Anti-Tax antibody levels in asymptomatic carriers, oligosymptomatic carriers, patients with rheumatologic disease or with HAM/TSP do not correlate with HTLV-1 proviral load.
BACKGROUND
HTLV-1 infects millions of people around the world and induces myelopathy (HAM/TSP), adult T-cell leukemia (ATL) or other inflammatory or rheumatologic diseases. The host-virus interaction causes asymptomatic carriers to develop HAM/TSP. Biomarkers are needed to predict patients who are at risk for HAM/TSP. Tax is highly immunogenic and is a major target protein recognized by cytotoxic T lymphocytes. Anti-Tax antibodies are involved in HAM/TSP pathogenesis.


OBJECTIVE
To assess anti-Tax IgG reactivity with a flow cytometry assay (FCA) using an infection/transfection system with Vaccinia virus and pLW44/Tax-expressing Tax and to correlate the anti-Tax response and the HTLV-1 proviral load.


METHODS
: We enrolled 81 individuals: 9 HTLV-1 seronegative (NP) and 72 HTLV-1 positive (23 HTLV-1 asymptomatic carriers (AC), 12 oligosymptomatic patients (OL), 7 with rheumatologic diseases (DR) and 30 with HAM/TSP (HT)). Anti-Tax reactivity was assessed by FCA, and HTLV-1 proviral load was measured with real time PCR.


RESULTS
The HT and DR groups showed greater anti-Tax IgG reactivity (p<0.001 and p<0.05 comparing HT to the OL and AC group, respectively; p<0.05 comparing DR to the OL group), and the reactivity in the DR+HT group was significantly different when compared to the AC group (p<0.05) and to the OL group (p<0.001). The proviral load was higher in the HT group compared to the OL (p<0.001) and in the HT+DR group compared to OL (p<0.001). There was no correlation between anti-Tax IgG reactivity and proviral load in any of the HTLV-1-infected groups.


CONCLUSIONS
These findings suggest that although anti-Tax IgG reactivity and the HTLV-1 proviral load are important markers of the development of HTLV-1-associated diseases, their levels are not correlated.
de Souza
Jaqueline Gontijo
JG
Laboratório de Biologia de Microrganismos Intracelulares, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais - UFMG, Belo Horizonte, Brazil.
da Fonseca
Flávio Guimarães
FG
Martins
Marina Lobato
ML
Martins
Camila Pacheco Silveira
CP
de Carvalho
Luciana Debortoli
LD
Coelho-dos-Reis
Jordana Grazziela Alves
JG
Carneiro-Proietti
Anna Bárbara Freitas
AB
Martins-Filho
Olindo Assis
OA
Barbosa-Stancioli
Edel Figueiredo
EF
D000914:Antibodies, Viral / Q000097:blood* / Q000276:immunology; D002353:Carrier State / Q000276:immunology*; D018929:Cell Culture Techniques; D005260:Female; D016356:Gene Products, tax / Q000276:immunology*; D015490:HTLV-I Infections / Q000276:immunology* / Q000821:virology; D015368:Human T-lymphotropic virus 1 / Q000235:genetics / Q000276:immunology; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D008297:Male; D015493:Paraparesis, Tropical Spastic / Q000276:immunology*; D011533:Proviruses / Q000276:immunology*; D019562:Viral Load
D000914:Antibodies, Viral; D016356:Gene Products, tax; D007074:Immunoglobulin G; C514970:tax protein, Human T-lymphotrophic virus 1