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.

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.

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.

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.

贝伐珠单抗联合埃克替尼克服一例非小细胞肺癌患者奥希替尼耐药（英文）

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.

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.