Provided in 1, below are the problem amino acids associated with the currently circulating Swine Flu. These are generally found in every pandemic virus and most seasonal flu viruses, and some relate to sensitivity to antivirals, etc. All the available Swine Flu virus gene sequences have these human/problem characteristics.
1. PB2: A199S; PB1 N(T)375S; PB1-F2 P(R)48Q; PA T129I and S409N; HA E190D, S221P, F251L and Y258F; NP V33I, R100V and Q357K; MP K27R, I168T and N224S; M2 none; NS2 F55L; NA none.
Provided in 2, below are those amino acids that this bug has not yet obtained, but if obtained, could be problematic. Some are more important that others. None of the Swine Flu viruses have these characteristics as far as I know, but we should all keep an eye out for them>
2. PB2 L(F)475M, D567N and E627K; PB1 none; PB1-F2 P28L, D55N, I(V)100A and T552S; HA multi-basic amino acids at the clevage site (usually associated only with poultry infections); NP G16D, L283P and F313Y; MP I15V, K101R, A166V and N207S; M2 E16G and S20N; NS none; NS2 none; NA H274Y and N294S.
In other words, the Swine Flu virus has about half of the problem amino acids already in its tool box. The only other viruses even close to this are some H9N2 viruses circulating widely in Hong Kong and H7N7 in the Netherlands. As to the wild type avian viruses, only the North American variety come close.
Take away: This is a problem virus that bears watching closely. Reassortment with seasonal flu or H5N1 could be interesting.