Truncated MTA-1: a pitfall in ELISA-based immunoassay of HTLV-1 infection.
HTLV-1 causes adult T-cell leukemia (ATL) and HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP). Recombinant envelope glycoprotein is used in production of diagnostic enzyme-linked immunosorbent assay (ELISA) kit. There are some reports that a significant percentage of Iranian HTLV-1 infected patients showed no seroreactivity with MTA-1 peptide, while HTLV-1 had been confirmed by PCR detection methods or ELISA kits containing a cocktail of HTLV-1 specific peptides. This report describes experiments designed to determine whether some discrepancies between ELISA and PCR results could be due to truncation of immunodominant epitopes using immunoassay method. We have cloned the MTA-1 epitope of env gene from HTLV-1 in NotI/NdeI sites of pET22b(+) expression vector. Sequencing analysis of recombinant plasmids revealed an insertion of a cytosine in position 271 causing a stop codon in the MTA-1 protein translation. SDS-PAGE analysis also failed to reveal the presence of the desired protein. Subjects with a mutant HTLV-1 env gene were shown to be seronegative using ELISA, but positive with PCR.
Abbaszadegan
Mohammad Reza
MR
Division of Human Genetics, Immunology Research Center, Bu-Ali Research Institute, Bu-Ali square, Mashhad 9196773117, Iran. abbaszadeganmr@mums.ac.ir
Jafarzadeh
Narges
N
Sankian
Mojtaba
M
Varasteh
Abdolreza
A
Mahmoudi
Mahmoud
M
Sadeghizadeh
Majid
M
Khatami
Fatemeh
F
Mehramiz
Neema
N
D016477:Artifacts; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005656:Fungal Proteins / Q000032:analysis* / Q000276:immunology; D015368:Human T-lymphotropic virus 1 / Q000276:immunology* / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction / Q000379:methods*
D005656:Fungal Proteins; C097997:MTA-1 protein, Neurospora crassa