High Frequency of Antiviral Resistance Mutations in HBV Genotypes A2 and H: Multidrug Resistance Strains in Mexico

Background and Aims:Lamivudine(3TC),telbivudine(LdT),entecavir(ETV),adefovir(ADF),and tenofovir(TFV)are drugs used to treat hepatitis B virus(HBV)infection,but specific mutations allow some viruses to become resistant to antiviral drugs or to acquire immune escape capacities.These mutations have not been thoroughly investigated in Mexico.This study aimed to estimate the prevalence of HBV antiviral resistance and escape mutations.Methods:This cross-sectional study analyzed 158 samples.HBV DNA was extracted,amplified,and sequenced in serum samples using the spin column method,PCR assay,and Sanger’s sequencing,respectively.HBV genotypes were determined,and HBV mutations were tested using the Geno2pheno tool.Results:Overall,68.4%(108/158)of HBV patients were infected with genotype H,followed by G(11.4%,18/158),A2(10.8%,17/158),F1b(6.9.0%,11/158),D(1.9%,3/158),and E(0.6%,1/158),and 5.1%(8/158)had evidence of recombination.The prevalence of resistance mutations was 8.2%(13/158)and the most common combined mutation was rt180M+rt204V.Notably,we found the combinations rt180M+rt204V+rt173L(n=2)and rt180M+rt204V+rt202G(n=1)that confer multidrug resistance to 3TC,LdT,and ETV.Resistance mutations were found in genotypes A2(11.8%,2/17),and H(10.2%,11/108),and escape mutations were detected in HBV genotypes A2(11.8%,2/17),H(10.2%,11/108),F1b(9.1%,1/11)and G(5.6%,1/18).Conclusions:The highest prevalence of antiviral resistance mutations or escape mutations was detected in HBV genotypes A2 and H.The earliest cases of HBV multidrug resistance were detected in Mexico.

Detection of Shigella gyrA mutations and correlations between gyrA mutations and quinolones resistance

118 clinical strains of Shigella were serotyped, in which 116 strains were tested to be S. flexneri. The susceptibilities of the S .flexneri strains to quinolones were measured by the disk-diffusion method. It was found that most S .flexneri strains were susceptible to norfloxacin and ciprofloxacin, but resistant to nalidixic acid. To study the correlation between gyrA mutations and quinolones resistance, a fragment within the gyrA gene was amplified by PCR. The SSCP （Single-Strand Conformation Polymorphism） analysis was applied to detect mutations in PCR products of different strains. The mutations were then confirmed by DNA sequencing. Altogether, two types of mutation were revealed, in which one type was single mutation （ C42-T）, and the other was double mutations （ C42-T and A54- G）. By statistical analysis, C42-T （encoding Ser83-keu substitution） was shown to have correlation with nalidixic-acid resistance in the clinical strains of Shigella, while A54-G （encoding Asp87-Gly substitution） was shown to have correlations with both norfloxacin resistance and ciprofloxacin resistance.

Nucleos(t)ide analogues causes HBV S gene mutations and carcinogenesis

BACKGROUND： The long-term use of nudeos（t）ide analogues causes drug resistance and mutations in the HBV reverse tran- scriptase （RT） region of the polymerase gene. The RT region overlaps the HBV surface gene （S gene） and therefore, the mutations in the RT region simultaneously modify S gene sequence. Certain mutations in the RT region bring about truncated S proteins because the corresponding changed S gene encodes a stop codon which results in the loss of a large portion of the C-terminal hydrophobic region of HBV surface protein. The rtA181T/sW172＊, rtM204I/sW196＊ and rtV191I/sW182＊ are the most frequently reported drug-resistant mutations with C-terminal truncation, these mutations have oncogenic potential. DATA SOURCES： PubMed and Web of Science were searched using terms： ＂hepatitis B virus＂, ＂HBV drug resistance mutation＂ ＂HBV surface protein＂ ＂HBV truncation＂, ＂hepatocellular carcinoma＂, ＂rtA181T/sW172＊＂, ＂rtM204I/sW196＊＂, ＂rtV191I/sW182＊＂, and relevant articles published in English in the past decades were reviewed. RESULTS： The rtA181T/sW172＊ and rtV191I/sW182＊ mutants occurred more frequently than the rtM204I/sW196＊ mutant both in chronic hepatitis B patients and the HBV-related hepatocellular carcinoma tissues. Although these mutations occur naturally, nudeos（t）ide analogues therapy is the main driving force. These mutations may exist alone or coexist with other HBV mutations. All these three mutants impair the virion secretion and result in HBV surface protein retention and serum HBV DNA level reduction. These mutations possess potential carcinogenic properties. The three mutations are resistant to more than one nucleos（t）ide analogue and therefore, it is difficult to treat the patients with the truncated mutations.CONCLUSIONS： Nucleos（t）ide analogues induce drug resistance and HBV S gene truncated mutations. These mutations have potential carcinogenesis.

