Typing of Egyptian Citrus tristeza virus (CTV) Isolates Based on the Capsid Protein Gene

Abstract

The capsid protein gene of three Egyptian CTV isolates from two locations was amplified by
immunocapture RT-PCR and analysed by single stranded conformation polymorphism and sequencing. The CTV
isolates studied did not differ significantly in sequence composition and each isolate consisted of very similar
haplotypes. Comparison with reference sequences from isolates elsewhere in the world showed that these haplotypes
clustered very close to the severe strain T3 from Florida causing quick decline and stem pitting. Analysis of the
deduced amino acid sequence showed the epitope characteristic of reactivity with the MCA13 antibody. Sequence
comparison with the sequence of an Egyptian isolate (Qaha) available in the Genbank showed a distance of about
8%, suggesting that it had a different origin.