What is the primary focus of a virologist's studies?

A virologist primarily focuses on the study of viruses, which includes understanding their structure, classification, and evolution, as well as their mechanisms of infection and the diseases they cause. This field encompasses the investigation of how viruses replicate, spread, and interact with host organisms, including the immune responses they provoke.

Virologists also play a crucial role in public health by researching viral outbreaks and developing vaccines and antiviral treatments. Their work is essential in combating diseases caused by viruses, such as influenza, HIV, and COVID-19. In contrast, the other options pertain to different microorganisms—bacteria, fungi, and parasites—each studied by specialists in those respective fields, such as bacteriologists, mycologists, and parasitologists.