During the spring of 2008, a new clinical project, with the aim of investigating mechanisms involved in development of FMD carrier animals, has been launched in the new FMD facilities of the Danish Veterinary Institute located at Lindholm Island. The project is based on a series of animal experiments, investigating the host response to FMD infection in sheep and cattle. FMD infection in ruminants involves initial viral replication in pharyngeal epithelia, from where the virus spreads systemically via the lymphatic system. Characteristic vesicular lesions develop in the cornified stratified squamous epithelia of the coronary bands and oral cavity within a few days of infection. Viremia occurs within 2-3 days of infection, but is rapidly cleared through the effect of circulating antibodies of the adaptive immune response. The host response involves initial activation of the innate immune response, with activation and recruitment of effector-cells, and subsequent activation of T- and B-cells, leading to the production of circulating antibodies, as well as activation of cytotoxic T-cells. In ruminants, approximately 50% of animals infected with FMDV develop into persistently infected carrier animals, with intermittent excretion of live virus, whilst remaining animals clear the infection effectively. Previous experiments have indicated that the site of persistent viral replication is located in pharyngeal lymphoid tissue, as well as the basal epithelia of the dorsal soft palate In these locations, FMDV is capable of persistent replication, without being detected by the host cellular immune response, which would normally be expected to clear virus infected cells. In an ongoing series of experiments, animals of 4-5 moths of age are infected with FMD O UKG 34/2001, either through subepidermo-lingual injection or direct contact with inoculated animals. Animals are kept for approximately 2 to 4 months, and the progression of infection is monitored through samples of oropharyngeal fluid (probang samples) and serum, which are analysed for presence of live virus and development of antibodies. During different fixed time points of the infection, biopsy samples of epithelial and lymphoid tissues from the pharynx and dorsal soft palate are collected with the use of an endoscope equipped with biopsy forceps. Biopsy samples are used to investigate the host’s cellular immune response at different time points during the infection, as well as the presence of FMDV antigen using immunohistochemistry. Samples will also be used to investigate expression of genes related to the innate and adaptive immune responses through qPCR at the mRNA level.
|Publication status||Published - 2009|
|Event||3rd Annual Meeting of EPIZONE - Antalya, Turkey|
Duration: 12 May 2009 → 15 May 2009
Conference number: 3
|Conference||3rd Annual Meeting of EPIZONE|
|Period||12/05/2009 → 15/05/2009|
Stenfeldt, C., Belsham, G., Tjørnehøj, K., & Alexandersen, S. (2009). Persistence of foot-and mouth disease virus in ruminants.. Poster session presented at 3rd Annual Meeting of EPIZONE, Antalya, Turkey.