Three years ago, the serum plate agglutination (SPA) test was Aviagen®’s gold standard for detecting Mycoplasma. The SPA test method produced excellent results for but had one disadvantage; it regularly produced false-positive results for Mycoplasma Synoviae (Ms). The false positive meant additional testing and more work and was reason enough for the veterinary team at Aviagen to seek out an enzyme-linked immunosorbent assay (ELISA) test as an alternative. The search ultimately ended with the Mycoplasma gallisepticum-synoviae (Mg/Ms) Combined Antibody ELISA test kit from BioChek.
Aviagen is the world’s leading poultry breeding company, providing premier breeding stock to chicken producers on virtually every continent under the Arbor Acres®, Indian River® and Ross® brand names. With global corporate headquarters in Huntsville, Alabama, the company has a number of wholly owned operations across the United Kingdom, Europe, Turkey, Latin America, India, Australia, New Zealand and the U.S., as well as joint ventures in Asia. Dual-breeding programs in the U.S. and U.K. ensure the security and integrity of the company’s exclusive brands. Eric L. Jensen, DVM, MAM, dACPV joined Aviagen North America in 1995 and became vice president of Veterinary Services in September 2015. In this position he is responsible for ensuring the health and welfare of the poultry and for the biosecurity programs used by Aviagen. “I work together with my team of veterinarians, microbiologists and the two diagnostic laboratories where ELISA kits from BioChek are in common use. Our laboratories are accredited by the U.S. Department of Agriculture (USDA) and are authorized to monitor the health of our flocks and ensure conformance with the National Poultry Improvement Plan (NPIP). Therefore, our products meet the strictest international health standards and may be exported worldwide,” says Jensen.
Damaging Mycoplasma disease
One of the diseases for which Aviagen tests flocks every two or three weeks is Mycoplasma. In chickens, the disease is caused by Mg and Ms and can result in considerable economic damage. Mycoplasma can lead to slower growth, lower egg production and poorer egg quality in laying flocks. In case of infection, primary breeders are required to depopulate flocks. “Fortunately, we have not had a Mycoplasma-infected flock in more than seven years thanks to Aviagen’s robust biosecurity program. However, we will continue our intensive monitoring program to verify our freedom from this disease. The test programs that we use are mandated by the NPIP. The NPIP prescribes the sample type, sampling frequency and test methodology,” explains Jensen.
Drawbacks of SPA
Before Aviagen started using the Mg/Ms ELISA kit from BioChek, the flocks were monitored with the serum plate agglutination test. “We had worked with the SPA test for many years. While the SPA is an adequate method, the procedure is labor-intensive and all generated data requires manual entry into our laboratory information management system. In addition, we were regularly confronted with positive results for Ms that later turned out to be false-positive. These faulty results required costly additional testing and unnecessary work. For us, this was sufficient reason to look for another test method: ELISA test,” continues Jensen.
One of the companies Aviagen approached in seeking an alternative test method was BioChek. “In our discussions with BioChek we explained that we had always been convinced that a SPA test was more sensitive and would detect Ms earlier than an ELISA test but would be open to a trial that demonstrated otherwise. Our interest prompted BioChek to conduct a research trial,” relates Jensen. In this trial, a research institute conducted a challenge study using two strains of Ms. The study compared the results between the SPA test and the ELISA tests from three manufacturers producing kits licensed by the USDA for use in poultry. The important questions were how early would the various test kits detect Ms-infected chickens and was there a difference in the sensitivity of the various assays in detecting chickens infected with the different strains of Ms. Different Ms strains have been identified that can be difficult to detect serologically. During the research trial it became apparent that some ELISA test kits had difficulty detecting one of the challenge strains used in the study. However, the ELISA test kit from BioChek did identify both strains. The trial data also demonstrated that the BioChek ELISA kit detects positive results on serological exams at least as early (seven to nine days post infection) and in some cases earlier than the SPA test.
The result: Fewer false positives and efficient data delivery
Aviagen has been satisfactorily using the Mg/Ms ELISA kit from BioChek for three years now, according to Jensen. “The test results have been extremely accurate, with a considerably lower number of false positive results than with the SPA test. When we started using the Mg/Ms ELISA kit, we had just 1.4 percent false-positive results. After consulting with the BioChek technical support team a few adjustments were made and this figure has dropped to 0.7 percent. In addition, the test results are highly consistent. Furthermore, because the results are automatically uploaded, efficiency is added to our process, which saves us a lot of work. With Mycoplasma, the antibody level is not as important as early detection of infection. However, this situation is different when processing and analyzing the test results of other diseases such as Newcastle disease, infectious bursal disease or infectious bronchitis. Thanks to the Mg/Ms ELISA kit, software and the data management systems of BioChek, we can consult the test results quickly, have confidence in their accuracy and most importantly, gain rapid insight into the effectiveness of our vaccination programs. Monitoring the health of breeding flocks has top priority for Aviagen, and that’s why an accurate and efficient disease-detection system is of utmost importance to us as a company.”