Value of hepatitis E virus nucleic acid,antigen,and antibodies in the diagnosis of hepatitis E virus infection

Objective To investigate the role of hepatitis E virus nucleic acid(HEV RNA),hepatitis E virus antigen(HEV Ag),hepatitis E virus antibodies(HEV IgM antibody and HEV IgG antibody) in the clinical diagnosis of hepatitis E virus infection. Methods A total of13 992 specimens,for which the detection of HEV IgM antibody and HEV IgG antibody were performed in Peking University People's Hospital,were collected,among which 1924 had positive HEV IgM antibody or HEV IgG antibody. Quantitative real-time PCR was used to determine HEV RNA and HEV genotype,and enzyme-linked immunosorbent assay was used to detect HEV Ag,HEV IgM antibody,and HEV IgG antibody and measure the levels of alanine aminotransferase(ALT),aspartate aminotransferase(AST),total bilirubin(TBil),and direct bilirubin(DBil). The non-parametric rank sum Mann-Whitney U test was used for comparison of continuous data between groups. Results Among the 1924 specimens with positive HEV IgM antibody or HEV IgG antibody,152(7. 9%) had positive HEV IgM antibody,1897(98. 6%) had positive HEV IgG antibody,62(3. 2%) had positive HEV RNA,and 55(2. 9%) had positive HEV Ag. Among the 152 specimens with positive HEV IgM antibody,62(40. 8%) had positive HEV RNA,and 55(36. 2%) had positive HEV Ag,and among the 62 specimens with positive HEV RNA,55(88. 7%) had positive HEV Ag. The HEV RNA-positive group with 62 specimens had significantly higher levels of ALT,AST,TBil,and DBil than the HEV RNA-negative group with 90 specimens(Z =-7. 609,-6. 942,-5. 815,and-6. 130,all P < 0. 001),and the HEV Ag-positive group with 55 specimens had significantly higher levels of ALT,AST,TBil,and DBil than the HEV Ag-negative group with 97 specimens(Z =-6. 413,-5. 786,-5. 199,and-5. 545,all P < 0. 001). Nested PCR amplification and sequencing showed that in the HEV RNA-positive group with 62 specimens,58 had positive HEV RNA and 4 had negative HEV RNA. The high level of positive HEV IgG antibody significantly reduced the S/CO value of HEV Ag detection and even yielded a negative result.Conclusion Compared with HEV antibodies,HEV Ag can improve the diagnostic level of hepatitis E and has certain clinical significance.High levels of aminotransferases or bilirubin can help with the diagnosis of hepatitis E. The high level of HEV IgG antibody may reduce the detection value of HEV Ag,and attention should be paid to HEV IgG antibody value when HEV Ag is negative.