Fig. 2.

1 A hypothetical contact network of PWID with known transmission pathway. Red circles – HIV-infected individuals, green circles – HIV-free individuals. Red arrows indicate the direction of infection (who infected whom), green lines indicate an injecting partnership that did not lead to an HIV transmission. 2 Phylogenetic trees reconstructed from a subset of a network of PWID. Panel A represents the phylogenetic tree based on the samples collected from the individuals 1, 3, 4, 5, 7 (who have higher degree of centrality). Panels B, C, and D represent phylogenetic trees reconstructed from the samples collected from individuals who have lower degree of centrality.