Lettuce (Lactuca sativa) is one of the most common vegetable planted in the world, so the identification of its viral disease is important because this kind of pathogen causes the loss of quantitative and qualitative characteristic of lettuce. Tobacco streak virus(TSV) is an ilarvirus with quasi-isometric particles, 27 - 35 nm in diameter. It has a wide host range and occurs worldwide but not often in epidemic proportions. In this study, 300 samples of lettuce were collected from lettuce fields in Tehran province. Infected plants show symptoms such as: mosaic, vein clearing, vein necrosis, yellowing and leaf distortion. DAS-ELISA (double antibody sandwich ELISA) was used with a polyclonal antiserum against TSV. Five isolates (T₁, T₂, T₃, T₄, T₅), which are respectivley collected from Mohammad abad (Karaj), Malek abad (Karaj), Hashtgerd (Karaj), Tarand balla (Varamin) and Deh mah sin (Pishva) were inoculated on 29 species of Cucurbitaceae, Amaranthaceae, Solanacea, Compositae, Leguminosae and Chenopodiacea. Chenopodium quinoa six days after inoculation showed necrotic local lesions. Gomphrena globosa ten days after inoculation developed chlorotic local lesions. Systemic symptoms were produced in Datura stramonium. Phaseolus vulgaris cv. Red Kidney five days after inoculation developed necrotic local lesions.Nicotiana tabacum seven days after inoculation showed necrotic and chlorotic local lesions. Nicotiana clevelandii 15 days after inoculation developed leaf distortion and vein necrosis. Lactuca sativa 10-15 days after inoculation developed leaf distortion and mosaic. In order to study transmission through seed, 200 seeds of C. quinoa(inoculated with TSV) were planted. After seedling and growth, TSV was tested in these plants by DAS-ELISA. The TSV seed infection rates from 2.2%-26% depending on isolate.

Key words: ELISA, transmission trough seeds, Tobacco streak virus.