Three sensitive and reliable serological assays for detection of potato virus A in potato plants

Vegetative propagation of seed potato often allows passaging of viruses to seed tubers, resulting in significant yield losses and reduction of potato tuber quality. Thus, virus detection approach is crucial for effective virus management programs and the production of virus-free seed potatoes. Among the reported potato-infecting viruses, potato virus A (PVA) is considered as one of the most important viruses in potato-growing regions worldwide. This study prepared four hybridoma lines secreting PVA-specific monoclonal antibodies (MAbs) (2D4, 8E11, 14A6 and 16H10) using purified PVA virions as an immunogen. Western blotting results indicated that all the four MAbs reacted strongly and specifically with the putative capsid protein of PVA. Using these four MAbs, this study developed antigen-coated plate enzyme-linked immunosorbent assay (ACP-ELISA), Dot-ELISA and Tissue print-ELISA for detection of PVA infection in potato plants. The results indicated that PVA can be detected in crude tissue extracts from infected potato plants diluted up to 1:327 680 (w/v, g mL–1) by ACP-ELISA or up to 1:10 240 by Dot-ELISA. The Tissue print-ELISA is the quickest and easiest approach among the three serological assays, and is more suitable for onsite large-scale potato screening programs. Further analyses of field-collected potato samples showed that the sensitivities and specificities of the three serological approaches were similar to those of RT-PCR in PVA detection and confirmed that PVA is currently widespread in Yunnan and Zhejiang provinces of China. Hence, the results strongly suggest that these highly sensitive serological approaches based on PVA-specific MAbs are useful and powerful for PVA-free seed potato production programs and PVA field surveys.