Inferring Mycobacterium Tuberculosis Drug Resistance and Transmission using Whole-genome Sequencing in a High TB-burden Setting in China

Objective China is among the 30 countries with a high burden of tuberculosis(TB)worldwide,and TB remains a public health concern.Kashgar Prefecture in the southern Xinjiang Autonomous Region is considered as one of the highest TB burden regions in China.However,molecular epidemiological studies of Kashgar are lacking.Methods A population-based retrospective study was conducted using whole-genome sequencing(WGS)to determine the characteristics of drug resistance and the transmission patterns.Results A total of 1,668 isolates collected in 2020 were classified into lineages 2(46.0%),3(27.5%),and 4(26.5%).The drug resistance rates revealed by WGS showed that the top three drugs in terms of the resistance rate were isoniazid(7.4%,124/1,668),streptomycin(6.0%,100/1,668),and rifampicin(3.3%,55/1,668).The rate of rifampicin resistance was 1.8%(23/1,290)in the new cases and 9.4%(32/340)in the previously treated cases.Known resistance mutations were detected more frequently in lineage 2 strains than in lineage 3 or 4 strains,respectively:18.6%vs.8.7 or 9%,P<0.001.The estimated proportion of recent transmissions was 25.9%(432/1,668).Multivariate logistic analyses indicated that sex,age,occupation,lineage,and drug resistance were the risk factors for recent transmission.Despite the low rate of drug resistance,drug-resistant strains had a higher risk of recent transmission than the susceptible strains(adjusted odds ratio,1.414;95%CI,1.023–1.954;P=0.036).Among all patients with drug-resistant tuberculosis(DR-TB),78.4%(171/218)were attributed to the transmission of DR-TB strains.Conclusion Our results suggest that drug-resistant strains are more transmissible than susceptible strains and that transmission is the major driving force of the current DR-TB epidemic in Kashgar.

Molecular Identification of Mycobacterium Strains Responsible of Bovine Tuberculosis Cases in Bobo-Dioulasso Slaughterhouse, Burkina Faso

Bovine tuberculosis (bTB) is an endemic zoonosis significantly affects animal health in Burkina Faso. The primary causative agent is Mycobacterium tuberculosis (M. tuberculosis) complex, mainly M. bovis. Cattle are considered as natural reservoir of M. bovis. However, in Burkina Faso, the circulation of these strains remains poorly understood and documented. This study aimed to identify and characterize Mycobacterium strains from suspected carcasses during routine meat inspection at Bobo-Dioulasso refrigerated slaughterhouse. A prospective cross-sectional study was conducted from January 2021 to December 2022 on cases of seizures linked to suspected bovine tuberculosis. Microbiological and molecular analyzes were used for mycobacterial strain isolation and characterization. Out of 50 samples, 24% tested positive by microscopy and 12% by culture. Molecular analysis identified 6 strains of Mycobacteria, exclusively Mycobacterium bovis specifically the subspecies bovis (Mycobacterium bovis subsp bovis). In conclusion, M. bovis subsp bovis is the primary agent responsible for bovine tuberculosis in Bobo-Dioulasso. Continuous monitoring of mycobacterial strains is therefore necessary for the effective control of this pathology in the local cattle population.

Tuberculosis in the Carcinal Environment in Chad Due to the Mycobacterium Tuberculosis Circulante Complex

Tuberculosis (TB) is a serious infectious disease and its control is considered a challenge, particularly among vulnerable populations such as prisoners. The prevalence of TB in prisons is an alarming public health problem in many countries. The aim of this study is to describe the epidemiology of tuberculosis and the strategies for controlling this disease in the Chadian prison population. During the course of our study, the prevalence of tuberculosis in prisons was 9.64%. The age group between 55 years and over (43.33%) was the most represented in this study, and all patients were men with a frequency of 62.66%. The cross-tabulation of Culture_7H9G and Culture_7H9P showed that out of our total positive sample, we found a total of 87 positive strains and 63 negative strains. Our study shows that it is essential to know the prevalence of tuberculosis in all the country’s prisons. Indeed, this can serve as an indication of the need for action in prisons to reduce TB rates, in particular by improving the structure of prison environments, diagnosing new cases quickly and accurately, identifying drug-resistant strains and implementing effective, direct treatment observed in people with tuberculosis.