Bevacizumab Combined with Icotinib Overcomes Osimertinib Resistance in a Patient of Non-Small Cell Lung Cancer

A 61-year-old Chinese woman was diagnosed as primary pulmonary adenocarcinoma of left superior lobe with epidermal growth factor receptor(EGFR)19 del mutation positive.Treatment with icotinib was given,but her disease progressed after 6 months remission.CT-guide needle biopsy for the new lesion in inferior lobe of left lung demonstrated intrapulmonary metastasis,and EGFR gene panel by Amplification Refractory Mutation System Polymerase Chain Reaction(ARMS-PCR)confirmed EGFR T790M mutation.Treatment with osimertinib was initiated.After 2 months remission,the disease progressed.Re-biopsy was performed for the tumor in the inferior lobe of left lung,and ARMS-PCR demonstrated no other gene mutation except EGFR 19 del.Icotinib was re-challenged,but disease progressed continuously.Bevacizumab was added,and partial response was achieved after 2-cycle of combination therapy.The non-small cell lung cancer(NSCLC)in this case maintained EGFR activating mutation and lost EGFR T790M mutation was a genetic change after osimertinib treatment.This case suggests the re-challenge of the first-generation EGFR-TKIs combined with bevacizumab may overcome the tumor resistance and prolong survival of NSCLC patient.

Pattern of HIV-1 Drug Resistance among Adults on ART in Nigeria

Background: The development of anitiretroviral drug resistance may limit the benefit of antiretroviral therapy. Therefore the need to closely monitor these mutations, especially the use of ART is increasing. This study was therefore designed to determine the ARV drug resistance pattern among ART na?ve and expose individuals attending a PEPFAR supported by antiretroviral clinic in Nigeria. Methodology: The study participants included patients attending the PEPFAR supported by University College Hospital (UCH), Ibadan ART clinic who have been on HIV treatment for at least one year with consecutive viral load of over 2000 copies/ml as well some ART Na?ve individuals with high (>50,000 copies/ml) baseline viral level attending the hospital for pre-ART assessment. Blood sample was collected from each individual for CD4 enumeration, viral load level determination and DNA sequencing for genotypic typing. Antiretroviral drug resistance mutations (DRM) were determined by using the Viroseq software and drug mutations generated by using a combination of Viroseq and Stanford algorithm. DRM were classified as major or minor mutations based on the June 2013 Stanford DR database. Results: The most common major NRTI, NNRTI and PI mutation were D67N (33.3%), Y181C (16.7%) and M46L/I (55.6%) respectively. Lamivudine (3TC) and emtricitabine (FTC);nevirapine (NVP) and nelfinavir (NFV) were the most common NRTI, NNRTI, and PI drugs to which the virus in the infected individuals developed resistance. Isolates from 4 patients were resistant to triple drug class, including at least one NRTI, NNRTI and a PI. Only one (4.8%) of the isolates from drug Na?ve individuals had major DRM that conferred resistance to any drug. Conclusion: Demonstration of high rates of antiretroviral DRM among patients on 1st and 2nd line ART and the presence of DRM in drug Na?ve individuals in this study show the importance of surveillance for resistance to ARV in line with the magnitude of scaling up of treatment program in the country.

