This paper describes the production and characterization of monoclonal antibodies (MAb) specific for citrus tristeza virus (CTV), a closterovirus that causes the most economically important viral disease of citrus worldwide. Researchers immunized BALB/c mice with CTV isolate T-308 and fused spleen cells with myeloma cells to generate hybridomas. Three high-titre clones producing IgG antibodies were established and characterized. These monoclonal antibodies successfully detected CTV in crude plant extracts using multiple immunoassay formats including ELISA-DAS, ELISA-IDAS, and immunoelectron microscopy. Crucially, all three MAb recognized 20 Spanish CTV isolates plus isolates from California, Iran, and Vietnam with uniform reactions and minimal background signal. When compared to conventional polyclonal antisera in routine field testing of 1,795 samples, MAb 3DF1 demonstrated superior sensitivity, detecting CTV in 12 samples that tested negative with polyclonal antibodies but later confirmed positive upon retesting. The low background noise with MAb enabled higher antibody dilutions and longer substrate incubation times while maintaining clean assay plates, improving practical utility for CTV diagnosis.

Key findings

• Three monoclonal antibodies specific for CTV were successfully produced via hybridoma technology and characterized as IgG molecules with high titres in cell culture and ascites fluid.
• All three MAb (3DF1, 3BH6, 3CA5) recognized all 23 CTV strains tested including isolates from Spain, California, Iran, and Vietnam, indicating recognition of conserved viral epitopes.
• MAb 3DF1 demonstrated superior sensitivity and lower background compared to polyclonal antisera in ELISA-DAS, detecting CTV in field samples missed by conventional antibodies.
• The monoclonal antibodies effectively detected CTV in crude plant extracts using ELISA-DAS, ELISA-IDAS, and immunoelectron microscopy formats with minimal cross-reactivity to healthy plant tissues.