Validation of Thermal Destruction of Avian Influenza Virus in Rendered Products

By Annel K. Greene, PhD, Center Director, Clemson University
Animal Co-Products Research and Education Center

As a microbiologist at Clemson University’s Livestock, Poultry Health/Veterinary Diagnostic Center in Columbia, SC, Dr. Adam Leaphart works to ensure the safety of the food supply and the health and welfare of humans and animals. Working with the state veterinarian and staff, Leaphart helps maintain surveillance against diseases that could have an impact on humans and animals. His work also provides diagnostic results that assist veterinarians in the medical treatment and disease eradication in domestic animals and wildlife. Leaphart and his colleagues also work to monitor safe food production and have been appointed as a primary response agency under the state emergency operations plan for protecting human and animal health.

In his work, Leaphart uses cutting edge diagnostic tools to monitor animal diseases. As a member of the Animal Co-Products Research and Education Center (ACREC) team, he is using these methodologies to validate the thermal destruction of avian influenza (AI) virus in rendered animal co-products.

Past studies on the thermal destruction of AI by other researchers have concentrated on the destruction of the virus in food products. However, in rendered animal co-products, the high fat matrix of the materials presented challenges in creating methods for accurate detection of the virus particles. In the initial stages of the project, fellow ACREC researcher Dr. Thomas R. Scott worked to develop a method to identify presence/absence of the virus in rendered products. Working with a technique known as “enzyme linked immunosorbent assay,” Scott developed methods to detect the virus particles based on reaction with two of the unique proteins found on the external surface of the AI virus particle – hemagglutinin and neuraminidase. However, upon adding the materials to typical poultry rendering materials, the high fat content interfered with the detection of the virus components and resulted in erroneous test results. Therefore, Scott and Leaphart worked together to develop a more sensitive detection method based on the technique known as polymerase chain reaction (PCR).

PCR methods allow more sensitive detection of specific components of the virus. In the technique, genetic materials known as ribonucleic acid (RNA) from the virus particle are copied or “amplified” to allow detection. Leaphart conducted trials and determined that the AI virus would be able to be detected in the rendering materials using his procedures. After development of the detection methodology, Scott and Leaphart, along with laboratory technician Laine Chambers and ACREC researcher Dr. Annel Greene, conducted the thermal trials using samples of rendering materials with experimentally added AI subparticles.

This project was designed to determine the least thermal treatment that would destroy AI in rendered products. Due to the nature of the test procedure, the PCR assay used in this experiment determined if any Type A influenza was destroyed in the sample. Therefore, this assay indicates a total melting of the RNA and not simply killing of the virus particle.

Results indicated that Type A influenza RNA was destroyed in 30 seconds or less at temperatures between 110 degrees to 140 degrees Celsius (230 degrees to 284 degrees Fahrenheit). A manuscript of the results has been prepared and submitted for publication in a refereed journal. Validation of thermal destruction of AI in rendered animal products is of critical importance in case of an outbreak of the disease as well as a selling tool to ensure safety of rendering products to potential customers. As new concerns emerge about other Type A influenza strains such as “swine flu,” this study becomes even more of interest to the rendering industry.

ACREC Solutions – April 2010 RENDER | back