Modernization of historical Avian Leukosis Virus extraneous agent testing

Abstract

The Virus Serum Toxin Act was enacted to ensure that veterinary biologics produced in the United States are safe and effective for the prevention of animal disease. The advancements in technology and transportation over the last century led to formation of the Center for Veterinary Biologics that is now the responsible body for regulating veterinary biologics in the United States. A part of that regulation includes requirements for manufacturers of veterinary biologics to test materials derived from avian origin or for end product use in poultry, for extraneous replicating Avian Leukosis Virus (ALV). ALV is a ubiquitous pathogen of chickens responsible for significant economic losses in the poultry industry. Current veterinary biologic testing for extraneous ALV includes a 21-day continuous growth period in chick embryo fibroblasts (CEFs) produced from Specific Pathogen Free Eggs followed by examination for the ALV p27 antigen using biological assays. The purpose of this research was to shorten the time needed to detect low levels of ALV, determine if new technologies such as real-time polymerase chain reaction (PCR) could benefit this extraneous testing, and find an alternative cell line that was free of endogenous ALV. A literature review describes the history of ALV research and testing for extraneous ALV through the past century, the challenges of the current testing process, and potential modifications to the testing process. Two reverse transcription PCRs including a real-time PCR assay were found to be as or more sensitive than the current p27 ELISA testing. In addition, through cell culture examination it was determined that low levels of ALV can be detected effectively after 10 days in continuous culture. Although endogenous ALV- free cell lines were tested, none met the criteria needed to replace the current CEFs used for testing.