL-10 , IL-12 protein, NF-κB p65 protein nuclear translocation as well as IκB-α degradation and ERK protein phosphorylation were inhibited by HBsAg in a dose-dependent manner. Conclusion HBsAg inhibit the activation of TLR2 and TLR4 signaling pathway.

Viruses have been classified into enveloped and non-enveloped subtypes according to their surface structures. The membrane proteins of the enveloped viruses are involved in the attachment, penetration, ncoating,
replication, and release of the viruses. The special membrane proteins are essential for the membrane fusion bywhich the enveloped viruses penetrate into host cells. Furthermore, structural data showthat class I and class II viral fusion proteins utilize a similar principle in membrane fusion. In addition, there are some viral membrane proteins, such as M2 of the influenza virus, Vpu of the human immunodeficiency virus type 1 ( HIV-1) , 3a of the severe acute respiratory syndrome coronavirus ( SARS-CoV) , among others, that have ion channel functions. The processes involved in viral membrane fusion and ion channel function provide newinsights into therapeutic design and proteins as potential targets of antivirals. Here we give three typical viral membrane fusion proteins as examples to reviewthe mechanisms of viral membrane fusion and viral ion channel function and the strategies of antiviral drug design.

Neutrophils can capture and kill pathogens by releasing neutrophil extracellular trap (NET) during anti-infection immunity. NET is a double-edged sword. On the one hand, it can maintain the homeostasis of the body; on the other hand, excessive NET or delayed removal may lead to the occurrence of some diseases. The mechanisms by which bacteria induce and resist NET are different. This article reviews the formation and release of NET and their roles in bacterial infection.

With the continuous improvement of people’s living standards, simply creating a comfortable air environment with suitable temperature and humidity can no longer meet the needs of people’s lives. Healthy and clean air quality has begun to become a focus of public concern. In recent years, SARS-CoV-2 has been raging around the world, and aerosol transmission as one of the infection routes deserves sufficient attention. Air purification and disinfection technology is of great significance in preventing the spread of pathogens such as bacteria and viruses. This article mainly introduces a variety of physical and chemical air purification and disinfection technologies in detail, points out the problems existing in the research and application of these technologies, and finally proposes the characteristics that ideal air purification and disinfection technologies in the future should have.

Tremendous advances have been made in developing oncolytic viruses in the last few years. Viral infection and amplification eventually induce cancer cells into cell death pathways and elicit host antitumor immune responses. Specifically targeted molecules or signaling pathways in cancer cells or in the tumor microenvironment have been studied and a variety of oncolytic viruses such as adenovirus, herpes simplex virus, poxvirus, measles virus, Newcastle disease virus and influenza virus have been identified. In this review, the characteristics of oncolytic viruses for cancer therapy are discussed.

Accumulating evidence indicates that the gut microbiota is closely linked with the development of obesity , insulin resistance and other metabolic diseases, with the detailed molecular mechanism being elucidated.The gut microbiota can not only regulate energy metabolism and promote excessive fat accumulation,but also act as one of the predisposing factors for driving the host systemic, low-grade chronic inflammationand subsequent insulin resistance and other metabolic disorders. The gut microbiota may become a new target for the prevention and treatment of obesity.

 

Microbial culture, ELISA, nucleic acid testing are the main methods for clinic microbial testing today. An effective method for microbial enrichment not only will be helpful on optimizing the sensitivity of the follow-up testing, but also will determine the availability of some testing methods when the amount of microorganisms are extremely low in the sample. The research progress on microbial enrichment methods and its applications are reviewed and discussed in this report.

Autophagy is an important form of programmed cell death that regulates the growth and development of cells. It acts as a ‘two-edge sword’. On one side, autophagy eliminates microbes; on the other, many bacteria have developed distinct mechanisms to regulate and interfere with autophagy for their own replication and survival. Autophagy is an important event in the innate immune response. It can initiate a response to bacteria and bacterial toxins through Toll-like receptor mechanisms or mucosal immune system. Effector cells of the cellular immune system can regulate autophagy by secreting different cytokines, allowing the organism to re-tune its adaptive immune response. Autophagy may play a pivotal role in regulating the immune polarization of Th1/Th2 in fighting intracellular bacteria.

