Investigation of potential viral etiologies in the pathogenesis of feline vaccine site-associated sarcomas

by Kidney, Beverly Anne

The pathogenesisof félinevaccine site-associatedsarcomas (VSSs) remairu obscure. The low prwalence of VSSs suggests that congenital or aqumd genetic factors within individual susceptîîIe cats may act as initiatorsof oncogenesis. The pqse of the study was to investigate potentid viral candidates in the etiopathogenesis of VSSs. RetroWuses investigated included feline immmodeficiency virus (Fm, feline foamy virus (FeFV) and endogenous feline leukemia vims (enFeLV). Vaccination couid increase replication and/or expressionof Iatent retroWuses or endogenous retroviniseswithin proliferating fibroblasts ador infiltrathg leukocytes. Malignant transfomation could then result hminsertional activationor inactivation of ceU cycle regulatory genes. DNA viruses evaluated included papillomavirus (PV),polyomavinis (PyV) and herpemirus. Members of these three virai familieshave oncogenic potential and could be inttoduced either as vaccine contaminants or as skin contaminantsîmsported to the subcutis by vaccination. Also, non-pathogenic or latent Wuses pre-existing in hast tissues codd become oncogenic within the local milieucreatedby vaccination. Fifty formalin-fixed, para5-embedded VSSs wen negativefor the five exogenous virus using polymerase chah reaciion (PCR) andlof immunohistochemistry. The level of enFeLV RNA in VSSs was mt signincantiy different compared to thatin non vaccine site-associatedfehe fibrosarcoma~ ushg semi-quantitative revemetranscriptasePCR. The si&cance of these tCSUIts is that the retroviruses FIV, FeFV and enFeLV, and the DNA vinises PV, PyV and hqesvim do not appeatto be directiyinvofved in the etiopathogenesisof VSSs.