Unity in HIV-1 Sequence Diversity: Identification and Characterization of Korean Clade in HIV-1 Isolated from Korean

Through molecular phylogenetic analysis using the nef gene sequences of HIV-l isolated from Korean registered in the NCBI GenBank together with 41 reference strains and 94 foreign isolates, we verified that most (${\sim}80%$) of Korean isolates belonged to subtype B and 78% of subtype B were clustered together exclusively of foreign isolates, and this cluster was named Korean clade subtype B ($K_cB$). Similarity study suggested that the $K_cB$ cluster was more homogeneous than and clearly distinctive from the non-Korean subtype B ($NK_cB$). Comparison of the consensus amino acid sequences of the $K_cB\;or\;NK_cB$ revealed characteristic $K_cB$ signature amino acid pattern comprised of 13 amino acid residues. The $K_cB$ signature amino acid residues were critical in separating the $K_cB$ ftom the $NK_cB$, since substitution of the $NK_cB$ sequences with $K_cB$ signature amino acids relocated them to the Koran clade, and vice versa. Synonymous and nonsynonymous substitution rate study suggested positive selection event for the $K_cB$.