Periwinkle (Catharanthus roseus L.) grown in the Mecca region contains more than 100 alkaloids such as vincristine and vinblastine used to treat leukaemia. The members of family Potyviridae, including Catharanthus mosaic virus (CatMV), cause natural infections in periwinkle. The presence of CatMV in collected samples was tested by double antibody sandwich enzyme linked immunosorbent assay and was confirmed by reverse transcription polymerase chain reaction using specific primers. The effect of CatMV infection on vincristine and vinblastine was determined by chromatographic techniques. All the isolated mixtures were evaluated by high-performance liquid chromatography. Vinblastine and vincristine were isolated by the use of a charcoal column. We evaluated the potential use of plant growth-promoting rhizobacterial isolates (Bacillus subtilis and Bacillus pumilus) against virus infection to stimulate resistance induction in host plants.