1. Division of Parasitic Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
2. Atlanta Research and Educational Foundation, Atlanta, Georgia.
3. Department of Medicine, St. Petersburg State University, St. Petersburg, Russia.
4. Laboratory of Immunopharmacology, State Institute of Highly Pure Biopreparations, St. Petersburg, Russia.
5. Biology Centre of the Academy of Sciences of the Czech Republic, C. Budejovice, Czech Republic.
6. University of South Bohemia, Faculty of Agriculture, C. Budejovice, Czech Republic.