A novel technique of endoscopical collection of small tissue samples was used to obtain sequential tissue samples from the dorsal soft palate (DSP) of individual cattle infected with foot-and-mouth disease virus (FMDV) at different phases of the infection. Levels of mRNA encoding interferon (IFN)-α and IFN-β as well as tumour necrosis factor (TNF)-α were measured in these samples by quantitative reverse transcriptase polymerase chain reaction. Expression of IFN-β mRNA was significantly down-regulated in the biopsy samples harvested during the acute phase of infection, while there was no statistically significant effect on the expression of IFN-α mRNA compared with baseline levels. In contrast, the mRNA encoding TNF-α was significantly up-regulated in samples collected during both acute and late (>28. days post infection) phases of infection. There were also significantly higher levels of TNF-α mRNA expressed in samples derived from animals that were identified subsequently as persistently infected FMDV-carriers. It was concluded that there was a significant difference in the host-response in the DSP of calves that were identified as persistently infected, subclinical carriers of FMDV.
Bibliographical noteFunding Information:
This work was financed in part by a PhD scholarship to CS funded by the Technical University of Denmark (DTU) and the Research School for Animal Production and Health at the Faculty of Life Sciences , Copenhagen University. Dr S. Alexandersen, CFIA-NCAD, Winnipeg, Canada, is acknowledged for having supplied the original virus inoculum. J. Bashiruddin, IAH-Pirbright is thanked for having assisted with experimental protocols for the gene-expression analysis. K. Tjørnehøj is thanked for assistance during performance of animal experiments. Animal care-takers H. Andersen, J. Oxfeldt, H. Lehman, O. Bille and M. Petersen are thanked for their assistance. P. Normann, J. Borch, J. Christiansen, J. Jensen, T. Rasmussen and T. Frederiksen are thanked for excellent technical assistance with the analysis of samples.
- Cytokine mRNA
- Foot-and-mouth disease
- Pharyngeal epithelium