The genomic map of hepatitis A virus: an alternate analysis

Recently Najarian et al. reported a complete cDNA sequence of the genomic RNA of hepatitis A virus (HAV) and the amino acid sequence inferred from it. As a picornavirus, HAV contains a single-stranded plus-sense RNA encoding a single 'polyprotein' which is post-translationally cleaved to yield the mature structural and non-structural proteins. In order to identify putative cleavage sites a combined function of predicted secondary structure and hydropathy was calculated by Najarian et al. for the polyproteins of HAV and poliovirus type 1 (Mahoney) (PV-1) and the two plots were aligned on the basis of a short homology in capsid protein VP3. Several of the proteins thereby predicted fail to conserve features found in all other picornaviruses that have been examined and, indeed, on the basis of these predictions HAV would hardly be a picornavirus. By an alternate analysis utilizing the computer programs FASTP and PRTALN we find that a putative protein processing map which does preserve these features can be constructed.