The landscape of 8q24 cytoband in gastric cancer (Review).

Worldwide, gastric cancer (GC) is estimated to be the fifth most common type of cancer type in both sexes, ranking sixth for new cases, with >640,850 cases per year, and fourth in terms of mortality rate. Cancer presents numerical and structural alterations in chromosomes, often through gains and losses of regions. In GC, there are multiple genetic alterations, in which those located in cytoband 8q24 have been frequently described; essential genes are present in this cytoband, regulating the homeostasis of crucial biological processes, such as the MYC gene, which induces expression of selective genes to promote cell growth and proliferation. Conversely, DNA sequence variations can also occur when a single nucleotide in the genome sequence is altered, and this is termed a single nucleotide polymorphism (SNP). These alterations, which can serve as a biological marker, are present in at least 1% of the population and assist in identifying genes associated with GC. In the present review, 12 genes present in cytoband 8q24 related to GC (NSMCE2, PCAT1, CASC19, CASC8, CCAT2, PRNCR1, POU5F1B, PSCA, JRK, MYC, PVT1 and PTK2) are discussed. The PSCA gene was cited more frequently than others; it has four known SNPs associated with GC (rs2978980, rs2294008, rs2976392 and rs9297976). Thus, these SNPs should be further studied in different populations to determine their risk value in patients with GC.

Copy number alterations and epithelial­mesenchymal transition genes in diffuse and intestinal gastric cancers in Mexican patients.

Gastric cancer (GC) is a common malignancy with the highest mortality rate among diseases of the digestive system, worldwide. The present study of GC alterations is crucial to the understanding of tumor biology and the establishment of important aspects of cancer prognosis and treatment response. In the present study, DNA from Mexican patients with diffuse GC (DGC), intestinal GC (IGC) or non­atrophic gastritis (NAG; control) was purified and whole­genome analysis was performed with high­density arrays. Shared and unique copy number alterations (CNA) were identified between the different tissues involving key genes and signaling pathways associated with cancer. This led to the molecular distinction and identification of the most relevant molecular functions to be identified. A more detailed bioinformatics analysis of epithelial­mesenchymal transition (EMT) genes revealed that the altered network associated with chromosomal alterations included 11 genes that were shared between DGC, IGC and NAG, as well as 19 DGC­ and 7 IGC­exclusive genes. Furthermore, the main molecular functions included adhesion, angiogenesis, migration, metastasis, morphogenesis, proliferation and survival. The present study provided the first whole­genome high­density array analysis in Mexican patients with GC and revealed shared and exclusive CNA­associated genes in DGC and IGC. In addition, a bioinformatics­predicted network was generated, focusing on CNA­altered genes associated with EMT and the hallmarks of cancer, as well as precancerous alterations that may lead to GC. Molecular signatures of diffuse and intestinal GC, predicted bioinformatically, involve common and distinct CNA­EMT genes related to the hallmarks of cancer that are potential candidates for screening biomarkers of GC, including early stages.

Circulating microRNAs and their role in the immune response in triple-negative breast cancer.

Breast cancer (BC) is the most common type of cancer in women worldwide, and despite advances in treatments, its incidence and mortality are increasing. Therefore, it is necessary to develop new, non-invasive tests that provide more accurate diagnosis and prognosis in a timely manner. A promising approach is measuring the presence of biomarkers to detect tumors at various stages and determine their specific characteristics, thus allowing for more personalized treatment. MicroRNAs (miRNAs) serve a role in gene expression, primarily by interacting with messenger RNAs, and may be potential biomarkers for detecting cancer. They are detectable in tissues and blood, including plasma and/or serum, are stable and often tumor specific. Also, different miRNAs are associated with specific BC molecular subtypes. Triple-negative BC (TNBC) is a type of BC in which the primary targets for hormonal therapy are absent. It is an aggressive phenotype, which frequently metastasizes and is associated with an unfavorable prognosis. The present review focuses on circulating miRNAs in patients with TNBC, with an emphasis on their interaction with the immune response checkpoint genes PD-1, PD-L1 and CTLA4. Modulation and response of the immune system are of interest in cancer treatment due to the success of immunotherapy in the treatment of various neoplasms. Based on the findings of this literature review and the in silico analysis performed as part of this review, it is concluded that circulating hsa-miR-195 and hsa-miR-155 in TNBC interact with checkpoint genes involved in the immune response. Further analysis of the expression of these circulating miRNAs and their association with prognosis in patients with TNBC treated with immunotherapy should be assessed to evaluate their possible use as non-invasive predictive biomarkers. In addition, functional studies to analyze biologically relevant targets in the development and prognosis of TNBC, which could be therapeutic targets, are also recommended.

