Identification of hepatitis A virus non-structural protein 2B and its release by the major virus protease 3C.
The RNA genome of hepatitis A virus (HAV) encodes a giant polyprotein that is putatively cleaved proteolytically into four structural and seven non-structural proteins. So far, most of the proposed non-structural proteins and their respective cleavage sites have not been identified. A vaccinia virus recombinant (vRGORF) containing the complete HAV ORF under the control of the bacteriophage T7 promoter was used to express HAV in recombinant animal cells (BT7-H) that constitutively expressed T7 DNA-dependent RNA polymerase. A HAV-specific 27.5 kDa expression product was identified as peptide 2B. The 27.5 kDa 2B antigen was also found in HAV-infected MRC-5 cells. The N-terminal amino acid residues of the new peptide 2B are Ala-Lys-Ile-Ser-Leu-Phe and polyprotein cleavage between 2A and 2B occurred at amino acids 836-837 (Gln-Ala). Furthermore, heterologous expression in the same system of regions P1-P2 and of the protease 3C (3Cpro) gene, showed that P1-P2 polyprotein is not cleaved autocatalytically but by 3Cpro. Hence, 3Cpro is effective in cleaving the polyprotein 2A-2B junction.
Gosert
R
R
Institute for Clinical Microbiology and Immunology, St Gallen, Switzerland.
Cassinotti
P
P
Siegl
G
G
Weitz
M
M
D000086042:3C Viral Proteases; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003546:Cysteine Endopeptidases / Q000494:pharmacology*; D006507:Hepatovirus / Q000737:chemistry*; D007106:Immune Sera / Q000276:immunology; D008969:Molecular Sequence Data; D011817:Rabbits; D014616:Vaccinia virus / Q000235:genetics; D017361:Viral Nonstructural Proteins / Q000032:analysis* / Q000737:chemistry / Q000276:immunology; D014764:Viral Proteins
D007106:Immune Sera; D017361:Viral Nonstructural Proteins; D014764:Viral Proteins; D003546:Cysteine Endopeptidases; D000086042:3C Viral Proteases