The application of immunogold silver staining (IGSS) for the detection of transmissible gastroenteritis virus in fixed tissues.

Protein A-gold (PAG) and a primary porcine antiserum were used in immunogold silver staining (IGSS) for the detection of transmissible gastroenteritis virus (TGEV) in formalin-fixed paraffin-embedded tissue sections of small intestine originating from infected pigs. Immunogold electron microscopy was used to evaluate the reactivity of the prepared PAG marker with the specific porcine TGEV antiserum. Gold particles were closely associated with single virions and immune aggregates of TGEV. When IGSS, using PAG as the marker, was applied to tissue sections, dark staining of TGEV-infected villous enterocytes was observed. Background was low, allowing good visualization by light microscopy of the distribution of viral antigen. Two other gold conjugates, protein A/G-gold (PA/GG) and protein G-gold (PGG), were tested in IGSS. The labeling with PA/GG was comparable to that obtained with PAG. However, no staining was observed when PGG was used. The use of IGSS and PAG offers advantages and may represent a useful technique for the detection of other viral pathogens.