Feasibility Studies for WHO Serological Panel T. cruzi Type II
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Proposal and results of feasibility studies for a WHO serological reference panel focusing on T. cruzi Type II. Investigation includes raw material analysis, epidemiological data, and clinical sensitivity. Performance evaluation carried out through EQAS in multiple regions.
Feasibility Studies for WHO Serological Panel T. cruzi Type II
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Presentation Transcript
Proposed candidate materials and results of the feasibility studies for a WHO serological reference panel T.cruzi type II Márcia Otani Fundação Pró-Sangue Hemocentro de São Paulo
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Raw material - Reactivity Epd = end point dilution (OD/CO) > 1 Prototype = 260ml of positive + 1240 ml of negative plasma from 7 donors units. (4.8 times diluted.)
Raw material - serial dilution OD/CO ratio = Prototype = M2
Elisa cruzi Chagatek Bioschile IFI Pure 4,962 5,406 3,143 1/80 1/2 4,792 4,774 3,042 1/40 1/4 4,677 3,619 2,803 1/20 1/8 3,758 2,703 2,287 Negative 1/16 2,612 1,910 2,020 Negative 1,297 1/32 1,896 1,616 Negative 1,362 1/64 0,865 1,309 Negative 1,046 1/128 0,923 0,542 Negative 1/256 0,581 0,477 0,768 Negative 1/512 0,435 0,413 0,579 Negative M2 OD/CO ratio
Prototype OD/CO ratio
Evaluating the Prototype • EQAS to evaluate performance in loco. • Send 1.8ml of the prototype serum to 25 reference centers in 16 countries in LA. • Included 4 other non diluted not pooled samples to the same panel. • Sep 2007 (OPS0207), Apr 2008 (OPS0108) and Sep 2008 (OPS0208).
Cut off Data from Latin America Reference Centers – PAHO Regional EQAS
Sep 2007 Apr 2008 Sep 2008 Data from Latin America Reference Centers – PAHO Regional EQAS
Sep 2007 Apr 2008 Sep 2008 Data from Latin America Reference Centers – PAHO Regional EQAS
Sep 07 Apr 2008 Sep 08 Data from Latin America Reference Centers – PAHO Regional EQAS
Data from Latin America Reference Centers – PAHO Regional EQAS
Data from Latin America Reference Centers – PAHO Regional EQAS
Data from Latin America Reference Centers PAHO Regional EQAS
Volume Prototype volume available = 1.4 liters 2 times dilution = 2.8 liters It is possible to obtain a total of 6 liters Mexico Units M2 volume available = 400 mL 4 times dilution = 1.6 liters
Conclusion • The mixture of 3 positive samples (from south of Latin America) diluted 4.8 times in negative samples have produced a prototype that presented stability at –20 ºC. • We need to define the reactivity of the cut off value. Here we have used the dilution that is IIF = 1/20. • Reactivity of the prototype diluted 2 times were 2 to 4 times de cutoff value in most of the tests evaluated and the IIF = 1/20. • Perhaps we should submit this prototype to RIPA, Western Blot and Abbott Immunoassay.
1 1 2 2 3 4 5 6 7 10 8 9 11 12 13 Data from Latin America Reference Centers PAHO Regional EQAS