USE OF IMMUNOHISTOCHEMISTRY AND POLYMERASE CHAIN-REACTION FOR DETECTION OF ONCORNAVIRUSES IN FORMALIN-FIXED, PARAFFIN-EMBEDDED FIBROSARCOMAS FROM CATS

Objective-To determine whether there was intralesional infection or ex pression of FeLV or feline sarcoma virus in suspected vaccine-associat ed fibrosarcomas in cats. Design-Prospective case series. Sample Popul ation-130 suspected vaccine-associated fibrosarcomas from cats and 1 m ulticentric fibrosarcoma from 1 cat. Procedure-Excisional biopsy speci mens were fixed in formalin and embedded in paraffin. Expression of Fe LV antigen was assessed, using a polyclonal goat anti-FeLV glycoprotei n 70 (gp 70) serum and an avidin-biotin immunoperoxidase staining tech nique. The FeLV genome was detected with a polymerase chain reaction ( PCR), using primers targeted to a conserved sequence in the untranslat ed region of the long terminal repeat (LTR) of the FeLV. Results-FeLV gp 70 and LTR sequence were detected in a multicentric fibrosarcoma. A ll 130 of the suspected vaccine-associated fibrosarcomas were FeLV gp 70 negative on the basis of immunohistochemical test results; 100 fibr osarcomas also were examined by use of PCR and were negative for FeLV LTR region. Clinical Implications-Exogenous retroviruses, FeLV, and fe line sarcoma virus were not detected in these suspected vaccine-associ ated fibrosarcomas, using immunohistochemistry and PCR. Additional tes ting will be required to determine the nature of genomic alterations t hat are involved in the oncogenesis of vaccine-associated fibrosarcoma s in cats.