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 nec rosis strain of potato virus Y (PVY(N)), initial enzyme-linked immunos orbent assay (ELISA) screening with one monoclonal antibody (MAb 295.5 ) followed by a second ELISA screening with a panel of several MAbs (4 E7, Bioreba, 1F5 and 295.5) was assessed as a means of rapidly identif ying 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 th e second ELISA, MAbs 4E7, IF5 and Bioreba all enhanced test specificit y relative to the retest with MAb 295.5. All the MAbs were found to re act, 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 obser ved 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% fo r the other MAbs.