Biophysical and Biochemical Characterization of Hepatitis A Virus

Abstract

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 (VPl), 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 × 10⁶ when measured under nondenaturing conditions and 2.8 × 10⁶ when measured under fully denaturing conditions. The genome contains a 40–80 nucleotide sequence of polyadenylic acid 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° for 1 h, indicate that hepatitis A virus should now be classified as an Entero-virus within the family Picornaviridae.

Hepatitis A Virus Replication: An Intermediate in the Uncoating Process

“…38,57]. Dense HAV particles isolated from CsCl gradients have also been reported to sediment as mature virions when subsequently centrifuged over sucrose gradients [58], agreeing with data presented here.…”

Identification and characterization of incomplete hepatitis A virus particles

“…However, analysis was confined to HAV antigenic material in a density range of 1.29 g/ml to 1.36 g/ml (in CsCI), and more extensive and precise characterization was not attempted. Furthermore, empty capsids were also observed in stool samples of infected individuals by electron microscopy, but were poorly characterized (for a review see Coulepis et al, 1982). This finding indicates that empty capsids are not only a product of HAV replication in vitro, but also occur in natural infections.…”

Primary structure and gene organization of human hepatitis A virus.

“…The viral RNA is 7.5 kilobases long, is of (+)-strand polarity, contains a poly(A) stretch at the 3' end, and may be covalently linked to a protein at the 5' terminus designated VPg (1)(2)(3). Evidence for virion proteins of Mrs 33,000, 29,000, and 27,000, designated VP1, VP2, and VP3, respectively, and additional peptides of Mrs 22,000 and 10,000 has been presented (4)(5)(6).…”