Detection of hepatitis B virus surface antigen in liver of swine by immunofluorescence staining. Different frozen sections of HBsAg-positive cells (A and B) from liver of pigs stained in green using Alexa Fluor 488-conjugated anti-mouse IgG as secondary antibody. Evans Blue (red) and DAPI (blue) counterstained all liver sections. Images were examined under a confocal immunofluorescent microscope (Original magnifications x40). Liver sections from negative Hepadnavirus-DNA animals were used as negative controls (C).