Rapid visual detection of Giardia duodenalis in faecal samples using an RPA-CRISPR/Cas12a system.

Giardiasis is a common intestinal infection caused by Giardia duodenalis, which is a major economic and health burden for humans and livestock. Currently, a convenient and effective detection method is urgently needed. CRISPR/Cas12a-based diagnostic methods have been widely used for nucleic acid-based detection of pathogens due to their high efficiency and sensitivity. In this study, a technique combining CRISPR/Cas12a and RPA was established that allows the detection of G. duodenalis in faecal samples by the naked eye with high sensitivity (10-1 copies/µL) and specificity (no cross-reactivity with nine common pathogens). In clinical evaluations, the RPA-CRISPR/Cas12a-based detection assay detected Giardia positivity in 2% (1/50) of human faecal samples and 47% (33/70) of cattle faecal samples, respectively, which was consistent with the results of nested PCR. Our study demonstrated that the RPA-CRISPR/Cas12a technique for G. duodenalis is stable, efficient, sensitive, specific and has low equipment requirements. This technique offers new opportunities for on-site detection in remote and poor areas.

Adsorption mechanism of rhein-coated Fe3O4 as magnetic adsorbent based on low-field NMR.

In the present study, a magnetic adsorbent, rhein-coated magnetic Fe3O4 nanoparticle (RMNP), for Pb2+ and Mg2+ had been developed, and adsorption mechanism was studied via low-field NMR. RMNP was characterized by TEM, FTIR, and XRD. RMNP could adsorb and remove Pb2+ and Mg2+ from water and was successfully applied to remove Pb2+ and Mg2+ from wastewater, with satisfactory recovery rates and high adsorption capacities. The calculated maximum adsorption capacity for Mg2+ and Pb2+ was approximately 69.3 and 64.9 mg g-1 of RMNP, respectively, which was better than some results reported. Low-field NMR results showed that Pb2+ or Mg2+ enhanced the T2 relaxation time of RMNP, which suggested that RMNP selectively coordinated with Pb2+ or Mg2+ and led to the aggregation of RMNP, furthermore removal of Pb2+ or Mg2+ from water. The standard curves for △T2-cation concentration exhibited good line correlation. The linear ranges were from 4.2 × 10-6 to 2.0 × 10-4 mol L-1 for Pb2+ and from 5.0 × 10-6 mol L-1 to 1.0 × 10-4 mol L-1 for Mg2+, respectively. The limits of detection were 1.4 × 10-6 mol L-1 for Pb2+ and 2.1 × 10-6 mol L-1 for Mg2+, respectively. In short, low-field NMR could clearly display the interaction between RMNP and Pb2+ or Mg2+, even be used to detect Pb2+ or Mg2+ in suitable condition. Besides, this method could be expanded to study the interaction between other magnetic adsorbents and analytes.

RNA-seq reveals tight junction-relevant erythropoietic fate induced by OCT4 in human hair follicle mesenchymal stem cells.

BACKGROUND: Human hair follicle mesenchymal stem cells (hHFMSCs) isolated from hair follicles possess multilineage differentiation potential. OCT4 is a gene critically associated with pluripotency properties. The cell morphology and adhesion of hHFMSCs significantly changed after transduction of OCT4 and two subpopulations emerged, including adherent cells and floating cell. Floating cells cultured in hematopoietic induction medium and stimulated with erythropoetic growth factors could transdifferentiate into mature erythrocytes, whereas adherent cells formed negligible hematopoietic colonies. The aim of this study was to reveal the role of cell morphology and adhesion on erythropoiesis induced by OCT4 in hHFMSCs and to characterize the molecular mechanisms involved. METHODS: Floating cell was separated from adherent cell by centrifugation of the upper medium during cell culture. Cell size was observed through flow cytometry and cell adhesion was tested by disassociation and adhesion assays. RNA sequencing was performed to detect genome-wide transcriptomes and identify differentially expressed genes. GO enrichment analysis and KEGG pathway analysis were performed to analysis the functions and pathways enriched by differentially expressed genes. The expression of tight junction core members was verified by qPCR and Western blot. A regulatory network was constructed to figure out the relationship between cell adhesin, cytoskeleton, pluripotency, and hematopoiesis. RESULTS: The overexpression of OCT4 influenced the morphology and adhesion of hHFMSCs. Transcripts in floating cells and adherent cells are quite different. Data analysis showed that upregulated genes in floating cells were mainly related to pluripotency, germ layer development (including hematopoiesis lineage development), and downregulated genes were mainly related to cell adhesion, cell junctions, and the cytoskeleton. Most molecules of the tight junction (TJ) pathway were downregulated and molecular homeostasis of the TJ was disturbed, as CLDNs were disrupted, and JAMs and TJPs were upregulated. The dynamic expression of cell adhesion-related gene E-cadherin and cytoskeleton-related gene ACTN2 might cause different morphology and adhesion. Finally, a regulatory network centered to OCT4 was constructed, which elucidated that he TJ pathway critically bridges pluripotency and hematopoiesis in a TJP1-dependent way. CONCLUSIONS: Regulations of cell morphology and adhesion via the TJ pathway conducted by OCT4 might modulate hematopoiesis in hHFMSCs, thus developing potential mechanism of erythropoiesis in vitro.

