Interferon expression in feline Borna disease

Abstract: Borna disease is caused by Borna disease virus (BDV). This disease is characterised as a neurogical illness of the central nervous system (CNS), known to occur in several vertebrates like horses, cats and sheep. Cats mainly at the age of 1 to 4 years, living outdoors, have also been shown to subtract the BDV infection. A typical sign in cats of BDV infection is a change in behaviour, i.e. some cats get increased affection and meow more than usually. In addition, a lot of cats get ataxic and their balance is adversely affected. The route of infection is still not fully known. One theory is that the virus spreads and infects through saliva and the respiratory tract, respectively. Some studies have shown that the infection is not commonly transmitted between cats. Thus, it seems more likely that another species, such as rodents or birds, are the carrier of the disease. This hypothesis seems more likely since the cats that have been diagnosed as carriers of BDV have been living outdoors. There are no sufficient diagnostic methods for BDV. Therefore necropsy and histopathologic examination of the brain tissue is the method for diagnosis and confirmation of BDV infection. The aim of this study was to investigate whether the gene expression, measured by quantitative RT-PCR, of IFN-α , -β and -γ in the brain tissues of Borna disease diagnosed cats is induced. To normalize the IFN gene expression, the reference genes, HPRT, RPS7 and YWHAZ, were used. In addition, PCR-products were confirmed by gel electrophoresis. With the use of different PCR measurements for the expression of reference genes it was studied whether Borna disease was associated with gene expression of cytokines in the brain. When comparing the Ct-values of IFN- with the histopathological finding it was clearly evident that Borna disease diagnosed cats had a much higher gene expression than the other cats. However, a majority of non virus diagnosed cats showed higher Ct-values or no Ct-values at all. Consequently, results showed clear association between Borna disease diagnosis and increased IFN-γ gene expression.