Will WHO Test Swine in the United States for WSN/33?
Recombinomics Commentary
May 8, 2005
The WHO has now been presented with overwhelming evidence that WSN/33 sequences are in 2004 and 2005 swine. WHO's investigation of WSN/33 in swine has also identified 27 H1N2 isolates on two farms in Korea. WHO analysis of these sequences indicated that they were similar to H1N2 isolated from farms in the United States in 2001. These H1N2 sequences have also been reported in Korea in 2002, suggesting the isolates may have been imported into Korea from the United States.
The 2005 swine analyzed by Sang Seo had three serotypes. In addition to H1N2, H1N1 sequences that were closely related to WSN/33 were detected, as were H9N2 avian isolates closely related to 2004 Korean H9N2 isolates from swine and chickens.
Thus, it would seem that the H1N2 sequences originated in the United States on or before 2002, and the H9N2 avian sequences originated in Korea in 2004. However, the time and location of the WSN/33 sequences is unclear. Details on the WSN/33 sequences can be heard here.
Recently, false negatives for H5N1 bird flu in Vietnam have been revealed. Some of these false negatives may be due to evolution of the H5N1 2005 sequences away from the 2004 H5N1 sequences. Problems identifying WSN/33 may be related to use of the incorrect primers. WHO has been given primer sequences for detecting WSN/33 H1. It would seem that testing of swine in the United States with those primers would be appropriate and long overdue.