Gastric Mucosa-Associated Microbial Signatures of Early Gastric Cancer.

Alterations in the microbiome are associated with the development of gastric cancer. Our study aimed to identify dysbiotic features in early gastric cancer (EC). The gastric microbiome was assessed in EC (n = 30), advanced gastric cancer (AC) (n = 30), and chronic gastritis (CG) (n = 60). The results demonstrated significant differences in the microbial profile and composition between EC and AC, suggesting alterations associated with gastric cancer progression. Linear discriminant analysis (LDA) effect size (LEfSe) analyses identified 32 bacterial genera that were associated with EC. Functional analyses of the gastric microbiome showed that the production of urease and synthesis of bacterial flagella were weakened in EC, while the glycolysis of fructose and hydrolysis of glycosides were enhanced. A classifier based on a random forest (RF) machine learning algorithm identified a microbial signature that distinguished EC from CG or AC with high accuracy. The correct identification of the signature was further validated in independent cohorts. This signature enriched of bacteria with varied abundance, high degree of bacterial interactions and carcinogenic potentials. Constrained principal coordinate analyses revealed that the presence of Helicobacter pylori and the cagA and vacA virulence genotypes influenced the structure of the gastric microbiome. To determine the impacts of host genetic variations on the gastric microbiome, six previously reported single nucleotide polymorphisms (SNPs) were examined. The minor allele of MUC1 rs4072037 was associated with an increased abundance of Ochrobactrum. The gastric microbiome altered in EC, which might be attributed in part to host genetic variations, H. pylori infection, bacterial virulence and environmental adaptations. The identified microbial signature could serve as biomarkers for clinical assessment of gastric cancer risk in high-risk patients.

A Novel Anti-Microbial Peptide from Pseudomonas, REDLK Induced Growth Inhibition of Leishmania tarentolae Promastigote In Vitro.

Leishmaniasis is a prevalent cause of death and animal morbidity in underdeveloped countries of endemic area. However, there is few vaccine and effective drugs. Antimicrobial peptides are involved in the innate immune response in many organisms and are being developed as novel drugs against parasitic infections. In the present study, we synthesized a 5-amino acid peptide REDLK, which mutated the C-terminus of Pseudomonas exotoxin, to identify its effect on the Leishmania tarentolae. Promastigotes were incubated with different concentration of REDLK peptide, and the viability of parasite was assessed using MTT and Trypan blue dye. Morphologic damage of Leishmania was analyzed by light and electron microscopy. Cellular apoptosis was observed using the annexin V-FITC/PI apoptosis detection kit, mitochondrial membrane potential assay kit and flow cytometry. Our results showed that Leishmania tarentolae was susceptible to REDLK in a dose-dependent manner, disrupt the surface membrane integrity and caused parasite apoptosis. In our study, we demonstrated the leishmanicidal activity of an antimicrobial peptide REDLK from Pseudomonas aeruginosa against Leishmania tarentolae in vitro and present a foundation for further research of anti-leishmanial drugs.

In vitro leishmanicidal activity of antimicrobial peptide KDEL against Leishmania tarentolae.

