KI and WU Polyomaviruses and CD4+ Cell Counts in HIV-1–infected Patients, Italy
Figure. Maximum likelihood phylogenetic analysis of KI polyomavirus (KIPyV) and WU polyomavirus (WUPyV) small T antigen sequences. Strains identified in this study are in boldface. The tree was rooted by using the midpoint rooting method. Branch lengths were estimated by using the best fitting nucleotide substitution (Hasegawa, Kishino, and Yano) model according to a hierarchical likelihood ratio test (6,7) and were drawn to scale. Scale bar indicates 0.8 nt substitutions per site. Asterisks along the branches indicate significant statistical support for the clade subtending that branch (p<0.001 by the zero-branch-length test and bootstrap support >65%).