Simple immunoblot and immunohistochemical detection of Penaeus stylirostris densovirus using monoclonal antibodies to viral capsid protein expressed heterologously

Penaeus stylirostris densovirus (PstDNV), called formerly infectious hypodermal and hematopoietic necrosis virus (IHHNV), is an important shrimp pathogen which can cause mortality in the blue shrimp Penaeus (Litopenaeus) stylirostris and stunting in the whiteleg shrimp Penaeus (Litopenaeus) vannamei. Five monoclonal antibodies (MAbs) were produced against the 37 kDa capsid protein 3 (CP3) of PstDNV expressed heterologously in the form of a fusion protein with glutathione-S-transferase called GST-CP3. All MAbs belonged to the IgG2b subclass and could bind to GST-CP3 at 300 pg/spot in immunodot-blot tests. They could detect CP3 in naturally infected shrimp extracts by Western blotting and dot blotting and in shrimp tissues by immunohistochemistry without cross-reactivity to extracts from uninfected shrimps or shrimps infected with several other viruses. Although dot blot assay sensitivity was approximately 1000 times lower than that of one step PCR for PstDNV, it easily detected PstDNV infections in field samples of Penaeus monodon and Penaeus vannamei.