The physicochemical properties of infectious hepatitis A virions

Abstract

The propagation of hepatitis A virus (HAV) in the cell line PLC/PRF/5 made possible the radiolabelling in vivo of mature, infectious hepatitis A virions and the determination of their physicochemical properties. In contrast to poliovirus type 2 (160S, 1.340 g/ml), HAV had a sedimentation coefficient of 156 +/- 2S and a buoyant density of 1.332 g/ml in CsCl. The genome of HAV consisted of linear single-stranded RNA which sedimented at 32.5S under non-denaturing conditions. Compared to the size and sedimentation behaviour of poliovirus RNA (2.6 X 10(6) mol. wt., 35S) this corresponds to a mol. wt. of 2.3 X 10(6). Electrophoresis under fully denaturing conditions, however, revealed a mol. wt. of 2.8 X 10(6) and indicates the existence of relatively extended regions with secondary structure. The purified virus genome, containing a poly(A) sequence, served as a messenger for the synthesis of virus antigen in PLC/PRF/5 cells. Finally, in accordance with previous observations, the capsid of the virion was found to be constructed of three major polypeptides (VP1, 31 X 10(3); VP2, 26 X 10(3); VP3, 21 X 10(3) mol. wt.) and of two less readily demonstrable components probably corresponding to VP4 (8 X 10(3) to 10 X 10(3) mol. wt.) and the precursor polypeptide VP0 (40 X 10(3) mol. wt.).