Viruses

Abstract

Tiny, transmittable particles which have the capacity to cause diseases are known as viruses. Since their emergence, they have made a significant impact on the world. Dating back to the late 19^th century, these infectious particles are credited for causing a plethora of diseases in humans, plants, and animals. How did these highly dominant particles come to be? When early scientists were conducting research on viruses, they did not particularly know what they were dealing with. In 1886, Adolph Meyer discovered that a disease of tobacco plants could be transferred from a diseased plant to a healthy plant. A few years later in 1892, Dmitri Ivanowski conducted an experiment using a filter to study what is now known as the tobacco mosaic virus. The filter identified and removed the bacterial particles, yet for an unknown reason the plant was still infected. After this experiment, the substance got the name of “virus”, which means poison in Latin. Although the virus was discovered in the 1800s, the virus could not be seen until the invention of the microscope in the 1940s. This was only the beginning to what we now know as virology, the study of viruses.  Today, viruses are continually being researched and make up two-thirds of all new human pathogens¹.

            Much like viruses, bacteria can also cause you to get sick. A common misconception is that bacteria and viruses are the same. This is not the case, however. Bacteria differ from viruses in size, shape, and reproduction methods. Moreover, bacteria are considered to be a living organism because they are independent of a host cell and are single-celled. Contrarily, viruses are not considered to be living because they do not have cells within themselves and cannot perform the reproductive cycle without a host cell. Another difference between the two is how their infections are treated. For example, if one encounters a bacterial infection, antibiotics would be a helpful agent. On the contrary, a vaccination or antiviral medication would help in prevention and treatment of a viral infection. Despite not having basic features, viruses do have genetic variation and nucleic acid genomes, alike to all living creatures. In this chapter, we will examine the viruses’ structure, processes of replication, classification, and the role they play in human disease.