Detection of HTLV-I/II proviral DNA in seroindeterminate individuals among different populations in Argentina

BERINI C, EIRIN ME, SALOMÓN H, BIGLIONE M

Montego Bay, Jamaica

Conferencia; 12th International Conference on Human Retrovirology; 2005

International Retrovirology Association and The University of the West Indies

Introduction: HTLV-I/II infection in South America has been reported in different populations. HTLV-I/II, as well as HIV have the same mechanisms of transmission A frequent problem in HTLV-I/II diagnosis is the high prevalence of indeterminate serological results by Western Blot (WB). These cases have been reported all around the world, with prevalence rates that vary considerably according to the country and the population of study. In the present study we analyzed  56 samples indeterminate by WB in different population of Argentina. Materials and methods: Out of the 56 samples, 4 were from injecting drug users (IDUs), 9 female sex workers (FSW), 9 men who have sex with men (MSM) and  34 were blood donors. Antibodies anti-HTLV-I/II were detected by particle agglutination (PA) (Serodia, Fujirebio, Japan) and  reactive samples were confirmed by  western blot (WB) (HTLV Blot 2.4 Genelabs Diagnostics, Singapore). A highly sensible nested PCR was used for detection of  pol gene (primers SK110 /SK111)  and tax gene (primers SK43/SK44) for both retroviruses. Results: The indeterminate WB patterns observed were classified as HGIP (Human Gag Indeterminate Pattern) with the bands corresponding to p19, p26, p28, p32 and p53; GAG pattern with p19 or p24; ENV pattern with GD21 or Uncommon patterns which do not classify in none of these groups. Out of the 54 samples, 2 were confirmed HTLV-I positive while 12 amplified one sequence only (pol or tax from HTLV-I). All other samples were negative for both HTLV-I and II. Both HTLV-I positive samples where from IDUs exhibiting an ENV pattern with  GD21. Among the 12 indeterminate (1 gene amplified only), 3 were HGIP (2 amplified  pol I  and 1 tax I), 1 was ENV (amplified pol I), 5 were GAG (amplified pol I), 3 had other patterns (amplified pol I). In 3 samples antibodies anti-Tripanozoma cruzi were detected while the remaining 51 samples were negative. Discussion: In this study we confirmed infection by HTLV-I in 2 UDIs with an ENV (GD21) profile. Even though none of the blood donors resulted HTLV-I/II positive, in 2 of them there was amplification for one of the analyzed genes. Their pattern were HGIP and GD21, p19. These individuals remain with an indeterminate diagnosis. As showed in previous studies, we could discard that indeterminate patterns were due to cross reaction with proteins of Tripanozoma cruzi.The HGIP pattern, commonly described among blood donors, was also observed in all populations studied We can observe that most indeterminate cases are not associated to infection by HTLV-I/II and possibly the nearest hypothesis for these results may be the activation of the immune response that cross-reacts with endogenous proteins. However, we cannot ensure that all these indeterminate cases do not present infection or harbor proviral DNA, independently of the the WB pattern or the population studied.