Biophysical and Biochemical Characterization of Hepatitis A Virus

Biophysical and biochemical analysis of hepatitis A virus has shown it to be a 27- to 32-nm icosahedral particle with 32 capsomers. The mature virion has a buoyant density of 1.33-1.34 g/cm3, a sedimentation coefficient of 156-160S, and is composed of four polypeptides with molecular weights of 30,000-33,000 (VP1), 24,000-27,000 (VP2), 21,000-23,000 (VP3), and 7,000-14,000 (VP4). The genome of hepatitis A virus consists of a single piece of single-stranded RNA which sediments at 32-35S and has a buoyant density of 1.64 g/cm3. The molecular weight of RNA is 2.25 x 10(6) when measured under nondenaturing conditions and 2.8 x 10(6) when measured under fully denaturing conditions. The genome contains a 40-80 nucleotide sequence of polyadenylic and is capable of infecting cell cultures. These findings, together with the observation that the virion is stable at pH 3.0 and resistant to ether and a temperature of 60 degrees for 1 h, indicate that hepatitis A virus should now be classified as an Enterovirus within the family Picornaviridae.