Resveratrol Activates Neuronal Autophagy Through AMPK in the Ischemic Brain.

During cerebral ischemia, oxygen and glucose levels decrease, producing many consequences such as the generation of reactive oxygen species, tissue injury, and the general metabolism collapse. Resveratrol triggers signaling dependent on the protein kinase activated by adenosine monophosphate (AMPK), the sensor of cellular energy metabolism that regulates autophagy, eliminates damaged mitochondria, and increases energy sources. In the present study, we investigated the participation of AMPK activation in the protective effect of resveratrol on cerebral ischemia and excitotoxicity. We found that resveratrol increased the levels of phosphorylated AMPK in the cerebral cortex of rats subjected to middle cerebral artery occlusion (MCAO) and in primary cultured neurons exposed to glutamate-induced excitotoxicity. Resveratrol (1.8 mg/Kg; i. v.; administered at the beginning of reperfusion) decreased the infarct area and increased survival of rats subjected to MCAO. In neuronal cultures, resveratrol treatment (40 µM, after excitotoxicity) reduced the production of superoxide anion, prevented the overload of intracellular Ca+2 associated to mitochondrial failure, reduced the release of the lactate dehydrogenase enzyme, and reduced death. It also promoted mitophagy (increased Beclin 1 level, favored the recruitment of LC3-II, reduced LAMP1, and reduced mitochondrial matrix protein HSP60 levels). In both models, inhibition of AMPK activation with Compound C obstructed the effect of resveratrol, showing that its protective effect depends, partially, on the activation of the AMPK/autophagy pathway.

Molecular subtypes and clinicopathological features of breast cancer in Mexican women. / Subtipos moleculares y características clinicopatológicas de cáncer de mama en mujeres mexicanas.

BACKGROUND: Breast cancer is a multifactorial and heterogeneous disease with distinct molecular features and histopathologic subtypes involving different therapeutic responses and clinical outcomes. Classification of breast cancer in molecular subtypes has made possible an approach to develop therapeutic strategies in order to have a better understanding of the breast cancer development. Due to the heterogeneity of the disease, there are still features to be elucidated in the behavior, etiology and clinical outcomes of each molecular subtype in breast cancer. METHODS: Variables measured in 1,695 cases of invasive breast carcinoma were age, histopathological diagnosis, histopathological grade, expression of estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor-2 (HER2), cell proliferation marker (Ki67) and basal cytokeratins (CK 5/6). P values were obtained using Chi square test and hazard ratios were calculated with 95% confidence intervals. RESULTS: An increase of aggressive molecular subtypes of breast cancer was observed. The mean age of incidence of breast cancer patients is decreasing, and breast cancer Patients younger than 40-years-old showed higher risk to exhibit Triple negative and Basal-like tumors. CONCLUSIONS: The mean age for this pathology is decreasing in our population and there is predominance in the differential occurrence of etiologically distinct entities of breast cancer affecting to the young women.