Early Prosthetic Valve Endocarditis with Mycobacterium Tuberculosis after Mitral Valve Replacement: A Case Report

Background: Tuberculous endocarditis is a rare but serious complication of heart valve replacement surgery. We report the case of a 24-year-old patient, who presented with tuberculous endocarditis after mechanical mitral valve replacement, with a favorable clinical course following anti-tuberculosis treatment. Case Presentation: We report a 24-year-old male patient, admitted to the cardiac surgery department of the Fann Hospital (Dakar, Senegal), for the management of severe mixed (rheumatic and endocarditic) mitral insufficiency with associated tricuspid insufficiency. He had a history of recurrent angina and polyarthralgia in childhood, was hospitalized several times for refractory global cardiac decompensation, and for a suspected infective endocarditis a month before his admission. On admission, the clinical examination revealed signs suggestive of mitral and tricuspid insufficiency. Transthoracic echocardiography revealed severe post-endocarditic mitral insufficiency with A3 amputation, highly mobile 15 mm vegetations on the free edge of the large valve, moderate tricuspid insufficiency, and severe pulmonary artery hypertension. Mechanical mitral valve replacement and tricuspid valve annuloplasty using autologous pericardial strip were performed via median sternotomy. After ten days, the patient presented with global cardiac decompensation associated with a clinico-biological infectious syndrome, and tans-oesophageal echography revealed an abscess at the sinotubular junction, communicating with the aorta. A thoraco-abdomino-pelvic CT scan was done, which revealed a bilateral alveolar-interstitial syndrome with mediastinal lymphadenopathy. Anti-tuberculosis treatment with RHZE was initiated for 06 months. The clinical course was favorable. Conclusion: Tuberculous endocarditis in prostheses is a serious complication of heart valve replacement surgery, which may evolve favorably under medical treatment.

Comparison of Xpert MTB/RIF, Real Amp, and CPA Tests in Detecting Mycobacterium tuberculosis

Today, tuberculosis (TB) remains a global public health threat associated with significantly high rates of morbidity and mortality. The World Health Organization's (WHO) Global Tuberculosis Report 2018[1] has reported that in 2017, 10.0 million people across the world had developed TB diseases that resulted in an estimated 1.6 million deaths, and 889, 000 people developed TB in China that led to 39, 000 TB-related deaths. Therefore, rapid and accurate detection of Mycobacterium tuberculosis (MTB) is important for initiating early treatment and reducing mortality. Traditional diagnostic methods for pulmonary TB incorporate chest radiography and sputum smear microscopy;however, several cases of tuberculosis go undiagnosed because of the low sensitivity of smear microscopy[2].

Mutation Characteristics of inhA and katG Genes in Isoniazid-Resistant Mycobacterium Tuberculosis Patients in Xinjiang

