Application of immuno-diagnosis for plant viruses occurring in India

Abstract

Diseases caused by viruses cause heavy crop losses worldwide including India. Correct diagnosis of viruses is the primary requirement for disease management. Of the different methods available for diagnosis, serological methods are useful in the detection of viruses in seeds, plants and insect vectors. The production of virus specific antiserum is the basis for a successful serological method. The earliest serological methods such as precipitin tests are low in sensitivity. With the advent of enzyme linked immunosorbent assay (ELISA) and its subsequent application to plant virus detection during 1980s, some laboratories in India also started working on the same. During 1990s, ELISA and its variants became more popular in many laboratories of India working on plant viruses. During the same period Indian researchers also used other serological methods such as dot immunobinding assay (DIBA), immunosorbent electron microscopy (ISEM), electro-blot immunoassay (EBIA) and florescent antibody technique in the detection of plant viruses. Immunocapture PCR (IC-PCR) which combines both serology and PCR has also been used by many Indian researchers in the identification and characterization of viruses infecting different crops. Lateral flow immunoassay technology is the recent technique that offers several advantages over traditional immunoassays, such as procedural simplicity, limited requirement for special skills or expensive equipment, and rapid results is also gaining importance in the country. During the last decade, recombinant antibody (rAb) engineering has emerged as one of the promising approaches in plant virus diagnosis. rAb fragments in all various formats (Fab, Fv and scFv) can be expressed in different systems including bacteria, insect, yeast, plant and mammalian cells, which can be used efficiently in various format of ELISA for diagnosis of plant viruses. India also started a modest beginning in this area now.