Stability of hepatitis A virus.

The stabilities of hepatitis A virus (HAV) and of poliovirus type 2 were compared under strictly controlled, identical conditions of pH value, temperature, and salt concentration. Although the resistance of the viruses proved to be the same from pH 3 to 11, the temperature at which 50% of poliovirus particles became disintegrated during heating at pH 7.0 for 10 min (T50,10 = 43 degrees) differed significantly from that characteristic for HAV (T50,10 = 61 degrees). In the presence of 1 M MgCl2, the T50,10 for poliovirus and for HAV shifted to 61 degrees and 81 degrees, respectively. Destabilization of the physical integrity of HAV by heating resulted in the release of viral RNA and, simultaneously, in the generation of several 'empty' capsid structures or dissociation products thereof. Empty capsids and further dissociation products were still serologically reactive with anti-HAV IgG contained in human convalescent sera. With further heating (greater than T50,10 = 67 degrees or greater than T50,1 = 87 degrees), however, they irreversibly lost this reactivity.