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Immunofluorescence assay reactivity patterns of serum samples presenting indeterminate Western blot results for antibodies to HIV-1 and HTLV-I/II in Cordoba, Argentina

Parâmetros de reatividade de amostras de soro com resultados indeterminados por Western blot para anticorpos contra HIV-1 e HTLV I/II em Córdoba, Argentina

René GASTALDELLO Sandra GALLEGO María Beatriz ISA Eduardo MATURANO Santos SILEONI Silvia NATES Silvia MEDEOT About the authors

Serum samples (n: 110) from blood donors and high risk individuals from Cordoba, Argentina with indeterminate HIV-1 and HTLV-I/II Wb profiles were studied for specific antibodies to HTLV-I/II and HIV-1 by indirect immunofluorescence assay (IFA) and for the presence or absence of HIV-1 and HTLV-I/II specific bands by Wb. This study was carried out in order to characterize their putative reactions with HIV-1 and HTLV-I/II proteins and to resolve the retrovirus infection status of these individuals. Results indicated that blood donors sera displaying indeterminate HIV-1 or HTLV-I/II Wb patterns were not immunoreactive to HTLV-I/II and HIV-1 on IFA. However, a high rate of indeterminate HIV-1 and HTLV-I/II Wb samples from high risk individuals had positive HTLV-I/II and HIV-1 IFA results respectively. Our study supports the growing evidence that HTLV-HIV indeterminate seroreactivity in low risk population is due to a cross reaction against nonviral antigens, and in high risk populations the indeterminate samples show serological cross-recognition between HIV-1 proteins and HTLV-I/II proteins on Wb. These results point out the necessity to investigate the HTLV-I/II reactivity in indeterminate HIV-1 samples and viceversa in order to confirm the diagnosis. Finally, this study shows the potential usefulness of IFA in elucidating the status of HIV-1 and HTLV-I/II infection of individuals with indeterminate Wb profiles, thus enabling resolution of retrovirus infection status.

Retroviruses; HIV-1; HTLV-I/II; Confirmatory testing; Indeterminate results; Western blot; Indirect immunofluorescence assay

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