Real-time RT-PCR for pandemic H1N1 influenza in veterinary medicine
When swine-origin pandemic H1N1 influenza (pH1N1) was first identified in 2009, the importance of the infection of livestock and poultry, which can be infected with many influenza strains, was unknown. Therefore, there was a critical need to have a rapid and accurate diagnostic test for veterinary specimens that could quickly identify and differentiate the pH1N1 from other influenza viruses. As soon as the genetic data and first isolates became available, a genetic test was developed that could identify the pH1N1 virus and also differentiate it from the classical H1N1 swine influenza viruses already circulating in U.S. swine and turkey populations. Additionally, analysis of the official USDA screening test (the “M gene test”), which detects all influenza A viruses, identified important gene sequence mismatches that required that the test be updated to assure acceptable sensitivity and specificity for pH1N1. The test protocol was first provided to the Diagnostic Virology Laboratory at the USDA-APHIS, National Veterinary Services Laboratories (NVSL). The ARS South Atlantic Area team worked with NVSL personnel to collect additional field validation data and further optimize the test so it could be implemented by state and regional veterinary diagnostic laboratories of the National Animal Health Laboratory Network (NAHLN).
In early June 2009, the tests were adopted by the NVSL as official USDA tests and subsequently implemented by the NAHLN. These are currently the official tests for pH1N1 in veterinary specimens and have been used to identify infection in swine, turkeys, ferrets and cheetahs, among other species. Equally important, these tests have allowed veterinary diagnostic laboratories to rule out the presence of pH1N1 in samples.
The tests were also made available without restriction through the OFFLU network (a collaboration on influenza between the World Organization for Animal Health [OIE] and UN Food and Agriculture Organization) to any interested veterinary laboratory and bilaterally with Canada and Mexico to support their surveillance and diagnostic efforts.
The diagnostic tests that were previously available took one to two weeks to provide results, cost at least $50 per sample, and could only be run in a few of the most well-equipped laboratories. The ARS South Atlantic team developed and validated new tests for pH1N1 that could provide results in 3-4 hours, cost $8- 12 per sample, and be run in most veterinary diagnostic laboratories. These tests have been run with thousands of samples and have saved substantial amounts of time and money since their implementation.