Objective:To analyze the mutation characteristics of inhA and katG genes in isoniazid-resistant Mycobacterium tuberculosis in Xinjiang.Methods:The katG and inhA in 148 strains of isoniazid-resistant Mycobacterium tuberculosis were amplified through fluorescence quantitative PCR,and the amplified products were sequenced and compared.Results:The inhA gene mutation rate of 148 strains of isoniazid-resistant mycobacterium tuberculosis was 13.51%(20/148),among which the inhA gene mutation rate among patients of Han,Uygur,and Kazakh ethnicity were 15.87%,13.21%,and 17.65%,respectively.There was no significant difference in the inhA mutation rate among nationalities(c^(2)=2.897,P>0.05).The mutation rate of the katG gene was 84.46%(125/148),among which the mutation rates of patients of Han,Uyghur,and Kazak ethnicities were 82.54%,84.91%,and 76.47%,respectively.The Hui and other ethnic groups were all affected by the katG gene mutation.There was no significant difference in the mutation rate of the katG gene among different ethnicities(c^(2)=3.772,P>0.05).The mutation rates of the inhA gene in southern Xinjiang,northern Xinjiang,and other provinces were 18.60%,9.28%,and 37.50%,respectively.The mutation rates of the inhA gene in different regions were statistically different(c^(2)=6.381,P<0.05).There was no significant difference in the inhA mutation rate between patients from southern and northern Xinjiang(c^(2)=2.214,P>0.05)and between southern Xinjiang and other provinces(c^(2)=1.424,P>0.05).However,the mutation rate of the inhA gene in patients from other provinces was higher than that in northern Xinjiang(c^(2)=5.539,P<0.05).The mutation rates of the katG gene in southern Xinjiang,northern Xinjiang,and other provinces were 81.40%,87.63%,and 62.50%,respectively.There was no significant difference in the mutation rates of the katG gene among different regions(c^(2)=3.989,P>0.05).Conclusion:katG gene mutation was predominant in isoniazid-resistant tuberculosis patients in Xinjiang Uygur Autonomous Region,and inhA and katG gene mutation were no different among different ethnic groups.

Diagnostic Evaluation of GeneXpert MTB/RIF Assay for the Detection of Rifampicin Resistant Mycobacterium tuberculosis among Pulmonary Tuberculosis Patients in Bangladesh

Background: The emergence of multidrug resistant tuberculosis (MDR-TB) and extensively drug- resistant tuberculosis (XDR-TB) has highlighted the need for early accurate detection and drug susceptibility. Objective: The purpose of the present study was to evaluate the accuracy of GeneX-pert MTB/RIF assay for the detection of Mycobacterium tuberculosis and rifampicin resistance. Methodology: This cross sectional study was done in the Department of Microbiology at Sir Salimullah Medical College, Dhaka and National Institute of Chest Disease & Hospital (NIDCH), Dhaka during the period of January 2014 to December 2014 for a period of 1 (one) year. Sputum samples from suspected MDR-TB patients were collected by purposive sampling technique from OPD of Sir Salimullah Medical College (SSMC) and NIDCH. Microscopy, liquid culture in liquid MGIT 960 media and GeneXpert MTB/RIF were done for MTB diagnosis and detection of rifampicin resistance. MGIT 960 media were also used for determination of drug resistance. Result: Liquid culture yielded higher growth (68%) from 100 samples while GeneXpert MTB assay showed similar result (67% positive and 33% negative). Drug susceptibility test in MGIT 960 media showed that out of 68 positive cases Rifampicin resistant cases were 15 (22.05%) whereas GeneXpert MTB assay detected 14 (20.89%) were Rifampicin resistant out of 67 MTB positive samples. When compared to liquid culture the calculated sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV) and accuracy of GeneXpert MTB were 98.52%, 100%, 96.96%, 100% and 99%. Conclusion: GeneXpert MTB/RIF assay is high detection rate of pulmonary tuberculosis and multidrug resistant tuberculosis.

GenoType MTBDRplus as a Complementary Tool for the Typing of Mycobacterium tuberculosis

The aim of this study was to investigate the usefulness of combining profiles obtained by using a line probe assay (LPA) originally intended to characterize the resistance of two major anti-tuberculosis drugs to the association of spoligotyping and MIRU-VNTR, in order to improve its discriminatory power. For this purpose, 74 strains of Mycobacterium tuberculosis belonging to the same cluster after spoligotyping were further typed by using the 24 loci MIRU/VNTR. These strains were then tested by the GenoType MTBDRplus, and profiles obtained were analyzed within previously obtained clusters. The combination of spoligotying and MIRU-VNTR led to the consolidation of 56 of them (75.7%) in 9 clusters. Most of the strains (54, 96.4%) were multidrug resistant (MDR). From the 9 initial clusters, the addition of GenoType MTBDRplus helped to define 26 profiles including 11 unique profiles, and 3 original clusters remained undifferentiated. Results obtained express the relevance of combining this method which improved quite significantly the discriminatory power in typing Mycobacterium tuberculosis.

