Occurrence of Telosma mosaic virus causing passion fruit severe mosaic disease in Thailand and immunostrip test for rapid virus detection

• The causal virus of mosaic disease in purple passion fruit was Telosma mosaic virus.
• Its host range, morphology, and coat protein gene sequence was investigated.
• Rabbit polyclonal antibody against purified virions was produced.
• An immunostrip test kit for rapid virus diagnosis was developed.
• The research served need for production of virus-free stocks for farmers.

The cause of leaf and fruit severe mosaic disease in purple passion fruit (Passiflora edulis) in Chiang Mai province, Thailand, was identified and virus diagnostic kit was developed. Symptomatic plants collected from diseased mother plants in the nursery at the Royal Pangda research station (RPRS) was used for virus isolation through single lesion transfer in Chenopodium amaranticolor, followed by virus propagation for purification in Nicotiana benthamiana, and back inoculation to purple passion fruit. Electron microscopy of leaves with typical symptoms revealed potyvirus-like flexuous rod particles, ca. 750 nm long and pinwheel inclusion bodies in the cytoplasm of infected cells. The deduced amino acid sequence of the complete coat protein revealed that the isolated virus was a strain of Telosma mosaic virus with which it shared 84% identity. A rabbit polyclonal antiserum was produced against purified virions, and used to develop a gold-labeled immunostrip for rapid virus diagnosis. The test strip could detect the virus in diseased passion fruit sap up to a dilution of 1: 640, and positive test line could be read within 3–5 min. Application of strip test for virus assay in RPRS nursery's mother plants help screen clean stocks. This strip test kit supports RPRS program of producing virus-free planting materials for farmers.