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Open Access

HTLV-I proviral load in Argentinean subjects with indeterminate western blot patterns

  • Andrea Mangano1Email author,
  • Natalia Altamirano1,
  • Mirta Remesar2,
  • María B Bouzas3,
  • Paula Aulicino1,
  • Inés Zapiola3,
  • Ana D Pozo2 and
  • Luisa Sen1
Retrovirology20118(Suppl 1):A245

Published: 6 June 2011


Proviral LoadAlbumin GeneProviral SequenceLog10 CopyBlot Pattern


A considerable high proportion of HTLV-I/II seroindeterminate blood donors have been documented in many countries including Argentina. In 5-10% of indeterminate Western Blot (WB) cases proviral sequences are detected. The aim of the study was to evaluate HTLV-I proviral load (pVL) in WB indeterminate PCR positive cases.


A total of 87 indeterminate WB samples (HTLV blot 2.4 assay- Genelabs Diagnostics-) were studied over a 10 year period referred from the Blood Bank at Garrahan Hospital (n=83) and from the Virology Unit at Muñiz Hospital (n=4). HTLV-I and –II tax and pol proviral sequences were amplified by in-house nested PCR assays. HTLV-I pVL was estimated by a quantitative real-time PCR assay targeting the HTLV-I pol gene and the albumin gene as normalizer. The limit of detection of the assay was 2.6 log10 copies of HTLV-I/106 PBMCs (0.04% copies/100 PBMCs).


In 8/87 samples HTLV proviral sequences were amplified, 7 HTLV-I and one HTLV-II. Proviral load was detectable in 4 of the 7 HTLV-I positive samples ranging from 2.72 log10 copies/106 PBMCs (0.05%) to 4.65 log10 copies/106 PBMCs (4.5%), but was undetectable in the remaining 3 (<0.04%). One of the subjects followed for 5 years remained with low pVL (median = 0.36%, range 0.05-1.43%) and without changes in the WB profile.


Detectable HTLV-I proviral load in half of the cases with indeterminate WB profiles with positive PCR underlies the importance to conduct follow-up studies to evaluate the evolution of the infection.

Authors’ Affiliations

Laboratorio de Biología Celular y Retrovirus-CONICET, Hospital “J. P. Garrahan”, Ciudad Autónoma de Buenos Aires, Argentina
Servicio de Hemoterapia, Hospital “J. P. Garrahan”, Ciudad Autónoma de Buenos Aires, Argentina
Unidad de Virología, Hospital Muñiz, Ciudad Autónoma de Buenos Aires, Argentina


© Mangano et al; licensee BioMed Central Ltd. 2011

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.