This subfield of Microbiology is the study of biological viruses, including how they infect cells and the disease process and treatment. The Virologist is an expert on the structure, function, and means of classification of many known viruses. He is also familiar with the pathelogical effects of viruses and means of replication, including their attachment, penetration, and uncoating phases. He is highly knowledgeable about the immune defenses of creatures and the control and treatment of viral infections. He can also study their genetic structure in an effort to gain clues about their nature. The Virologist can specialize in specific viral categories and even a specific strain.