Molecular characterization of Indian isolate of peanut mottle virus and immunodiagnosis using bacterial expressed core capsid protein.

Peanut mottle virus (PeMoV), a seed borne potyvirus was recorded in India in 1978, however the virus was not characterized at molecular level. In the present study, an isolate of PeMoV infecting peanut in southern India was characterized based on host reactions and coat protein (CP) gene sequence, which revealed that the Indian isolate was very close to a peanut isolate reported from Israel and distinct from pea isolate reported from USA. The core region of CP gene that contained majority of the predicted epitopes was successfully expressed (1.75 mg/l) in Escherichia coli as a 22 kDa protein. A high titer polyclonal antibody (PAb) to the expressed core CP was produced, which efficiently detected PeMoV. The antiserum was useful in specific detection of PeMoV as it showed negligible cross reactivity with the other potyviruses e.g., peanut stripe virus, potato virus Y, papaya ringspot virus and onion yellow dwarf virus. The PAb was validated in ELISA using 1,169 field and greenhouse samples of peanut which showed 1.85-26.3 % incidence of PeMoV in peanut seed multiplication field during 2011-2012. This is the first report of immunodiagnosis of PeMoV with a PAb to recombinant core CP of PeMoV.