INTRODUCCIÓN: El cáncer de mama es una enfermedad heterogénea y multifactorial. Presenta distintas características clínicas, moleculares e histopatológicas, las cuales se asocian con la respuesta a los esquemas terapéuticos, así como al resultado clínico. La clasificación en subtipos moleculares (luminales, HER2, triple negativo y basales) ha permitido el desarrollo y aplicación de estrategias terapéuticas particulares. Sin embargo, dada la gran heterogeneidad de la enfermedad, existen aún características por elucidar en el comportamiento, etiología y resultados clínicos de cada subtipo molecular de cáncer de mama. MÉTODOS: Se obtuvieron datos de 1695 casos de cáncer de mama invasor. Se realizaron correlaciones entre las siguientes variables: edad, diagnóstico histopatológico, grado histológico, expresión del receptor de estrógenos (ER), receptor de progesterona (PR), receptor 2 del factor de crecimiento epidérmico humano (HER2), marcador de proliferación celular (Ki67) y citoqueratinas basales (CK 5/6). Los valores de p fueron calculados utilizando Chi cuadrada y el cociente de riesgo fue calculado con un intervalo de confianza de 95%. RESULTADOS: Se observó un incremento en la frecuencia de los subtipos moleculares más agresivos, así como una disminución en el valor de la media de la edad en las pacientes diagnosticadas con cáncer de mama. El análisis de la información indica que en pacientes menores de 40 años existe mayor riesgo a la presencia de tumores triple negativo o basales. CONCLUSIONES: En población mexicana, la media de edad para el diagnóstico primario de cáncer de está disminuyendo y hay mayor frecuencia de subtipos moleculares más agresivos en pacientes jóvenes.

Biology of SARS-CoV-2: Towards understanding and treating COVID-19. / Biología del SARS-CoV-2: hacia el entendimiento y tratamiento de COVID-19.

During the last two decades, three different epidemics, caused by three different coronaviruses, have affected humankind. The most recent, known as COVID-19, has caused in only five months, more than 340,000 deaths worldwide. Knowing the biology of coronavirus is key, not just to face the current pandemic, but to prepare ourselves for future epidemics. With this in mind, this article is focused on the biology of coronaviruses emphasizing SARS-CoV-2, the agent that causes COVID-19. This is a comprehensive review article, which covers different topics, from the biology and taxonomy of viruses, to the molecular biology of SARS-CoV-2, its mechanisms of action, and the immune response this virus elicits. We have also addressed clinical aspects of COVID-19, its methods of detection, treatment, and vaccines.

Durante las últimas dos décadas, tres epidemias de gran magnitud, causadas por tres distintos tipos de coronavirus, han impactado a la humanidad. La más reciente, conocida como COVID-19, ha provocado en tan solo cinco meses, más de 340 000 muertes en todo el mundo. Conocer la biología de los coronavirus es fundamental, tanto para enfrentar la pandemia actual, como para prepararnos para futuras epidemias. En este contexto, el presente artículo está enfocado en la biología de los coronavirus con énfasis en el SARS-CoV-2, agente causal de COVID-19. La temática que se incluye es muy amplia, abarca desde la biología general de los virus y su taxonomía, hasta aspectos muy puntuales de la biología molecular de SARS-CoV-2, así como de sus mecanismos de acción y la respuesta inmune. También presentamos distintos aspectos clínicos de COVID-19, de los métodos para su detección y algunos enfoques terapéuticos, incluyendo tratamientos antivirales y vacunas.

Detection of cytomegalovirus in plasma of patient's HIV by duplex real time PCR / Detección de citomegalovirus en plasma de pacientes con VIH mediante PCR dúplex en tiempo real

