Synthesis and Shape-Selective Catalytic Application of Ordered Cubic Ia3Ì d Supermicroporous Materials Templated by Rosin-Derived Quaternary Ammonium Salt with a Hydroxyl Radical in the Headgroup.

We described the comprehensive synthesis, characterization, and catalytic performance of a novel type of the ordered cubic Ia3̅d supermicroporous silicas by using tetraethyl orthosilicate as a silicon source and a hydroxyl-functionalized quaternary ammonium salt as a template under alkali conditions. The effects of various reaction conditions on the pore structure and morphology of the silica materials were thoroughly investigated. Our results showed that under a wide range of reaction conditions, supermicroporous silicas with a highly ordered cubic Ia3̅d structure can be produced with a large BET specific surface area of 1741 m2/g, high pore volume of 0.91 cm3/g, concentrated pore size at 19.1 Å, and crystalline morphology. After Al doping, the obtained aluminosilicates preserved a highly ordered cubic supermicroporous structure. By using the H-form aluminosilicates as catalysts, we selectively dimerized ß-pinene. The catalysts exhibited an excellent catalytic activity for ß-pinene dimerization with a conversion yield up to 100%. Compared with conventional mesoporous H-form Al-MCM-48 catalysts, the prepared supermicroporous catalysts exhibited superior catalytic performance due to their excellent shape-selective properties, producing the ß-pinene dimer in a yield up to 72.4% with dimer/oligomer ratios in the range of 7.5-10.1. This study featured a detailed preparation and characterization of supermicroporous silica with novel microstructures and showed its utility in catalytic dimerization.

Derivatization of Natural Compound ß-Pinene Enhances Its In Vitro Antifungal Activity against Plant Pathogens.

BACKGROUND: The development of new antifungal agents has always been a hot research topic in pesticide development. In this study, a series of derivatives of natural compound ß-pinene were prepared, and the antifungal activities of these derivatives were evaluated. The purpose of this work is to develop some novel molecules as promising new fungicides. METHODS: Through a variety of chemical reactions, ß-pinene was transformed into a series of ß-pinene-based derivatives containing amide moieties and acylthiourea moieties. The antifungal activities of these derivatives against five plant pathogens including Colletotrichum gloeosporioides, Fusarium proliferatum, Alternaria kikuchiana, Phomopsis sp. and Phytophthora capsici were tested; preliminary structure-activity relationship was discussed. RESULTS: Some derivatives exhibited moderate or significant antifungal activity due to the fusion of the amide moiety or the acylthiourea moiety with the pinane skeleton. The structure-activity relationship analysis showed that the fluorine atom and the strong electron withdrawing nitro group, or trifluoromethyl group on the benzene ring of the derivatives had a significant effect on the improvement of the antifungal activity against Colletotrichum gloeosporioides, Fusarium proliferatum, Alternaria kikuchiana and Phomopsis sp. Meanwhile, the introduction of an ethyl group at the meta-position on the benzene ring of the derivatives could improve the antifungal activity against Phytophthora capsici. Compounds 4e, 4h, 4q, 4r exhibited broad-spectrum antifungal activity against the tested strains. Compound 4o had significant antifungal activity against Phytophthora capsici (IC50 = 0.18 µmol/L). These derivatives were expected to be used as precursor molecules for novel pesticide development in further research.

Density functional theory study on structure and stability of BeBn+ clusters.