尘肺结核患者Mycobacterium tuberculosis耐药基因突变研究

研究尘肺结核患者结核分枝杆菌(Mycobacterium tuberculosis,MTB)耐药基因突变与耐药性的关系。在97例尘肺结核患者痰中检出MTB菌株28株,采用PCR-SSCP法检测katG、rpoB和rpsL基因突变,并与采用常规药敏试验(AST)法检测的耐药结果进行对比分析。采用PCR-SSCP法检测katG、rpoB和rpsL基因,突变率分别为42.86%(12/28)、42.86%(12/28)和32.14%(9/28),采用AST法检测INH、RFP和SM,耐药率分别为64.23%(18/28)、60.71%(17/28)和53.57%(15/28),两者之间差异均无显著性(P>0.05)。其中多耐药株20例(71.43%),包括耐三种药物12例(42.86%),耐两种药8例(28.57%),单耐药株6例(21.43%),敏感株2例,耐药率92.86%。PCR-SSCP法检出3个基因联合突变8株,与AST法符合率为66.67%(8/12);2个基因突变5株,符合率为62.50%(5/8);单基因突变2株,符合率为33.33%(2/6)。结果表明:PCR-SSCP技术适用于MTB katG、rpoB和rpsL耐药基因突变的筛选,对指导尘肺结核患者临床用药上具有重要意义。

Molecular Characterization of Drug-Resistant Beijing Family Isolates of Mycobacterium Tuberculosis from Tianjin,China

Objective Tuberculosis remains a severe public health issue, and the Beijing family of mycobacterium tuberculosis （M. tuberculosis） is widespread in East Asia, especially in some areas in China, like Beijing and Tianjin. This study aimed at determining the mutation patterns of drug-resistant Beijing strains of M. tuberculosis isolated from Tianjin, China. Methods A total of 822 M. tuberculosis isolates were screened for drug resistance by an absolute concentration method and the genotype was identified by PCR. 169 drug-resistant isolates of the Beijing family were analyzed for the potential mutations in the rpoB, katG, inhA promoter region and in rpsL, rrs and embB genes, which are associated with resistance to rifampin （RFP）, isoniazid （INH）, streptomycin （SM） and ethambutol （EMB） respectively by PCR and DNA sequencing. Results Fifty-eight out of 63 RFP-resistant isolates were found to carry the mutations within the 81-bp RFP resistance determining region （RRDR） of the rpoB gene and the most frequent mutations occurred at codon 531 （44.4%）, 526 （28.6%）, and 516 （7.9%） respectively. 16 mutation pattems affecting 12 different codons around the RRDR of rpoB were found. Of 116 INH-resistant isolates, 56 （48.3%） had the mutation of katG 315 （AGC→ACC） （Ser→Thr）, 3 （2.6%） carried S315N （AGC→AAC） and 27 （16.0%） had the mutation of inhA-15A→T. 84 out of 122 SM-resistant isolates （68.9%） displayed mutations at the codons 43 or 88 with AAG→AGG （Lys→Arg） of the rpsL gene and 22 （18.0%） with the mutations at positions 513A→C, 516C→T or 905 A→G in the rrs gene. Of 34 EMB-resistant isolates, 6 had mutation with M306V （ATG→GTG）, 3 with M306I （ATG→ATT）, 1 with M306I （ATG→ATA）, 1 with D328Y （GAT→TAT）, 1 with V348L （GTC→CTC）, and 1 with G406S （GGC→AGC） in the embB gene. Conelusion These novel findings extended our understanding of resistance-related mutations in the Beijing strains of M. tuberculosis and may provide a scientific basis for development of new strategies for diagnosis and control of tuberculosis in China and other countries where Beijing strains are prevalent.

