Feline herpesvirus type-1 transcription is associated with increased nasal cytokine gene transcription in cats

The etiopathogenesis of chronic nasal discharge in the cat is poorly understood. The objective of this study was to investigate alterations in transcription of genes for cytokines and chemokines in association with feline herpesvirus-1 (FHV-1) mRNA transcription. Nasal samples from 21 cats were submitted for FHV-1 virus isolation (VI), traditional endpoint polymerase chain reaction (PCR) detection of FHV-1 DNA, and quantitative real-time TaqMan PCR analysis of cytokines and chemokines (interleukin [IL]-4, IL-5, IL-6, IL-10, IL-12p40, IL-16, IL-18, interferon [IFN]-γ, tumor necrosis factor [TNF]-α, and regulated on activation normal T cell expressed and secreted protein [RANTES]) and of FHV-1 mRNA and DNA. Co-infection with feline calicivirus or Chlamydophila spp. was excluded in all cats. Gene transcription in nasal samples from four specific pathogen free (SPF) cats served as the calibrator for cytokines. FHV-1 was detected by VI in 14 of 21 samples, by traditional PCR in 18 of 21 samples, and by quantitative PCR in 13 (mRNA+) and 18 (DNA+) samples. Nasal samples from cats positive for FHV-1 mRNA displayed significantly increased transcription of IL-6, IL-10, IL-12p40, IL-18, IFN-γ, TNF-α, and RANTES (P < 0.05) in comparison to samples from cats negative for FHV-1 mRNA. The cycle threshold for FHV-1 DNA was significantly higher in cats with detectable FHV-1 mRNA (P < 0.05). Increased transcription of cytokines/chemokines in cats with detectable mRNA for FHV-1 suggests a role for FHV-1 in nasal inflammation.