Although Indirect Immuno-Fluorescent Antibody Test (IFAT), performed employing “in house” prepared antigen, is considered by several authors as the golden standard for the quantisation of anti-leishmania antibodies ...Although Indirect Immuno-Fluorescent Antibody Test (IFAT), performed employing “in house” prepared antigen, is considered by several authors as the golden standard for the quantisation of anti-leishmania antibodies in dogs, there is a lack of papers reporting a description of the different patterns of fluorescence that can be observed. An incorrect identification of patterns of fluorescence may be an important source of bias in the interpretation of results. Previous papers report different criteria to define as “positive” a specific pattern of fluorescence, namely: membrane fluorescence, homogeneous fluorescence of the body, or homogeneous fluorescence of the body plus flagellum. In this paper, we report a detailed description of preparation of slides and of the patterns of fluorescence that can be obtained employing “in house” prepared antigen. At least six main patterns of fluorescence may be observed: 1): homogeneous cytoplasmatic green fluorescence;2): membrane pattern, in which the fluorescence is mainly localized along the entire perimeter of the parasites;3): coarse-speckled cytoplasmatic fluorescence;4): flagellar pattern, in which the fluorescence is localized exclusively onto the flagellum;5): punctiform pattern, in which the fluorescence is localized exclusively at the basis of the flagellum;6): nuclear pattern, in which only the nucleus of the parasite shows a homogeneous green fluorescent. The significance of each pattern is discussed.展开更多
The levels of anti-Leishmania infantum antibodies are relevant with the diagnosis and the followup of infected dogs. Both ELISA (Enzyme-Linked Immunosorbent Assay) and IFAT (Indirect Immuno-Fluorescent Antibody Test) ...The levels of anti-Leishmania infantum antibodies are relevant with the diagnosis and the followup of infected dogs. Both ELISA (Enzyme-Linked Immunosorbent Assay) and IFAT (Indirect Immuno-Fluorescent Antibody Test) may be employed to estimate the antibody levels in dogs, but at present, the correlation between ELISA absorbance and IFAT titer has not been investigated. In this paper, we compared the optical densities obtained with a commercial ELISA, Leiscan?(Laboratorios Dr. Esteve S.A.), versus the titers obtained by in house IFAT. We measured ELISA absorbance of: 44 IFAT negative samples coming from an endemic area;10 negative samples coming from a non endemic area;29 samples with an IFAT titer between 1/40 and 1/80;10 samples with an IFAT titer of 1/160;9 samples with an IFAT titer of 1/320;10 samples with an IFAT titer of 1/640;10 samples with an IFAT titer ≥ of 1/1280. Results show that: a) there is a poor correlation between IFAT titer and ELISA absorbance;b) Leiscan? is not able to distinguish between IFAT negative samples and IFAT titers up to 1:160;c) IFAT negative samples from an endemic or non endemic area show different ELISA absorbance;d) the performance of the kit may be improved by the use of a more appropriate cut-off.展开更多
文摘Although Indirect Immuno-Fluorescent Antibody Test (IFAT), performed employing “in house” prepared antigen, is considered by several authors as the golden standard for the quantisation of anti-leishmania antibodies in dogs, there is a lack of papers reporting a description of the different patterns of fluorescence that can be observed. An incorrect identification of patterns of fluorescence may be an important source of bias in the interpretation of results. Previous papers report different criteria to define as “positive” a specific pattern of fluorescence, namely: membrane fluorescence, homogeneous fluorescence of the body, or homogeneous fluorescence of the body plus flagellum. In this paper, we report a detailed description of preparation of slides and of the patterns of fluorescence that can be obtained employing “in house” prepared antigen. At least six main patterns of fluorescence may be observed: 1): homogeneous cytoplasmatic green fluorescence;2): membrane pattern, in which the fluorescence is mainly localized along the entire perimeter of the parasites;3): coarse-speckled cytoplasmatic fluorescence;4): flagellar pattern, in which the fluorescence is localized exclusively onto the flagellum;5): punctiform pattern, in which the fluorescence is localized exclusively at the basis of the flagellum;6): nuclear pattern, in which only the nucleus of the parasite shows a homogeneous green fluorescent. The significance of each pattern is discussed.
文摘The levels of anti-Leishmania infantum antibodies are relevant with the diagnosis and the followup of infected dogs. Both ELISA (Enzyme-Linked Immunosorbent Assay) and IFAT (Indirect Immuno-Fluorescent Antibody Test) may be employed to estimate the antibody levels in dogs, but at present, the correlation between ELISA absorbance and IFAT titer has not been investigated. In this paper, we compared the optical densities obtained with a commercial ELISA, Leiscan?(Laboratorios Dr. Esteve S.A.), versus the titers obtained by in house IFAT. We measured ELISA absorbance of: 44 IFAT negative samples coming from an endemic area;10 negative samples coming from a non endemic area;29 samples with an IFAT titer between 1/40 and 1/80;10 samples with an IFAT titer of 1/160;9 samples with an IFAT titer of 1/320;10 samples with an IFAT titer of 1/640;10 samples with an IFAT titer ≥ of 1/1280. Results show that: a) there is a poor correlation between IFAT titer and ELISA absorbance;b) Leiscan? is not able to distinguish between IFAT negative samples and IFAT titers up to 1:160;c) IFAT negative samples from an endemic or non endemic area show different ELISA absorbance;d) the performance of the kit may be improved by the use of a more appropriate cut-off.
