Affiliation: | Department of Microbiology and Immunology, College of Physicians and Surgeons, Columbia University, 701 W. 168th St., New York, New York 10032,1. Departments of Ophthalmology and Molecular Microbiology and Genetics, University of Pittsburgh, 203 Lothrop St., Pittsburgh, Pennsylvania 15213,2. Department of Microbiology and Immunology, Queen''s University, 18 Stuart St., Kingston, Ontario, Canada K7L 3N63. |