Hepatitis A The E.Coli derived 44 kDa recombinant protein fused to a GST tag contains the VP4-VP2 immunodominant regions, amino acids 55-164. 10mM CBB, pH9.6, 0.1% SDS and 50% glycerol.HAV VP4-VP2 antigen is suitable for ELISA and Western blots, excellent antigen for detection of HAV with minimal specificity problems.; HAV VP4-VP2 Protein was purified by proprietary chromatographic technique. Immunoreactive with sera HAV-infected individuals.