Virology is the study of viruses – submicroscopic, parasitic particles of genetic material enclosed in a protein coat – and virus-like agents. Virology is a subfield of microbiology, and overlaps with other fields such as immunology, cell biology, molecular biology, pathology, and infectious disease.
A virologist is a scientist who specializes in the study of viruses. Virology research focuses on understanding how viruses cause infection and disease in animals and plants, how they are transmitted between hosts, how to control viral infections using vaccines or antiviral drugs. In addition to their medical importance, many viruses have significant economic impact on agriculture and livestock production.
Viruses are very diverse; they can be classified according to their shape (e.g., rod-shaped or spherical), size (e.g., smallpox virus or vaccinia virus), genome type (DNA or RNA), host range (the types of cells or organisms that they infect), mode of transmission (direct contact, airborne droplets, vectors such as insects or ticks), replication strategy (lytic or lysogenic), and antigenicity (the ability to provoke an immune response).
The term “virus” comes from the Latin word for “poison” or “sap”; early observers noted that diseases such as rabies made victims seem poisonous. The first scientific reports about viruses were published in 1892 by Dmitri Ivanovsky and Martinus Beijerinck; both scientists observed that tobacco mosaic disease could be transmitted by filtered extracts from infected leaves without bacteria present. In 1898 Friedrich Loeffler and Paul Frosch showed that foot-and-mouth disease was caused by a filterable agent; these workers coined the term “virus” to describe these agents.
Infectious diseases caused by viruses include COVID-19 pandemic coronavirus SARS-CoV-2 respiratory illness , common cold , influenza , Ebola hemorrhagic fever , West Nile fever , yellow fever , dengue fever , hepatitis A , hepatitis B , herpes simplex encephalitis . Vaccination is the most effective way to prevent these diseases