miRNAs used by HTLV-2 as strategic weapons to prevent HIV-1 replication

Background: Several co-infections with HIV-1 and other pathogens have been described as a potential novel mechanism of HIV-1 protection (Margolis L Nat. Biotech., 2003). In particular, HTLV-2/HIV-1 coinfection, a condition frequently observed in LTNPs, has been associated with a delayed progression to AIDS (Casoli et al. AIDS Rev, 2007). Here, we attempt to study some aspect of innate and adaptive immunity of HTLV-2/HIV-1 multiply exposed-uninfected seronegative (HTLV-2/HIV-1MEU) individuals, in comparison to those of HIV-1 mono-infected individuals (LTNP, naive and MEU), by analysing their miRNAs profile. Methods: Evaluation of expression profile of 377 miRNAs in ex-vivo CD4+ T-cells isolated from whole blood by immunomagnetic separation. The miRNA separation will be performed by the mirVanaTM miRNA Isolation kit. Then, miRNA expression will be obtained by real-time quantitative PCR (TaqMan®MicroRNA arrays ) and 2-ΔΔCt method, by which the PCR signal of miRNAs transcript in CD4+ T-lymphocytes from infected subjects were related to that of healthy donors. Results: Significant differences in expression of miRNAs in either HTLV-2 or HIV-1 patient classes were evaluated using a mixed effects model of ANOVA followed by Bonferroni post hoc tests. By this analysis 36 miRNA were revealed in HTLV-2/HIV-1MEU and 29 differences occurred in the three HIV-1 patient classification. Analysing these miRNA identified by the comparison of the two viral infection, 4 miRNAs (329, 337-5p, 379, and 503) were down-regulated and 6 miRNAs (34a, 125a-3p, 155, 203, 449a, and 502-5p) were up-regulated in both conditions, suggesting a retroviral exposure signature. Other 9 miRNAs (1, 135a, 202, 325, 370, 381, 409-5p, 452, 655) were only up-regulated in HTLV-2. Additional data showed that these miRNAs were not modulated in HTLV-2 transformed cell lines. Conclusion: These findings enable us to better understand the role of host specific genes and pathways involved in the development of resistance to HIV-1 infection, as observed in HTLV-2/HIV-1MEU subjects.