Leishmaniasis, caused by the intracellular protozoan parasite Leishmania, remains an important neglected tropical infectious disease. Infection may be lethal if untreated. Currently, the available drugs for the disease are limited by high toxicity and drug resistance. There is an urgent need to develop novel anti-leishmanial strategies. Antimicrobial peptides (AMPs) have been described as the first-line immune defense against pathogenic microbes and are being developed as emerging anti-parasitic therapies. In the present study, we showed the anti-leishmanial activity of the synthetic 4-amino acid peptide lysine, aspartic acid, glutamic acid, and leucine (KDEL), the endoplasmic reticulum retention sequence, against Leishmania tarentolae promastigote and amastigote. Different concentrations of KDEL peptides were incubated with promastigotes, MTT viability assay, and promastigote assay were carried out. Macrophages infected with GFP-transfected L. tarentolae promastigotes were incubated with KDEL peptides, and the anti-amastigote activity of the KDEL peptides was measured by fluorescence microscopy. The damage of L. tarentolae was observed by light microscopy and electron microscopy. The cell apoptosis was analyzed using the Annexin V-FITC/PI apoptosis detection kit and mitochondrial membrane potential assay kit and by flow cytometry. Results showed that L. tarentolae was susceptible to KDEL peptides in a dose-dependent manner, and KDEL peptides disrupted the surface membrane integrity and caused cell apoptosis. In our study, we found for the first time an AMP KDEL from Pseudomonas aeruginosa and proved its significant therapeutic potential as a novel anti-leishmanial drug.

Metabolism of hyperpolarized 13 C-acetoacetate to ß-hydroxybutyrate detects real-time mitochondrial redox state and dysfunction in heart tissue.

Mitochondrial dysfunction is considered to be an important component of many metabolic diseases yet there is no reliable imaging biomarker for monitoring mitochondrial damage in vivo. A large prior literature on inter-conversion of ß-hydroxybutyrate and acetoacetate indicates that the process is mitochondrial and that the ratio reflects a specifically mitochondrial redox state. Therefore, the conversion of [1,3-13 C]acetoacetate to [1,3-13 C]ß-hydroxybutyrate is expected to be sensitive to the abnormal redox state present in dysfunctional mitochondria. In this study, we examined the conversion of hyperpolarized (HP) 13 C-acetoacetate (AcAc) to 13 C-ß-hydroxybutyrate (ß-HB) as a potential imaging biomarker for mitochondrial redox and dysfunction in perfused rat hearts. Conversion of HP-AcAc to ß-HB was investigated using 13 C magnetic resonance spectroscopy in Langendorff-perfused rat hearts in four groups: control, global ischemic reperfusion, low-flow ischemic, and rotenone (mitochondrial complex-I inhibitor)-treated hearts. We observed that more ß-HB was produced from AcAc in ischemic hearts and the hearts exposed to complex I inhibitor rotenone compared with controls, consistent with the accumulation of excess mitochondrial NADH. The increase in ß-HB, as detected by 13 C MRS, was validated by a direct measure of tissue ß-HB by 1 H nuclear magnetic resonance in tissue extracts. The redox ratio, NAD+ /NADH, measured by enzyme assays of homogenized tissue, also paralleled production of ß-HB from AcAc. Transmission electron microscopy of tissues provided direct evidence for abnormal mitochondrial structure in each ischemic tissue model. The results suggest that conversion of HP-AcAc to HP-ß-HB detected by 13 C-MRS may serve as a useful diagnostic marker of mitochondrial redox and dysfunction in heart tissue in vivo.

Esterase-Catalyzed Production of Hyperpolarized 13C-Enriched Carbon Dioxide in Tissues for Measuring pH.

13C Magnetic resonance imaging of hyperpolarized (HP) 13C-enriched bicarbonate (H13CO3-) and carbon dioxide (13CO2) is a novel and sensitive technique for tissue pH mapping in vivo. Administration of the HP physiological buffer pair is attractive, but poor polarization and the short T1 of 13C-enriched inorganic bicarbonate salts are major drawbacks for this approach. Here, we report a new class of mixed anhydrides for esterase-catalyzed production of highly polarized 13CO2 and H13CO3- in tissue. A series of precursors with different alkoxy and acyl groups were synthesized and tested for chemical stability and T1. 13C-enriched ethyl acetyl carbonate (13C-EAC) was found to be the most suitable candidate due to the relatively long T1 and good chemical stability. Our results showed that 13C-EAC can be efficiently and rapidly polarized using BDPA. HP 13C-EAC was rapidly hydrolyzed by esterase to 13C-enriched monoacetyl carbonate (13C-MAC), which then decomposed to HP 13CO2. Equilibrium between the newly produced 13CO2 and H13CO3- was quickly established by carbonic anhydrase, producing a physiological buffer pair with 13C NMR signals that can be quantified for pH measurements. Finally, in vivo tissue pH measurements using HP 13C-EAC was successfully demonstrated in the liver of healthy rats. These results suggest that HP 13C-EAC is a novel imaging probe for in vivo pH measurements.

