Cloning and expression of hexon protein of human respiratory adenovirus of three serotypes and analysis of antigenicity of the recombinant proteins

Objective To clone and express the hexon protein of three prevalent human adenovi -rus strains causing respiratory disease and analyze the antigenic characteristics of the recombinant proteins . Methods The full length genes encoding hexon protein of human adenovirus serotype 3（HAdV3）, serotype 4（HAdV4） and serotype 7（HAdV7） were cloned by PCR and sequenced , respectively.The alignment anal-ysis was performed by using hexon gene sequences from GenBank .The major antigenic regions of hexon pro-tein of the three serotypes were expressed in E.coli and purified.The antigenicity, immunogenicity and cross reactivity of the recombinant proteins were determined by ELISA and Western blot assay .Results The full length gene sequence encoding hexon protein of human adenovirus serotype 4 was firstly reported in China , which showed more than 99%homology in both nucleotide and amino acid sequences with the human adeno-virus type 4 NHRC3 strain.The partial hexon protein sequence of HAdV 3, HAdV4 and HAdV7 containing all of the 7 hyperviriable regions （ HVRs） were expressed in E.coli, respectively .The purified recombinant proteins could be recognized by antiserum of the three serotypes of adenovirus .The antiserum samples against the three recombinant proteins could cross-react with particles of the three serotypes of adenovirus . The possible type-and species-specific epitopes were predicted .Conclusion The major antigenic regions of hexon protein of the three serotypes were successfully expressed .The purified recombinant proteins contai-ning both intertypes and type-specific epitopes showed a strong immunogenicity . Key words: Human respiratory adenovirus; Hexon; Recombinant expression; Antigenicity; Epitope