Development of Novel Egg Yolk Antibody (IgY)-Based Immunological Tools for the Early Detection of White Spot Syndrome Virus in Shrimp.

Abstract

The white spot syndrome virus (WSSV) is a major threat to shrimp farming and causes substantial economic losses in aquaculture. The VP28 envelope protein of WSSV facilitates initial systemic infection in shrimp. Although mammalian-derived antibodies are used for diagnostic tests, high costs and animal welfare concerns necessitate alternative strategies. This study produced specific yolk immunoglobulin (IgY) by immunising laying hens with the VP28 envelope protein as a cost-effective alternative for WSSV detection. IgY antibody titres and specificity were assessed using ELISA and western blotting, and their performance was compared with that of IgG rabbit antibodies. Stability was tested under various pH and salinity conditions. A time-course infectivity experiment analysed infection progression. Western blot analysis using IgY detected WSSV in shrimp samples at 6 h post-infection (h p.i.) in the haemolymph and eyestalk. By 12 h p.i., the gills, head soft tissue, appendages and other organs showed positive. Shrimp mortality occurred at 36 h p.i. Western blot findings matched those of IgG rabbit antibodies, proving that IgY antibodies were viable. Based on these findings, a validation study was conducted using 55 field samples collected from various regions of India. IgY serves as an innovative biological recognition component for early diagnosis of WSSV, offering an ethical and economical option for disease management in aquaculture.