Antibodies against aquaporin-4 are specific and pathogenetic
for Neuromyelitis Optica. In a previous study, 3 linear
intracellular B- cell epitopes were found. One epitope
presented a high molecular similarity with a fraction of the
human TAX1BP1 protein, which is necessary for the
replication of HTLV-1 virus, the etiological agent of HAM/TSP.
Aim of the Study
The aim of the study was to investigate whether
immunization of mice with the TAX1BP1 peptide could
produce epitope spreading against linear or conformational
13 peptides (MAP) – 2 homologous peps & 11 AQP4 epitopes
16 female C57Bl/6 mice, 6-8 weeks old.
8 immunized with 100λ ΤΑΧ1ΒΡ1pep 1mg/ml in Complete
Freud’s Adjuvant (CFA)
8 received equal volumes of CFA in PBS 1x (control group)
ELISA & Inhibition Assays
All sera were evaluated by ELISA assays for antibodies against the peptide
TAX1BP1pep, the homologous AQP4 peptide AQPpep8’ and all linear AQP4
epitopes. Homologous and cross-inhibition assays were performed to evaluate
Cell Based Assays
The existence of antibodies against conformational AQP4 epitopes was evaluated
by a cell based assay, using M23-transfected HEK293 cells.
All immunized animals showed high reactivity against the immunization peptide,
its’ homologous AQPpep8’ and the full linear AQP4 epitope AQPpep8 [252-275].
Reactivity gradually increased after each immunization boos
No antibodies were produced against any other linear epitopes.
Sera obtained from control animals presented no reactivity against the peptides.
No antibodies were produced against conformational epitopes.
Inhibition assays confirmed binding specificity.
Our study demonstrated the production of highly specific
antibodies against the linear intracellular AQP4 epitope
AQPpep8, after immunization. Epitope spreading is a very
important mechanism towards enhancement of the
immune response. The lack of epitope spreading in our
experiments implies that the cross-reactivity of the anti-
TAX1BP1pep and anti-AQPpep8 antibodies may be an
epiphenomenon. However, studies have described
relapses of autoimmune disorders in the absence of
epitope spreading, therefore the pathogenetic activity of
the anti-TAX1BP1pep antibodies could be confined to
cases of HTLV-1 latent infection.
Alexopoulos, H., E. I. Kampylafka, I. Chatzi, et al (2013). "Reactivity to
AQP4 epitopes in relapsing-remitting multiple sclerosis." J Neuroimmunol
Kampylafka, E. I., J. G. Routsias, H. Alexopoulos, et al (2011). "Fine
specificity of antibodies against AQP4: epitope mapping reveals
intracellular epitopes." J Autoimmun 36(3-4): 221-227.