- aD94N, S123P, S133A, S154N, T156A, T188I, Q222L, and G224S mutations in HA are known to be associated with increased binding to human-like receptor (α-2,6 sialic acid)
- bL89V and D256G mutations in PB2 are known to be associated with increased virulence in mice. Q591K, E627K, and D701N mutations in PB2 are known to be associated with increased viral replication in mammals
- cR57Q mutation in PA is known to be associated with host specificity shift. A515T mutation in PA is known to be associated with H5 transmissibility in ferrets
- dN30D, I43M, T215A mutations in M1 are known to be associated with increased virulence in mice
- eP42S, 80–84 deletion, A223E, V226T, and ESEV PDZ binding motif mutations in NS are known to be associated with increased virulence in mice. S87P is known to be associated with host specificity shift
- fPB1: D3V Increased polymerase activity and viral replication in avian and mammalian cell lines, D622G Increased polymerase activity and virulence in mice and in PB1-F2: N66S Enhanced replication, virulence and antiviral response in mice
