RESUMEN
BACKGROUND/AIMS: Studies of genotypes and changes in nucleotide and amino acid sequences of hepatitis A virus (HAV) may provide valuable information on the epidemiological aspects of a particular region. In Korea the prevalence of anti-HAV in the 1 - 20 year age group declined from 60% in 1980 to 9% in 1995. As a result this age group has a high risk of HAV infection. Actually over 1,500 cases of clinically overt hepatitis A occurred in 1998 while few cases of clinical hepatitis A had been reported until the early 1990s. The aims of this study are to determine the genotypes of HAV which have been circulating in Korea and to define the phylogenetic relationships of geographically defined isolates. METHOD: From 1994 - 1998 a total of 18 serum specimens was obtained from patients in Korea with sporadic form acute hepatitis A. The HAV nucleic acid from serum specimens was subjected to genomic sequence analysis following viral RNA extraction, reverse transcription and amplification of the cDNA by PCR. DNA sequencing was performed in both directions of each PCR product. RESULTS: All isolates clustered within the subgenotype IA irrespective of the geographic locations and timing of the clinical hepatitis. Among 18 Korean isolates, 9 isolates had 2 amino acid sequence changes and 2 isolates had 1 amino acid sequence change. These changes in the amino acid sequences are unique and have never been reported in HAV subgenotype IA. CONCLUSIONS: All isolated HAV had genotype (IA). Eleven of 18 isolates had unique changes in amino acid sequences. These data indicate that the endemic HAV has been circulating in Korea over a long period of time.