Objective To investigate the antimicrobial resistance of enterococcus faecalis and enterococcus faecium in our hospital for the rational use of antibiotic. Methods GPI plate was applied for bacterial identification and susceptibility testing.Whonet5 software was used for data analysis. Results Less than 50% of enterococcus faecalis and enterococcus faecium isolates were resistant to chloramphenicol and nitrofurantoin. Less than 1% of enterococcus faecalis and enterococcus faecium isolates were resistant to vancomycin. The resistance rate of enterococcus faecalis to penicillin G, high concentration gentamicin, ciprofloxacin, rifampicin and erythromycin descend year by year, and that of enterococcus faecium to ciprofloxacin, rifampicin and nitrofurantoin was opposite. In addition, the resistance rate of enterococcus faecium to most antibiotic was higher than enterococcus faecalis. Conclusions The enterococcus faecalis and enterococcus faecium is becoming multi-resistant bacteria. Antimicrobial therapy should be decided according to the results of susceptibility testing.

Respiratory syncytial virus (RSV) infection is an important global health problem. There is lack of specific treatment methods in clinical practice. Active prevention by vaccination or passive prevention by using antibody preparations are important measures to avoid severe infections and reduce deaths. Different RSV vaccines need to be developed for different populations. There are four main types of RSV vaccines under development. Live attenuated vaccines may be most suitable for infants. Subunit vaccines have the risk of causing enhanced respiratory diseases and are not suitable for infants with negative RSV serum vaccination, but they are mainly suitable for the elderly and pregnant women. Ensuring safety and immunogenicity is an important issue that needs to be solved in the development of RSV vaccines. Although there are many challenges in the development of RSV vaccines, more than 30 RSV vaccines have entered the clinical research stage, showing potential for application. Among them, the F nanoparticle vaccine has taken the lead in entering phase III clinical trials, but it has not achieved the expected effect in the elderly and pregnant women. Before the RSV epidemic season, using specific antibody is also an effective means to prevent severe infection in high-risk groups. The long-acting monoclonal antibody MEDI8897, which is more cost-effective than palivizumab, has entered phase III clinical trials, and has got priority R&D qualification. Polyclonal immunoglobulin RI-002 has shown good preventive effects in immunodeficiency populations, and has practical significance for further research.

Objective To explore the characteristic and reason for indeterminate HIV Western Blot(WB),the limitation of WB and the possible amendatory measures.Methods Summing up and analysis the distribution of the indeterminate HIV WB among the tested people,the laboratory test results,the follow-up and the final HIV antibody outcome.Results The relative healthy people including the people of voluntary counseling and testing,the blood donors and pregnant women make up 50% of the indeterminate HIV WB,the follow-up for the indeterminate HIV WB is difficult and the there are few people of the indeterminate HIV WB have HIV antibody test again.There is false-positive in WB test,especially the false-positive of P24 is serious.Conclusion The indeterminate HIV WB is related to the false positive of WB test,measures should be taken to reduce the indeterminate HIV WB and to interpret the result accurately.

Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)is the causative agent of the coronavirus disease 2019(COVID-19), which spreads rapidly in humans and endangers global health and economy. There are no specific and effective antiviral drugs for the treatment of COVID-19 currently. To infect host cells successfully for a virus, receptor binding and virus internalization are considered to be the initial steps. A key to combat SARS-CoV-2 infection is to investigate the viral receptors, which determine its infectivity and host range. The discovery and identification of cell receptors for SARS-CoV-2 will provide new therapeutic targets for COVID-19. This article reviews the recent findings on the entry and attachment receptors for SARS-CoV-2.

