|Polek,, Marylou - CDFA, CCTEA TULARE, CA|
Submitted to: International Organization of Citrus Virologists Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: August 20, 2007
Publication Date: October 17, 2007
Citation: Yokomi, R.K., Polek,, M. 2007. Elevated Background in DAS-I ELISA for the Detection of Citrus Tristeza Virus in Mandarin Varieties. In: Proceedings of the 17th Conference International Organization of Citrus Virologists, October 22-26, 2007, Adana, Turkey. p. 66. Technical Abstract: Healthy tissue extracts from mandarin orange varieties occasionally resulted in elevated absorbance which can exceed twice that of healthy sweet orange tissue extracts in DAS-I-ELISA detection with an expressed coat protein polyclonal antiserum of Citrus tristeza virus (CTV). This problem occurs seasonally from March to May from field and nursery trees in central California. Suspect samples resulting from this problem and tested by immunocapture (IC) RT-PCR were negative for CTV. Several variations of ELISA protocols were examined to identify the nature of this problem. Elevated absorbance was related to the high sensitivity of the conjugate as well as to the high binding capacity of some plates. Two simple solutions were developed: i) select a different enzyme conjugate and ELISA plate combination where the problem does not exist; or ii) cross absorption of the detecting antibody by incorporating extracts from uninfected mandarin tissue into the antiserum buffer. Since this problem was not encountered with several other CTV antiserum sources, another solution is to use a different but proven antiserum.