RESUMEN
A method for genotyping hepatitis B virus by partial HBsAg gene sequencing with primers common to all known genotypes was developed. Mutations related to anti-HBs resistance are also detected with this method. Samples from 103 Brazilian patients were analyzed. Precore and core region of these viruses were also sequenced in 101 patients. Genotypes A, B, C, D, and F were found with frequencies of 49.5, 2.9, 13.6, 24.3, and 9.7%, respectively. Genotypes B and C were found only in Asian patients, whereas genotypes A, D, and F were more common in patients without an Asian background. Precore mutants were found in 32 (31.7%) of 101 patients, with a higher frequency in those infected with genotype D (22 of 25 [88.0%]). Analysis of nucleotide 1858 showed presence of thymine in all patients with genotypes B, C, and D and in a few patients with genotypes A (10.0%) and F (30.0%), who showed more frequently the presence of cytosine. This nucleotide was closely related to the presence of precore mutants. Mutations in the basal core promoter were found in 64 of 101 (63.4%) samples. These mutations were more frequent in patients infected with genotype F (90.0%) and less frequent in patients infected with genotype B (33.3%). Deletions in this region were found in two genotype C-infected patients.
Asunto(s)
Virus de la Hepatitis B/genética , Hepatitis B Crónica/virología , Mutación , Secuencia de Aminoácidos , Femenino , Antígenos de Superficie de la Hepatitis B/genética , Virus de la Hepatitis B/clasificación , Humanos , Masculino , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa , Regiones Promotoras Genéticas , Análisis de Secuencia de ADNRESUMEN
TTV e um virus DNA recentemente descoberto no Japao a partir de um paciente portador de hepatite pos-transfusional de origem desconhecida. Neste estudo, avaliamos a presenca deste virus em pacientes com hepatopatias cronicas dos estados de Sao Paulo e do Para, representando duas regioes geograficamente diferentes. O DNA do TTV foi encontrado em 21/105 (20 por cento) e 9/20 (45 por cento) dos casos de Sao Paulo e do Para, respectivamente. O sequenciamento do DNA amplificado confirmou a presenca dos genotipos 1a e 2a, bem como de outros genotipos ainda nao descritos ate o momento. Em conclusao, TTV esta presente em casos de hepatopatias cronicas do Sudeste e do Norte do Brasil. por outro lado, maiores estudos ainda sao necessarios antes de se estabelecer relacao causal entre o TTV e a hepatite em seres humanos