We confirmed that the tree clustering inside the N1 subtype family is robust regarding different tree generation methods and added this also to the text. We also provide the suggested JTT distance tree with variable rates as supplementary at http://mendel.bii.a-star.edu.sg/ SEQUENCES/H1N1/. " This indicates that, similar to the current outbreak, scenarios of breaches in the species barrier between human and pigs have already arisen out of closely related H1N1 strains as also evidenced by further reports in the literature [26, 27] ." The wording of this sentence is somewhat unclear. It appears that the authors wish to state that H1N1 like strains have crossed species boundaries on other occasions, but this is not necessarily clear in the sentence.