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Proposed candidate materials and results of the feasibility studies for a WHO serological reference panel

This study presents raw materials, epidemiological data, and results of a feasibility study for a WHO serological reference panel focusing on T. cruzi type II. The study evaluates prototype dilutions, clinical sensitivity, and specificity using various serological assays. It highlights the need for further testing with RIPA, Western Blot, and Abbott Immunoassay. The study includes data from Latin America reference centers and emphasizes the importance of evaluating the prototype's performance in different regions.

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Proposed candidate materials and results of the feasibility studies for a WHO serological reference panel

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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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