RATIONALE: Boride compounds hold promise for broad applications in the field of optoelectronics due to their high-temperature resistant, corrosion resistant and antioxidant properties. In order to reveal the formation mechanism of alkali and alkaline earth metal doped boron clusters, theoretical studies of these systems are required. METHODS: All the possible geometrical structures of BeBn+ clusters (n = 1-8) were optimized at the B3LYP/6-311+G(d) level; the harmonic vibration frequencies were obtained to examine the true stability and give the zero-point vibration energy at that theoretical level. The single point energies of all the structures were computed at the CCSD(T)/aug-cc-pVDZ level. For the most stable structures, the average binding energy (Eb ), the fragmentation energy (EF ) and second-order difference of total energy (Δ2 E) were used to evaluate the relative stability of clusters. RESULTS: Most of the BeBn+ clusters are planar in structure; the B atoms tend to aggregate to form a boron ring, and the coordinating Be atoms are on the periphery of the clusters. The fragmentation energy and second-order difference of total energy show that there is an obvious odd-even alteration as n increases, and local-maxima when n is odd. CONCLUSIONS: A systematic theoretical investigation on the geometries, stabilities and electronic properties of BeBn+ clusters has been carried out where n = 1-8. The results provide a useful reference for understanding the formation mechanism and stability of these clusters, as well as guidance for finding larger size clusters.

Hydronopylformamides: Modification of the Naturally Occurring Compound (-)-ß-Pinene to Produce Insect Repellent Candidates against Blattella germanica.

The development of a novel repellent plays an important role in the integrated control of Blattella germanica. A series of novel hydronopylformamides derivatives were synthesized from a naturally occurring compound (-)-ß-pinene. The structures of these hydronopylformamides derivatives were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (¹H-NMR and 13C-NMR), and electron impact mass spectrometry (EI-MS). Repellency of these hydronopylformamides derivatives against Blattella germanica was evaluated by the using petri dish arena method. The results showed that four derivatives (compounds 8a, 8b, 8c and 8e) exhibited repellency against Blattella germanica at a concentration of 20 mg/mL. Compound 8a was the most active compound among these derivatives, where the repelling ratios of compound 8a against Blattella germanica were 66.10%, 50.46%, 48.26%, at concentrations of 20 mg/mL, 10 mg/mL, and 5 mg/mL, respectively. In addition, compound 8a showed better repellency than the traditional insect repellent N, N-diethyl-3-methylbenzamide (DEET), which indicated that compound 8a had a good application prospect in the prevention of Blattella germanica. This research hopes to promote the value-added utilization of (-)-ß-pinene and the development of novel German cockroach repellents.

Annual risk of tuberculosis infection in rural China: a population-based prospective study.

Prospective population data on the incidence of tuberculosis (TB) infection has been sparsely reported in the global literature.A population-based prospective study was conducted in rural China to investigate the annual risk of TB infection, and its persistence using serial tuberculin skin tests (TSTs) and an interferon-γ release assay. In total, 13 580 eligible participants from four rural sites, identified as TST negative (<10 mm) or QuantiFERON-TB Gold In-Tube (QFT) (an interferon-γ release assay) negative from a baseline survey, were included in the first year's follow-up examination.The annual conversion rate of QFT among the study sites ranged between 2.1% and 4.9% (average 3.1%), and the incidence of TST conversion ranged between 6.0% and 31.1% (average 14.5%). During the second year's follow-up, infection persistence was investigated using 390 subjects with QFT conversions. Among them, 49.7% (164 out of 330) were found to be consistently QFT positive. Both the conversion and the persistence of QFT positivity were found to be significantly increased with increasing age.In conclusion, the annual TB infection rate was suggested to be ∼1.5% based on persistent positive results after QFT conversion in rural China. Therefore, infection control among those high-risk populations, including the elderly, should be prioritised for TB control in China.

One-pot synthesis and antimicrobial evaluation of novel 3-cyanopyridine derivatives of (-)-ß-pinene.

A series of novel 3-cyanopyridine derivatives of (-)-ß-pinene were designed and synthesized by one-pot four-component domino reactions. The targeted compounds were evaluated for their antimicrobial activity against four bacteria (Klebsiella pneumoniae, Enterobacter aerogenes, Staphylococcus aureus, Staphylococcus epidermidis) and a fungus (Candida albicans). The results showed that most of the minimal inhibitory concentrations (MICs) of these 3-cyanopyridine derivatives against the tested strains was in the range of 15.6-125 mg/L. Among these 3-cyanopyridine derivatives, the MICs of compound 5h against S. epidermidis and C. albicans were 15.6 mg/L, which revealed that compound 5h featured double fluoro substituents at meta- and para-position was the most active compound. In addition, the preliminary structure-activity relationship analysis indicated that the change of substituents on the pyridine ring and benzene ring of 3-cyanopyridine derivatives was an important factor for inducing antimicrobial activity. This research would promote the development of heterocyclic derivatives of ß-pinene with antimicrobial activity.

