Figure. Western blot analysis of serum reactivity to Enterocytozoon bieneusi proteins, Czech Republic. Serum selection: HIV-positive persons (indirect fluorescence antibody [IFA] assay titers >400); blood donors, professionals with risk exposure (IFA titers >200). Serum samples diluted 1:100. Molecular weight markers (Precision Plus Protein Standard, Bio-Rad Laboratories, Hercules, CA, USA): lane 1, positive control (HIV/AIDS patient with proved E. bieneusi infection); lane 2, negative control (seronegative blood donor); lanes 3–8, selected samples from HIV-positive persons (3–6 IFA positive); lanes 9–14, selected samples from blood donors (9–11 IFA positive); lanes 15–20, selected samples from persons with occupational exposure to animals (15–18 IFA positive). Arrow indicates the 32-KDa protein fraction. Values on the left are in kilodaltons.