Opportunistic pathogens do not cause infectious disease when the immune systemis intact. However, under microdysbiosis or in an immunocompromised host, they can cause clinical infectious disease and mortality. Opportunistic infections are gradually increasing with the prolonged survival of immunocompromised patients with congenital immunodeficiency or cancer by modern medical treatment and as a result of microdysbiosis that may be caused by the abuse of antibiotics and increases in resistant strains ( single - drug or multi - drug resistant strains) . Clinical manifestations of opportunistic infections appear to be more complex and atypical. Great difficulties exist in clinical treatment of this type of infection. Therefore, careful examination of common opportunistic pathogens and their characteristics has great clinical significance in the accurate diagnosis and treatment of opportunistic infections.

Sequence analysis of human enterovirus (HEV) is now widely applied. The technology of sequencing-based identification and typing of HEV is reviewed in the present paper.

LipL32 is not only the most abundant protein of the outer membrane but also an immunodominant antigen that is highly conserved in pathogenic Leptospira. Recombinant LipL32 (rLipL32) purified under natural conditions was adapted to immunize BALB/c mice for developing monoclonal antibodies (mAbs). Twenty-nine mAbs against eight epitopes were produced and characterized. The capture and detection of antibodies were selected using a one-by-one pairing method with biotin-conjugated mAbs. To evaluate the sensitivity and specificity of the mAb pairs, antigen capture enzyme-linked immunosorbent assay (ELISA) was applied to detect antigens extracted from 15 pathogenic Leptospira strains and from other pathogenic bacteria. One pair of mAbs was selected and the detection capability of rLipL32 by ELISA was found to be approximately 1 ng/ml. mAbs produced with rLipL32 purified under natural conditions may be promising in the further detection of leptospiral antigens.

Oral and gut microbiota are important components of microbiota system, there is a close relationship between them. In recent years, the interaction between them has become a research hotspot. Combined with the recent research progress, this paper systematically introduces the interaction between them in the state of health and the interaction changes in the state of disease, so as to provide new enlightenment for diagnosis and treatment.

细菌生物膜是指微生物（细菌、真菌等）黏附、聚集形成的一个群体，该群体产生并分泌胞外聚合物（extracellular polymeric substance，EPS），形成一定的三维结构及含有营养物质、氧气等生长必需的物质交换通道，微生物细胞在EPS中增殖、生存^[1]。生物膜结构可阻止抗生素或抗体等大分子有效杀伤微生物细胞，目前尚无有效的预防措施和治疗方法控制细菌生物膜所带来的危害。细菌生物膜形成机制的研究能为预防和解决生物膜引起的各种问题奠定良好的基础。在生物膜研究中，需模拟体内或多种环境以观察生物膜的形态和形成，检测生物膜细菌基因组和蛋白质组表达等。因此......

Infection with hepatitis C virus (HCV) is currently treated with interferon-α( IFN-α) , but the molecular mechanismby which IFN inhibits HCV replication still remains elusive. Therefore, in this study, we attempted to elucidate the possible mechanismfor the IFN-inducible protein, Viperin, against HCV. Over-expression of Viper in could significantly down-regulate intracellular levels of HCV protein and RNA in both the replicon and HCVcc systems. Membrane flotation analysis indicated that expression of Viperin could interfere with the association of HCV NS3 and NS5A with the lipid raft, resulting in increased sensitivity of these two proteins to the treatment of non-ionic detergent. Furthermore, Viperinwas able to interact with FPPS because co-transfection of Viperin with FPPS could partially reverse the anti-HCV effects of Viperin in replicon cells. The above results indicate a possible novel mechanismof IFN-induced antiviral activity, that is, over-expression of Viperin can interfere with the microdomain of intracellular lipid raft and, therefore, further disrupt the stability of viral replicase complex to inhibit its functions.