Pinonic Acid Derivatives Containing Thiourea Motif: Promising Antifungal Lead Compound Targeting Cellular Barrier of Colletotrichum fructicola.

In order to explore novel antifungal lead compounds from plant essential oil, thirty-two pinonic acid derivatives containing thiourea groups were designed and synthesized using α-pinene as a raw material. One of these pinonic acid derivatives compound 3a exhibited noteworthy in vitro antifungal activity against Colletotrichum fructicola (EC50 = 9.22 mg/L), which was comparable to that of the positive control kresoxim-methyl (EC50 = 9.69 mg/L). Structure-activity relationship (SAR) studies demonstrated that the introduction of thiourea groups, F atoms, and Cl atoms into the structure of pinonic acid derivatives significantly improved their antifungal activity. The in vivo antifungal test revealed that compound 3a could effectively control pear anthracnose. It also proved that compound 3a showed low acute oral toxicity to honeybees (LD50 > 100 µg/bee) and low or no cytotoxicity to LO2 and HEK293 cell lines. The preliminary mechanism of action studies revealed that compound 3a caused mycelium deformity, increased cell membrane permeability, blocked the normal process of phospholipase C on the cell membrane, and reduced mycelium protein content. The results of molecular docking studies demonstrated the stable binding of compound 3a to phospholipase C and chitin synthetase. This study suggested that compound 3a could be used as a promising lead compound for the development of novel antifungal agents targeting the cellular barrier of C. fructicola.

Antifungal Activity and Mechanism of Camphor Derivatives against Rhizoctonia solani: A Promising Alternative Antifungal Agent for Rice Sheath Blight.

Rice sheath blight, caused by the fungus Rhizoctonia solani, poses a significant threat to rice cultivation globally. This study aimed to investigate the potential mechanisms of action of camphor derivatives against R. solani. Compound 4o exhibited superior fungicidal activities in vitro (EC50 = 6.16 mg/L), and in vivo curative effects (77.5%) at 500 mg/L were significantly (P < 0.01) higher than the positive control validamycin·bacillus (66.1%). Additionally, compound 4o exhibited low cytotoxicity and acute oral toxicity for adult worker honeybees of Apis mellifera L. Mechanistically, compound 4o disrupted mycelial morphology and microstructure, increased cell membrane permeability, and inhibited both PDH and SDH enzyme activities. Molecular docking and molecular dynamics analyses indicated a tight interaction of compound 4o with PDH and SDH active sites. In summary, compound 4o exhibited substantial antifungal efficacy against R. solani, serving as a promising lead compound for further optimization of antifungal agents.

Synthesis, antifungal activity and action mechanism of novel citral amide derivatives against Rhizoctonia solani.

