The present invention relates to polypeptide(s) comprising the amino acid sequence as set forth in SEQ ID No. 1 of hepatitis E virus ORF 2 or its fragment, which is in the form of n-polymeric polypeptide, wherein n is an integer from 1-180; to a chimeric protein consisting of a polypeptide of the present invention and a conserved fragment of hemagglutin antigen from influenza virus; to a polypeptide of the present invention bound to a polypeptide containing epitope from hepatitis E virus ORF3 or an immunogenic fragment thereof; to a recombinant expression vector comprising the DNA molecule encoding the above polypeptides and the host cell transformed with said recombinant expression vector which is able to express polypeptide of the present invention. The present invention further relates to a vaccine composition against hepatitis E virus which comprises the above-mentioned polypeptide, or diagnostic kit for hepatitis E virus infection comprising the above-mentioned polypeptide, which includes IgG, IgM, or total antibody diagnostic kit for hepatitis E virus, and to the use of vaccine composition and diagnostic kit for prophylaxis, diagnosis and/or treatment of hepatitis E virus infection.