Dr. Osiowy is Chief of the Viral Hepatitis and Bloodborne Pathogens Section at the National Microbiology Laboratory (NML) in Winnipeg, Manitoba. She received her doctorate and research training in virology at the University of Calgary with post-doctoral training at Health Canada’s Bureau of Microbiology in Ottawa. At the NML she is responsible for managing serological and molecular diagnostic reference services for the five hepatitis viruses, investigating HAV and HBV outbreaks or suspected transmission events, and conducting viral hepatitis research including collaborators such as the Canadian Blood Services and the Canadian Hepatitis B Network.

Title: Defining a Hepatitis D Virus Antibody Testing Algorithm for Accurate Screening

Background: Chronic hepatitis D virus (HDV) infection affects 3- 5% of the chronic hepatitis B population of Canada, and comprises persons at high risk of STBBI and immigrants from HDV endemic countries. With new drugs available to treat HDV, screening and diagnosis are a priority.

Purpose: To determine the most appropriate algorithm for accurate HDV antibody screening concurring with active HDV infection.

Method: A comparison of two HDV IgG testing platforms was conducted with serum specimens from HBsAg positive persons (Wantai HDV IgG manual ELISA assay, n=170; and the DiaSorin Murex anti-HDV CLIA assay, n=130). HDV RNA was tested in all samples.

Result(s): Calculated antibody values indicated potential false positive results with the DiaSorin assay, particularly in relation to RNA positivity, such that antibody +, RNA – samples were observed with 60.4% (32/53; DiaSorin) and 35.8% (24/67; Wantai) samples within a specific AU/mL and A/CO range, respectively.

Conclusion(s): An algorithm to accurately screen HDV antibody predictive of RNA positivity may include a 2-step screening process starting with the DiaSorin assay and confirmation with the Wantai assay.