Phylogenetic analysis of the HIV-1 envelope sequences from North India. All the reference sequences from M-group & outlier group were retrieved from Los Almos Data Base and used for constructing neighbor joining phylogenetic tree. Indian CRF02_AG strains are represented as 'Black Circles'; 'Black Square' for subtype C; and 'Black Diamond' as subtype B. The evolutionary history was created using Neighbor-Joining Method in MEGA4. Similar evolutionary pattern was detected when Maximum Likelihood and UPGMA methods were used (data not shown). Mother-child pairs were shown by filled and empty circles by numbers (1 and 2). Empty circles denote maternal envelope sequences while filled circles denote infant envelope sequences.