Production of Antisera to Grapevine Viruses

A good supply of antisera to two isolates (type II and type III) of the long clostroviruses associated with grapevine leafroll (GLRaV) has been produced as well as a low tittered antiserum to the type IV GLRaV. These antisera have been evaluated and optimized for ELISA test. Monoclonal antibodies are produced to type III of GLRaV and the titer of the antibody is guite high when evaluated in ELISA tests. A high-tittered antiserum to grapevine fanleaf virus (GFLV) has been produced. A low-tittered antiserum to tomato ringspot virus (TmRSV, causal agent of grapevine yellow vein disease) has been produced and works quite well in ELISA tests. The antisera conditions have been optimized for GFLV and GYW detection in ELISA tests and they are routinely being used to test the foundation stocks at FPMS. The same GFLV antiserum is also being used by the California Department of Food and Agriculture (CDFA), Pest Exclusion branch for testing the registered grapevine material in the registration and certification program. An antiserum to grapevine corky bark virus (GCBaV) has also been produced and conditions for optimizing the reactivity of the antiserum in ELISA tests were done. Some monoclonal antibody lines were produced for GCBaV but subsequently lost their ability to produce specific antibodies. Our attempt has failed to purify enough rupestris stempitting associated virus for the production of antiserum. We have attempted to make a cDNA clone from the dsRNA and use it in a cDNA hybridization system as a diagnostic tool, but it failed. The attempt will be continued. A source for GLRaV-type I was identified. Amounts of virus was purified and used to immunize a rabbit, but the titer of produced antiserum was very low and was not useable in ELISA. A new source of GLRaV type I has been found. Quantities of virus have been purified. A rabbit has been immunized with the purified virus. The preliminary tests indicated that the specific antibody titer is building up in the animal. The rabbit will be given boost injections with the same virus to develop a high tittered antibody for GCBaV T I.