Here is the genetic makeup of the S-OIV (H1N1) virus since 1918:
Only 3 of the 8 genes are Swine... nice pretty colors!
"...In April 2009, near the end of the usual influenza season in the Northern Hemisphere, the first two cases of S-OIV were identified in the United States.43 The CDC confirmed that these cases were caused by a genetically similar swine virus that had not been previously identified in the United States.44 Genetic analysis of the strains showed that they were derived from a new reassortment of six gene segments from the known triple reassortant swine virus, and two gene segments (NA and matrix protein) from the Eurasian influenza A (H1N1) swine virus lineage.43,45"
(n engl j med 361;3 nejm.org july 16, 2009)