Human immunodeficiency virus type I （HIV-1） infection leads to severe immune dysfunction. In addition to the progressive depletion and dysfunction of CD4+ T cells, HIV-1 infection also leads to extensive defects in the humoral arm of the immune system. This study aimed to describe the distribution of B cell subpopulations and profiles of activated, apoptosis-associated and costimulatory molecules in each subpopulation. The results showed that the peripheral blood B cell counts in HIV-1 infected patients were significantly lower than that in the healthy controls, but could be restored by antiretroviral therapy (ART). The decline of B cell counts was manifested by the decrease of immature B cells, Naïve B cells, resting memory B cells, and plasmablast. However, tissue-like memory B cells increased significantly. ART could restore the frequencies of naïve B and tissue-like memory B cells, but not the resting memory B cells. CD38 was significantly upregulated in immature B cells, naïve B cells, resting memory B cells and tissue-like memory B cells in HIV-1-infected patients, when compared to healthy controls. All subpopulations showed higher expression of CD95, and naïve B cells, tissue-like memory B cells and plasmablasts exhibited decreased levels of Bcl-2. PD-1 was elevated only in the resting memory cells and plasmablasts. The mean fluorescent intensity of CD40 was diminished in all B cell subpopulations, whereas CD70 decreased in all subpopulations except immature B cells. However, ART could only partially restore the altered expression of the mentioned molecules. These results suggest that HIV-1 infection leads to perturbation of B cell subpopulations, and B cell subpopulations display hyperactivation, susceptibility to apoptosis and impaired interaction with T cells. These alterations could only be restored partially by successful ART, therefore, effective immune intervention strategies should be required.

Tuberculosis remains a leading infectious cause of morbidity and mortality worldwide despite the availability of the bacille Calmette Guérin (BCG) vaccine and chemotherapy. Progress has been made in understanding immuopathogenesis and vaccine development in recent years. Mycobacterium tuberculosis (Mtb) may activate innate immunity of macrophage by Toll-like receptors (TLRs) and other pattern recognition receptors (PRRs) , which can eliminate the bacteria and regulate the acquired immune responses. Besides major histocompatibility complex (MHC) restricted CD4 ⁺ and CD8 ⁺ T cells, CD1- restricted T cells and γ δ T cells also take part in immune responses to Mtb infection. Memory T cells and regulatory T cells play a special role in regulating immune responses to mycobacterial infection. In view of poor BCG protective efficacy in adults, improved control of tuberculosis requires development of new and more effective vaccines. Various vaccine candidates including recombinant BCG, live-attenuated Mtb, and booster vaccines , such as recombinant modified vaccinia virus Ankara expressing Mtb antigen, nucleic acid vaccines, and subunit protein vaccines with novel adjuvants , are at different stages of development. One promising vaccine strategy is priming with BCG or BCG replacement vaccine followed by boosting with subunit vaccines. However, the vaccine strategy, optimal dose, route, frequency, and timing of the boost remain to be determined. The challenges facing tuberculosis vaccine development include a lack of immune markers for protection in humans, difficulty in prioritizing which candidates to move to clinical trials, shortage of clinical trial sites, lengthy time required for vaccine evaluation, and high cost.

The genes encoding 19kD lipoprotein and early secreting antigenic target-6( ESAT-6) were amplified from genome of the standard Mycobacterium tuberculosis H37Rv using polymerase chain reaction, and then cloned into the vector pMD18-T followed by subcloning into the expression vector pET-21a, respectively. Recombinant 19kD-ESAT6 was expressed in E. coli, and then purified by Ni-NTA. The antigenicity of the fusion protein was analyzed by Western blot analysis. The recombinant 19kD-ESAT6 plasmid was constructed successfully, and could be expressed efficiently in E. coli BL21 ( DE3) . The relative molecular mass of the fusion protein was approximately 29 ×10³ by SDS-PAGE. The recombinant 19kD-ESAT6 protein showed specific antigenicity as determined by Western blot, and can be used for the development of serodiagnostic reagents.