Immune formulation-assisted conventional therapy on anti-infective effectness of multidrug-resistant Mycobacterium tuberculosis infection mice

Objective:To study the effect of immune formulation-assisted conventional therapy on antiinfective ability of multidrug-resistant Mycobacterium tuberculous infection mice.Methods:BALB/c mice were used as experimental animals,multidrug-resistant Mycobacterium tuberculosis infection models were built,randomly divided into model group,moxifloxacin group,thymopentin group and combined treatment group and given corresponding drug intervention,and then colony numbers in the spleen and lung,T lymphocyte subset contents and programmed death-1(PD-1) expression levels in peripheral blood were detected.Results:Colony numbers in lung and spleen of moxifloxacin group and thymopentin group were significantly lower than those of model group and colony numbers in lung and spleen of combined treatment group were significantly lower than those of moxifloxacin group and thymopentin group:contents of CD3^+CD4^+T cells,Thl and Thl7 in peripheral blood of moxifloxacin group and thymopentin group were higher than dtose of model group,and contents of CD3^+CD8^+T cells.Th2 and Treg were lower than those of model group;contents of CD3^+CD4^+T cells.Th 1 and Th 17 in peripheral blood of combined treatment group were higher than those of moxifloxacin group and thymopentin group,and contents of CD3^+CD8^+T cells.Th2 and Treg were lower than those of moxifloxacin group and thymopentin group:PD-I expression levels on T lymphocyte,B lymphocyte and monocyte surface in peripheral blood of moxifloxacin group and thymopentin group were lower than those of model group,and PD-I expression levels on T lymphocyte.B lymphocyte and monocyte surface in peripheral blood of combined treatment group were lower than those of moxifloxacin group and thymopentin group.Conclusions:Immune formulation thymopentin can enhance the anti-infective ability of multidrug-resistant Mycobacterium tuberculosis infection mice,decrease bacterial load in lung and spleen,and enhance immune function.

Fluoroquinolones for the treatment of latent Mycobacterium tuberculosis infection in liver transplantation

Solid organ transplantation(SOT)is the best treatment option for end-stage organ disease.Newer immunosuppressive agents have reduced the incidence of graft rejection but have increased the risk of infection,particularly due to the reactivation of latent infections due to opportunistic agents such as Mycobacterium tuberculosis.Active tuberculosis(TB)after SOT is a significant cause of morbidity and mortality.Most cases of posttransplant TB are secondary to reactivation of latent tuberculosis infection(LTBI)due to the effects of long-term immunosuppressive therapy.Risk minimization strategies have been developed to diagnose LTBI and initiate treatment prior to transplantation.Isoniazid with vitamin B6 supplementation is the treatment of choice.However,liver transplantation(LT)candidates and recipients have an increased risk of isoniazid-induced liver toxicity,leading to lower treatment completion rates than in other SOT populations.Fluoroquinolones(FQs)exhibit good in vitro antimycobacterial activity and a lower risk of drug-induced liver injury than isoniazid.In the present review,we highlight the disease burden posed by posttransplant TB and summarize the emerging clinical evidence supporting the use of FQs for the treatment of LTBI in LT recipients and candidates.

Diagnosis of intestinal tuberculosis using a monoclonal antibody to Mycobacterium tuberculosis

