Phylogenetic analysis of the viral segments of influenza H7N9 isolated from human patients. Using the software program Mega 6.02, phylogenetic trees were inferred by using the Maximum Likelihood method based on the General Time Reversible Model with 1000 bootstrap replications. Bootstrap support values ≥70% are shown. Branch lengths are proportional to number of substitutions per site. Unmarked strain names: Eastern cluster from the first wave of the disease; blue circle: Eastern cluster from the second wave of the disease; red circle: Southern cluster from the second wave of the disease; Yellow highlight: viral isolates from Shantou; blue highlight: strain of avian or environmental origin.