In Thailand, agriculture has signifi cantly contributed to the nation’s economic growth. Pests and pathogens present serious problems to crop production by reducing both quantity and quality of the products. An ability to detect and identify plant pathogens is essential to epidemiological and disease management studies. The accurate detection system is also required for selective breeding programs for pathogen-resistant plants and certifi cation of disease-free seeds for import and export. Despite of commercial availability, the antibodies and diagnostic test kits for plant pathogens are extremely expensive. Development of rapid, specific, accurate and cost effective diagnosis system is therefore essential for crop production in Thailand.

The aims of our researches are to produce monoclonal antibodies (MAbs) and develop immunological assays with high efficiency in detection plant pathogens for applications in agriculture and seed inspection business. In collaboration with Plant Research Group/ BIOTEC, Kasetsart University and Khon Kaen University, we have successfully developed antibodies and various immunological assays to detect plant pathogens that cause serious diseases in crops such as whitefl y-transmitted geminiviruses, tomato yellow leaf curl virus (TYLCV), tospovirus serogroup IV, melon yellow spot virus (MYSV), potyviruses, watermelon mosaic virus-2 (WMV-2) and Acidovorax avenae subsp. citrulli (Aac).

For detection of whitefl y-transmitted geminiviruses, we produced monoclonal antibodies to the recombinant coat protein of tomato yellow leaf curl virus (TYLCV). Two MAbs were generated from this project. MAb M1 specifi cally reacted with TYLCV (narrow specifi c antibody) while MAb D2 reacted with whitefl y-transmitted geminiviruses in general (broad spectrum antibody).

Geminivirus-infected-plants-in-Thailand
Geminivirus infected plants in Thailand

For tospovirus project, we fi rst characterized tospoviruses found in Thailand based on nucleotide and amino acid sequence analysis of viral nucleocapsid (N) protein gene. Two main groups of tospoviruses have been identifi ed in Thailand including tospovirus serogroup IV and melon yellow spot virus (MYSV). Monoclonal antibodies and polyclonal antibodies were produced against recombinant N proteins of various tospoviruses. Three groups of antibodies obtained can specifi cally react with tospovirus serogroup IV, with MYSV, and with both tospovirus serogroup IV and MYSV.

Tospovirus-infected-plants-in-Thailand
Tospovirus infected plants in Thailand

For detection of watermelon mosaic virus-2, MAbs were produced against recombinant coat protein of WMV-2. Two different characteristics of monoclonal antibodies were obtained. The fi rst group of MAbs specifi cally reacted with WMV-2 (narrow specifi c antibodies). The second group of MAbs reacted not only with WMV-2 but also with other potyviruses (broad spectrum antibodies).

For detection of Acidovorax avenae subsp. citrulli, MAbs were raised against sonicated cell suspension of Aac. MAb, designated 11E5, specifi cally reacted with only Aac and did not cross-react with other phytopathogenic and saprophytic bacteria. In collaboration with the Department of Agriculture, immunochromatographic strip test has already been developed for efficient detection of this bacterium.

Acidovorax-avenae-subsp.-Citrulli-(Aac)
Acidovorax avenae subsp. Citrulli (Aac)
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With all these available antibodies, various immunological assays were developed for efficient detection of the plant diseases. Moreover, many of these antibodies have already been commercialized from our research unit.

Besides antibodies to plant pathogen, we also collaborate with Animal Physiology Laboratory/BIOTEC and Chiang Mai University to produce MAbs against progesterone. Using our established antibodies, we successfully developed competitive ELISA for progesterone detection in bovine milk and serum. This diagnostic tool facilitates hormone monitoring, identifi cation of estrus before insemination and pregnancy exclusion diagnosis.

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We collaborate with Food Biotechnology Laboratory/BIOTEC and the Department of Medical Sciences in production of MAbs to Listeria monocytogenes and also with Microarray NanoAsia Company Limited in development of antibody array for multiplex detection of food pathogens.

National Center for Genetic Engineering and Biotechnology (BIOTEC)
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