Generation and evaluation of nanobodies specific for the proteins from infectious hypodermal and hematopoietic...

Infectious hypodermal and hematopoietic necrosis virus (IHHNV) represent the smallest virus affecting shrimp. IHHNV has a broad host range and is highly contagious, causing significant damage to the shrimp aquaculture. In this study, the corresponding variable new antigen receptors (vNARs) against two non-structural proteins (nsp1, nsp2) and a viral capsid protein (cp) of IHHNV were screened from constructed natural phage-display library and immune phage-display library of white-spotted bamboo shark (Chiloscyllium punctatum), respectively. The screened nanobodies were produced by the Escherichia coli expression system, and their affinity and specificity were compared through enzyme linked immunosorbent assay (ELISA) and western blot. The results of ELISA demonstrated that the affinity of the nanobodies screened from the immune phage-display library was superior to that of the nanobodies selected from the natural phage-display library for all the three different antigens. The colloidal gold immunochromatographic test strips for the detection of IHHNV were prepared by combining high specificity and affinity nanobodies with colloidal gold. The application of such test strip offers several advantages, including a short detection time, convenience, and low cost. These characteristics make it suitable for on-site testing in shrimp farms and significantly contribute to the detection and prevention of diseases in shrimp aquaculture.