Phylogenetic trees of 12 alignment datasets were reconstructed using the ML approach implemented in PhyML 3.412 [56] . The robustness of the ML tree topology was assessed by comparing the ML topology with the topologies sampled in the BMCMC analysis performed in MrBayes version 3.1.2 [57] , and with bootstrapping analyses of 1,000 pseudo-replicate datasets. ML and NJ trees were estimated from the bootstrap datasets using PhyML [56] and PAUP* version 4beta10 [58] , respectively. A general-time-reversal (GTR) substitution model with gamma distributed rate heterogeneity of 4 rate categories (C 4 ) and a proportion of invariable sites were used in all tree reconstruction methods. Phylogenies were rooted with the H5N1 HPAI strain A/Ck/HK/YU324/2003, which is genetically close to the newly reported Hunan strains [17] , and shares comparable genetic proximity to Indonesian clade.