2 flu strains in 1 pig led to new H1N1

2 flu strains in 1 pig led to new H1N1 -- chicagotribune.com:

" Somehow, a single pig became simultaneously infected with that virus and a pure swine flu strain found in pigs in Europe and Asia. The two strains swapped genetic material to produce the new H1N1 strain, which then began to infect humans."