BACKGROUND: Cytomegalovirus (CMV) is able to cause serious and even deadly diseases in immunocompromised patients. It is important to have a sensitive, specific and molecular viral tests for its detection, using as targets, key genes for viral replication. The following genes have been used in the molecular detection of CMV: UL122 (replication) and UL83 (most abundant protein of the tegument). OBJECTIVE: Detect and quantify CMV, by real-time duplex PCR, from a minimum amount of plasma. MATERIAL AND METHODS: The UL122 and UL83 genes were amplified with different fluorophores, by real-time duplex PCR. To quantify CMV, curves were generated, starting with DNA-CMV (1.0-0.0000001 ng). RESULTS: The dynamic range of "master" duplex straight had a pendent (m) −3.0, the amplification efficiency was 115.44% plasmas from patients with HIV viral load ≥ 100,000 copies/mL, 11.36% were true positive for CMV and 88.64% had no amplifications or they were outside of the linear range of molecular detection. CONCLUSIONS: This test identified two important CMV genes (UL122 and UL83) in a single reaction (FAM:VIC), viral detection was confirmed from a minimum amount of plasma. This mean a smaller amount of biological sample required and would add a tool to the clinical area, as well as a lower consumption of reagents and materials.

INTRODUCCIÓN: El citomegalovirus (CMV) es capaz de provocar enfermedades graves e incluso mortales en pacientes inmunocomprometidos. Es importante contar con pruebas moleculares de detección viral, sensibles y específicas, utilizando como blanco los genes clave para la replicación viral. En la detección molecular de CMV se han utilizado los genes UL122 (replicación) y UL83 (proteína más abundante del tegumento). OBJETIVO: Detectar y cuantificar el CMV mediante reacción en cadena de la polimerasa (PCR) dúplex en tiempo real, a partir de una mínima cantidad de plasma. MATERIAL Y MÉTODOS: Los genes UL122 y UL83 se amplificaron con diferentes fluoróforos mediante PCR dúplex en tiempo real. Para cuantificar el CMV se generó una recta estándar, a partir de DNA del CMV (1.0-0.0000001 ng). RESULTADOS: El rango dinámico de la «recta maestra¼ tuvo una pendiente (m) de -3.0; la eficiencia de amplificación fue del 115.44%; de los plasmas de pacientes con infección por el virus de la inmunodeficiencia humana (VIH) con una carga viral ≥ 100,000 copias/ml, el 11.36% fueron verdaderos positivos para CMV y el 88.64% no tuvieron amplificaciones o estuvieron fuera del rango lineal de detección molecular. CONCLUSIONES: Esta prueba identificó dos genes importantes del CMV (UL122 y UL83) en una sola reacción (FAM:VIC), y se ratificó la detección viral a partir de una mínima cantidad de plasma. Esto se traduce en una menor cantidad de muestra biológica requerida y sumaría una herramienta al área clínica, así como un menor consumo de reactivos y materiales.

Aged garlic extract and S-allylcysteine increase the GLUT3 and GCLC expression levels in cerebral ischemia.

BACKGROUND: During cerebral ischemia, energy restoration through the regulation of glucose transporters and antioxidant defense mechanisms is essential to maintain cell viability. Antioxidant therapy has been considered effective to attenuate brain damage; moreover, the regulation of transcription factors that positively regulate the expression of glucose transporters is associated with this therapy. Recently, it has been reported that the use of antioxidants such as S-allylcysteine (SAC), a component of aged garlic extract (AGE), improves survival in experimental models of cerebral ischemia. OBJECTIVES: The aim of this study was to determine the effect of AGE and SAC on the level of mRNA expression of the main neuronal glucose transporter (GLUT3) and the glutamate cysteine ligase catalytic subunit (GCLC) in rats with transient focal cerebral ischemia. MATERIAL AND METHODS: Cerebral ischemia was induced in male Wistar rats by middle cerebral artery occlusion (MCAO) for 2 h. The animals were sacrificed after different reperfusion times (0-48 h). Animals injected with AGE (360 mg/kg, intraperitoneally (i.p.)) and SAC (300 mg/kg, i.p.) at the beginning of reperfusion were sacrificed after 2 h. The mRNA expression level was analyzed in the fronto-parietal cortex using quantitative polymerase chain reaction (qPCR). RESULTS: Two major increases in GLUT3 expression at 1 h and 24 h of reperfusion were found. Both treatments increased GLUT3 and GCLC mRNA levels in control and under ischemic/reperfusion injury animals. CONCLUSIONS: This data suggests that SAC and AGE might induce neuroprotection, while controlling reactive oxygen species (ROS) levels, as indicated by the increase in GCLC expression, and regulating the energy content of the cell by increasing glucose transport mediated by GLUT3.

