Multi-spot, label-free detection of viral infection in complex media by a non-reflecting surface

The measurement of the intensity of light reflected by interfaces with extremely low reflectivity in water enables the label-free, multiplex detection of bio-molecular interactions. The binding of targets in solution to surface-immobilized probes (e.g. antibodies) can be quantified using a simple instrumental set-up, comprising a LED source and a camera. The condition of low reflectivity can be achieved by using a perfluorinated plastic substrate with refractive index very close to that of water. Here we show that, despite its simplicity, the method enables label-free detection in complex samples with high absorbance and turbidity. Diagnostic markers of Tomato spotted wilt virus are revealed in crude plant extracts of Datura stramonium leaves at early stage of infection. The measuring procedure requires only the addition of the sample into a cuvette and the acquisition of a series of images for a few minutes. The light reflectivity of the spots of specific antibodies increases more rapidly if the sample is prepared with infected plants

First report of Tobacco vein banding mosaic virus in China (Xian, Shaanxi Province) in Datura stramonium and tobacco

International audienceTobacco vein banding mosaic virus (TVBMV) has been reported in Taiwan (1), North America (Tennessee) (2), and Japan (3) and induces a severe disease of tobacco. During surveys on viruses of vegetables in China, TVBMV was isolated from a Datura stramonium weed plant in July 1998 in Shaanxi Province. It showed severe mosaic with blistering of the leaves. The plant was also infected by Cucumber mosaic virus (CMV). When sap from D. stramonium was frozen, thawed, and mechanically inoculated, only TVBMV was recovered. The 3′-end of the viral genome was amplified by reverse transcription-polymerase chain reaction (RT-PCR) using primers derived from the potyviridae primers (4) and cloned in pBlueScript. The sequence of 1,630 bp (GenBank AF274315) was determined on both DNA strands and found to have approximately 94% homology with other TVBMV sequences (L 28816 from Tennessee, X77637 from Taiwan, and AB020524 from Japan). The host range of the Chinese isolate was similar to that reported for the U.S. isolate. D. stramonium, Nicotiana benthamiana, N. clevelandii, N. glutinosa, N. tabacum Samsun, White Burley type and Xanthi, Lycopersicon esculentum cv. Marmande, and Petunia hybrida were systemically infected. A local infection developed in N. rustica, Chenopodium amaranticolor, C. quinoa, and Ocimum basilicum. The Chinese isolate did not infect Capsicum annuum cv. Quadrato d'Asti, Solanum melongena, or several Cucurbitaceae and Leguminosae species. Myzus persicae transmitted the Chinese TVBMV in a non-persistent mode from both D. stramonium and tobacco to the same plants and to tomato. No seed transmission occurred in experimentally infected D. stramonium (20 seedlings), tobacco White Burley type (200 seedlings), and tomato cv. Marmande (100 seedlings). The virus was found in the roots of D. stramonium and tobacco. Since the virus was not seed-transmissible, overwintering rootstocks may provide sites for winter survival of the virus. An antiserum was produced against the virus and an enzyme-linked immunosorbent assay survey was carried out in solanaceous crops including D. stramonium collected in July 1999 in Shaanxi, Shanxi, Henan, and Hebei provinces and Beijing surroundings. TVBMV was found only in the same field as in 1998 in four D. stramonium plants in association with CMV and in a tobacco plant 200 m from D. stramonium. TVBMV was not found in the closest tomato crops, where infection of CMV was severe. This is the first report of TVBMV in China, and Xian is the most northern location in which this virus has been found

Presence of tobacco vein-banding mosaic virus in Xian (Shaanxi province, China) in Datura stramonium and tobacco

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