Factors associated with DAA virological treatment failure and resistance-associated substitutions description in HIV/HCV coinfected patients

AIMTo describe factors associated with treatment failure and frequency of resistance-associated substitutions （RAS）.METHODSHuman immunodefciency virus （HIV）/hepatitis C virus （HCV） coinfected patients starting a first direct-acting antiviral （DAA） regimen before February 2016 and included in the French ANRS CO13 HEPAVIH cohort were eligible. Failure was defned as： （1） non-response [HCV-RNA remained detectable during treatment, at end of treatment （EOT）]; and （2） relapse （HCV-RNA suppressed at EOT but detectable thereafter）. Sequencing analysis was performed to describe prevalence of drug class-specifc RAS. Factors associated with failure were determined using logistic regression models.RESULTSAmong 559 patients, 77% had suppressed plasmaHIV-RNA 〈 50 copies/mL at DAA treatment initiation41% were cirrhotic, and 68% were HCV treatmentexperienced. Virological treatment failures occurred in22 patients and were mainly relapses （17, 77%） thenundefined failures （3, 14%） and non-responses （29%）. Mean treatment duration was 16 wk overall. Posttreatment NS3, NS5A or NS5B RAS were detected in10/14 patients with samples available for sequencinganalysis. After adjustment for age, sex, ribavirin useHCV genotype and treatment duration, low platelecount was the only factor signifcantly associated with ahigher risk of failure （OR： 6.5; 95%CI： 1.8-22.6）. CONCLUSIONOnly 3.9% HIV-HCV coinfected patients failed DAAregimens and RAS were found in 70% of those failingLow platelet count was independently associated withvirological failure.

Diagnostic and therapeutic progress of multi-drug resistance with anti-HBV nucleos(t)ide analogues

Nucleos(t)ide analogues(NA) are a breakthrough in the treatment and management of chronic hepatitis B.NA could suppress the replication of hepatitis B virus(HBV) and control the progression of the disease.However,drug resistance caused by their long-term use becomes a practical problem,which influences the long-term outcomes in patients.Liver transplantation is the only choice for patients with HBV-related end-stage liver disease.But,the recurrence of HBV after transplantation often caused by the development of drug resistance leads to unfavorable outcomes for the recipients.Recently,the multi-drug resistance(MDR) has become a common issue raised due to the development and clinical application of a variety of NA.This may complicate the antiviral therapy and bring poorly prognostic outcomes.Although clinical evidence has suggested that combination therapy with different NA could effectively reduce the viral load in patients with MDR,the advent of new antiviral agents with high potency and high genetic barrier to resistance brings hope to antiviral therapy.The future of HBV researches relies on how toprevent the MDR occurrence and develop reasonable and effective treatment strategies.This review focuses on the diagnostic and therapeutic progress in MDR caused by the anti-HBV NA and describes some new research progress in this field.

Molecular characterization of antimicrobial multi-drug resistance in non-typhoidal Salmonellae from chicken and clam in Mangalore, India

Salmonella enterica has been documented as one of the leading causes of salmonellosis throughout the world and is most commonly associated with the consumption of contaminated food products. Thus, this research was aimed at studying the antimicrobial susceptibility pattern and detection of quinolone resistance in Salmonella spp isolated from food of animal origin. Thirty-six Salmonella isolates comprising 8 from poultry and 28 from seafood（clams） were identified, serotyped and characterized for their antimicrobial susceptibility against 10 different antibiotics. Plasmid DNA was isolated from all the isolates by alkaline lysis, quinolone resistant non-typhoidal S. Weltevreden were examined for mutation in the DNA gyrase coding gene. Among the 36 Salmonella isolates, 20 were S. weltevreden（8 from poultry and 12 from seafood） and 16 were S. Typhimurium（from seafood）. All the isolates showed multiple resistance to nalidixic acid, tetracycline, co-trimoxazole and nitrofurantoin, but, interestingly, the isolates were 100% susceptible to ampicillin, chloramphenicol and gentamicin. Resistant isolates from the study carried the genes responsible for resistance to respective antibiotics. The strain S130 isolated in the study showed single point mutation,Asp87Gly, at position 87 in quinolone resistance determining region. It revealed mutation in quinolone resistance determining region as a cause for quinolone resistance in non-typhoidal Salmonellae. The occurrence of genes accountable for plasmid mediated resistance to quinolones（viz., qnrA, qnrB and qnrS） in plasmid of non-typhoidal Salmonellae isolates provides evidence for plasmid mediated quinolone resistance.