Carbapenem-resistant Enterobacteriaceae (CRE) is a common clinical drug-resistant bacteria, and its detection rate has been increasing in recent years. CRE infection is an independent risk factor for the death of patients. The emergence of CRE strains is mainly due to the production of carbapenemase including Klebsiella pneumoniae carbapenemase (KPC), metallo-β-lactamase (MBL) and oxacillinase (OXA), and a few are due to the changes in bacterial outer membrane proteins and high expression of efflux pump. The most common clinical CRE is Klebsiella pneumoniae. Intensive care unit (ICU) is the department with the most frequent outbreak of CRE infection. The high-risk factors of CRE infection include the contact with medical institutions, the various invasive procedures, and the history of antibiotic use. Regarding the treatment of CRE infection, due to the lack of data from prospective clinical trials, the empirical multi-drug combination treatment is currently used for high-risk patients. Some “old” drugs such as polymyxin, tigecycline and fosfomycin have played an unexpected effect in the treatment of CRE infection. At the same time, some “new” drugs such as ceftazidime-avibactam have also been put into clinical use and played a certain role. This article reviews the epidemiological characteristics of CRE infection in recent years and the main clinical drugs.

Campylobacter jejuni ( C. jejuni) is a common causative pathogen of bacterial gastroenteritis in humans. Chemotaxis, adirectional movement of bacteria towards suitable parasitic positions, is the initial key step for C. jejuni to achieve colonization on jejunal mucosa of hosts. The chemotactic migration was controlled and regulated by bacterial chemotaxis-associated two-component signaling system( che-TCS) in a MCPs→Ches→Flis/Mots manner. FliG, amember of Fli protein family, has been confirmed in some other bacterial pathogens to be a flagellar motor protein as well as an essential component of switch complex in bacterial flagellar motor. However, the function of FliG protein in chemotaxis of C. jejuni remains unknown. In the present study we generated a fliG gene knockout ( fliG^- ) mutant from C. jejuni strain NCTC11168 based on homologous recombination, and the motility, chemotaxis and colonization of fliG^- mutant were subsequently determined. The motility test and chemotaxis test in vitro demonstrated that the diameters of colonies on semisolid agar plate and chemotactic rings towards 0. 2 mol/L sodiumdeoxycholate ( SDC) in hard agar plus (HAP) of fliG^- mutant were significantly smaller than those of the wild type strain ( P < 0. 05) . Compared to the wild type strain, the numbers of fliG^- mutant adhering to the surface of jejunal mucosa and existing in jejunal content of BALB/c-ByJ mice were also significantly decreased ( P <0. 05) . All the results of this study lead a conclusion that fliG is an essential gene for flagellar motility and chemotactic movement towards jejunal
mucosa of C. jejuni during infection.

As the research progresses on intestinal flora, more and more evidences show that the imbalance of intestinal flora is closely related to the occurrence and progression of many chronic diseases. Probiotic treatment has become a worldwide hotspot, and Akkermansia muciniphlia (A. muciniphila), a common colonizer in the mucous layer of human intestines, has gradually been regarded as a promising candidate for the next-generation probiotics. The present paper summarizes the ameliorating effects of A. muciniphila on chronic diseases and the possible mechanisms, providing a new idea for the treatment of diseases.

The purpose of the current study was to evaluate the role of cholesterol of the membrane microdomain in the uptake of Francisella tularensis ( F. tularensis) LVS by mouse macrophages. A shuttle plasmid, pFNLTP6 gro-gfp, was transformed by electroporation to F. tularensis LVS. Cell cholesterol was stained with Filipin Ⅲ, and caveolin-1 was detected with monoclonal antibody and visualized with Alexa 594 conjugated goat anti-mouse antibodies. F. tularensis LVS infection was analyzed using a fluorescencemicroscope equipped with amotorized Z-focus. In order to evaluate the effect of depletion of the membrane microdomain on F. tularensis entery into macrophages, interference with lipid-rich plasmamembrane through the depletion of cholesterol was performed by methyl-β-cyclodextrin. The cholesterol-binding agent, Filipin III, was used to detect the effect of cholesterol depletion. The results showed that cell cholesterol was co-localized with F. tularensis live vaccine strain in the early uptake stage, and both had close contact with the membrane microdomain-associated components, such as caveolin-1. F. tularensis requires cholesterol-rich membrane microdomains for entry into macrophages. These findings suggest that cholesterol-rich membrane microdomains and caveolin-1 play an important role in F. tularensis early entry into macrophages.

