Molecular evidence of human T-cell lymphotropic virus types 1 and 2 (HTLV-1 and HTLV-2) infections in HTLV seroindeterminate individuals from São Paulo, Brazil.
BACKGROUND
Using enzyme immunoassays and Western blot (Wb) tests, HTLV serodiagnosis yields indeterminate results in a significant number of cases.


OBJECTIVE
To determine the prevalence of HTLV infection among HTLV-seroindeterminate individuals.


METHODS
We studied peripheral blood mononuclear cells from 65 anti-HTLV Wb-seroindeterminate individuals by attempting to amplify proviral DNA sequences (tax and pol) to identify HTLV-1 and HTLV-2 infections.


RESULTS
These 65 specimens exhibited predominantly (43%) anti-HTLV antibodies to gag-coded antigens in the absence of anti-p24 on Wb analysis. Tax proviral sequences were detected in 6 (9.2%) samples. According to restricted fragment polymorphism analysis (RFLP), we identified HTLV-1 proviral DNA in 4 samples, HTLV-2 in one and sequences from both in another. Nested PCR for the pol region was positive in 3 (4.6%) specimens, which were also positive for tax sequences. After hybridization HTLV-1 infection was confirmed in 2 samples (3.1%) and HTLV-2 in another (1.5%). Detection of a single HTLV DNA sequence may be due to infection by defective provirus, but its significance remains undefined. In this cohort, no Wb reactivity pattern was predictive of proviral detection. HTLV-1 infection was demonstrated in an individual who had Wb reactivity to gag-coded antigens only.


CONCLUSIONS
This emphasizes the importance of clinical and laboratory follow-up of HTLV-seroindeterminate individuals from endemic areas.
Costa
José Marcos Pereira
JM
Department of Infectious Diseases, University of São Paulo, Brazil.
Segurado
Aluisio Cotrim
AC
D000328:Adult; D000914:Antibodies, Viral / Q000097:blood; D001938:Brazil; D005260:Female; D015490:HTLV-I Infections / Q000175:diagnosis* / Q000276:immunology / Q000821:virology; D015491:HTLV-II Infections / Q000175:diagnosis* / Q000276:immunology / Q000821:virology; D015368:Human T-lymphotropic virus 1 / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D015367:Human T-lymphotropic virus 2 / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000821:virology*; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction / Q000379:methods; D012150:Polymorphism, Restriction Fragment Length; D011533:Proviruses / Q000235:genetics / Q000302:isolation & purification; D055815:Young Adult
D000914:Antibodies, Viral