Erratum: A proposed method for the relative quantification of levels of circulating microRNAs in the plasma of gastric cancer patients.

[This corrects the article DOI: 10.3892/ol.2017.5816.].

A proposed method for the relative quantification of levels of circulating microRNAs in the plasma of gastric cancer patients.

Gastric cancer (GC) is the fifth most common type of malignancy and the third leading cause of cancer-associated mortality worldwide. It is necessary to identify novel methods aimed at improving the early diagnosis and treatment of GC. MicroRNA expression profiles in the plasma of patients with GC have demonstrated a potential use in the opportune diagnosis of this neoplasm. However, there are currently no standardized targets for use in the normalization of microRNA Cq values for different neoplasms. The present study tested two normalization approaches while analyzing plasma derived from patients with GC and non-atrophic gastritis. The first method utilized a panel of small nucleolar RNAs (snoRNAs) and a small nuclear RNA (snRNA) provided by a commercial array. The second normalization approach involved the use of hsa-miR-18a-5p and hsa-miR-29a-3p, which were identified by a stability analysis of the samples being tested. The results revealed that the snoRNAs and snRNA were not expressed in all samples tested. Only the stable microRNAs allowed a narrow distribution of the data and enabled the identification of specific downregulation of hsa-miR-200c-3p and hsa-miR-26b-5p in patients with GC. hsa-miR-200c-3p and hsa-miR-26b-5p have been previously linked to cancer, and a Kyoto Encyclopedia of Genes and Genomes analysis demonstrated that these microRNAs were associated with cell adhesion, cell cycle and cancer pathways.

MicroRNAs in hereditary diffuse gastric cancer.

In 2012, gastric cancer (GC) was the third cause of mortality due to cancer in men and women. In Central and South America, high mortality rates have been reported. A total of 95% of tumors developed in the stomach are of epithelial origin; thus, these are denominated adenocarcinomas of the stomach. Diverse classification systems have been established, among which two types of GC based on histological type and growth pattern have been described as follows: Intestinal (IGC) and diffuse (DGC). Approximately 1-3% of GC cases are associated with heredity. Hereditary-DGC (HDGC), with 80% penetrance, is an autosomal-type, dominant syndrome in which 40% of cases are carriers of diverse mutations of the CDH1 gene, which encodes for the cadherin protein. By contrast, microRNA are non-encoded, single-chain RNA molecules. These molecules regulate the majority of cellular functions at the post-transcriptional level. However, analysis of these interactions by means of Systems Biology has allowed the understanding of complex and heterogeneous diseases, such as cancer. These molecules are ubiquitous; however, their expression can be specific in different tissues either temporarily or permanently, depending on the stage of the cell. Due to the participation of microRNA in the processes of cellular proliferation, cell cycle control, apoptosis, differentiation and metabolism, these have been indicated to have a role in the development of cancerous processes, finding specific patterns of expression in different neoplasms, including GC, in which the microRNA expression profile is different in samples of non-cancerous versus cancerous tissues. A difference has been observed in the expression patterns of DGC and IGC. However, the role of microRNA in HDGC has not yet been established. The present study reviews the investigations that describe the participation of microRNA in the regulation of genes CDH1, RHOA, CTNNA1, INSR and TGF-ß in different neoplasms, such as HDGC.

[Detection of cytomegalovirus by real-time PCR in HIV-positive plasm]. / Detección de citomegalovirus por PCR en tiempo real en plasmas positivos a VIH.