BACKGROUND: Rice sheath blight caused by Rhizoctonia solani is a severe threat to the yield and quality of rice. Due to the unscientific abuse of common fungicides causing resistance and environmental issues, the development of new fungicides is necessary. In this study, we used citral as the lead compound, designed and synthesized a series of novel citral amide derivatives, and evaluated their antifungal activity and mode of action against R. solani. RESULT: Bioassay results indicated that the antifungal activities of most citral amide derivatives against R. solani were significantly improved compared to citral, with EC50 values ranging from 9.50-27.12 mg L-1. Among them, compound d21 containing the N-(pyridin-4-yl)carboxamide group exhibited in vitro and in vivo fungicidal activities, with curative effects at 500 mg L-1 as effectively as the commercial fungicide validamycin·bacillus. Furthermore, d21 prolonged the lag phase of the growth curve of R. solani, reduced the amount of growth, and inhibited sclerotium germination and formation. Mechanistically, d21 deformed the mycelia, increased cell membrane permeability, and inhibited the activities of antioxidant and tricarboxylic acid cycle (TCA)-related enzymes. Metabolome analysis showed the abundance of some energy-related metabolites within R. solani increased, and simultaneously the antifungal substances secreted by itself reduced. Transcriptome analysis showed that most genes encoding ATP-binding cassette (ABC) transporters and peroxisomes upregulated after the treatment of d21 and cell membrane destruction. CONCLUSION: This study indicates that novel citral amide derivatives possess antifungal activity against R. solani and are expected to develop an alternative option for chemical control of rice sheath blight. © 2024 Society of Chemical Industry.

Novel Design of Citral-Thiourea Derivatives for Enhancing Antifungal Potential against Colletotrichum gloeosporioides.

Although much progress has been made in developing botanical fungicides to combat fungal diseases in crops, there remains a great need to improve the efficiency and long-term safety of these fungicides. This study proposes a novel strategy for designing citral-thiourea derivatives that feature such desirable properties. The motivation of the work herein was to enhance the antifungal activity of citral against C. gloeosprioides by exploiting the synergistic effect that arises from combining citral and thiourea compounds, thereby producing citral-thiourea derivatives that exhibit good long-term safety. The results revealed that the generated compounds e1, e3, e6, e18, and g showed remarkable antifungal activities against C. gloeosprioides, with corresponding EC50 values reaching 0.16, 1.66, 1.37, 4.76, and 4.60 mg/L, respectively, showing that the compounds significantly outperformed both the positive control kresoxim-methyl and the commercially available fungicide carbendazim. Furthermore, compound g showed stronger protective efficacy against C. gloeosprioides than carbendazim on mango fruit at 25 mg/L. Investigating the preliminary structure-activity relationship (SAR) of the compounds also revealed that the citral-thiourea derivatives exhibited higher antifungal activities against C. gloeosprioides compared to citral and thiourea compounds. This reinforcement of antifungal activity observed in the derivatives was found to be attributable to the two characteristics of low molecular size and the presence of a fluorine atom in the meta-position of the benzene ring. Beyond this, it was determined from QSAR that two molecular descriptors (the Kier-Hall index (order 3) and Tot dipole of the molecules) were negatively related to the antifungal activity of the citral-thiourea derivatives, while one other (the maximum resonance energy of a C-H bond) was positively related to their antifungal activity. More importantly, the citral-thiourea derivatives with high antifungal activities (i.e., compounds e1, e3, e6, e14, e15, e18, and g) exhibited negligible cytotoxicity to LO2 and HEK293T cell lines. The antifungal mechanism of the generated citral-thiourea derivatives was investigated by scanning electron microscopy (SEM) and relative conductivity. The derivatives were found to affect mycelial morphology and increase fungal cell membrane permeability, thereby resulting in the destruction of fungal cell membranes. These promising results provide novel insights into the study and potential application value of citral-thiourea derivatives as high-efficiency antifungal agents against C. gloeosprioides.

Synthesis, Antifungal Activity, Cytotoxicity and QSAR Study of Camphor Derivatives.

Control of fungal phytopathogens affecting crops and woodlands is an important goal in environmental management and the maintenance of food security. This work describes the synthesis of 37 camphor derivatives, of which 27 were new compounds. Their antifungal effects on six fungi were evaluated in vitro. Compounds 3a, 4a and 5k showed strong antifungal activity against Trametes versicolor, with EC50 values of 0.43, 6.80 and 4.86 mg/L, respectively, which were better than that of tricyclazole (EC50 118.20 mg/L) and close to or better than that of carbendazim (EC50 1.20 mg/L). The most potent compound, 3a, exhibited broad-spectrum antifungal activity towards six fungi with EC50 values within the range of 0.43-40.18 mg/L. Scanning electron microscopy demonstrated that compounds 3a, 4a and 5k gave irregular growth and shriveling of the mycelia. In vitro cytotoxicity evaluation revealed that the tested camphor derivatives had mild or no cytotoxicity for LO2 and HEK293T cell lines. Quantitative structure-activity relationship (QSAR) analysis revealed that the number of F atoms, relative molecular weight, the atomic orbital electronic population and total charge on the positively charged surfaces of the molecules of camphor derivatives have effects on antifungal activity. The present study may provide a theoretical basis for a high-value use of camphor and could be helpful for the development of novel potential antifungals.

