High prevalence of HIV-1 intersubtype B'/C recombinants among injecting drug users in Dehong, China

Abstract

Objective: To examine the distribution of HIV-1 genotypes among injecting drug users (IDUs) from Dehong, Yunnan province.

Materials and methods: Blood samples from a total of 95 HIV-positive IDUs were retrospectively analyzed. Samples were collected between 2005 and 2009 from four cities in Dehong prefecture, western Yunnan province, the geographical origin of the HIV epidemic in China. HIV-1 gag, partial pol, vpr-env fragment, half-genome, or near-full-length sequences were analyzed to determine the HIV-1 genotypes of each subject. Results were compared with findings from past studies of IDUs in Dehong and in neighboring Myanmar.

Results: We observed a high prevalence of B'/C recombinants (82.4%) among IDUs in Dehong, the structural profiles of which do not match those previously reported in Dehong or in Myanmar. Furthermore, statistically significant differences in geographical and temporal distributions of HIV-1 genotypes were characterized by a predominance of HIV-1 B'/C recombinant forms among older subjects(p = 0.034), subjects from Longchuan district (p = 0.022), and subjects diagnosed between 2000 and 2004 (p = 0.004).

Conclusions: The increasing prevalence of multiple, new B'/C recombinant forms suggest that HIV-1 intersubtype recombination is substantial and ongoing in western Yunnan. This reflects the high-risk behavior of IDUs in this region and argues the need for stronger monitoring and prevention measures in Dehong and other high-prevalence areas around China.

Figure 1. Maps depicting study sites and the geographical distribution of HIV-1 genotypes.

(A) Illustration of the geographical location of Dehong prefecture (Dehong Dai-Jingpo autonomous region) in Yunnan Province, southwestern China, with the “golden triangle” (▵) region highlighted as a nearby area of significant opiate drug trafficking. (B) Illustration of the geographical location of the four districts within Dehong prefecture observed in this study and the numbers of subjects from each district. Pie charts depict HIV-1 genotype distribution in each of these districts. The category labeled “other” includes CRF01_AE, C/CRF01_AE and B′/C/CRF01_AE genotypes.

Figure 2. Phylogenetic tree and the boot-scanning plots of near-full-length sequences of HIV-1 strains isolated from Dehong.

(A) The phylogenetic tree of 33 near-full-length sequences of from Dehong IDUs was constructed with MEGA 5.0 using the neighbor-joining method. The subtype reference sequences from the Los Alamos HIV Sequence Database were included as the reference sequences. The stability of the nodes was assessed by bootstrap analyses with1,000 replications. Only bootstrap values of more than 70 are shown at the corresponding nodes. The sequences from IDUs in Dehong are labeled by solid red circles. The nine clusters are shown in red lines. (B)The bootscanning plots of 25 near-full-length sequences in the nine clusters.(C)The bootscanning plots of 8 near-full-length sequences outside the clusters and 6 previously published near full-length sequences of B′/C recombinants in China. In the recombination analyses, a subtype C strain from India (95IN21068) ( pink) and a subtype B′ strain from Yunnan (RL42) (blue) were used as subtype references, and a CRF01_AE strain from Thailand (CM240) (green) was used as an out-group control. In (B) and (C), the number after the sequences ID showed the year of diagnosis of each case.

Figure 3. The phylogenetic tree and the bootscanning plots of near-full-length sequences of HIV-1 strains isolated from Dehong and Myanmar.

(A) The phylogenetic tree of near-full-length sequences from IDUs in Dehong (red circles) and Myanmar (black circles).(B)The bootscanning plots of near-full-length sequences from the cluster that included sequences from IDUs both in Dehong and in Myanmar with bootstrap values above 70. In the recombination analyses, a subtype C strain from India (95IN21068) (pink) and a subtype B′ strain from Yunnan (RL42) (blue) were used as subtype references, and a CRF01_AE strain from Thailand (CM240) (green) was used as an out-group control.

Figure 4. Recombination map of sequences in clusters 4, 5, and 9, and sub-region neighbor-joining tree.

(A)The recombination map of sequences in the clusters 4, 5, and 9 of the near-full-length sequences phylogenetic tree.(B)The sub-region tree of corresponding regions as shown by roman numerals. The closely related sequences from Asian countries and subtype reference sequences are included.

Figure 5. The bootscanning plots of 26 near-full-length sequences and 6 half-genome sequences of HIV-1 strains isolated from Dehong IDUs with diagnosis year in chronological order.

In the recombination analyses, a subtype C strain from India (95IN21068) (pink) and a subtype B′ strain from Yunnan (RL42) (blue) was used as subtype references, and a CRF01_AE strain from Thailand (CM240) (green) was used as an out-group control.