BACKGROUND: Cytomegalovirus is a betaherpesvirus responsible for persistent infections that are generally asymptomatic in healthy individuals. In the absence of an effective immune response, as in neonates, cancer patients, organ transplant recipients, individuals with AIDS, etc., cytomegalovirus may cause severe disease. Early detection of this virus would prevent serious health consequences in immunocompromised patients; it is important to employ sensitive methods and accurate detection to support treatment-related decision making. Real-time molecular methods, such as the polymerase chain reaction, possess higher sensitivity to detect positive samples. METHODS: We compared the sensitivity and specificity of the following detection methods: the endpoint PCR trade-validated method (Pol, viral gene target) and real-time PCR, which detects viral genes Pol (early gene), and pp65 (late gene). We performed a cross-sectional study of 43 human immunodeficiency virus-positive samples. RESULTS: The molecular detection methods in real-time detected a greater number of cytomegalovirus-positive samples than those at the endpoint. CONCLUSIONS: There must be at least two independent cytomegalovirus target-genes in order to make the detection by real-time PCR.

INTRODUCCIÓN: el citomegalovirus es responsable de infecciones persistentes, generalmente asintomáticas en personas sanas pero que en ausencia de una respuesta inmune efectiva puede causar enfermedad severa, por ello es muy importante su detección temprana en los individuos con trastornos de la inmunidad. El objetivo de esta investigación fue hacer un análisis del límite de detección, sensibilidad y concordancia de la reacción en cadena de la polimerasa (PCR) en punto final con los obtenidos con la PCR en tiempo real. MÉTODOS: se realizó un estudio transversal con 43 muestras de plasma humano positivas al virus de la inmunodeficiencia humano, provenientes de individuos de 18 o más años de edad, de uno u otro sexo. Todas las muestras tuvieron una carga viral-VIH mayor a 100 000 copias/mL. Para la PCR en punto final se empleó un método comercial para identificar UL54 (gen viral blanco) y para la PCR en tiempo real se amplificaron fragmentos de los genes UL54 (gen temprano) y UL83 (gen tardío) del citomegalovirus humano. RESULTADOS: mediante PCR en punto final (método comercial-validado) solo tres individuos fueron positivos a citomegalovirus humano (7 %), con una la carga viral de 1500 a 1670 copias/mL. Las muestras positivas a citomegalovirus humano mediante PCR en tiempo real tuvieron un rango de 4.36 a 4692.86 copias de citomegalovirus humano CONCLUSIONES: es necesario tener al menos dos genes blancos de citomegalovirus humano para detectarlo de manera ratificada mediante PCR en tiempo real.

Is human cytomegalovirus associated with breast cancer progression?

BACKGROUND: It has been hypothesized that human cytomegalovirus (HCMV) may be associated with breast cancer progression. However, the role of HCMV infection in breast cancer remains controversial. We aimed to assess whether HCMV genes (UL122 and UL83) could be detected in breast carcinomas and reinvestigated their possible association with breast cancer progression. DNA from paraffin-embedded tissues was analyzed by real-time PCR. We investigated 20 fibroadenomas and 27 primary breast carcinomas (stages II, III, and IV). FINDINGS: Two carcinomas were positive for HCMV, one was positive for two TaqMan viral detection probes, and one was positive for a sole TaqMan viral detection probe (UL83), whereas the remainder of the samples was negative. CONCLUSIONS: Samples studied showed no association between HCMV infection and breast cancer progression.

Glucose transporters regulation on ischemic brain: possible role as therapeutic target.