Novel Citral-thiazolyl Hydrazine Derivatives as Promising Antifungal Agents against Phytopathogenic Fungi.

To develop new antifungal agents against phytopathogenic fungi, a series of citral-thiazolyl hydrazine derivatives were designed, synthesized, and characterized by FT-IR, 1H NMR, 13C NMR, and HRMS. Antifungal activity results showed that most synthetic compounds exhibited broad-spectrum antifungal activities against six phytopathogenic fungi in vitro. Notably, compounds b and c15 exhibited remarkable antifungal activity against Colletotrichum gloeosprioides, Rhizoctonia solani, Phytophthora nicotianae var. nicotianae, Diplodia pinea, Colletotrichum acutatum, and Fusarium oxysporum f. sp. niveum, which were all superior to the positive control tricyclazole. Structure-activity relationship (SAR) studies demonstrated that introducing electron-withdrawing groups such as F on the benzene ring exhibited outstanding antifungal activities against all the tested fungi. Furthermore, compound b could effectively control rice sheath blight and showed higher curative activities against R. solani than validamycin·bacillus in vivo. In addition, the in vitro cytotoxicity results indicated that compound b possessed moderate cytotoxicity activity, and all citral-thiazolyl hydrazine derivatives exhibited lower or no cytotoxicity to the LO2 and HEK293 cell lines. In addition, the acute oral toxicity test showed that compound b had moderate toxicity (level II) with an LD50 value of 310 mg/kg bw (95% confidence limit: 175-550 mg/kg bw). Finally, a preliminary action mechanism study showed that causing obvious malformation of mycelium and increasing cell membrane permeability are two of the potential mechanisms by which compound b exerts antifungal activity. The present work indicates that some of these derivatives may serve as novel potential fungicides, and compound b is expected to be the leading structure for the development of new antifungal agents.

[Application of denaturing high perfomance liquid chromatography in detection of rpoB mutations associated with rifampin resistance in Mycobacterium tuberculosis].

OBJECTIVE: to explore the value of denaturing high performance liquid chromatography (DHPLC) in detection of rpoB mutations in rifampin-resistant M. tuberculosis, in order to establish a convenient and rapid approach to screening rpoB gene mutations in M. tuberculosis. METHODS: rifampin resistance-determining region of rpoB gene in M. tuberculosis was amplified by PCR and further analyzed by DHPLC to screen mutations at optimized denaturation temperature (65.4 degrees C), which utilized heteroduplex formation between wild-type and mutated DNA strands to identify mutations. The PCR products from strains with different chromatographic profiles were sequenced further to evaluate the sensitivity and specificity. RESULTS: there were 46 M. tuberculosis strains including 42 rifampin resistance strains and 4 rifampin sensitive strains. From these strains, 15 different chromatographic profiles were produced by DHPLC. Combined with the results of gene sequencing, it was shown that strains with different chromatographic profiles had distinct mutations. Except D108 and D24 which had same chromatographic profiles but different genetic polymorphisms, all other strains showed consistent chromatographic profiles with genetic polymorphisms, i.e. if they had identical chromatographic profiles, their genetic polymorphism were the same; but if they had different chromatographic profiles, their genetic polymorphism were also different. CONCLUSION: DHPLC is a simple, efficient, high-throughput and automatic method with high sensitivity and specificity, which may be useful in the rapid detection of rpoB gene mutation in M. tuberculosis.

