Full-length genome characterization and genetic relatedness analysis of hepatitis A virus outbreak strains associated with acute liver failure among children.

Clinical infection by hepatitis A virus (HAV) is generally self-limited but in some cases can progress to liver failure. Here, an HAV outbreak investigation among children with acute liver failure in a highly endemic country is presented. In addition, a sensitive method for HAV whole genome amplification and sequencing suitable for analysis of clinical samples is described. In this setting, two fatal cases attributed to acute liver failure and two asymptomatic cases living in the same household were identified. In a second household, one HAV case was observed with jaundice which resolved spontaneously. Partial molecular characterization showed that both households were infected by HAV subtype IA; however, the infecting strains in the two households were different. The HAV outbreak strains recovered from all cases grouped together within cluster IA1, which contains closely related HAV strains from the United States commonly associated with international travelers. Full-genome HAV sequences obtained from the household with the acute liver failure cases were related (genetic distances ranging from 0.01% to 0.04%), indicating a common-source infection. Interestingly, the strain recovered from the asymptomatic household contact was nearly identical to the strain causing acute liver failure. The whole genome sequence from the case in the second household was distinctly different from the strains associated with acute liver failure. Thus, infection with almost identical HAV strains resulted in drastically different clinical outcomes.