Optimization of human T-cell lymphotropic virus type 1 (HTLV-1) serological and molecular diagnosis for alternative blood samples.

HTLV-1 is a bloodborne virus that poses diagnostic challenges and can cause severe complications. Diagnosis is made by serological and molecular assays that are laborious in some conditions. This study aims to optimize methods for molecular and serological diagnosis using less invasive samples and rapid assays. A total of 125 individuals donated whole blood, dried blood spots (DBS), and serum samples. Loop mediated isothermal amplification (LAMP) was used for HTLV-1 detection in whole blood (extracted, in natura, and inactivated) and DBS samples while electrochemiluminescence assay (ECLIA) was used to detect anti-HTLV1/2 in serum and DBS. HTLV LAMP presented the highest performance in whole blood (extracted) with sensitivity of 92 % and specificity of 100 %. LAMP for inactivated samples had a sensitivity of 47.4 % and specificity of 100 %, whereas in natura samples had a sensitivity of 50 % and specificity of 100 %. The whole blood HTLV-1 LAMP had a limit detection of 0.02 ng/µL and 100 % precision. DBS LAMP carried out after DNA extraction yielded similar results, with a sensitivity 43 of 90 % (36/40). The average DNA concentration was 5.05 ± 5.2 ng/µL. For anti-HTLV1/2 testing, DBS yielded sensitivity of 97.6 % (86/88) and total specificity (0/29). The mean SD of optical density to cut off (OD/CO) value was 37.2 ± 36.8 in reactive samples and 0.3 ± 0.05 in negative samples. In conclusion, DBS testing demonstrated high sensitivity and specificity for detecting anti-HTLV-1 and HTLV DNA, which could facilitate the diagnosis of this infection.