AIM:To investigate the utility of immunohistochemical(IHC) staining with an antibody to Mycobacterium tuberculosis(M.tuberculosis) for the diagnosis of intestinal tuberculosis(TB).METHODS:We retrospectively identified 10 patients(4 males and 6 females;mean age = 65.1 ± 13.6 years) with intestinal TB.Clinical characteristics,including age,gender,underlying disease,and symptoms were obtained.Chest radiograph and laboratory tests,including sputum Ziehl-Neelsen(ZN) staining,M.tuberculosis culture,and sputum polymerase chain reaction(PCR) for tubercle bacilli DNA,as well as Tuberculin skin test(TST) and QuantiFERON-TB gold test(QFT),were examined.Colonoscopic records recorded on the basis of Sato's classification were also reviewed,in addition to data from intestinal biopsies examined for histopathological findings,including hematoxylin and eosin staining,and ZN staining,as well as M.tuberculosis culture,and PCR for tubercle bacilli DNA.For the present study,archived formalin-fixed paraffin-embedded(FFPE) intestinal tissue samples were immunohistochemically stained using a commercially available species-specific monoclonal antibody to the 38-kDa antigen of the M.tuberculosis complex.These sections were also stained with the pan-macrophage marker CD68 antibody.RESULTS:From the clinical data,we found that no patients were immunocompromised,and that the main symptoms were diarrhea and weight loss.Three patients displayed active pulmonary TB,six patients(60%) had a positive TST,and 4 patients(40%) had a positive QFT.Colonoscopic findings revealed that all patients had type 1 findings(linear ulcers in a circumferential arrangement or linear ulcers arranged circumferentially with mucosa showing multiple nodules),all of which were located in the right hemicolon and/or terminal ileum.Seven patients(70%) had concomitant healed lesions in the ileocecal area.No acid-fast bacilli were detected with ZN staining of the intestinal tissue samples,and both M.tuberculosis culture and PCR for tubercle bacilli DNA were negative in all samples.The histopathological data revealed that tuberculous granulomas were present in 4 cases(40%).IHC staining in archived FFPE samples with anti-M.tuberculosis monoclonal antibody revealed positive findings in 4 patients(40%);the same patients in which granulomas were detected by hematoxylin and eosin staining.M.tuberculosis antigens were found to be mostly intracellular,granular in pattern,and primarily located in the CD68 + macrophages of the granulomas.CONCLUSION:IHC staining with a monoclonal antibody to M.tuberculosis may be an efficient and simple diagnostic tool in addition to classic examination methods for the diagnosis of intestinal TB.

Luciferase reporter phage phAE85 for rapid detection of rifampicin resistance in clinical isolates of Mycobacterium tuberculosis

Objective:To evaluate luciferase reporter phage(LRP)phAE85 in rapid detection of rifampicin resistance in a region where TB is endemic.Methods:One hundred and ninety primary isolates on Lowenstein-Jensen medium were tested.Middlebrook 7H9 complete medium with and without rifampicin at 2μg/mL was inoculated with standard inoculum from suspensions of the clinical isolate.After incubation for 72 h,LRP was added.Following 4 h of further incubation,light output from both control and test was measured as relative light units.Strains exhibiting a reduction of less than 50%relative light units in the drug containing vial compared to control were classified as resistant.Results were compared with the conventional minimum inhibitory concentration method(MIC)of drug susceptibility testing.Results:The two methods showed high level of agreement of 97%(CI 0.94,0.99)and P value was 0.000 1.The sensitivity and specificity of LRP assay for detection of rifampicin resistance were 91%h(CI 0.75,0.98)and 99ct(CI0.95,1.00)respectively.Time to detection of resistance by LRP assay was 3 d in comparison with 28 d by the minimum inhibitory concentration method.Conclusions:LRP assay with phAE85 is 99%specific,91%sensitive and is highly reproducible.Thus the assay offers a simple procedure for drug sensitivity testing,within die scope of semi-automation.

Immunological Evaluation of a Novel Mycobacterium tuberculosis Antigen Rv0674

Objective This study aimed to characterize the diagnostic and vaccine potential of a novel Mycobacterium tuberculosisantigen Rv0674. Methods To evaluate thediagnostic potential and antigenicity of Rv0674, IgG was evaluated using ELISA and interferon (IFN)-γ was done by using ELISpot assay among TB patients and healthy donors. For immunogenicity evaluation, BALB/c mice were immunized with Rv0674. Cytokine production was determined by cytokine release assay using an ELISA kit, and the antibodies were tested using ELISA. Results The results of serum Elisa tests showed that Rv0674 specific immunoglobulin G (IgG) response was higher in TB patients than negative controls. And Rv0674 had good performance in serological test with sensitivity and specificity of 77.1% and 81.1%, respectively. While it shows poor sensitivity and specificity of 26.23% and 79.69% for IFN-γ tests. In BALB/c mice, Rv0674 adjuvant by DDA/PolyI:C could also induce a high level of IFN-γ, interleukin-2 and interleukin-6 as well as a high IgG titer in both high-and low-dose groups indicating that Rv0674 is essential in humoral and cellular immunity. Moreover, the cytokine profile and IgG isotypecharacterized Rv0674 as a Th1/Th2-mixed-type protective immunity with the predominance of Th1 cytokines. Conclusion Rv0674 may be a good potential candidate for the development of TB serological diagnosis and a new TB vaccine.

