Alarm lateral flow immunoassay for detection of the total infection caused by the five viruses

This study presents new type of the lateral flow immunoassay (LFIA) for multi-target analysis. A test, named alarm-LFIA, has an essentially new function that consists in notice (signaling the danger) about the presence at least one target from the controlled list without identification. The design of the alarm-LFIA assumes one test zone, which contains a mixture of antibodies, and multi-specific conjugate that binds the several targets. The alarm test is based on the novel conjugate with broaden specificity due to the immobilisation of a mix of antibodies, specific to several structurally different targets, on the surface of gold nanoparticles. For proof of concept, multi-specific conjugate to five important potato viruses (potato virus X, -M, -S, -Y and potato leaf roll virus) was fabricated using five antibodies with different specificity. The alarm-LFIA was developed for rapid detection of the total infection caused by up to five viruses. Detection limits of the viruses in potato leaf extracts are from 10 to 30 ng/mL. The alarm-LFIA was successfully used for viruses' detection in potato leaves; results were confirmed by enzyme-linked immunosorbent assay. The proposed approach of alarm-LFIA shows great potential for the various cases when different targets of interest can occur simultaneously or separately in samples.