Synthesis of ordered lamellar supermicroporous silica with rigid neutral and long-chain cationic composite templating route.

Using a mixture of neutral primary amine dehydroabietylamine (DHAA) and long-chain cetyltrimethyl ammonium bromide (CTAB) as the template, ordered lamellar supermicroporous silicas were synthesized with NaOH as the base source and tetraethylorthosilicate (TEOS) as the silica source. The concentrations of DHAA, CTAB, and NaOH in the synthesis system had great effects on the structural properties of the samples. When the molar ratio of components was nTEOS:nCTAB:nDHAA:nNaOH:nH2O = 1:0.114:0.00457:0.5:60, the material showed a lamellar phase with the highest ordering degree. By adding only a trace amount of DHAA into the synthesis system, the structure of the samples could be transformed from cubic phase to lamellar phase, since the added DHAA solubilized in CTAB micelles to change the effective surfactant ion pair packing parameter. The dosage of CTAB should be moderate; too high or too low will decay the ordering degree of the lamellar structure.A much higher concentration of NaOH resulted in an ethanol-rich solvent in which the DHAA did not solubilize in the micelles of CTAB, but adsorbed at the hydrophilic headgroup-solvent interface. Accordingly, a structural transformation from lamellar phase to hexagonal phase occurred.

Incidence of active tuberculosis in individuals with latent tuberculosis infection in rural China: follow-up results of a population-based, multicentre, prospective cohort study.

BACKGROUND: The management of latent Mycobacterium tuberculosis infection is a new priority action for the WHO End Tuberculosis (TB) Strategy. However, national guidelines on latent tuberculosis infection testing and treatment have not yet been developed in China. Here, we present the results from the 2-year follow-up of a study that aimed to track the development of active disease in individuals with latent tuberculosis infection, identify priority populations for latent infection management, and explore the most suitable latent infection diagnostic approach. METHODS: A population-based multicentre prospective study was done in four sites in rural China, between 2013 and 2015. The baseline survey in 2013 measured the prevalence of latent tuberculosis infection using QuantiFERON-TB Gold In-Tube (QFT) and tuberculin skin test (TST) in eligible participants. During the follow-up phase between 2014-15, we assessed individuals who had tuberculosis infection at baseline (QFT-positivity or TST tuberculin reaction size [induration] of ≥10 mm) for the development of active disease through active case finding. Eligible participants included in follow-up survey had a birth date before June 1, 2008 (5 years or older in 2013), and continuous residence at the study site for 6 months or longer in the past year. Participants with current active tuberculosis at baseline survey were excluded. FINDINGS: Between Sept 1, 2013, and Aug 31, 2015, 7505 eligible participants (aged 5 years or older) were included in tuberculosis infection test positive cohorts (4455 were QFT positive, 6404 had TST induration ≥10 mm, and 3354 were positive for both tests) after baseline examination. During the 2-year follow-up period, 84 incident cases of active tuberculosis were diagnosed. Of participants who developed active tuberculosis, 75 were diagnosed with latent infection by QFT, 62 were diagnosed by TST, and 53 were diagnosed by both tests. An incidence rate of 0·87 (95% CI 0·68-1·07) per 100 person-years was observed for individuals who tested positive with QFT, 0·50 (0·38-0·63) per 100 person-years for those who tested positive with TST (p<0·0001), and 0·82 (0·60-1·04) per 100 person-years for those who tested positive with both tests. Male sex and a history of tuberculosis were significantly associated with increased risk of disease development with adjusted hazard ratios of 2·36 (95% CI 1·30-4·30) for male sex and 5·40 (3·34-8·71) for a history of tuberculosis. INTERPRETATION: Our results suggest that high-risk populations in communities in rural China, such as individuals at a high risk of disease reactivation from previous tuberculosis, should be targeted for latent infection screening and treatment with an interferon-γ releasing assay rather than a TST. FUNDING: National Science and Technology Major Project of China, Program for Changjiang Scholars and Innovative Research Team in University of China, CAMS Innovation Fund for Medical Sciences, and Sanming Project of Medicine in Shenzhen.

