Evaluation of the use of real-time PCR for human T cell lymphotropic virus 1 and 2 as a confirmatory test in screening for blood donors

Abstract

Introduction: HTLV-1/2 screening among blood donors commonly utilizes an enzymelinked immunosorbent assay (EIA), followed by a confirmatory method such as Western blot (WB) if the EIA is positive. However, this algorithm yields a high rate of inconclusive results, and is expensive. Methods: Two qualitative real-time PCR assays were developed to detect HTLV-1 and 2, and a total of 318 samples were tested (152 blood donors, 108 asymptomatic carriers, 26 HAM/TSP patients and 30 seronegative individuals). Results: The sensitivity and specificity of PCR in comparison with WB results were 99.4% and 98.5%, respectively. PCR tests were more efficient for identifying the virus type, detecting HTLV-2 infection and defining inconclusive cases. Conclusions: Because real-time PCR is sensitive and practical and costs much less than WB, this technique can be used as a confirmatory test for HTLV in blood banks, as a replacement for WB.

Human T-Lymphotropic Virus Type 1 and Type 2 Seroprevalence, Incidence, and Residual Transfusion Risk Among Blood Donors in Brazil During 2007–2009

“…Confirmation of EIA results is necessary with a more specific test such as Western blot (WB), and discriminatory testing is required to differentiate HTLV type (1 and/or 2), 3 but both are often not performed in low income countries because of cost. 4 Although the exact number of individuals who are seropositive for HTLV-1 and -2 is not known, it is estimated that 15 to 20 million persons are seropositive worldwide, mostly with HTLV-1. 5,6 The areas of the world with the highest prevalence rates for HTLV-1 include southwestern Japan, several sub-Saharan African countries, Central and South America, 7 and localized areas of Iran and Melanesia.…”

A New and Frequent Human T-Cell Leukemia Virus Indeterminate Western Blot Pattern: Epidemiological Determinants and PCR Results in Central African Inhabitants

“…Confirmatory tests are immunofluorescence (IF) (23) but mostly Western blot (WB) analyses (30,35,38,39,64,71). Moreover, research of integrated provirus, in the DNA from peripheral blood cells, could be done by qualitative and/or quantitative PCR (2,4,8,68). Despite some improvements in the WB assays specificity during the last two decades, indeterminate serological patterns are frequent following WB analysis and represent a major concern for routine screening in blood banks in Europe, the Americas, and Africa (7,10,11,16,20,40,61,63).…”

Human T-Lymphotropic Viruses (HTLV)

“…Many protocols for HTLV diagnosis by PCR has been developed in-house, with no commercial tests yet licensed. PCR for HTLV-1 and 2 has been particularly useful for: investigation of neonatal transmission, since the serological tests in infants can detect maternal antibodies ; discrimination between infection by type 1 or type 2 virus; definition of dual infection (HTLV-1 and HTLV-2); definition of virus subtypes; diagnostic in subjects with suspected of seroconversion; and resolution of cases with seroindeterminate results (Andrade et al, 2010, Costa et al, 2011Waters et al, 2011). Since HTLV not presents large quantities of viral RNA circulating, the use of plasma or serum is not suitable for HTLV molecular diagnosis.…”

“…However, different biological samples containing potentially infected cells may be used for virus identification, in case of specific research studies. Currently, real-time PCR has been preferentially employed over conventional PCR because of its very higher sensitivity and specificity, low contamination risk, easeness of performance and rapidity in obtaining results, showing be viable to substitute confirmatory serological test for HTLV-1/2 diagnosis (Andrade et al, 2010, Costa et al, 2011Waters et al, 2011).…”