Characterization of a novel citrus tristeza virus genotype within three cross-protecting source GFMS12 sub-isolates in South Africa by means of Illumina sequencing.

Tristeza disease (caused by citrus tristeza virus, CTV) is currently controlled in South Africa by means of cross-protection. In this study, we characterized the CTV populations of three grapefruit mild strain 12 (GFMS12) single-aphid-transmission-derived sub-isolates at the whole-genome level using Illumina sequencing technology. A novel South African isolate (CT-ZA3, of the T68 genotype) was shown to be the dominant genotype in all GFMS12 sub-isolates tested, along with reads unique to various other genotypes occurring as minor components. Uncertainty remains as to the significance of these minor components.