Sensitive Method for Testing Peanut Seed Lots for Peanut stripe and Peanut mottle viruses by Immunocapture-Reverse Transcription-Polymerase Chain Reaction

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Abstract
An immunocapture-reverse transcription-polymerase chain reaction (IC-RT-PCR) method was developed for testing peanut (Arachis hypogaea) seed lots for infection by Peanut stripe virus (PStV) and Peanut mottle virus (PeMV). A small slice was removed from each seed distal to the radicle of a random 100-seed sample, the slices were extracted in buffer and centrifuged, and a portion of the supernatant was incubated in a tube that had been coated with antiserum to either PStV or PeMV. Following immunocapture of the virus, the tube was washed, the RT-PCR mix (with primers designed from conserved sequences within the capsid region of each virus) was placed in the same tubes, and the test completed. Results obtained on 15 previously untested seed lots from the collection indicated good correlation between virus detected by the IC-RT-PCR method and virus detected from the same seed lots by enzyme-linked immunosorbent assay (ELISA). The IC-RT-PCR method detected three lots infected with PeMV and none with PStV from 106 seed lots grown in Ecuador (results confirmed by ELISA). The IC-RT-PCR method is more sensitive than ELISA (currently used on samples consisting of five seeds), is useful for testing large numbers of seed lots of peanut germ plasm, and could be adapted to test other plants and detect other viruses.