Fig. 4From: Continuing evolution of H6N2 influenza a virus in South African chickens and the implications for diagnosis and controlMaximum likelihood phylogenetic tree of segment 1 encoding the polymerase B2 (PB2) protein of South African H6N2 chicken and reference viruses. Green = Gauteng Province; Blue = North West Province; Red = KwaZulu-Natal Province; clear = reference strains. Viruses sequenced in the present study are in boldface. Genetic clusters are labelled A, B and CBack to article page