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Feasibility Studies for WHO Serological Panel T. cruzi Type II

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.

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Feasibility Studies for WHO Serological Panel T. cruzi Type II

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  1. 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

  2. Raw materialEpidemiological data

  3. 4 y 5 3 1 2 3

  4. Epidemiological Questionnaire

  5. 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.)

  6. Raw material - serial dilution OD/CO ratio = Prototype = M2

  7. Clinical Sensitivity and Specificity

  8. 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

  9. Prototype OD/CO ratio

  10. 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).

  11. Cut off Data from Latin America Reference Centers – PAHO Regional EQAS

  12. Sep 2007 Apr 2008 Sep 2008 Data from Latin America Reference Centers – PAHO Regional EQAS

  13. Sep 2007 Apr 2008 Sep 2008 Data from Latin America Reference Centers – PAHO Regional EQAS

  14. Sep 07 Apr 2008 Sep 08 Data from Latin America Reference Centers – PAHO Regional EQAS

  15. Data from Latin America Reference Centers – PAHO Regional EQAS

  16. Data from Latin America Reference Centers – PAHO Regional EQAS

  17. Data from Latin America Reference Centers PAHO Regional EQAS

  18. 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

  19. 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.

  20. 1 1 2 2 3 4 5 6 7 10 8 9 11 12 13 Data from Latin America Reference Centers PAHO Regional EQAS

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