Diverse forms of HIV-1 among Burmese long-distance truck drivers imply their contribution to HIV-1 cross-border transmission

Abstract

Background: The China-Myanmar border is a particularly interesting region that has very high prevalence of and considerable diversity of HIV-1 recombinants. Due to the transient nature of their work, long-distance truck drivers (LDTDs) have a comparatively high potential to become infected with HIV-1 and further spread virus to other individuals in the area they travel within. In this study, we hypothesized that Burmese LDTDs crossing the China-Myanmar border frequently may potentially be involved in the cross-border transmission of HIV, and contribute to the extremely high prevalence of HIV-1 inter-subtype recombinants in this border region.

Methods: A molecular epidemiology study was conducted among 105 Burmese LDTDs between 2008 and 2010. HIV-1 genetic fragments including p17, pol, vif-vpr, vpr-env, and C2V3 were amplified and sequenced. The subtype characterization and HIV-1 transmission were determined by both phylogenetic and phylogeographic analyses.

Results: Diverse forms of HIV-1, including subtypes CRF01_AE (41.9%), C (8.6%), B (4.8%), CRF02_AG (1.0%), and inter-subtype recombinants (33.3%), as well as dual infection (10.5%), were detected among the tested LDTDs. Phylogeographic analyses based on pure subtype revealed that 77.8% Burmese LDTDs acquired HIV-1 infection in Yunnan, and the others in Myanmar. Both the C-related and CRF01_AE-related recombinants from these LDTDs appeared to have close genetic relationship with those from IDUs in Myanmar and Dehong.

Conclusions: Burmese LDTDs may contribute to HIV-1 transmission along the China-Myanmar border. The results may provide some new perspective for understanding the on-going generation and prevalence of HIV-1 recombinants in the border region.

Figure 1

Molecular epidemiological characterization of HIV-1 circulating among Burmese LDTDs. (A) the proportion of HIV-1 subtypes, CRFs, recombinants and dual infection (B) the proportion of various recombinants (C) the proportion of dual infection (DI) patterns.

Figure 2

Bootscanning plot and phylogenetic analysis of the clone sequence 08mLDTD003-1 and 09mLDTD011-23/25 based on pol segment. A) the bootscan plot (left panel) and phylogenetic trees of three sub-segments (right panel) of 08mLDTD003-1 based on pol region. B) and C) the bootscan plots and sub-region trees for clone 09mLDTD011-23 and 09mLDTD011-25, respectively. 08mLDTD003-1 and all other clone sequences from 08mLDTD003 were highlighted by red and blue closed circle. 09mLDTD011-23, 09mLDTD011-25 and all other clone sequences from 09mLDTD011 were highlighted by red, green and purple closed circles, respectively. The subtype references for bootscan were selected as follows: A (92UG037), B’ (RL42), C (95IN21068), CRF01_AE (90CM240). The phylogenetic trees for each sub-segments were constructed by MEGA 5.0 using the neighbor-joining method, and with the clones’ sequence obtained from the same driver as well. The stability of the nodes was assessed by bootstrap analysis with 1000 replications, and only bootstrap values of >75% were shown.

Figure 3

Bayesian maximum clade credibility (MCC) trees of HIV-1 strains from Burmese LDTDs. HIV-1 subtype B (A), C (B) and CRF01_AE (C). The trees were reconstructed based on p17 sequences. The tree branches were signed by different color according to their respective geographical location. The black solid circle and the blue solid star indicated the sequences from Burmese LDTDs having geographic origin in Yunnan and Myanmar, respectively.

Figure 4

Bayesian maximum clade credibility (MCC) trees of HIV-1 URFs from Burmese LDTDs. p17 fragments of HIV-1 URFs belong to subtype C (A) or CRF01_AE (B). Trees were also reconstructed based on p17 sequences. The reference sequences were comprised of pure subtype and the corresponding parts of the URFs from Myanmar and Dehong (download from the ref 2, 3, 4, 8). The tree branches were signed by different color according to their respective geographical location. The pink shade and lilac shade in the part A highlighted C-related URFs of Burmese LDTDs originating from Dehong IDUs and Myanmar IDUs, respectively. In the part B, the grey shade highlighted the relationship of CRF01_AE-related URFs between Myanmar IDUs and LDTDs.

Figure 5

HIV-1 subtype characterization and transmission among different high- risk groups in the China-Myanmar border area. Data on HIV-1 subtype characterization among IDUs and sexual-infected group were taken from refs. 1, 3, 4, 6 and 9. The grey line showed the transport routes of Burmese LDTDs, which links Ruili city (in Dehong prefecture), China and Mandalay, Myanmar. The solid arrows indicated HIV-1 transmission routes obtained by phylogeographic analyses (Figures 3, 4), and the dotted arrows indicated potential HIV-1 transmission routes that need to be verified by future studies.