Comparison of Detection Methods for Citrus Tristeza Virus in Field Trees During Months of Nonoptimal Titer

Abstract

Enzyme-linked immunosorbent assay (ELISA) can reliably detect citrus tristeza virus (CTV) in samples collected during approximately 6 months of a typical year. Two reverse transcriptase polymerase chain reaction (RT-PCR) methods (total nucleic acid extract and immunocapture based) were evaluated and compared to ELISA in order to develop a more sensitive assay for CTV. From May 1994 to October 1995, 6 sweet orange trees infected with CTV from each of 2 geographic areas (Riverside and the San Joaquin Valley) were tested monthly by each method. In the months of August (San Joaquin Valley samples) and September (Riverside and San Joaquin Valley samples) several of the trees had a significant loss of virus titer such that CTV was not reliably detected by ELISA. By contrast, the 2 PCR methods gave definitive positive results for CTV in samples collected during these months. Different tissue types were analyzed by each of the above assays. Petioles and midribs, both phloem-rich tissues, were each satisfactory for ELISA, while distal leaf tips did not always produce a positive result. All tissue types were equally efficient in producing a positive result in both PCR-based assays. The results of this study provide a basis for CTV testing by PCR in months when virus titer drops to a level generally unacceptable for using ELISA.

Detection ofCitrus tristeza virus(CTV) from Satsuma Owari mandarins(Citris unshiu)by direct tissue blot immunoassay (DTBIA), DAS‐ELISA, and biological indexing

“…This result is in agreement with previously reported studies of virus titres and sampling times by various researchers on different citrus hosts (Garnsey et al 1987;mathews et al 1997;Korkmaz 2002;Cambra et al 2004) and in Satsuma mandarins (Cambra et al 2002). For testing samples collected at different times, DTBia results were as good as eLiSa results under field conditions.…”

Serological and molecular characterisations of the Egyptian isolate ofBean common mosaic virus

“…The RT-PCR technique is highly sensitive, simple and useful in overcoming difficulties encountered with serological methods, such as low antigen titer, availability of antibodies and cross-reactivity of antibodies with heterologous antigens (Mattews et al 1997). It also seems that RT-PCR is faster than traditional methods; so, it can be concluded from our study that the RT-PCR assay has a great sensitivity which enables the detection of BCMV in infected samples.…”

Indexing Tools for Indian Citrus Ringspot Virus (ICRSV)

“…As ELISA lacks the sensitivity required for the detection of plant viruses, which occur in very low concentrations in infected tissues, many workers have used RT-PCR for indexing of different viruses to overcome this problem [27][28][29][30][31][32][33][34]. The procedure is extremely sensitive, fairly inexpensive and requires minimal skills to perform [35].…”