A new malyngamide from the marine cyanobacterium Moorea producens.

A new malyngamide (1) was isolated along with seven known compounds (2-8) from the marine cyanobacterium Moorea producens collected in Hawaii. Compound 1 represented the first reported malyngamide with a hydroxy moiety at C-7 of the characteristic fatty acid portion of the compound. Compound 1 showed cytotoxicity against L1210 cell line at an IC50 value of 2.9 mM and lethal toxicity against the shrimp Palaemon paucidens at a LD100 value of 33.3 mg/kg. The bioactivity of compound 1 was approximately 10-100 times weaker than those of isomalyngamides A and B (3, 4). These results indicated that the methoxy group at C-7 of the fatty acid section confers a degree of bioactivity in malyngamides.

Sensitive fluorescent assay for copper(ii) determination in aqueous solution using quercetin-cyclodextrin inclusion.

Environmentally friendly probe materials for detecting copper ions were studied in this research. Fluorescent emission of quercetin (Q) was observed in the buffer solution (pH = 7.40), and (2-hydroxypropyl)-ß-cyclodextrin (CD) could enhance the fluorescence intensity of Q. The UV/Vis spectrum showed that the Q-CD system was formed. After adding copper ions into the Q-CD system, the fluorescent emission intensity of Q-CD system generated quenching, and other metal ions could not bring change, which meant the Q-CD system showed good selectivity to copper ions. The fluorescence titration spectra showed that the concentration of copper ions was inversely proportional to fluorescence intensity, and gave a good linear change in fluorescence emission intensity in response to the concentration of copper ions ranging from 5.0 × 10-8 to 8.3 × 10-6 mol L-1. The calibration curve of the relationship between the intensity and copper ions concentration was y = -9.24x + 844.51 (R 2 = 0.997). The detection limit of copper ions was measured to be 2.3 × 10-8 mol L-1. The probable mechanism was studied by UV/Vis spectrum and Job's plot method. The results indicated that Q-CD-Cu(ii) complex was formed and intramolecular charge transfer (ICT) took place. At last, the probe was successfully applied for determination of copper ions in water bodies, vegetables and fruits with good recovery. The study showed that Q-CD system could detect copper ions as a fluorescent probe with high selectivity, sensitivity and larger linearity range.

A new diatom growth inhibition assay using the XTT colorimetric method.

Marine biofouling, which leads to significant operational stress and economic damage on marine infrastructures, is a major problem in marine related industries. Currently, the most common way to avoid marine biofouling involves the use of biocidal products in surface coatings. However, the need for environmentally friendly antibiofouling compounds has increased rapidly with the recent global prohibition of harmful antifoulants, such as tributyltin (TBT). In particular, periphytic diatoms have been shown to contribute significantly to biofilms, which play an important role in biofouling. Therefore, inhibiting the proliferation of fouling diatoms is a very important step in the prevention of marine biofouling. In this study, we developed a new, rapid, accurate, and convenient growth inhibition assay using the XTT colorimetric method to prevent the growth of the fouling periphytic diatom, Nitzschia amabilis Hidek. Suzuki (replaced synonym, Nitzschia laevis Hustedt). The feasibility of this method was verified by determining the growth inhibition activities of two standard photosynthetic inhibitors, DCMU and CuSO4. However, neither inhibitor had any cytotoxic activities at the range of concentrations tested. Moreover, this method was applied by screening and purification of herbicidic but non-cytotoxic compounds from cyanobacteria extracts. Our results demonstrate the utility of this newly established growth inhibition assay for the identification of marine anti-biofouling compounds.

[A Quercetin-Based Fluorescent Probe for the Recognition of Fluorid Ions].

