Use of immunohistochemistry and polymerase chain reaction for detection of oncornaviruses in formalin-fixed, paraffin-embedded fibrosarcomas from cats

Abstract

Objective - To determine whether there was intralesional infection or expression of FeLV or feline sarcoma virus in suspected vaccine-associated fibrosarcomas in cats. Design - Prospective case series. Sample Population - 130 suspected vaccine-associated fibrosarcomas from cats and 1 multicentric fibrosarcoma from 1 cat. Procedure - Excisional biopsy specimens were fixed in formalin and embedded in paraffin. Expression of FeLV antigen was assessed, using a polyclonal goat anti-FeLV glycoprotein 70 (gp 70) serum and an avidinbiotin immunoperoxidase staining technique. The FeLV genome was detected with a polymerase chain reaction (PCR), using primers targeted to a conserved sequence in the untranslated region of the long terminal repeat (LTR) of the FeLV. Results - FeLV gp 70 and LTR sequence were detected in a multicentric fibrosarcoma. All 130 of the suspected vaccine-associated fibrosarcomas were FeLV gp 70 negative on the basis of immunohistochemical test results; 100 fibrosarcomas also were examined by use of PCR and were negative for FeLV LTR region. Clinical Implications - Exogenous retroviruses, FeLV, and feline sarcoma virus were not detected in these suspected vaccine-associated fibrosarcomas, using immunohistochemistry and PCR. Additional testing will be required to determine the nature of genomic alterations that are involved in the oncogenesis of vaccine-associated fibrosarcomas in cats.