Antigencity identification of recombinant hepatitis E virus ORF2 protein expressed in Pichia pastoris

Objective To determine the antigencity of recombinant hepatitis E virus ORF2 (rHEV ORF2) protein expressed in Pichia pastoris (P pastoris) Methods By using the rHEV ORF2 protein from E coli as control, an indirect ELISA was adopted to identify the sensitivity, specificity and stability of rHEV ORF2 protein from P pastoris in detection of HEV IgM and IgG antibody in sera from patients with hepatitis E The reactivity of the rHEV ORF2 against 5 HEV ORF2 monoclonal antibodies (McAbs) was also tested Results The minimum concentration of coated antigen with which HEV IgG could be detected was 12 5 ng/ml, while the highest serum dilution to detect both IgM and IgG antibodies against HEV was 1∶5 120 No cross reaction was found with sera from patients with any other types of hepatitis The 37℃ acceleration test showed that the rORF2 was highly stable within 12 months at 4℃ The 5 HEV ORF2 McAbs showed better reaction with the rORF2 from P pastoris , especially that 4B2, 2E2, whose reaction against the rORF2 were 125 and 25 times respectively higher than that of rORF2 from E Coli Conclusion There may be more extensive conformational epitopes in the rHEV ORF2 from P pastoris The excellent antigenicity, sensitivity and stability suggest that it can be served as a new candidate antigen for the development of diagnostic reagents of hepatitis E