Submitted to: International Organization of Citrus Virologists Proceedings
Publication Type: Abstract only
Publication Acceptance Date: 11/7/2004
Publication Date: 11/30/2004
Citation: Sieburth, P.J., Nolan, K.G., Hilf, M.E., Lee, R.F., Moreno, P., Garnsey, S.M. 2004. Discrimination of stem pitting citrus tristeza virus isolates from other ctv isolates. International Organization of Citrus Virologists Abstracts, Page30. Interpretive Summary:
Technical Abstract: Technical Abstract: Stem pitting isolates of Citrus tristeza virus (CTV) are not thought to be widely distributed in Florida, but are of concern and a test was needed for rapid discrimination of stem pitting from other severe CTV isolates in field trees. Four published techniques were evaluated for their potential as a diagnostic tool for identifying isolates that cause stem pitting symptoms in biological indicators. CTV isolates from International CTV collections were used as biological indexing data was already available for many isolates. Primers PM33, RF 137 (type two isolates of CTV), primers for VT-1, and oligonucleotide probes (ONP) III, IV and V gave positive results for many isolates that caused stem pitting in sweet orange, grapefruit or both. Extraction technique was important for uniform, repeatable results with RNA extracts giving spurious bands, and immunocapture producing clear strong bands. No one technique was superior to the others and would stand alone. Orange stem pitting ELISA was not repeatable on oligonucleotide probe II gave inconsistent results in initial testing; both were dropped from further testing. False negatives were more common than false positives and new primers are being developed to detect isolates not identified by the current tests. Tests results from primers for Type II and VT-1 and ONP for probes II, IV and V were used together to obtain stem pitting profiles for isolates testing positive.