Loop-Mediated Isothermal Amplification (LAMP) Assay for Rapid and Accurate Confirmatory Diagnosis of HTLV-1/2 Infection.

Maria Gisele Gonçalves,Yago Gomes,Marco Antonio Lima,Karoline Campos,Marcus Tulius Silva,Adele Caterino-De-Araujo,Ana Claudia Leite,Otávio Espíndola,Abelardo Araújo

doi:10.3390/v12090981

Abstract

Laboratory diagnosis of human T-lymphotropic viruses (HTLV) 1 and 2 infection is performed by serological screening and further confirmation with serological or molecular assays. Thus, we developed a loop-mediated isothermal nucleic acid amplification (LAMP) assay for the detection of HTLV-1/2 in blood samples. The sensitivity and accuracy of HTLV-1/2 LAMP were defined with DNA samples from individuals infected with HTLV-1 (n = 125), HTLV-2 (n = 19), and coinfected with HIV (n = 82), and compared with real-time polymerase chain reaction (qPCR) and PCR-restriction fragment length polymorphism (RFLP). The overall accuracy of HTLV-1/2 LAMP (95% CI 74.8–85.5%) was slightly superior to qPCR (95% CI 69.5–81.1%) and similar to PCR-RFLP (95% CI 79.5–89.3%). The sensitivity of LAMP was greater for HTLV-1 (95% CI 83.2–93.4%) than for HTLV-2 (95% CI 43.2–70.8%). This was also observed in qPCR and PCR-RFLP, which was associated with the commonly lower HTLV-2 proviral load. All molecular assays tested showed better results with samples from HTLV-1/2 mono-infected individuals compared with HIV-coinfected patients, who present lower CD4 T-cell counts. In conclusion, HTLV-1/2 LAMP had similar to superior performance than PCR-based assays, and therefore may represent an attractive alternative for HTLV-1/2 diagnosis due to reduced working time and costs, and the simple infrastructure needed.

Highlights

Human T-lymphotropic virus (HTLV) type 1 and 2 are retroviruses transmitted among humans through the parenteral route, unprotected sexual intercourse, and from mother-to-child, by breastfeeding [1]
The human T-lymphotropic viruses (HTLV)-2 Mo strains, which belong to the HTLV-1 Cosmopolitan Japanese (1aB) and the HTLV-2a genotypes, respectively
Substitution was observed within the 50 region of the loop forward (LF) primer (Figure 1). This polymorphism was seen in the HTLV-1aA Middle East cluster, in addition to a A8014C substitution at the backward inner primers (BIP) 50 -terminal (Figure 1, B1c region)

Summary

Introduction

Human T-lymphotropic virus (HTLV) type 1 and 2 are retroviruses transmitted among humans through the parenteral route, unprotected sexual intercourse, and from mother-to-child, by breastfeeding [1]. HTLV-1 is endemic in regions of Japan, Caribbean, Central and West Africa, South America Peru), Middle East ( Iran), Romania, and Australo-Melanesia, and estimates indicate that 5 to 10 million individuals are infected by HTLV-1 worldwide [6,7]. These numbers are likely to be underestimated considering the lack of data for large areas, the increasing rate of human migration, and silent dissemination by sexual transmission in some endemic regions [8]. In Brazil, the risk of infection by these viruses varies considerably depending on individual factors, such as socioeconomic condition, genetic background and risk behaviors [4,11,13,15]

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