Production of monoclonal antibodies specific for the recombinant viral coat protein of Apple stem grooving virus-citrus isolate and their application for a simple, rapid diagnosis by an immunochromatographic assay

A simple and rapid immunochromatographic assay (ICA) for the diagnosis of Apple stem grooving virus (ASGV) in citrus was developed. Nine lines of monoclonal antibodies (mAbs) were produced by immunizing with a recombinant viral coat protein of ASGV as the antigen. According to the competitive-binding ELISA results, the 9 mAbs comprised 2 paratope groups, A and B. After screening for the most effective combination of mAbs, the two lines from different paratope groups (4A12 from group A and 6N31 from group B) were used to create a colloidal gold conjugate and for the test line, respectively, in ICA test plate preparation. The ICA detection using this test plate was accurate for positive and negative samples, and ASGV was detectable to a dilution of 1:2430 for the infected citrus sample. Furthermore, ICA was more sensitive than ELISA for the detection of ASGV isolates in citrus. The simple and sensitive ICA for ASGV provides a straightforward method for diagnosis by non-experts, including nursery workers and growers.