The mutation sequence of earth resistivity and earthquakes

Large amount of practically-observed iata were analyzed hased on the principles of fracture mechanics, and it was found that the mutation of earth resistivity was, to a certain extent, corrrelated with the rupture of media. Among the mutation sequences before most strong and moderate earthquakes had generally a relatively obvious maximum mutation. An approximately linear relation was found between the interval from starting of the maximum mutation to the occurrence of an earthquake and the magnitude and the epicentral distance of the earthquake. Furthermore, such a mutation showed a tendency to radiate from the epicenter to the peripheral areas. It is thus thought to be possible to use the mutation sequence to predict earthquakes. Finally, the paper also unfolds discussions on a number of practical problems in the earthquake prediction practice.

Predicting and overcoming resistance to CDK9 inhibitors for cancer therapy

Abnormally activated CDK9 participates in the super-enhancer mediated transcription of short-lived proteins required for cancer cell survival.Targeting CDK9 has shown potent anti-tumor activity in clinical trials among different cancers.However,the study and knowledge on drug resistance to CDK9 inhibitors are very limited.In this study,we established an AML cell line with acquired resistance to a highly selective CDK9 inhibitor BAY1251152.Through genomic sequencing,we identified in the kinase domain of CDK9 a mutation L156F,which is also a coding SNP in the CDK9 gene.By knocking in L156F into cancer cells using CRISPR/Cas9,we found that single CDK9 L156F could drive the resistance to CDK9 inhibitors,not only ATP competitive inhibitor but also PROTAC degrader.Mechanistically,CDK9 L156F disrupts the binding with inhibitors due to steric hindrance,further,the mutation affects the thermal stability and catalytic activity of CDK9 protein.To overcome the drug resistance mediated by the CDK9-L156F mutation,we discovered a compound,IHMT-CDK9-36 which showed potent inhibition activity both for CDK9 WT and L156F mutant.Together,we report a novel resistance mechanism for CDK9 inhibitors and provide a novel chemical scaffold for the future development of CDK9 inhibitors.

A substitution mutation in OsPELOTA confers bacterial blight resistance by activating the salicylic acid pathway

We previously reported a spotted-leaf mutant pelota（originally termed HM_（47）） in rice displaying arrested growth and enhanced resistance to multiple races of Xanthomonas oryzae pv. oryzae. Here, we report the mapbased cloning of the causal gene OsPELOTA（originally termed spl^（HM47））. We identified a single base substitution from T to A at position 556 in the coding sequence of OsPELOTA, effectively mutating phenylalanine to isoleucine at position 186 in the translated protein sequence. Both functional complementation and over-expression could rescue the spotted-leaf phenotype. OsPELOTA, a paralogue to eukaryotic release factor 1（eRF_1）, shows high sequence similarity to Drosophila Pelota and also localizes to the endoplasmic reticulum and plasma membrane.OsPELOTA is constitutively expressed in roots, leaves,sheaths, stems, and panicles. Elevated levels of salicylic acid and decreased level of jasmonate were detected in the pelota mutant. RNA-seq analysis confirmed that genes responding to salicylic acid were upregulated in the mutant. Our results indicate that the rice PELOTA protein is involved in bacterial leaf blight resistance by activating the salicylic acid metabolic pathway.

Characterization of isoniazid resistance and genetic mutations in isoniazid-resistant and rifampicin-susceptible Mycobacterium tuberculosis in China

Background Patients with tuberculosis resistant to isoniazid but susceptible to rifampicin(Hr-Rs TB)remain a neglected demographic,despite a high disease burden and poor outcomes of these patients.The aim of this study was to investigate the characteristics of isoniazid-resistance-related mutations in Mycobacterium tuberculosis and resistance rates to drugs included in WHO-recommended regimens for Hr-Rs patients.Methods Mycobacterium tuberculosis isolates(n=4922)obtained from national tuberculosis drug-resistance surveillance were subjected to whole-genome sequencing to identify Hr-Rs strains.The minimal inhibitory concentrations(MICs)were established for the Hr-Rs strains to determine the isoniazid resistance levels.We also identified drug-resistance-associated mutations for five drugs(fluoroquinolones,ethambutol,pyrazinamide,streptomycin,and amikacin)in the Hr-Rs strains.Results Of the 4922 strains,384(7.8%)were Hr-Rs.The subculture of seven strains failed,so 377(98.2%)strains underwent phenotypic MIC testing.Among the 384 genotypic Hr-Rs strains,242(63.0%)contained the katG Ser315Thr substitution;115(29.9%)contained the-15C>T in the promoter region of the fabG1 gene;and 16(4.2%)contained Ser315Asn in the katG gene.Of the 239 strains with the Ser315Thr substitution,229(95.8%)had MIC≥2µg/mL,and of the 114 strains with the-15C>T mutation,103(90.4%)had 0.25µg/mL≤MIC≤1µg/mL.The genotypic resistance rates were 0.8%(3/384)for pyrazinamide,2.3%(9/384)for ethambutol and fluoroquinolones;39.6%(152/384)of the strains were resistant to streptomycin,but only 0.5%(2/384)of the strains were resistant to amikacin.Conclusion Ser315Thr in katG was the predominant mutation conferring the Hr-Rs phenotype,followed by the fabG1-15C>T mutation.The combination of rifampicin,pyrazinamide,ethambutol,and levofloxacin should be effective in the treatment of patients with Hr-Rs tuberculosis because the resistance rates for these drugs in China are low.

