We obtained two NFLG sequences of 8345 bp (HXB2: 790–9135) and 8235 bp (HXB2: 790–9025) from BDL154 and BDL161, respectively. The NFLG N-J tree shows that these two NFLG sequences form different monophyletic branches with other subtypes and CRFs in the NFLG N-J phylogenetic tree, indicating that they should be novel recombination forms. As shown in Fig. 3A, the recombinant structure of BDL154 was based on the CRF01-AE backbone, with the insertion of a subtype B fragment, containing three subregions. As shown in Fig. 3B, BDL161 containeda subtype C backbone, within which two subtype B fragments and two subtype CRF01_AE fragments were identified, and contains eight subregions. The NFLG recombinant structures of BDL154 and BDL161 sequences were described as follows: BDL154 sequence, ICRF01_AE (nt 790– 2,153); IIB (nt 2,154–5,231); IIICRF01_AE (nt 5,232–9,135), BDL161 sequence: IC (nt 790–1,383); IIB(nt1,384–5,049); IIIC (nt 5,050–5,893); IVCRF01_AE (nt 5,894–6,112); VB (nt 6,113–6,649); VIC (nt 6,650–7,083); VIICRF01_AE (nt, 7,084–7,717);ⅧC (nt,7,718–9,025). Subregion phylogenetic trees of BDL154 and BDL161 analyzed the genetic origin of each fragment( Figs,4A and 4B). Figure 4A showed the clustering of two CRF01-AE fragments and one subtype B fragment of BDL154 with their respective reference sequences, respectively. Figure 4B showed the clustering of four subtype C fragments, two subtype B fragments and two CRF01_AE fragments of the BDL161 with their respective reference sequences, respectively.
In China, subtypes CRF01_AE and B are the main subtypes of HIV-1, and the recombinant forms of CRF01_AE and subtypes B are relatively common, and Hebei Province has also continuously reported many recombinant forms of CRF01_AE and B.10–14 Subtype C was first discovered in injection drug users in Yunnan Province, China in the early 1990s. In Hebei Province, subtype C is a secondary strain with a prevalence rate of only 0.8%.15 The CRFs related to subtypes C, B, and CRF01_AE have been mostly reported in Yunnan Province, China, such as CRF65_cpx,16 CRF78_cpx,17 CRF87_cpx,18 and CRF96_cpx.19. Many URFs have also been reported, most of which were found in heterosexuals or drug users.20,21 The NFLG of BDL161 in this study was first identified as the recombinant form composed of subtypes C, B, and CRF01_AE among MSM in Hebei Province, indicating that the MSM population in this area is relatively active.
In conclusion, CRF01_AE/B and C/B/CRF01_AE recombination forms were reported among MSM of Baoding City, Hebei Province. The emergence of C/B/CRF01_AE recombination form may reflect the continuous generation of various forms of inter-subtype recombinants in Hebei Province, China, indicating that it is importance for us to continuously monitor the dynamic changing of HIV-1 subtypes and recombination forms in high-risk populations in the region.