Felid herpesvirus-1 infection: influence on proinflammatory cytokine and toll like receptor expression in vitro

Abstract

Felid herpesvirus 1 (FeHV-1) causes an acute respiratory illness known as feline rhinotrachetitis. Moreover, it is associated with several syndromes in the feline eye including conjunctivitis, epithelial keratitis, herpes stromal keratitis (HSK) and corneal sequestration. The aim of this study was to gain first insights into the interaction between FeHV-1 and the feline innate immune system, specifically in peripheral blood mononuclear cells (PBMC). FeHV-1 infection in Crandell Reese Feline Kidney cells (CRFK) as well as in feline PBMC resulted in the induction of proinflammatory cytokine mRNA, i.e. for Interleukin-6 (IL-6), Interleukin-1 (IL-1) and Tumor necrosis factor alpha (TNF α). To evaluate a potential role of Toll like receptors (TLR) in the infection with FeHV-1, the level of TLR mRNA in non-infected as well as in infected feline cells was measured. Both TLR 2 and 3 mRNA were down-regulated in FeHV-1-infected cells. Results concerning the expression of TLR 9 mRNA were inconsistent, showing up-regulation in some instances and down-regulation in other instances. TLR 7 was clearly up-regulated upon infection of CRFK cells with FeHV-1, not only on the mRNA level but also in terms of function. Intriguingly, the same effect was not observed in feline PBMC. Thus, the interaction between FeHV-1 and the innate immune system proceeds in a celltype-specific manner. Key words: Felid herpesvirus 1 / innate immunity / Toll like receptor.