Detection of H5N1 high pathogenicity avian influenza virus in meat and tracheal samples from experimentally infected chickens

Authors: Das, Amaresh; Spackman, Erica; Thomas, Colleen; Swayne, David; Suarez, David

Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/8/2007
Publication Date: 3/26/2008
Citation: Das, A., Spackman, E., Thomas, C., Swayne, D.E., Suarez, D.L. 2008. Detection of H5N1 high pathogenicity avian influenza virus in meat and tracheal samples from experimentally infected chickens. Avian Diseases. 52:40-48.

Interpretive Summary: Avian influenza virus can cause of range of disease in poultry, including chickens and turkeys. The most severe form is highly pathogenic avian influenza, which can result in the loss of entire chicken flocks if they are infected. The highly pathogenic form of the virus can grow in many organs in the body, including the meat. There are many different types of avian influenza virus, and rarely some of these viruses may also infect people. Because highly pathogenic avian influenza can grow in the meat in chickens, there has been concern that humans could be infected by eating this contaminated meat. Fortunately in the U.S. we have meat inspection to keep sick birds from being used for food and in the unlikely possibility infected meat reached the consumer, earlier studies demonstrate proper cooking of meat will completely destroy any virus. This study examined the infection of chickens with a highly pathogenic avian virus and examined how quickly virus could be seen in the meat. Additionally, a rapid diagnostic test was developed to provide a convenient way of testing meat samples for viral contamination. In the study the birds became sick within 24 hours of infection at about the same time large amounts of virus were found in the meat.

Technical Abstract: The Asian H5N1 highly pathogenic avian influenza (HPAI) virus causes a systemic disease with high mortality of poultry and is potentially zoonotic. In both chickens and ducks, the virus has been demonstrated to replicate in both cardiac and skeletal muscle cells. Experimentally, H5N1 HPAI virus has been transmitted to chickens through the consumption of raw infected meat. In this study, we bench validated a modified real-time RT-PCR (RRT-PCR) test for detecting AI virus in infected cardiac and skeletal muscle. Samples of breast and thigh meat, heart and tracheal swabs from chickens intranasally inoculated with H5N1 HPAI virus were sampled at 6 h intervals through 48 h post inoculation (PI). Tracheal swabs were tested by real-time RT-PCR (RRT-PCR) and a commercial AI viral antigen detection test while meat samples were tested by RRT-PCR with a modified RNA extraction protocol and by virus isolation in embryonating chicken eggs. The HPAI virus was sporadically detected in meat and the tracheas of infected birds without any clinical signs of disease as early as 6 h PI, and was detected in all samples tested at 24 h PI and later. No differences in sensitivity were seen between virus isolation and RRT-PCR in meat samples. The AI viral antigen detection test on tracheal swabs was a useful method to identify infected chickens when they were sick or dead, but was less sensitive in detecting infected birds when they were preclinical. This study provides data that pre-slaughter tracheal swab testing can detect infected birds among the daily mortality and prevent infected flocks from being sent to processing plants. In addition, the modified RRT-PCR test on meat provides a rapid and sensitive method of identifying HPAI virus in illegal contraband or domestic meat samples to prevent HPAI virus from entering the food chain.