Use of Monoclonal Antibody to the Nonstructural Protein Encoded by the Small RNA of Tomato Spotted Wilt Tospovirus to Identify Viruliferous Thrips

Abstract

Tomato spotted wilt tospovirus (TSWV) replicates in and is transmitted by the western flower thrips (Frankliniella occidentalis). Monoclonal antibodies (MAbs) were made to the nonstructural protein (NSs) encoded by the small RNA of TSWV. NSs is produced in thrips in which TSWV has replicated and potentially could transmit TSWV. MAbs were used in antigen coated plate enzyme-linked immunosorbent assay (ACP-ELISA) with the Zwitterionic detergent Empigen-BB (E-BB) at 0.1% (a.i.) in antibody dilution buffer to reduce nonspecific binding that results in high absorbance readings of control samples, which are commonly observed with insects in ACP-ELISA. With E-BB, a 10-fold difference in absorbance values was observed between adult thrips that fed on healthy plants and adult thrips that fed on virus-infected plants as larvae, compared to ACP-ELISA with Tween 20, in which there was only a threefold difference in absorbance values between the same samples of thrips. The utility of ACP-ELISA in identifying viruliferous thrips was compared with transmission of TSWV by thrips to Petunia grandiflora. The two assays were in agreement 92% of the time. The errors were divided: 6% occurred when ACP-ELISA detected thrips with NSs but the thrips were not identified as transmitters in the plant transmission assay, and 2% occurred when ACP-ELISA did not detect thrips that were positive in the plant transmission assay. These findings show that ACP-ELISA with E-BB is a conservative and useful tool for identifying viruliferous thrips and has potential for use in forecasting to manage TSWV epidemics