<p>Microscopic distribution of FMDV structural (VP1) and non-structural (3D) protein in dorsal nasopharyngeal mucosa of non-vaccinated (A-C) and vaccinated (D-F) cattle at 24 hpi. Multichannel immunofluorescent technique. <b>A)</b> Nasopharyngeal mucosa of non-vaccinated steer at 24 hpi (animal number 3). FMDV VP1 (red) and 3D (aqua) proteins co-localize with cytokeratin (green) in foci of primary FMDV infection in superficial layer of follicle-associated epithelium. Scarce MHC II+ cells (purple) are present in the subepithelium. 20x magnification, scale bar 50μm. <b>B-C)</b> 40x magnification of region identified in (A). <b>B)</b> Select channel combinations demonstrating co-localization of FMDV VP1(red) and FMDV 3D (aqua) with cytokeratin (green), but not with MHC II (purple) <b>C)</b> Merge of all images shown in (B), scale bar 25μm. <b>D)</b> Nasopharyngeal mucosa of vaccinated steer at 24 hpi (animal number 11). FMDV VP1 (red) and 3D (aqua) proteins co-localize with cytokeratin (green) within follicle associated epithelium. Intra-epithelial MHC II+ cells (purple) are in close proximity to virus-infected epithelial cells. 20x magnification, scale bar 50μm. <b>E-F)</b> 40x magnification of region identified in (D). <b>E)</b> Select channel combinations demonstrating FMDV VP1 (red) and 3D (aqua) colocalization with cytokeratin (green)-expressing cells and with MHC II- expressing cells (purple). <b>E)</b> Merge of images shown in (F), scale bar 25μm.</p
