Journal of Clinical Virology 21 (2001) 81–89
Antibodies against full-length Tat protein and some
low-molecular-weight Tat-peptides correlate with low or
undetectable viral load in HIV-1 seropositive patients
M.C. Re
a,
*, M. Vignoli
a
, G. Furlini
a
, D. Gibellini
a
, V. Colangeli
b
,
F. Vitone
a
, M. La Placa
a
a
Department of Clinical and Experimental Medicine, Section of Microbiology, Uniersity of Bologna, Via Massarenti,
9 -40138 Bologna, Italy
b
Department of Clinical and Experimental Medicine, Section of Infectious Diseases, Uniersity of Bologna, Via Massarenti,
9 -40138 Bologna, Italy
Received 13 October 2000; accepted 18 December 2000
Abstract
Background : The efficacy of a specific humoral response to transactivating Tat protein was studied in a group of
HIV-1 seropositive drug addicts, who had previously received a similar course of anti-retroviral treatment with two
reverse transcriptase inhibitors. Objecties : The aim of the study was to evaluate the meaning of an immune response
to Tat protein in HIV-1 seropositive patients with different levels of HIV-1 RNA viremia. Study design : The study
analyzed the presence of anti-Tat antibody reacting either with full-length Tat or with individual overlapping
Tat-peptides (Tat
6–14
, Tat
11–24
, Tat
36–50
, Tat
46–60
, Tat
56–70
and Tat
65–80
), in a group of HIV-1 seropositive subjects
with different peripheral blood viral loads. Plasma samples were examined by immunoenzymatic assay for the
presence of anti-Tat IgG antibody and for the quantification of peripheral blood (plasma) viral load by branched
DNA assay. Results : The large majority of HIV-1 patients showed detectable levels of serum IgG to full-length-Tat,
and the anti-Tat antibody level presented an inverse correlation with viral load magnitude. The analysis of antibody
levels against individual overlapping Tat-peptides clearly showed that an undetectable viral load was significantly
associated with the presence of a high antibody concentration against Tat
6–14
, Tat
36–50
and Tat
46–60
(P =0.002,
P =0.027 and P 0.001, respectively). Conclusion : In HIV-1-infected patients, a strong humoral immune response
against HIV-1 Tat protein is inversely correlated to peripheral blood viral load and, in particular, a high level of
antibody against Tat peptides containing amino acid residues 6 – 14 (Tat
6–14
), 36–50 (Tat
36–50
) and 46–60 (Tat
46–60
)
is associated with an undetectable plasma viral load. These findings may help to tailor anti-HIV-1 Tat-containing
vaccines. © 2001 Elsevier Science B.V. All rights reserved.
Keywords: Anti-Tat antibody; HV-1 viral load; Tat protein
www.elsevier.com/locate/jcv
* Corresponding author. Tel.: +39-51-4290900; fax: +39-51-341632.
E-mail address: remc@med.unibo.it (M.C. Re).
1386-6532/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
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