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Little cherry, an economically important disease of cherry is caused by at least two different viruses. One of these is Little cherry virus 1 (LChV-1) for the detection of which no efficient serological tools are available, so that diagnosis is based on molecular methods. In this study, different immunization strategies for producing antibodies against the viral coat protein of LChV-1 were tried, using either purified virus preparations, or bacterially expressed protein, or a DNA vector that expressed the cloned coat protein (CP) gene in vivo. Effective induction of specific antibodies to LChV-1 CP was obtained using DNA intramuscular immunization followed by a single boost with the recombinant protein. The entire coat protein sequence was cloned in a mammalian expression vector and, after being coated by an amphiphilic non-toxic reagent was delivered into rabbit. A protein boost increased the specific immune response against the virus protein. The sensitivity of this antiserum is lower if compared with that of antisera raised conventionally against other viruses, thus it requires improvements for use for diagnostic purposes.

The Cucumber mosaic virus (CMV) is an isodiametric plant virus with an extremely wide host range, present worldwide. CMV chimeric particles (R9-CMV), engineered to express a 27-aa synthetic peptide derived from Hepatitis C virus (HCV), were demonstrated to be stable under simulated gastric and intestinal conditions. Then the possibility of inducing a humoral immune response in rabbits fed with R9-CMV infected lettuce plants was demonstrated, suggesting that this system could function as a confirming tool of a bioreactor for the production of a stable edible vaccine against HCV.

An RT-PCR/nested PCR technique was developed for the simultaneous detection and typing of plum pox virus (PPV) and its major types--Dideron (D), Marcus (M), El-Amar (EA) and Cherry (C). Degenerated oligonucleotides were synthesized for the general detection of PPV, flanking the coding sequence for the N-terminal portion of the coat protein (CP), within which strain-specific differences were identified. On the basis of these characteristic differences, degenerated primer pairs were designed to differentiate between the four major subgroups of the virus in nested PCR reactions. The validity of the technique was tested on viral strains and cloned cDNAs overlapping the CP region. High specificity was observed with no detectable cross-reactions. The results of general PPV detection with the new primers and those of the PCR-based detection of the 3' non-coding region of the viral genome correlated with complete coincidence. The PCR typing results correlated well with those of the RsaI-RFLP and serological typing and revealed a surprisingly high incidence of PPV-D in Hungary.