Successful development and validation of an in vitro replacement assay for Leptospira vaccine potency tests

The standard requirement for serial release potency testing of Leptospira bacterins in the United States is the hamster vaccination challenge test. It is a test that uses a large number of animals experiencing pain or distress, takes weeks to conduct, can be expensive and requires that laboratory personnel handle a viable zoonotic pathogen. In an effort to address these concerns, the United States Department of Agriculture (USDA) developed an in vitro method for potency testing of four Leptospira serovars. This enzyme-linked immunosorbent assay (ELISA) was subsequently validated in the target species. USDA informed their biologics licensees, permittees and applicants of the availability of reference bacterins and the regulatory acceptance regarding this alternative test method in notices issued in 2007 and 2009. This presentation describes how the initial research and subsequent development and validation work were accomplished.