Diagnosis of Sugarcane streak mosaic virus using recombinant coat protein antiserum in sugarcane

Sugarcane streak mosaic virus (SCSMV) is the most widespread virus associated with sugarcane mosaic in India and other Asian countries. After characterization of the virus, detailed studies were carried out to express the virus coat protein (CP) in an expression vector along with maltose binding protein (MBP) as a fusion protein. Later polyclonal antisera were produced against recombinant SCSMVcp and the serum detected the recombinant MBP-SCSMV-CP fusion protein upto 1:40,000 dilutions in direct antigen coating (DAC)-ELISA and sensitivity of the antiserum was found to be as low as 2.5 ng in ELISA. Further, in the assays the serum detected the virus antigen from infected leaf extracts diluted to 1:10,000. Subsequently the efficiency of the new antiserum was validated with 349 leaf samples collected from 332 sugarcane cultivars showing asymptomatic to varying degrees of mosaic/streak mosaic symptoms by DAC-ELISA. Among them, 251 leaf samples were found to be positive. This assay established that the SCSMVcp antiserum is highly efficient to detect SCSMV infection in naturally infected / asymptomatic sugarcane field samples. The polyclonal antiserum produced in this study will serve as an important resource for indexing of sugarcane tissue culture and mother stock materials for SCSMV infection.