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RESUMEN Se desarrolló un método de amplificación isotérmica mediada en lazo de transcriptasa inversa (RT-LAMP) para detectar Zika. Los primers se diseñaron basándose en la región NS5 de 64 genomas completos. Se usó reactivo LAMP liofilizado. Inicialmente, se probaron siete arbovirus diferentes y solo las muestras de Zika resultaron positivas. Además, las diluciones seriadas de una de los ARN de Zika se compararon mediante RT-LAMP y qRT-PCR, demostrando que RTLAMP es 1000 veces más sensible. También se evaluó 300 muestras de suero usando RT-LAMP y los resultados se compararon con los métodos de qRT-PCR estándar y obtuvimos un 99,3% (IC95%: 97,7 - 100,0) de sensibilidad, 100% (IC95%: 99,7 - 100,0) de especificidad, 100% (IC95%: 99,7 -100,0) de valor predictivo positivo y 99,3% (IC95%: 97,7 - 100,0) de valor predictivo negativo. En conclusión, este método brinda una alternativa de bajo costo, alto rendimiento, viabilidad y confiabilidad para el diagnóstico rápido de Zika en instalaciones de atención primaria de salud.
ABSTRACT A Reverse Transcription Loop-mediated Isothermal Amplification (RT-LAMP) method was developed to detect Zika. The primers were designed based on the NS5 region of 64 complete genomes. Lyophilized LAMP reagent was used. Initially, seven different arboviruses were tested and only Zika samples tested positive. Additionally, serial dilutions of one of Zika's RNA were compared using RT-LAMP and qRT-PCR, demonstrating that RT-LAMP is 1,000 times more sensitive. We also evaluated 300 serum samples with RT-LAMP comparing the results with standard qRT-PCR methods, and we obtained a 99.3% sensitivity, 100% specificity, 100% positive predictive value, and 99.3% negative predictive value. In conclusion, this method provides a low-cost, high-performance, viable, and reliable alternative for the rapid diagnosis of Zika in primary health-care facilities.
Subject(s)
Humans , Nucleic Acid Amplification Techniques/methods , Molecular Diagnostic Techniques/methods , Zika Virus/isolation & purification , Zika Virus Infection/diagnosis , Zika Virus Infection/virologyABSTRACT
Introducción. Se estima que 240 millones de personas en el mundo tienen infección crónica con el virus de la hepatitis B (HBV). En Colombia, la endemia es variable y circulan diferentes genotipos virales. Las mutaciones a lo largo del genoma se han asociado con resistencia antiviral, el escape ante la reacción de anticuerpos neutralizadores tras la vacunación o a la infección natural, la infección oculta y la progresión a carcinoma hepatocelular. Objetivo. Identificar los genotipos y las mutaciones presentes en la región codificante del antígeno de superficie (S) y del dominio de la transcriptasa inversa (reverse transcriptase, RT) de la polimerasa del HBV en muestras de suero remitidas al Instituto Nacional de Salud de Colombia para el diagnóstico de hepatitis B, entre el 2002 y el 2014. Materiales y métodos. En 495 muestras de suero positivas para el antígeno de superficie de la hepatitis B (HBsAg) se buscó el ADN viral, se amplificó y secuenció un fragmento de 1.591 nucleótidos y, posteriormente, se hizo el análisis filogenético correspondiente. Resultados. En 66 de las muestras se logró detectar el genoma viral y 28 de ellas se secuenciaron exitosamente. El análisis filogenético permitió identificar los genotipos y subgenotipos F3 y A2. Una muestra presentó simultáneamente las sustituciones de resistencia L180M y M204V, otra presentó la sustitución I169L y en una se identificó la mutación P120Q, previamente asociada con variantes de escape. Dos muestras presentaron una deleción de 105 nucleótidos en la región preS1-preS2. Conclusiones. Se corroboró la circulación en Colombia de los genotipos y subgenotipos F3 y A2, así como la presencia de mutaciones de resistencia y escape. El presente estudio constituye un aporte a la epidemiologia molecular del HBV en Colombia.