Quercetin (Q) is one of the most common flavonoids present in roots, stems, leaves, flowers and fruits of most plants. In this study, a quercetin-based fluorescent probe for detecting fluorid ions had been proposed. With good selectivity and sensitivity for fluorid ions, Q-based fluorescent probe was easier to prepare, more eco-friendly and more innoxious compared with traditional fluorescent probe obtained by organic chemistry synthesis operation. There was a major fluorescence emission peak at 500 nm for Q in dimethyl sulfoxide (DMSO) when the excitation wavelength was 390 nm. The changes of fluorescence spectra were investigated before and after adding different anions into Q solution. The fluorescence emission intensity of Q even had no change when adding Cl-，Br-，I-，ClO-4，H2PO-4, respectively. While adding fluorid ions, the fluorescence emission intensity of Q was decreased obviously, which suggested fluorid ions could induce fluorescence quenching of Q in DMSO. And the fluorescence emission intensity of Q-F- system had almost no significant change when adding other anions (Cl-，Br-，I-，ClO-4，H2PO-4), which meant the progress for detecting fluorid ions didn't be affected by other anions, and Q showed a good selectivity for fluorid ions. The fluorescence titration spectra showed that the fluorescence emission intensity of Q was decreased with the increase of concentration of fluorid ions, and they were in concentration-dependent manner. The fluorescence titration curve exhibited that the Q as fluorescent probe can be applied to the quantification of fluorid ions with a good linearity (R2=0.991), linear range of 1.0～8.0×10-6 mol·L-1 and the detection limit of 1.0×10-7 mol·L-1. Not only the changes appeared in fluorescence spectra, but also the changes appeared in UV-visible spectra, compared with Q absorption spectrum, the location of band at 375 nm had no change after adding Cl-，Br-，I-，ClO-4，H2PO-4, respectively. However, when adding fluorid ions, the band at 375 nm was shifted to 394 nm, and the color of the solution was changed into dark yellow, which revealed the interactions between Q and fluorid ions. The probable mechanism of fluorid ions inducing fluorescence quenching of Q was obtained with 1H NMR spectrum and the changes of fluorescence emission intensity of Q-F- system in different polar solvents (DMSO containing different concentration of water). The interaction mode about Q and fluorid ions in DMSO was related with hydrogen bond. Both experiments suggested that the possible recognition mechanism on fluorid ions was: fluorid ions were destroyed or weakened by original hydrogen bonds, and were promoted charge transfer within quercetin molecule, which resulted in fluorescence intensity decreasing of quercetin. This method was successfully applied in detecting fluorid ions of samples in DMSO with good recovery.

Hyperpolarized 15N-pyridine derivatives as pH-sensitive MRI agents.

Highly sensitive MR imaging agents that can accurately and rapidly monitor changes in pH would have diagnostic and prognostic value for many diseases. Here, we report an investigation of hyperpolarized (15)N-pyridine derivatives as ultrasensitive pH-sensitive imaging probes. These molecules are easily polarized to high levels using standard dynamic nuclear polarization (DNP) techniques and their (15)N chemical shifts were found to be highly sensitive to pH. These probes displayed sharp (15)N resonances and large differences in chemical shifts (Δδ > 90 ppm) between their free base and protonated forms. These favorable features make these agents highly suitable candidates for the detection of small changes in tissue pH near physiological values.

Two new lyngbyatoxin derivatives from the Cyanobacterium, Moorea producens.

The toxin-producing cyanobacterium, Moorea producens, is a known causative organism of food poisoning and seaweed dermatitis (also known as "swimmer's itch"). Two new toxic compounds were isolated and structurally elucidated from an ethyl acetate extract of M. producens collected from Hawaii. Analyses of HR-ESI-MS and NMR spectroscopies, as well as optical rotations and CD spectra indicated two new lyngbyatoxin derivatives, 2-oxo-3(R)-hydroxy-lyngbyatoxin A (1) and 2-oxo-3(R)-hydroxy-13-N-desmethyl-lyngbyatoxin A (2). The cytotoxicity and lethal activities of 1 and 2 were approximately 10- to 150-times less potent than lyngbyatoxin A. Additionally, the binding activities of 1 and 2 possessed 10,000-times lower affinity for the protein kinase Cδ (PKCδ)-C1B peptide when compared to lyngbyatoxin A. These findings suggest that these new lyngbyatoxin derivatives may mediate their acute toxicities through a non-PKC activation pathway.

Silencing RhoA inhibits migration and invasion through Wnt/ß-catenin pathway and growth through cell cycle regulation in human tongue cancer.