Latent tuberculosis infection in rural China: baseline results of a population-based, multicentre, prospective cohort study.

BACKGROUND: Prophylactic treatment of individuals with latent Mycobacterium tuberculosis infection is an essential component of tuberculosis control in some settings. In China, the prevalence of latent tuberculosis infection, and preventive interventions against this disease, have not been systematically studied. We aimed to assess the prevalence of latent tuberculosis and its associated risk factors in rural populations in China. METHODS: Between July 1, and Sept 30, 2013, we undertook a baseline survey of a population-based, multicentre, prospective cohort study of registered residents (≥5 years old) at four study sites in rural China. Eligible participants were identified by door-to-door survey with a household sampling design. We screened participants for active tuberculosis and history of tuberculosis then used a tuberculin skin test and an interferon-γ release assay (QuantiFERON [QFT]) to test for latent infection. We used odds ratios (ORs) and 95% CIs to assess variables associated with positivity of QFT and tuberculin skin tests. FINDINGS: 21,022 (90%) of 23,483 eligible participants completed a baseline survey. Age-standardised and sex-standardised rates of skin-test positivity (≥10 mm) ranged from 15% to 42%, and QFT positivity rates ranged from 13% to 20%. Rates of positivity for the tuberculin skin test and the QFT test were low in study participants younger than 20 years and gradually increased with age (p for trend <0·0001). Rates of latent tuberculosis infection were higher for men than women (p<0·0001). Overall agreement between the tuberculin skin test and the QFT test was moderate (81·06%; kappa coefficient 0·485), with skin-test-only positive results associated with the presence of BCG scar, male sex, and ages of 60 years and older, and QFT-only positive results associated with male sex and ages of 60 years and older. INTERPRETATION: On the basis of findings showing that the performance of the tuberculin skin test might be affected by various factors including BCG vaccination and age, our results suggest that the prevalence of latent tuberculosis in China might be overestimated by skin tests compared with interferon-γ release assays. FUNDING: The National Science and Technology Major Project of China, the Program for Changjiang Scholars and Innovative Research Team in University of China.

Molecular epidemiology of Mycobacterium tuberculosis in Gansu province of China.

BACKGROUND: Mycobacterial interspersed repetitive units-variable number tandem repeat (MIRU-VNTR) and Beijing family typing based on detecting the deletion of RD105 sequence are two common genotyping methods used to study the molecular epidemiologic characteristics of Mycobacterium (M.) tuberculosis. We collected 218 strains of M. tuberculosis between 2004 and 2006 in the Linxia Hui Autonomous Prefecture of Gansu province in Northwest China. METHODS: MIRU-VNTR analysis and Beijing family typing based on detecting the deletion of RD105 sequence were used to type the 218 strains, and their typing power was evaluated to look for practical and efficient genotyping methods suitable for the region. RESULTS: The MIRU typing yielded 115 distinct genotypes, including 98 unique isolates and 17 different clusters containing 120 isolates (55.05%); the cluster rate was 47.25%. By detecting the deletion of RD105 sequence, 188 of 218 (86.23%) isolates belonged to Beijing family. Combination of Beijing family typing and MIRU typing yielded 118 distinct patterns, including 101 unique isolates and 17 clusters containing 117 isolates (54.13%). The largest cluster contained 58 strains with MIRU genotype of 223325173533 which contained 50 strains belonging to Beijing family and 8 strains belonging to non-Beijing family. CONCLUSIONS: The Beijing family strains occupied a large proportion and the Beijing family MIRU genotype 223325173533 is a dominant strain in Linxia of Gansu. Combining detecting the deletion of RD105 and MIRU typing together provides a simple, fast, and effective method which is low in cost and might be practical and suitable for M. tuberculosis genotyping in China.