Research paperDevelopment of an oral fluid immunoassay to assess past and recent hepatitis E virus (HEV) infection

- Non-invasive sampling could improve community-based research participation.
- We developed saliva-based assays to assess past and recent hepatitis E virus (HEV) infection.
- The sensitivity and specificity of the salivary assays are comparable to serum based ELISAs.
- Salivary assays could improve our knowledge of the ecology and natural history of HEV.

BackgroundHepatitis E virus (HEV) infection causes significant morbidity and mortality worldwide, particularly among pregnant women. In clinical settings blood-based testing protocols are commonly used to diagnose HEV infection, but in community settings such invasive sampling can hinder study participation and limit discovery of the ecology and natural history of HEV infection. Oral fluid is a non-invasive biospecimen that can harbor pathogen-specific antibodies and has the potential to replace blood-based testing protocols.ObjectivesTo develop an immunoassay to assess past and recent HEV infection that uses oral fluid instead of serum or plasma.MethodsThe assay was validated using paired oral fluid and serum samples collected from 141 patients who presented either with (n = 76) or without (n = 65) symptoms of acute viral hepatitis at a clinical diagnostics center in Dhaka, Bangladesh. The sensitivity and specificity of the oral fluid-based immunoassay for HEV IgG (past HEV infection) and HEV IgA (recent HEV infection) antibodies was calculated in reference to Wantai's (Beijing Wantai) serum-based HEV enzyme-linked immunosorbent assay (ELISA) kits for IgG and IgM antibodies, respectively.ResultsThe sensitivity and specificity of the oral fluid-based immunoassay for HEV-IgG antibodies were 98.7% and 98.4%, respectively. The sensitivity and specificity of the oral fluid-based immunoassay for HEV IgA were 89.5% and 98.3%, respectively.ConclusionsThe high concordance of our non-invasive oral fluid-based immunoassays (HEV IgG and HEV IgA) with commercial high-performance serum HEV ELISA kits (IgG and IgM) means that population-based surveillance of past and recent HEV infection could be expanded to improve understanding of its ecology and natural history.