4 hours vs. 2 Weeks: Preventing Pandemic

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The pH1N1 virus was first recognized in humans in April 2009 as a novel influenza with genes primarily of North American swine origin, but with two genes most closely associated with European swine influenza viruses.

The number of cases rapidly increased in the human population and eventually became the first human pandemic virus of the 21st century.

As soon as the genetic data and first isolates became available in late April, Agricultural Research Service (ARS) researchers started developing a molecular test that could identify the pH1N1 virus and differentiate it from the classical H1N1 swine influenza viruses already circulating in U.S. swine and turkey populations.

Additionally, bioinformatic analysis of the official USDA real-time RT-PCR test for type A influenza or the “M gene test” (this test detects all influenza A viruses) identified important sequence mismatches that required updating the test to assure acceptable sensitivity and specificity of this important diagnostic screening tool. Completing the development and the initial validation of the pH1N1 test was given a top priority, and the team worked long hours to ensure that the test would be available as quickly as possible.

The test protocol was first transferred to the Diagnostic Virology Laboratory at the National Veterinary Services Laboratories (NVSL), USDA-APHIS, on May 3, 2009.

The ARS researchers worked with the NVSL researchers to collect additional field validation data and further optimize the test so that it could be implemented by the 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 diagnostic assays and were 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, cheetahs, and other species by the NVSL and NAHLN laboratories (currently the test has been implemented at 37 NAHLN labs).

Equally important, these tests have

allowed veterinary diagnostic labs to rule out the presence of pH1N1 in specimens. The tests were also transferred, without restriction, through the OFFLU network (collaboration on influenza between the OrE and United Nations Food and Agriculture Organization) to any interested veterinary laboratory and bilaterally to Canada and Mexico to support their surveillance and diagnostic efforts.

These real-time RT-PCR tests have numerous benefits over the previously available technology.

Without these tests, laboratories would have to rely on virus isolation to diagnose influenza, which can take from 1 to 2 weeks, and then an additional 2 to 3 days to identify the specific influenza strain as pH1N1 (or in some cases to rule out pH1N1) by genetic sequencing. These real-time RTPCR tests can identify influenza virus and determine whether it is pH1N1 within 3-4 hours.