We aimed to investigate whether the sequence length of HIV-1 increases over time. A longitudinal analysis of full-length coding region sequences (FLs) during an HIV-1 outbreak among pa-tients with hemophilia and local controls infected with the Korean subclade B of HIV-1 (KSB) was performed. Genes were amplified by overlapping RT-PCR or nested PCR and subjected to direct sequencing. Overall, 141 FLs were sequentially determined over 30 years in 62 KSB-infected patients. Phylogenetic analysis indicated that within KSB, two FLs from plasma donors O and P comprised two clusters together with 8 and 12 patients with hemophilia, respectively. Signature pattern analysis for the KSB of HIV-1 revealed 91 signature nucleotide residues (1.05%). In total, 48 and 43 signature nucleotides originated from clusters O and P, respectively. Only six positions contained 100% specific nucleotide(s) in clusters O and P. Additionally, in-depth FL analysis over 30 years indicates that the KSB FL significantly increased over time before combined antiretroviral therapy (cART) and decreased with cART. The increase occurred due to a significant increase in env and nef genes, originating in the variable regions of both genes. The increase in the sequence length of HIV-1 over time suggests that it has an evolutionary direction.

The objective of this study is to investigate whether the sequence length of HIV-1 increases over time. A longitudinal analysis of full-length coding region sequences (FLs) in an outbreak of HIV-1 infection among patients with hemophilia and local controls identified as infected with the Korean subclade B of HIV-1 (KSB). Genes amplified by overlapping RT-PCR or nested PCR were subjected to direct sequencing. In total, 141 FLs were sequentially determined over 30 years in 62 KSB-infected patients. Non-KSB sequences were retrieved from the Los Alamos National Laboratory HIV Database. Phylogenetic analysis indicated that within KSB, 2 FLs from plasma donors O and P comprised two clusters together with 8 and 12 patients with hemophilia, respectively. Signature pattern analysis for the KSB of HIV-1 revealed signature nucleotide residues at 1.05%, compared with local controls. Additionally, in-depth FLs sequence analysis over 30 years in KSB indicates that the KSB FL significantly increases over time before combined antiretroviral therapy (cART) and decreases on cART. Furthermore, the increase in FLs over time significantly occurred in the subtypes B, C and G, but, there was no increase in the subtypes D, A, and F1. Consequently, subtypes F1 and D had the shortest sequence length. Our analysis was extended to compare HIV-1 with HIV-2 and SIVs. Essentially, the longer the sequence length (SIVsm > HIV-2 > SIVcpz > HIV-1), the longer the survival period. The increase in the length of the HIV-1 sequence over time suggests that it might be an evolutionary direction toward attenuated pathogenicity.