Polyclonal Antibodies to Detect the CP-RT Protein of Potato Mop-Top Virus

Abstract. Potato mop-top virus (PMTV) causes an important re-emerging disease in potato crops in Colombia due to the increased incidence of its protozoan vector Spongospora subterranea f.sp. subterranea (Sss), the causing agent of Powdery scab disease. For an accurate detection of PMTV it is recommended to combine different diagnostic tests and evaluate multiple samples per plant or tissue. In order to increase the number of available tools for detection of PMTV, antibodies targeting the RT domain of the CP-RT protein were developed in this work. Sequencing of the RT domain from the colombian strain R25 was achieved and using bioinformatic analysis, a potential antigenic region was identified. A peptide mimicking the antigenic region was inoculated in rabbits for the production of polyclonal antibodies. The antibodies were tested by ELISA using Nicotiana benthamiana bait-plants infected with Sss cystosori and potato plants collected in La Union (Antioquia). The validity of serological tests was confirmed by RT-PCR. A complete sequence of the RT domain and 441 nt of the CP gene were obtained. Phylogenetic analysis identified strain R25 as closely associated to the PMTV lineage distributed worldwide. A total of 19.26 mg of anti-CP-RT polyclonal antibodies useful in detecting PMTV in infected plants were obtained. As CP-RT is involved in transmission of PMTV by Sss, these antibodies will be useful for supporting not only diagnostic programs but also basic and epidemiologic studies aimed at understanding interactions between PMTV and Sss.