FIG. 4.

Analysis of T-lymphocyte populations in pharyngeal tonsil and retropharyngeal lymph nodes. CD4⁺ and CD8⁺ lymphocytes from mock-infected and BHV-1-infected calves (7 dpi) were prepared from pharyngeal tonsil and retropharyngeal lymph node as described in Materials and Methods. Mononuclear cells were incubated with monoclonal antibodies directed against bovine CD4⁺ and CD8⁺ T cells. FITC- or PE-conjugated IgG that was directed against the monoclonal antibody was used as a secondary antibody. FITC- or PE-positive cells were identified by flow cytometry.