Specific and cross-reactive immune response against Mycobacterium tuberculosis antigens in mice immunized with proteoliposomes from Mycobacterium bovis BCG

Objective: To characterize the immunogenicity and the induction of cross-reactive responses against Mycobacterium tuberculosis(M. tuberculosis) of a proteoliposome(PL)from Mycobacterium bovis Bacillus Calmette–Guerin(BCG) with and without alum hydroxide(AL) as adjuvant(PLBCG-AL and PLBCG, respectively) in BALB/c mice.Methods: BALB/c mice were inoculated with phosphate buffer solution, BCG, PLBCG and PLBCG-AL. The humoral immunogenicity was determined by ELISA [immunoglobulin G(Ig G), Ig G1 and Ig G2a] and the cellular immunogenicity was evaluated in vivo by delayed type hypersensitivity. The humoral cross-reactive response against M. tuberculosis was determined by Western blot.Results: Sera from animals immunized with PLBCG-AL and PLBCG showed significant increase in specific total Ig G and Ig G1 antibodies and the presence of cross-reactive antibodies against M. tuberculosis antigens, which were more intense with the use of alum as adjuvant. Mice immunized with PLBCG and PLBCG-AL also showed a specific cellular response in vivo.Conclusions: The cellular and humoral immunogenicity of PLBCG and the capacity to induce cross-reactive responses against M. tuberculosis is in agreement with the protective capacity previously demonstrated by this vaccine candidate and supports the continuation of its evaluation in further stages.

Evaluation of Multidrug Resistant Loop-mediated Isothermal Amplification Assay for Detecting the Drug Resistance of Mycobacterium tuberculosis

Objective To evaluate multidrug resistant loop-mediated isothermal amplification(MDR-LAMP)assay for the early diagnosis of multidrug-resistant tuberculosis and to compare the mutation patterns associated with the rpoB,katG,and inhA genes at the Chinese Center for Disease Control and Prevention.Methods MDR-LAMP assay was evaluated using 100 Mycobacterium tuberculosis(Mtb)isolates obtained from the National Reference Laboratory for Tuberculosis in China.Phenotypic resistance to isoniazid and rifampicin and whole-genome sequencing served as reference standards.Results The sensitivity,specificity,positive predictive value(PPV),and negative predictive value(NPV)of MDR-LAMP were 85.5%,93.6%,96.7%,and 74.4%for the detection of resistance to isoniazid and rifampicin,respectively,and 80.5%,92.3%,98.6%,and 41.4%for the detection of Mtb cultured from smear-positive sputum samples,respectively.When DNA sequencing was used as the reference standard,the sensitivity,specificity,PPV,and NPV of MDR-LAMP were 93.1%,92.3%,97.2%,and 82.8%for the detection of katG and inhA gene mutations,respectively,and 89.1%,88.9%,93.4%,and 81.1%for the detection of rpoB gene mutation,respectively.Conclusion MDR-LAMP is a rapid and accessible assay for the laboratory identification of rifampicin and isoniazid resistance of Mtb isolates.

Effects of Mycobacterium vaccae vaccine in a mouse model of tuberculosis: protective action and differentially expressed genes

