Ruiz-Tachiquín Martha-Eugenia, Valdez-Salazar Hilda-Alicia, Juárez-Barreto Vicencio, Dehesa-Violante Margarita, Torres Javier, Muñoz-Hernández Onofre, Alvarez-Muñoz Ma-Teresa
Unidad de Investigación en Enfermedades Infecciosas, Unidad Médica de Alta Especialidad-Pediatría, Centro Médico Nacional-Siglo XXI, Instituto Mexicano del Seguro Social, México DF, México.
Virol J. 2007 Jan 11;4:6. doi: 10.1186/1743-422X-4-6.
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.
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.
Differences in genotype and in mutations in the "a" determinant were found between strains from asymptomatic and symptomatic HBV Mexican carriers.
乙型肝炎病毒（HBV）是一种含DNA的小病毒，有C、S、X和P 4个基因。S基因编码表面抗原（HBsAg），其中包含“a”决定簇，这是诱导保护性体液免疫反应的主要区域。目的是比较从无症状和有症状的墨西哥HBV携带者中分离出的毒株之间的基因型和“a”决定簇序列。
研究了21名无症状（献血者）和12名有症状（有临床体征且接受拉米夫定治疗超过1年）的HBV携带者；所有患者血清中的HBsAg均为阳性。测定血浆中的病毒载量、基因型和亚型。对包含“a”决定簇的S基因片段进行PCR扩增并测序，以确定基因型、亚型并识别突变。无症状携带者的平均病毒载量为0.7965×10⁴拷贝/ml，有症状患者为2.73×10⁶拷贝/ml。在无症状个体中鉴定出H、C和F基因型；而在有症状患者中H型占主导。从所有33名携带者中扩增出一段包含“a”决定簇的279 bp片段，并将序列与GenBank中的S基因序列进行比对。在无症状组中鉴定出的突变有Y100N、T126I、Q129H和N⁴⁶K，在有症状组中为F93I和A128V。
在无症状和有症状的墨西哥HBV携带者的毒株之间，发现了基因型和“a”决定簇突变的差异。