Introduction: Despite the availability of an effective vaccine and treatment to reduce the viral load and progressive hepatocellular injury, approximately 240 million people worldwide are chronically infected with the hepatitis B virus (HBV). In Colombia, the circulation of different viral genotypes has been confirmed. Mutations in the genome have been associated to antiviral therapy resistance, viral escape to neutralizing antibodies, occult infection and progression to hepatocellular carcinoma. Objective: To identify the genotypes and the presence of mutations in the coding region of the surface (S) antigen and the reverse transcriptase (RT) domain of the polymerase of HBV obtained from serum samples for hepatitis B diagnosis received by the Instituto Nacional de Salud during the period 2002-2014. Materials and methods: A total of 495 serum samples with previous HBsAg reactive result were used for molecular detection. A fragment of 1,591 nucleotides was sequenced, and the corresponding phylogenetic analysis was performed. Results: We detected the viral genome of HBV in 66 samples and 28 were successfully sequenced. The phylogenetic analysis allowed the identification of subgenotypes F3 and A2. The L180M and M204V resistance mutations were simultaneously identified in one sample, while the I169L resistance mutation was identified in another one. A single escape mutation, P120Q, was identified in one more. Two samples showed a deletion of 105 nucleotides in the preS1-preS2 region. Conclusions: The circulation of genotypes/subgenotypes F3 and A2 of HBV in Colombia was corroborated, as well as the presence of some resistance and escape mutations. The present study constitutes a contribution to the molecular epidemiology of HBV in Colombia.
Subject(s)
Hepatitis B virus , Genotype , RNA-Directed DNA Polymerase , MutationABSTRACT
BACKGROUND:Because of convenient source, multi-lineage differentiation and low immunogenicity, bone marrow mesenchymal stem cels are the ideal cel type to serve as vectors of transgenic cels in pain management. However, the replicative senescence and smal amount of cels obtained from the bone marrow restrict the application of bone marrow mesenchymal stem cels in pain research. OBJECTIVE:To construct human telomerase reverse transcriptase (hTERT)-immortalized rat bone marrow mesenchymal stem cels as transgenic celular vectors for pain therapy. METHODS:Bone marrow mesenchymal stem cels were obtained from whole rat bone marrow, and then transfected with a lentivirus containing the hTERT (pLV-Puro-EF1α-hTERT) folowed by puromycin selection. hTERT expression and telomerase activity in these transfected cels were determined by RT-PCR and TRAP. Morphological changes, capacity of cel growth and multi-lineage differentiation, chromosome karyotype and tumorigenicity were observed in vitro. Moreover, the expression of cel surface molecule, Nestin, MHC-I and MHC-II in transfected cels were also detected by flow cytometry and immunocytochemistry. RESULTS AND CONCLUSION: The bone marrow mesenchymal stem cels geneticaly modified by hTERT could be cultured and passaged through 30 generations in vitro. Compared to the primary and negative transfected cels, the hTERT-modified bone marrow mesenchymal stem cels showed higher expression of hTERT mRNA, telomerase activity and cel proliferation. Most of transfected cels stayed at G2/M and S stages. The proliferation index of the transfected cels were increased dramaticaly. The positive rates of CD29, CD44 and CD90 were over 70%, but the positive rates of CD34 and CD45 were less than 5%. Transfected cels were positive for Nestin in the cytoplasm, but negative for MHC-1 and MHC-11. In addition, this cel line continued to exhibit the characteristics of fibroblastic bone marrow mesenchymal stem cels, including phenotype, differentiation into osteoblasts, adipocytes and neuron-like cels. No chromosome abnormality and tumor formation were observed in this experiment. Taken together, these data suggests that the rat bone marrow mesenchymal stem cels immortalized by hTERT gene are constructed successfuly and stil maintain major stem cels characteristics, which provide safe and stable cel vectors as research base for pain therapy.