Background:Tuberculosis is a leading cause of death worldwide.BCG is an effective vaccine,but not widely used in many parts of the world due to a variety of issues.Mycobacterium vaccae(M.vaccae)is another vaccine used in human subjects to prevent tuberculosis.In the current study,we investigated the potential mechanisms of M.vaccae vaccination by determining differentially expressed genes in mice infected with M.tuberculosis before and after M.vaccae vaccination.Methods:Three days after exposure to M.tuberculosis H37 Rv strain(5×10~5 CFU),adult BALB/c mice randomly received either M.vaccae vaccine(22.5μg)or vehicle via intramuscular injection(n=8).Booster immunization was conducted 14 and 28 days after the primary immunization.Differentially expressed genes were identified by microarray followed by standard bioinformatics analysis.Results:M.vaccae vaccination provided protection against M.tuberculosis infection(most prominent in the lungs).We identified 2,326 upregulated and 2,221 downregulated genes in vaccinated mice.These changes could be mapped to a total of 123 signaling pathways(68 upregulated and 55 downregulated).Further analysis pinpointed to the MyD88-dependent TLR signaling pathway and PI3 K-Akt signaling pathway as most likely to be functional.Conclusions:M.vaccae vaccine provided good protection in mice against M.tuberculosis infection,via a highly complex set of molecular changes.Our findings may provide clue to guide development of more effective vaccine against tuberculosis.

Cloning,expression,identification and bioinformatics analysis of Rv3265c gene from Mycobacterium tuberculosis in Escherichia coli

Objective:To clone and express Rv3265c gene of Mycobacterium tuberculosis in Escherichia coli (E.coli) under optimistic conditions,obtain and identify protein expressed,analyze the structure and characteristics of the protein using bioinformatics methods for future applications.Methods: Rv3265c gene from Mycobacterium tuberculosis H37Rv was amplified by polymerase chain reaction,and was cloned into the pET-30a vector after purification and recovery.The recombinant plasmid was sequenced and expressed in E.coli BL21(DE3),and then purified and identified by western blotting.The essential physical-chemical properties of the protein were predicated by bioinformatics tools,including subcellular location,secondary structure,domains,antigenic epitopes,etc.Tertiary structure of the protein based on homology modeling was estabUshed,while multi-sequence homological alignment and phylogenetic analysis were preformed.Results:The recombinant protein was obtained in soluble fraction from expression system in E.coli B121(DE3) carrying pET30- Rv3265c plasmid,and Rv3265c gene was expressed correctly.Bioinformatics analysis showed the protein contained no signal peptide and transmembrane helices,located outside of membrane.Secondary structure analysis revealed it containedα-helix,extended strand and random coil,46.8%,14.6%,38.6%,respectively.Furthermore,it possessed six potential antigenic epitopes,one glycosyl transferase domain.A simple three-dimensional model of this protein was constructed by Swiss-model sever.Both sequences and structures were conservative and especial either in gene or in protein.Conclusions:Rv3265c gene might be a desirable molecular target for anti-tuberculosis drug and vaccine.The purified protein from expression will be utilized to study the kinetics of L-rhamnosyltransferase and to develope an enzyme assay for screening vaccine or drug.

Construction, Expression and Identification of a Recombinant BCG Vaccine Encoding Human Mycobacterium Tuberculosis Heat Shock Protein 65

Heat shock protein 65 (HSP65) is one of the most important protective immunogens against the tuberculosis infection. The signal sequence of antigen 85B and the whole HSP65 DNA sequence of human Mycobacterium tuberculosis (M. tuberculosis) were amplified from BCG genome and plasmid pCMV-MTHSP65 respectively by polymerase chain reactions (PCR). These two sequences were cloned into the plasmid pBCG-2100 under the control of the promoter of heat shock protein 70 (HSP70) from human M. tuberculosis, yielding the prokaryotic shuttle expression plasmid pBCG-SP-HSP65. Results of restriction endonuclease analysis, PCR detection and DNA sequencing analysis showed that the two cloned DNA sequences were consistent with those previously reported, and the direction of their inserting into the recombinant was correct and the reading frame had been maintained. The recombinants were electroporated into BCG to construct the recombinant BCG vaccine and induced by heating. The induced expression detected by SDS-PAGE showed that the content of 65 kD protein expressed in recombinant BCG was 35.69 % in total bacterial protein and 74.09 % in the cell lysate supernatants, suggesting that the recombinant HSP65 gene could express in BCG with high efficiency and the expressed proteins were mainly soluble. Western-blot showed that the secretive recombinant proteins could specifically combine with antibody against M. tuberculosis HSP65, indicating that the recombinant proteins possess the biological activity of HSP65.