Interferon-β plays an important role in innate immunity against viral infection. Hepatocytes, as hepatitis viruses-harboring cells, are reported to possess the potential to inductively express interferon-β. However, a practical in vitro cell model for investigating the interplay between hepatitis B virus and host cells is rarely reported. Here, we determined the inductive expression of interferon-β by interferon-β agonists〔(Newcastle disease virus, NDV) and poly(I∶C)〕in immortalized primary hepatic cell line, PH5CH8,and hepatocarcinoma cell lines, Huh-7 and HepG2. The data demonstrated that inductive expression of interferon-β in PH5CH8 cells was significantly higher than that in Huh7 or HepG2 cells. In addition, the expression level of key molecules critical for interferon-β induction was investigated to clarify the underlying mechanism. The results showed that the background expression level was fairly low in Huh7 and HepG2 cell lines, compared to that in PH5CH8 cells. It is suggested that PH5CH8 cells possess intact potential to produce interferon-β and reconstitution of a selective interferon-deficient hepatic cell line might be achieved via introduction of related molecules critical for interferon induction.

According to World Health Qrganization (WHO)’s global tuberculosis control report, up to one-third of the global population is estimated to carry latent Mycobacterium tuberculosis （M.tb）infection. Although following M.tb infection, only 5 to 10% of immunocompetent individuals develop active tuberculosis （TB）, this disease remains a major health problem particularly in low-income developing countries, which currently causes over 2 million deaths annually and is predicted to be among the 10 leading causes of disease burden even in the year 2020. India, China, Pakistan and Indonesia together account for 50% of the global TB epidemic. In sub-Sahara Africa, because of high HIV prevalence the TB incidence reaches 290 per 100 000 which is a hundred times of developed countries. Molecular epidemiology studies have shown that diverse strains of different genotypes were prevalence in different regions such as the predominance of W-Beijing family, one of the most successful M.tb families, in countries of East Asia. The notion that some strains of a single genotype, such as the W-Beijing genotype, are more virulent than others is supported by results obtained with animal and cellular models. The inhibition of the host immune response by mycobacterial strains of the W-Beijing family has recently been confirmed in vivo. This review discusses the phylogenetic studies that have been made in discovering how certain M.tb has achieved its virulence as a successful pathogen.

Viral encephalitis/meningitis is a severe inflammatory disease of the central nervous system that poses a significant threat to public health. Despite the crucial role played by medical history, symptoms, routine tests and imaging in its diagnosis, and continuous improvements in molecular diagnostic techniques, limitations including technical limitations, assay variability, sample types, and detection time windows still constrain its diagnosis. Moreover, the selection of appropriate diagnostic techniques depends on different clinical features, leaving 40% to 60% of patients with an unclear etiology. Timely and accurate diagnosis is fundamental for initiating targeted and appropriate treatment. Sixty to eighty percent of patients with viral encephalitis initially seek medical attention at primary healthcare institutions. However, due to technical constraints, the diagnostic rate in these institutions is below 20%. Therefore, establishing a standardized diagnostic pathway based on etiology and implementing a tiered diagnostic strategy are particularly necessary. In situations where resources are limited at primary healthcare institutions, the preliminary diagnosis can be established by detailed inquiry into medical history, comprehensive physical examination, and basic laboratory tests. Based on the suspected etiology, routine molecular biology techniques such as polymerase chain reaction (PCR) can be employed for initial pathogen screening. In cases whose PCR results are negative or not feasible, non-targeted broad-coverage techniques like metagenomic next-generation sequencing (mNGS) should be considered. The establishment of a multidisciplinary team for diagnosis and treatment, along with the creation of clinical diagnostic and treatment networks, are essential to enhance the diagnostic rate and improve clinical outcomes. With advancements in diagnostic technologies and the application of artificial intelligence, the diagnosis of viral encephalitis is expected to become more precise.