DETECTION OF HTLV-I/II PROVIRAL DNA IN SEROINDETERMINATE WESTERN BLOT INDIVIDUALS AMONG POPULATIONS IN ARGENTINA

BERINI C; EIRIN ME; PANDO MA; SALOMON H; BIGLIONE M

Montego Bay

Conferencia; 12th International Conference on Human Retrovirology; 2005

  Introduction: 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.   Objective: The aim of this study was to analyze 58 samples indeterminate by WB in different populations of Argentina.   Materials and Methods: Out of the 58 samples, 4 were injecting drug users (IDUs), 11 female sex workers (FSWs), 12 men who have sex with men (MSM), 4 neurological patients and 27 blood donors (BD). Antibodies anti-HTLV-I/II were detected by particle agglutination (Serodia, Fujirebio) and  reactive samples were confirmed by WB (HTLV Blot 2.4 Genelabs Diagnostics).  DNA was extracted from peripheral mononuclear cells and a highly sensible nested PCR was performed with 2 primer pairs from the pol and tax region. Fragments of 198bp (HTLV-I) and 138bp (HTLV-II) of pol gene were amplified by using external primers SK110 /SK111 and internal primers pol1.1/pol3.1 and pol1.2/3.2 respectively. Fragments of 159bp (HTLV-I) and 128bp (HTLV-II) of tax gene were detected using external primers SK43/SK44.   Results: The indeterminate WB patterns observed were classified as HGIP (p19, p26, p28, p32 and p53); GAG (p19 or p24); ENV (GD21) or Uncommon (UP) which do not classify in none of these groups (Table 1). Out of the 58 WB patterns, 20 were HGIP, 18 GAG, 8 ENV and 12 UP. 4 samples (6.8%) were confirmed HTLV-I positive (2 were IDUs coinfected with HTLV-II) while 6 amplified pol from HTLV-I only. One  HGIP resulted to be HTLV-I. Anti-Tripanozoma cruzi antibodies were detected in 3 samples only. The final prevalence of indeterminate samples has significantly diminished from 1.44% (21/1453) to 0.4% (6/1453) (Table 2).   Conclusions: Among the 58 seroindeterminate cases, 10 amplified at least one of the proviral genes. All positive samples corresponded to the at-risk population including all possible patterns. This data suggests that seroindeterminate blood donors with no risk of infection from non- endemic areas could be negative for HTLV-I/II infection. We conclude that molecular diagnosis should be recommended for confirming true infection and consider specific recommendations for counselling individuals with indeterminate diagnosis.