P-466 - Biological characterization of cactus carlavirus 2 (CCV-2) in dragon fruit (Hylocereus spp)

Global dragon fruit (Hylocereus spp.) production has increased substantially in the past decade, yet viral studies on this crop remain limited. This study applied high-throughput sequencing (HTS) to a single DNase-treated RNA sample extracted from 100 mg of fresh cladode tissue of a Hylocereus hybrid (‘Pink Panther’) collected from a commercial field in Ecuador. Sequencing was performed using Illumina’s TruSeq Stranded Total RNA Library on a NextSeq2000 platform (2×150 bp). A total of 11.9 million reads were processed in Geneious Prime. BLAST analyses of de novo assembled contigs identified two viral sequences: a 5,871-nt contig homologous (96% nt identity) to cactus virus X (CVX) and an 8,428-nt contig matching (77% nt identity) cactus carlavirus 2 (CCV-2). Viral read abundance varied significantly, with 50.1% assembling into the CVX contig and only 0.8% into the CCV-2 contig. As CCV-2 has previously only been detected in orchid cacti (Epiphyllum hybrids), this study aimed to characterize its presence in dragon fruit. After obtaining the terminal genomic sequences by Rapid Amplification of cDNA Ends (RACE), an infectious CCV-2 clone (GenBank: PP751658) was developed, and single infections were evaluated in Hylocereus polyrhizus seedlings, where no symptoms were observed. Mechanical inoculations failed to transmit the virus to Nicotiana benthamiana. Results from ongoing experiments aimed to identify the natural vector of this novel carlavirus and evaluate its pathogenicity in single and mixed infections with CVX across different dragon fruit cultivars will be presented.