Patrones Indeterminados de Western Blot en sueros reactivos por anticuerpos contra los virus linfotrópicos de células T tipo I/II (HTLV I/II) en donantes de sangre en Costa Rica

human t lymphotropic virus type i and ii (htlv i/ii) are retroviruses associated with different clinical manifestations. htlv i was the first retrovirus associated to human disease, and it is the etiological agent of two main pathologies: adult`s t-cell leukemia (atl) and myelopathy/tropical spastic paraparesis (ham/tsp). htlv-ii has been related to similar neurological disorders. central america, south america and the caribbean are areas of high prevalence. in many countries, including costa rica, blood screening has been implemented to prevent retroviral blood transmission. applying the western blot (wb) technique, screening for htlv i/ii in blood donors has shown incomplete antibody reactivity against viral antigens, which has been classified as an indeterminate pattern. between december 2002 and march 2006, enzyme immunoassay (elisa) reactive samples were reported as 39 (0,02%) positive, 254 (0,14%) indeterminate and 113 (0,06%) negative. for further study with the commercial system (htlv i/ii blot 2.4), there were selected 42 indeterminate samples and 25 positive ones. the results for the positive group were: 15 htlv-i, 8 htlv-ii and 2 indeterminate. in the indeterminate group we found 4 discordant results: 1 htlv ii, 1 htlv and 2 negative samples. in this research, using national serum samples, it is weak show positive patterns can be related to indeterminate wb or to partial reactivity of htlv ii infected donors. the most characteristic indeterminate pattern is the htlv-i gag indeterminate (hgip), which has been defined as a protein profile which includes p19, p26, p28, p32, p36 and p53, but excludes p24 or envelope glycoproteins (gp 46, gp 61/68). in the present study, a similar pattern was observed in 22 samples. however, there were 6 samples with patterns that include p24. this first analysis of indeterminate patterns in national samples demonstrates the importance of molecular studies to establishing the htlv infection status in national blood donors with