- Volume 67, Issue 1, 1986

Monoclonal antibodies (MAb) specific for citrus tristeza virus (CTV) were obtained from hybrid cells produced by fusion of a non-secreting myeloma cell line with spleen cells from BALB/c mice immunized with isolate T-308 of CTV. Three MAb were characterized for their immunoglobulin isotype and their titres in cell culture and ascites fluids. Each MAb was conjugated with alkaline phosphatase and used in a double-antibody sandwich enzyme-linked immunosorbent assay for CTV. When tested against 23 strains of CTV, each MAb recognized all the strains with uniform reactions and low background.

The enzyme responsible for cauliflower mosaic virus (CaMV) DNA replication has been studied by isolating virus replication complexes and assaying the associated polymerase activity using activated calf thymus DNA or poly(rCm).oligo(dG)12–18 as template-primer. The activity of the enzyme was specifically inhibited by immune serum raised against a synthetic peptide corresponding to a portion of the viral gene V protein. This result provides further evidenes that this protein is the reverse transcriptase involved in CaMV replication.

Red clover necrotic mosaic virus (RCNMV) has two RNA species of mol. wt. about 1.5 × 106 (RNA 1) and 0.5 × 106 (RNA 2). An English strain (H) and a Czechoslovakian strain (TpM-34) of RCNMV could be distinguished serologically, by solid-phase RNA hybridization analysis (Northern blotting) and by the symptoms they induced in cowpea. Studies of pseudorecombinants, formed following inoculation of plants with heterologous combinations of the RNA species of each strain, showed that RNA 2 determines the morphology of lesions induced by the isolates in cowpea and their ability to invade the plants systemically.