Ras homolog gene family member A (RhoA) has been identified as a critical regulator of tumor aggressive behavior. In this study, we assessed the role of RhoA in the mechanisms underlying growth, migration, and invasion of squamous cell carcinoma of tongue (TSCC). Stable RhoA knockdown of TSCC cell lines SCC-4 and CAL27 were achieved using Lentiviral transfection. The effects of RhoA depletion on cell migration, invasion, and cell proliferation were determined. The possible underlying mechanism of RhoA depletion on TSCC cell line was also evaluated by determining the expression of Galectin-3 (Gal-3), ß-catenin, and matrix metalloproteinase-9 (MMP-9) in vivo. Meanwhile, the underlying mechanism of TSCC growth was studied by analysis of cyclin D1/2, p21CIP1/WAF1, and p27Kip1 protein levels. Immunohistochemical assessments were performed to further prove the alteration of Gal-3 and ß-catenin expression. We found that, in mice injected with human TSCC cells in the tongue, RhoA levels were higher in primary tumors and metastasized lymph nodes compared with those in the normal tissues. Silencing of RhoA significantly reduced the tumor growth, decreased the levels of Gal-3, ß-catenin, MMP-9, and cyclin D1/2, and increased the levels of p21CIP1/WAF1 and p27Kip1. In vitro, RhoA knockdown also led to inhibition of cell migration, invasion, and proliferation. Our data suggest that RhoA plays a significant role in TSCC progression by regulating cell migration and invasion through Wnt/ß-catenin signaling pathway and cell proliferation through cell cycle regulation, respectively. RhoA might be a novel therapeutic target of TSCC.

Colon cancer bears overexpression of OTUB1.

OBJECTIVE: OTUB1 is a member of deubiquitinating enzymes; however, its expression and function in colon cancer are still unclear. The present study aimed at investigating the expression of OTUB1 in colon cancer and the relationship between the expression and some clinicopathologic parameters. METHODS: Immunohistochemistry and quantitative real-time PCR were carried out in selected colon cancer and normal mucosa tissues. RESULTS: The expression of OTUB1 protein in the colon cancer was significantly higher than normal mucosa, and the OTUB1 mRNA in colon cancer was also 3.15-fold higher than the normal mucosa. The higher expression of OTUB1 in colon cancer was related with tumor size, differentiation and lymph node metastasis. CONCLUSIONS: OTUB1 may play an important role in colon cancer development and metastasis.

A new lyngbyatoxin from the Hawaiian cyanobacterium Moorea producens.

Lyngbyatoxin A from the marine cyanobacterium Moorea producens (formerly Lyngbya majuscula) is known as the causative agent of "swimmer's itch" with its highly inflammatory effect. A new toxic compound was isolated along with lyngbyatoxin A from an ethyl acetate extract of M. producens collected from Hawaii. Analyses of HR-ESI-MS and NMR spectroscopies revealed the isolated compound had the same planar structure with that of lyngbyatoxin A. The results of optical rotation and CD spectra indicated that the compound was a new lyngbyatoxin A derivative, 12-epi-lyngbyatoxin A (1). While 12-epi-lyngbyatoxin A showed comparable toxicities with lyngbyatoxin A in cytotoxicity and crustacean lethality tests, it showed more than 100 times lower affinity for protein kinase Cδ (PKCδ) using the PKCδ-C1B peptide when compared to lyngbyatoxin A.

[Primary drug resistance of HIV-1 infected men who have sex with men in Shenzhen, China].

OBJECTIVE: To evaluate the status of drug resistance among treat-naive HIV-1 infected men who have sex with men (MSM) in Shenzhen during the period of 2008 - 2010. METHODS: Plasma samples of 227 treatment-naive HIV-1 infected MSM were collected in Shenzhen. HIV-1 pol genes (RT and PR) were amplified by nested-polymerase chain reaction (PCR) from RNA. Phylogenetic and drug resistance analyses were performed on the nucleotide sequence data. RESULTS: A total of 164 pol gene sequences were amplified. The prevalence of primary genotypic drug resistance was 14.6%. The overall prevalence of drug-resistant mutations was 22.6%, corresponding to 8.54% for protease inhibitors (PI) minor drug resistance mutation, 1.22% for nucleotide reverse transcriptase inhibitors (NRTI) drug resistance mutation and 13.41% for non-nucleotide reverse transcriptase inhibitors (NNRTI) drug resistance mutation. The prevalence of drug-resistant mutations was 30.88% for CRF01_AE strain and 19.23% for B strain. CONCLUSION: The prevalence of drug resistance is relatively moderate in the treat-naive HIV-1 infected MSM in Shenzhen. The prevalence of drug-resistant HIV-1 among MSM in Shenzhen should raise a high alert.