Occult hepatitis B virus infection in hemodialysis patients in Recife, State of Pernambuco, Brazil

Abstract

INTRODUCTION: Persistence of the hepatitis B virus (HBV) genome in individuals negative for the HBV surface antigen (HBsAg) reflects occult infection. The aim of this study was to identify occult HBV infection among hemodialysis patients at 5 clinics in Recife, State of Pernambuco, Brazil, between August 2006 and August 2007. METHODS: Serum samples underwent enzyme-linked immunosorbent assay to investigate total antibodies against HBcAg (anti-HBc), HBsAg, and antibodies against HBsAg (anti-HBs). Samples that were HBsAg-negative were tested for total anti-HBc, and those that were positive for total anti-HBc were tested for anti-HBs. HBV DNA was investigated with an in-house PCR technique to identify samples positive for total anti-HBc. Subsequently, the samples positive for HBV DNA were sequenced to identify the genotype and mutations. RESULTS: The study population (n = 752) had a mean age of 50 15.1 years and included both sexes. All samples analyzed were negative for HBsAg. The seroprevalence of total anti-HBc was 26.7% (201/752), while that of anti-HBs was 67.2% (135/201). Total anti-HBc alone was detected in 5.7% of the patients. Occult infection was found in 1.5%, comprising genotypes A (33.3%, 1/3) and D (66.7%, 2/3). No mutations were found. CONCLUSIONS: The study detected occult hepatitis B virus infection in hemodialysis patients. Molecular studies on HBV are of fundamental importance because they identify patients that had been considered virus-negative but who, in reality, host the virus and have the ability to transmit it to other patients and staff.INTRODUÇÃO: A persistência do genoma do vírus da hepatite B (HBV) em indivíduos com o antígeno de superfície para o HBV (HBsAg) negativo, caracteriza-se como infecção oculta. O objetivo desse trabalho foi identificar infecção oculta pelo HBV em hemodialisados provenientes de cinco clínicas de Recife, Estado de Pernambuco, Brasil, de agosto de 2006 a agosto de 2007. MÉTODOS: Os soros foram submetidos à pesquisa do HBsAg, anticorpos totais para o AgHBc (anti-HBc total) e para os anticorpos contra o antígeno de superfície do HBV (anti-HBs) pelo ensaio imunoenzimático (ELISA). As amostras negativas para o HBsAg foram testadas para o anti-HBc total e os soros reativos, foram testados para o anti-HBs. O DNA-HBV foi analisado pela reação em cadeia da polimerase (PCR) in house nas amostras anti-HBc total reagentes. As amostras DNA-HBV positivas foram sequenciadas para a identificação do genótipo e pesquisa de mutação. RESULTADOS: A população estudada foi de 752 hemodialisados, com média de idade de 50±15,1 e ambos os sexos. Todos os soros analisados foram HBsAg negativos. A soroprevalência para o anti-HBc total e anti-HBs foi de 26,7% (201/752) e 67,2% (135/201), respectivamente. O anti-HBc total foi encontrado em 5,7% dos pacientes. A infecção oculta foi identificada em 1,5% (3/201) das amostras, sendo 33,3% com o genótipo A e 66,7% com o D. Nenhuma mutação foi observada. CONCLUSÕES: O estudo encontrou infecção oculta na amostra analisada. A infecção oculta encontrada mostra a importância de estudos moleculares, pois pacientes HBsAg negativos podem albergar o vírus disseminando-o para os demais pacientes.