Low proviral load is associated with seroindeterminate Western Blot patterns in Human T-Cell Lymphotropic Virus Type 1 infected individuals: could punctual mutations be related?

CÁNEPA C; SALIDO J; RUGGIERI M; FRAILE SA; PATACCINI G; BERINI C; BIGLIONE M

Viruses

MDPI AG

Lugar: Basel; Año: 2015

1999-4915

Background: Indeterminate Western Blot (WB) patterns are a major concern for diagnosis of HTLV-1 infection, even in non-endemic areas. Objectives: a) to define the prevalence of indeterminate WB among different populations from Argentina; b) to evaluate if low proviral load (PVL) is associated to indeterminate WB; and c) to describe mutations in LTR and tax sequences. Results: Among 2031 samples, 294 resulted reactive by screening. Out of them, 48 (16.3%) were WB indeterminate and of those 15 (31.3%) were PCR+. qPCR was performed to 52 HTLV-1+ samples, classified as Group 1 (G1): 25 WB+ samples from individuals with pathologies; Group 2 (G2): 18 WB+ samples from asymptomatic carriers (AC); and Group 3 (G3): 9 seroindeterminate samples from AC. PVL median values were 4.78, 2.38 and 0.15 HTLV-1 copies/100 PBMCs, respectively; a significant difference (p=0.003) was observed. Age and sex were associated with PLV in G1 and G2. Mutations in the distal(dr) and central regions(cr) of Tax Responsive Elements (TRE) 1 and 2 of G3 were observed, though not associated with PVL. 8403A>G mutation of the dr, previously related to high PVL, was absent in G3 although present in 50% of WB+ samples (p= 0.028). Conclusions: WB indeterminate results confirmed later as HTLV-1 positive may be associated to low PVL levels. Mutations in LTR and Tax are described although their functional relevance remains to be determined.