Diversity of citrus tristeza virus strains indicated by hybridization with cloned cDNA sequences.

Cloned cDNA sequences 500-2000 base pairs long, derived from a severe citrus tristeza virus (CTV) isolate, were used to study sequence homology with RNA of nine other serologically indistinguishable CTV isolates which differed in their biological properties. Six of the nine CTV isolates hybridized positively with the tested cDNA clones, while three others hybridized differentially with these cDNA clones. The potential use of cloned viral sequences for typing of virus strains is discussed.