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Objective To establish a novel and convenient method to study the phenotype of drug resistant hepatitis B virus (HBV) isolates,and to analyze the drug susceptibility by replacing the reverse transcriptase (RT) domain of wild-type HBV with that of the drug resistant HBV isolates.Methods Full length of HBV isolates was amplified and cloned from the sera of patients prior to nucleoside/nucleotide analogues (NA) treatment.Wild-type full-length HBV genomes was used to construct the recombinant expression plasmids PHY536207 (genotype B) and PHY97 (genotype C).The restriction enzyme sites were introduced in the upstream and downstream region of reverse transeription (RT) domain to construct plasmid,which were named as mPHY536207 and mPHY97,respectively.Lamivudine (LAM) resistant mutant and adefovir (ADV) resistant mutant were isolated and cloned to construct recombinant expression plasmids PHY634 and PHY6923,respectively.Subsequently,the RT domain of mPHY536207 was replaced by that of drug resistant mutant to construct the plasmids RT634 (LAM-resistant) and RT6923 (ADVresistant).The HBV constructs were transfected into Huh7 cells.The HBsAg levels in supernatant were determined by enzyme-linked immunosobent assay (ELISA),and the amount of intracellular HBV DNA was assayed by real-time polymerase chain reaction and Southern blot analysis.Results The plasmids PHY536207 and PHY97 containing genotype B and genotype C wild-type fulllength HBV genomes were constructed successfully,both of which could replicate in Huh7 cells.Intracellular HBV DNA extracted from cells in each of six-well culture plates was more than 1 × 107 copy/ mL,and the introduction of Pst Ⅰ restriction enzyme site did not affect the viral replication and HBsAg secretion.PHY634 and RT634,in which mutant RT domain was replaced into a wild type HBV expressing vector,exhibited the same HBV DNA replication under the treatment with different doses of LAM,the value of 50％ inhibitory concentration (IC50) was ＞100 μmol/L,while the IC50 of mPHY536207 was 0.18μmol/L.Moreover,wild-type isolate was sensitive to ADV (IC50 =1.2 μmol/L),while PHY6923 and RT6923 were resistant to ADV treatment (IC50 ＞100 μmol/L).Conclusion The phenotypic assay is successfully developed in this study based on replacing RT domain of wild-type HBV strains with that of clinical isolated drug resistant strain.
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Objective To investigate the effect of hydroxyapatite nanoparticles (nHAP) mediated human telomerase re-verse transcriptase (hTERT) RNA interference of A549 human lung cancer cells in vitro. Methods The nHAP were synthe-sized by the homogeneous precipitation method. The structure of the nanoparticles was observed under transmission electron mi-croscope. The nHAP were prepared using nltrasonication and Na_2CO_3 and modified with poly-L-lysine (PLL) at pH 7. 4. The transfection of pGenesil-hTERT into A549 was divided into four groups as follows: nHAP-PLL group mediated by hydroxyapatite nanoparticles modified with poly-L-lysine ( nHAP-PLL), liposome group mediated by Lipefectamine, nHAP group mediated by hydroxyapatite nanoparticles and control group. The growth ability of cells was assayed with methyl thiazolyl tetrazolium meth-od. The expression level of hTERT protein was examined by Western blotting. Flow cytometry was used to detect the apeptosis ratio of A549 cells line. Results Under transmission electron microscope, the synthesized product presented needle-like and well dispersed particles with evenly distributed sizes of (15-20) nm × (60-80) nm. The proliferation of A549 cells of nHAP-PLL group, liposome group and nHAP group were obviously inhibited as compared with the control group (P < 0.05 ).The inhibition rate of nHAP-PLL group was more than the other groups. There was a significant difference inhibition rate be-tween the nHAP-PLL group compared with the liposome group and nHAP group (P <0.05 ). The level of hTERT protein hada similar varietal tendency with the result of proliferation of each group. Flow cytometry showed the apoptasis ratio of nHAP-PLL group, liposome group, nHAP group and control group was (28.1±1.4)%, (19.2±1.3)%, (10.9±1.2)% and (0.3±0.2 ) %, respectively. There was a significant difference in apoptosis ratio between the nHAP-PLL group, liposome group and nHAP group compared with control group( P < 0.05 ). Conclusion A549 human lung cancer cells overexpreas hTERT and this may be a target for inhibiting proliferation of A549. Hydroxyapatite nanoparticles can induce apeptosis of ASA9 cells in vitro. Hydroxyapatite nanoparticles modified with poly-L-lysine can effectively combine and protect DNA and mediate gene transfection to A549, it can mediate human telomerase reverse transcriptase RNA interference of A549 cells and inhibit the pro-liferation of ,4549 in vitro.