| Sumario: | Strangles is a severe equine respiratory infection, caused by the bacterium Streptococcus equi subspecies equi affecting horses of all ages and types worldwide. Infected horses suffer from fever, coughing and copious nasal discharge as well as abscesses in lymph nodes in the head and throat. S. equi invades the body through the mouth or nose of the horse, and previous studies have shown that the interaction is dependent on various extracellular proteins, several of which have been characterized. In this project one of these proteins, FNE, has been studied. FNE is a secreted fibronectin- and collagen- binding protein unique to S. equi. The main purpose of this project was to identify the collagen- and fibronectin-binding parts of the protein. This was performed by designing primers and truncating the protein from both N- and C-termini (Appendix I). The binding capacities of the truncated proteins were assayed by dot blotting. To further examine the properties of the truncated proteins inhibition assays with antibodies against FNE were performed. Results show that fibronectin binding is restricted to the C-terminal part of the protein and that the amino acids GLEGGSS (228 – 234) are required for the binding. By contrast, collagen binding regions seem to be present at both N- and C-termini, i.e. the collagen binding domain is fairly large. Antibodies seem to be directed to the central part of the protein, and consistent with the above results, interaction with antibodies inhibits fibronectin- and collagen- binding. The results will hopefully contribute to a deeper basic knowledge about S. equi and the FNE protein as well as be important in the progress towards the development of a safe and effective vaccine against strangles.
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