Virology

Definition

Virology is the study of viruses and their role in disease. The science includes human, animal, insect, plant, fungal, and bacterial virology. Researchers may work in clinical, ecological, biological, or biochemical fields.

History

The first studies of viruses and their role in causing disease began thousands of years ago in China, when an early form of vaccination against smallpox was developed. This early process involved applying tiny amounts of secretions from a person who had smallpox to those who had not yet been infected to keep them from becoming infected. Viruses began to receive closer study in 1892, when Russian bacteriologist Dmitri Ivanovsky noticed in an experiment that the agent that carried tobacco mosaic disease could pass through filters that kept out bacteria. Though the question still existed as to what exactly this agent was, it was soon discovered by Dutch microbiologist Martinus Beijerinck that the agent grew in the host and, therefore, was not a toxin. However, the agent had other characteristics not found in bacteria. Louis Pasteur then experimented with immunizations using viruses, and others continued these studies throughout the nineteenth century and into the twentieth century.

The modern study of virology began early in the twentieth century with the discovery of bacteriophages, viruses that infect bacteria. Plant viruses and bacteriophages are fairly easy to grow in a laboratory environment, so it became easier to experiment with and observe these viruses. Animal viruses normally require a living host, which impeded study in virology until 1931, when it was demonstrated that the influenza virus could be grown in fertilized chicken eggs. This method is still used to develop flu vaccines.

Also in the early twentieth century, discussions began about how viruses could cause cancer by transduction (that is, by transferring genetic material from one bacterium to another using a bacteriophage). Virologist Peyton Rous described this type of oncovirus in chickens in 1911; it was later determined to be a retrovirus, a type that includes the human immunodeficiency virus (HIV).

By 1937, the yellow fever virus was being grown in chicken eggs, and vaccines were being developed with many different viruses. With the introduction of the electron microscope in the 1940s came the ability to see viruses. With improved technology and data, virologists developed various systems for classifying virus types, as well as useful methods for mathematical modeling of viruses in terms of both structure and spread.

Viruses have been the cause of many of the epidemics and pandemics that have occurred worldwide. Historical examples include the yellow fever epidemics of 1793 and 1878 and the Spanish flu pandemic of 1918. Viruses discovered for the first time in the late twentieth and early twenty-first centuries have also caused outbreaks at the epidemic or pandemic scale, including of HIV infection, severe acute respiratory syndrome (SARS), H1N1 influenza, and coronavirus 2019 (COVID-19).

Virologists

As undergraduates, virologists generally study biology or chemistry, with a focus on biochemistry and cell biology. (The biology of viruses is closely tied to cell biology.) Other common areas of study are epidemiology, behavioral and social sciences, and the humanities because of the impact of viruses on human health. Virologists have extensive science backgrounds and also may take courses in physics, mathematics, molecular biology, immunology, and structural biology.

Most virologists continue their education to earn a medical degree (MD). They attend medical school for four years, complete a residency of three years, and train in postdoctoral research for three to five years. Others earn a doctoral degree (PhD) by attending graduate school for four to six years and then training in postdoctoral research for three to five years. Graduates may then pursue research in a variety of areas, including human health, infectious diseases, and epidemiology. Virologists who intend to teach often substitute formal teacher training for postdoctoral research.

Impact

Public health officials, including virologists, continually work to identify threats from viral infections and ways to counter them. For example, each year, researchers attempt to determine what types of influenza viruses are likely to cause the most infections during the yearly flu season. Virologists help to craft a vaccine to keep these viruses from spreading. Virology is also crucial to understanding and containing newly emerging diseases, as with the sudden appearance of the Ebola virus in humans in the 1970s or the identification of novel coronaviruses in the 2000s and 2010s.

Even more broadly, virology has a significant impact on science in general, as it involves the investigation of crucial aspects of cellular function and other fields of biology. One important area of research is how a bundle of proteins called interferon, which are produced during a viral infection of a cell, triggers an immune response. These proteins somehow inhibit the replication of the virus in the cell. Another cutting-edge aspect is looking at how viruses may cause some types of cancers and how viruses cause the body’s immune response to occasionally malfunction and develop autoimmune disorders. Viruses have an interesting role in genetics because of their ability to carry extra genetic material into host cells. This ability has been studied by virologists through transferring material specifying a particular enzyme into the nucleus of host cells that lack the ability to synthesize that enzyme. This method has particular interest for those studying hereditary enzyme-deficiency diseases, such as diabetes, because these gene transfers may help treat or cure such diseases.

Following the mistrust expressed by some consumers during the COVID-19 pandemic, individuals in the field of virology began calling for better communication between the public and the scientific community. Additionally, understanding emerging and reemerging viruses, the evolution of viruses, and the interaction of viruses within their hosts continue to be priorities for modern virologists. Trends in the industry include interdisciplinary collaborations, research concerning equality in health access, accurate disease prediction, and early identification of the evolution of viruses.

Bibliography

Carter, John, and Venetia Saunders. Virology: Principles and Applications. 2nd ed., John Wiley & Sons, 2013.

Crawford, Dorothy H. Viruses: A Very Short Introduction. 3rd ed., Oxford UP, 2022.

Dimmock, Nigel J., et al. Introduction to Modern Virology. 7th ed., John Wiley & Sons, 2016.

Meštrović, Tomislav. "What Is Virology?" News-Medical.Net, 25 Sept. 2022, www.news-medical.net/health/What-is-Virology.aspx. Accessed 10 Dec. 2024.

Norkin, Leonard C. Virology: Molecular Biology and Pathogenesis. ASM Press, 2010.

O'Brien, Harvey. Advanced Principles of Virology. Callisto Reference, 2019.

Sanyal, Sumana. “Crossroads in Virology: Current Challenges and Future Perspectives in the Age of Emerging Viruses.” Disease Models & Mechanisms, vol. 16, no. 10, 2023, doi.org/10.1242/dmm.050476. Accessed 10 Dec. 2024.

Shors, Teri. Understanding Viruses. 2nd ed., Jones & Bartlett Learning, 2013.