Ischemic stroke is a major cause of death worldwide that provokes a high society cost. Deprivation of blood supply, with the subsequent deficiency of glucose and oxygen, triggers an important number of mechanisms (e.g. excitotoxicity, oxidative stress and inflammation) leading to irreversible neuronal injury. Consequently, ischemia increases the energy demand which is associated with profound changes in brain energy metabolism. Glucose transport activity may adapt to ensure the delivery of glucose to maintain normal cellular function, even at the low glucose levels observed in plasma during ischemia. In the brain, the main glucose transporters (GLUTs) are GLUT3 in neurons and GLUT1 in the microvascular endothelial cells of the blood brain barrier and glia. The intracellular signaling pathways involved in GLUT regulation in cerebral ischemia remain unclear; however, it has been established that ischemia induces changes in their expression. In this review, we describe the effect of glutamate-induced excitotoxicity, mitochondrial damage, glucose deprivation, and hypoxia on GLUTs expression in the brain. Additionally, we discuss the possible role of GLUTs as therapeutic target for ischemia. Despite of the intense research, current therapeutics options for stroke are very limited, therefore it is especially important to find new options. Few studies have examined the neuroprotective potential of GLUT up-regulation in ischemic stroke; however, evidence suggests that augmented GLUTs could be related to a protective mechanism. Increased understanding of the beneficial effects of GLUTs activation provides the rationale for targeting GLUT in the development of new therapeutic strategies.

Glioma-like proliferation within tissues excised as tubers in patients with tuberous sclerosis complex.

We describe diffuse glioma-like infiltrates in excised tubers in five out of forty Tuberous sclerosis complex (TSC) patients undergoing excision of a tuber at our institution within the last 10 years. All patients presented with refractory seizures. Resection specimens from four patients had the pathognomonic histologic features of neuroglial hamartomas (tubers) and in one case there was cortical microdysgenesis lacking cells typical of TSC. All lesions were associated with an infiltrate of atypical, mostly elongate, glioma-like small cells, which were immunoreactive for GFAP in three, and pS6 (a marker for activity of the mTOR pathway), in two cases. MAP-2 and CD34, were negative and MIB-1 (Ki67) immunostains ranged from <1-21%. Array-based comparative genomic hybridization revealed that these proliferative phenomena were associated with 21 different copy number aberrations in comparison with a tuber without atypical infiltrates. Postoperatively (follow-up period ranging from 8 to 34 months) none of the patients have any evidence of a glioma. We report that tubers resected for treatment of seizures are sometimes associated with glioma-like lesions, which are indistinguishable from infiltrating gliomas by morphology and immunohistochemistry. Genomic analysis with SNP arrays revealed copy number changes which may be associated with the pathogenesis of such infiltrates.

Molecular analysis of hepatitis B virus "a" determinant in asymptomatic and symptomatic Mexican carriers.

BACKGROUND: Hepatitis B virus (HBV) is a small DNA-containing virus with 4 genes, C, S, X and P. The S gene codes for the surface antigen (HBsAg), which contains the "a" determinant, the main region for induction of a protective humoral immune response. To compare the genotype and sequence of the "a" determinant between strains isolated from asymptomatic and symptomatic Mexican HBV carriers. RESULTS: 21 asymptomatic (blood donors) and 12 symptomatic (with clinical signs and with >1 year lamivudine treatment) HBV carriers were studied; all patients were positive for the HBsAg in serum. Viral load, genotypes, and subtypes were determined in plasma. A fragment of the S gene including the "a" determinant was PCR amplified and sequenced to determine genotype, subtype and to identify mutations. Mean viral load was 0.7965 x 104 copies/ml in asymptomatic carriers and 2.73 x 106 copies/ml in symptomatic patients. Genotypes H, C, and F were identified in asymptomatic individuals; whereas H was dominant in symptomatic patients. A fragment of 279 bp containing the "a" determinant was amplified from all 33 carriers and sequences aligned with S gene sequences in the GenBank. Mutations identified were Y100N, T126I, Q129H and N146K in the asymptomatic group, and F93I and A128V in the symptomatic group. CONCLUSION: Differences in genotype and in mutations in the "a" determinant were found between strains from asymptomatic and symptomatic HBV Mexican carriers.