Comparison between detection methods for citrus tristeza closterovirus
Comparison studies were made in California (US) on detection methods for citrus tristeza closterovirus (CTV - EPPO A2 quarantine pest) in field trees, in particular during months when the virus titer may be low. From May 1994 to October 1995, six sweet orange trees infected with CTV from each of 2 geographic areas (Riverside and San Joaquin Valley) were tested monthly by three different methods: ELISA, RT-PCR and immunocapture RT-PCR. It was observed that during August (San Jaoquin) and September (Riverside, San Joaquin) several citrus samples presented such a low virus titer that CTV was not reliably detected by ELISA, whereas the two PCR methods were effective. In addition, the best type of plant tissue to be sampled was studied. Petioles and mid-ribs gave satisfactory results for ELISA testing, while distal leaf tips did not always give a positive result. All tissues were adequate for PCR methods. This study shows the usefulness of PCR techniques during the months when virus titer is low, and in the detection of early infection which is a critical point in the virus management.
Sources
Mathews, D.M.; Riley, K.; Dodds, J.A. (1997) Comparison of detection methods for citrus tristeza virus in field trees during months of nonoptimal titer.
Plant Disease, 81(5), 525-529.