Factor V Leiden mutation in one family of Chinese origin

目的 研究中国人FVLeiden基因突变引起的抗活化蛋白C现象 (APCR)。方法 采用APTT±APC方法、多聚酶链反应 (PCR)、MnLI限制性内切酶分析 ,序列特异性引物 (PCR SSP)和DNA测序方法 ,对中国汉族 30例“正常”无关个体和 2 0例血栓性疾病患者进行APCR测定和FVLeiden基因突变分析。结果 发现一例正常人抗APC敏感值比值 (APC SR)明显减低 (0 8) ,并确诊为FVLeiden基因 (Arg50 6 Gln)突变杂合子 ,其叔祖父、父亲、弟弟和儿子同样确定为FVLeiden基因杂合子 ;有 3例血栓性疾病患者APC SR低于正常 ,但均无FVLeiden基因突变。结论 这是在国内发现的首例四代FVLeiden突变所致的APCR现象的家系。中国人血栓症中APCR的产生是否导致其它未知的基因缺陷 ,尚待进一步研究。

Alectinib: a novel second generation anaplastic lymphoma kinase(ALK) inhibitor for overcoming clinically-acquired resistance

The development of inhibitors for the tyrosine anaplastic lymphoma kinase (ALK) has advanced rapidly, driven by biology and medicinal chemistry. The first generation ALK inhibitor crizotinib was granted US FDA approval with only four years of preclinical and clinical testing. Although this drug offers significant clinical benefit to the ALK-positive patients, resistance has been developed through a variety of mechanisms. In addition to ceritinib, alectinib is another second-generation ALK inhibitor launched in 2014 in Japan. This drug has a unique chemical structure bearing a 5H-benzo[b] carbazol-11(611)-one structural scaffold with an IC50 value of 1.9 nmol/L, and is highly potent against ALK bearing the gatekeeper mutation L1196M with an IC50 of 1.56 nmoL/L. In the clinic, alectinib is highly efficacious in treatment of ALK-positive non-small cell lung cancer (NSCLC), and retains potency to combat crizotinib-resistant ALK mutations L11.96.M, F1174L, R1275Q and C1156Y. (C) 2015 Chinese Pharmaceutical Association and Institute of Materia Medica, Chinese Academy of Medical Sciences. Production and hosting by Elsevier B.V. All rights reserved.

Study of isolation of fluoroquinolone-resistant Ureaplasma urealyticum and identification of mutant sites

To study the resistance mechanism of clinical isolates of Ureaplasma urealyticum resistant to fluoroquinolones Methods Thirteen isolates of Ureaplasma urealyticum resistant to six fluoroquinolones were selected out of 184 clinical isolates and their QRDRs (quinolone resistance determining region) gyrA, gyrB, parC and parE were amplified by PCR Sequencing results were compared to those susceptible reference strains and a comparison of deduced amino acid sequences were performed Results Sequence comparison revealed a C to A change at 87nt of gyrA QRDR leading to the substitution of Asp95 with glutamic acid and a C to T change at 50nt of parC QRDR leading to the substitution of Ser80 with leucine Conclusion These results suggest that a C to A change at 87nt of gyrA QRDR and a C to T change at 50nt of parC QRDR are associated with fluoroquinolone resistance of Ureaplasma urealyticum