What is 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 received 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.

Already in 1903, discussions had begun about how viruses caused cancer by
transduction (by transferring genetic material from one bacterium to another using
a bacteriophage). Peyton Rous described this type of oncovirus in chickens in 1911, and
it was later determined to be a retrovirus, a type that includes the
human
immunodeficiency virus.

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 1940’s came the ability to see viruses.

Viruses have been the cause of many of the epidemics and
pandemics that have occurred worldwide. These epidemics
include the yellow fever epidemics of 1793 and 1878 and the Spanish flu pandemic
of 1918. Late twentieth and twenty-first century viruses have caused epidemics and
pandemics of human immunodeficiency virus (HIV) infection, severe acute respiratory
syndrome (SARS), and H1N1
influenza.

Virologists

As undergraduates, virologists generally studied 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 (M.D.). 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 (Ph.D.) 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

Each year, public health officials, including virologists, attempt to determine, for example, 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 also is studying 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. Virology also
is looking at how viruses may cause some types of cancers and at how viruses cause
the body’s immune response to occasionally malfunction and develop
autoimmune
disorders.

Viruses have an interesting role in genetics too 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 to cure such diseases.

Bibliography

Carter, John, and Venetia Saunders. Virology: Principles and Applications. Hoboken, N.J.: John Wiley & Sons, 2007. Basic virology textbook with an “at-a-glance” feature for each chapter, a list of abbreviations, and a glossary.

Dimmock, N. J., A. J. Easton, and K. N. Leppard. Introduction to Modern Virology. 6th ed. Hoboken, N.J.: Wiley-Blackwell, 2007. Includes the definition of viruses and discusses laboratory techniques and the evolution of viruses. Chapters focus on specific groups of viruses.

Norkin, Leonard. Virology: Molecular Biology and Pathogenesis. Washington, D.C.: ASM Press, 2010. A detailed account of virus structure and replication and the basis for disease pathology.

Shors, Teri. Understanding Viruses. Sudbury, Mass.: Jones and Bartlett, 2008. Includes historical perspectives on viruses and treatment and prevention information.