CONSECUTIVE ELISA SCREENING WITH MONOCLONAL-ANTIBODIES TO DETECT POTATO VIRUS-Y(N)

In a 1992 survey of potato fields in Canada for the tobacco veinal necrosis strain of potato virus Y (PVY(N)), initial enzyme-linked immunosorbent assay (ELISA) screening with one monoclonal antibody (MAb 295.5) followed by a second ELISA screening with a panel of several MAbs (4E7, Bioreba, 1F5 and 295.5) was assessed as a means of rapidly identifying positive samples prior to confirmation by bioassay. MAbs 4E7 and Bioreba were used in double antibody sandwich (DAS) ELISA, while MAbs 1F5 and 295.5 were used in triple antibody sandwich (TAS) ELISA. In the second ELISA, MAbs 4E7, IF5 and Bioreba all enhanced test specificity relative to the retest with MAb 295.5. All the MAbs were found to react, to some degree, with isolates of the common strain of PW (PVY(O)), but MAb 4E7 was the most specific with no cross-reaction being observed at, or above, the signal to noise (S:N) threshold of 4:1. However, this MAb was also the least sensitive. At the S:N threshold of 4: 1, its sensitivity was 68%, compared to a sensitivity of close to 100% for the other MAbs.