Abstract
An immunohistochemical procedure was described for demonstration of avian leukosis virus (ALV) antigens in cell culture (1), utilizing the “unlabeled antibody enzyme method” developed by Sternberger et al. (2). We now have applied this procedure to detect ALV antigen in paraffin-embedded tissues of the intact host.
Antiviral antisera were obtained from chickens infected either with RAV-1, which belongs to ALV serotype A, or with RAV-6, which is serotype B. In neutralization tests the antisera reacted only with viruses of the homologous serotype. Pancreas, which is a particularly rich source of ALV in infected birds, was obtained from chickens infected with the F-42 strain of ALV, which belongs to serotype A. Pancreases of uninfected birds from a flock known to be free of ALV infection were used as controls. Tissue samples, fixed overnight with 4% formaldehyde in 0.1 M phosphate buffer (pH 7.2), were washed in the buffer, dehydrated by passage through a graded ethanol series, cleared with cedar-wood oil, and embedded in paraffin using routine histologic procedures. Xylene or similar solvents are most commonly used as clearing agents for paraffin embedment, however, the prolonged treatment necessary for clearing the tissue samples apparently modified the viral antigen and greatly reduced the intensity of specific staining. This was avoided by the use of cedarwood oil as a clearing agent. Sections 5 μm thick were mounted on coverglasses and the paraffin was removed with xylene. This brief treatment with xylene did not detectably affect the intensity of staining as compared with sections in which ether was used to remove paraffin. The sections were rehydrated through graded ethanol, and the immunohistochemical procedure carried out as described in detail previously (1). Briefly, the tissues were first allowed to react with antiviral antibodies prepared in chickens.
Get full access to this article
View all access options for this article.