Laboratory diagnosis of human T-lymphotropic virus in Brazil: assays, flowcharts, challenges, and perspectives

Abstract

INTRODUCTION We present a data analysis and review of recent studies regarding the laboratory diagnosis of human T-lymphotropic virus 1 and 2 (HTLV-1/2) infections in Brazil. METHODS Target populations, available diagnostic serological assays (screening and complementary tests), molecular assays (in-house), causes of false-positive and false-negative results, and flowcharts were analyzed. RESULTS A table presents the target populations, two diagnostic flowcharts (depending on laboratory infrastructure and study population), and recent research that may improve how HTLV-1/2 is diagnosed in Brazil. CONCLUSIONS: Our results support the implementation of public policies to reduce HTLV-1/2 transmission and its associated diseases.

Development and Validation of Multiplex Quantitative Real-Time PCR Assays for Simultaneous Detection and Differentiation of HTLV-1 and HTLV-2, Using Different PCR Platforms and Reagent Brands

“…The laboratory diagnosis of HTLV-1 and -2 is performed on blood samples from patients using screening tests followed by confirmatory tests. The screening tests detect antibodies against HTLV-1/2 in plasma/serum samples; they have high sensitivities, and negative results exclude HTLV-1/2 infection ( da Silva Brito et al, 2018 ; Caterino-de-Araujo et al, 2021 ). The most common screening tests are the particle agglutination (PA), enzyme immunoassays (EIA or ELISA), and chemiluminescence immunoassays (CLIA) ( Okuma et al, 2020 ; Caterino-de-Araujo et al, 2021 ; Rosadas et al, 2021a ).…”

“…The screening tests detect antibodies against HTLV-1/2 in plasma/serum samples; they have high sensitivities, and negative results exclude HTLV-1/2 infection ( da Silva Brito et al, 2018 ; Caterino-de-Araujo et al, 2021 ). The most common screening tests are the particle agglutination (PA), enzyme immunoassays (EIA or ELISA), and chemiluminescence immunoassays (CLIA) ( Okuma et al, 2020 ; Caterino-de-Araujo et al, 2021 ; Rosadas et al, 2021a ). Confirmatory serologic tests identify antibodies specific for HTLV-1 and -2 antigens in plasma/serum samples, and the most common types of these tests are western blotting (WB) and the line immunoassay (LIA).…”

“…Confirmatory serologic tests identify antibodies specific for HTLV-1 and -2 antigens in plasma/serum samples, and the most common types of these tests are western blotting (WB) and the line immunoassay (LIA). Both these serologic confirmatory assays help in diagnosis, but in some cases, inconclusive results may occur (HTLV untyped and indeterminate), especially when samples obtained from patients with HTLV-2 infection and those from patients coinfected with HIV, and/or HBV, and/or HCV ( Campos et al, 2017a , b , 2020 ; Caterino-de-Araujo et al, 2021 ) are tested. LIA has a greater accuracy in comparison to WB for the confirmation of HTLV-1 and -2 infection ( Campos et al, 2020 ; Okuma et al, 2020 ), but in cases of LIA- or WB-indeterminate and untyped results, molecular assays that amplify segments of the proviral DNA present in the HTLV-infected cells samples, must be conducted ( Caterino-de-Araujo et al, 2021 ; Rosadas et al, 2021a ).…”

“…Both these serologic confirmatory assays help in diagnosis, but in some cases, inconclusive results may occur (HTLV untyped and indeterminate), especially when samples obtained from patients with HTLV-2 infection and those from patients coinfected with HIV, and/or HBV, and/or HCV ( Campos et al, 2017a , b , 2020 ; Caterino-de-Araujo et al, 2021 ) are tested. LIA has a greater accuracy in comparison to WB for the confirmation of HTLV-1 and -2 infection ( Campos et al, 2020 ; Okuma et al, 2020 ), but in cases of LIA- or WB-indeterminate and untyped results, molecular assays that amplify segments of the proviral DNA present in the HTLV-infected cells samples, must be conducted ( Caterino-de-Araujo et al, 2021 ; Rosadas et al, 2021a ). These molecular tests are based on polymerase chain reaction (PCR) in various formats: nested PCR (n-PCR), PCR followed by restriction fragment polymorphism analysis (PCR-RFLP), real-time quantitative PCR (qPCR), and loop-mediated isothermal amplification (LAMP) ( Gomes et al, 2020 ; Caterino-de-Araujo et al, 2021 ; Rosadas et al, 2021a ).…”

Blocking HTLV-1/2 silent transmission in Brazil: Current public health policies and proposal for additional strategies

“…Antenatal screening is strongly recommended at the first trimester, which would allow proper confirmatory testing and counselling for those seropositive mothers prior to delivery. The diagnostic algorithm should be similar as to the general population, using an ELISA or CMIA as screening test, followed by confirmation using PCR, WB, or LIA [ 64 ]. Pregnancy does not adversely affect HTLV-1 diagnosis[ 65 ].…”