In order to better understand the evolution of poliovirus vaccine strains, I've included a brief overview of the virus and its history...
Taxonomy
Poliovirus is a member of the family Picornaviridae, genus Enterovirus. (Picornaviridae also includes members of the Rhinovirus genus. Rhinoviruses target the upper respiratory system and are typically responsible for the common cold.) Poliovirus primarily infects the gastrointestinal tract, although in rare cases, it can migrate through the blood stream and infect brain and spinal cord neurons.
Structure and genome
Polioviruses are composed of a genome surrounded and protected by a proteinaceous capsid. The capsid, composed of 60 “protomer” subunits, is capable of self-assembly (imagine this process as a jigsaw puzzle putting itself together). The poliovirus genome is linear, single stranded RNA. The host cell mistakenly recognizes the viral genome as its own mRNA, and uses it to synthesize viral proteins.
History
Although poliovirus was isolated in the 1930s and was officially named in 1955, it has coexisted with humans for thousands of years. Clinical reports of poliovirus infections date back as far as 1400B.C. in Europe.
For centuries, poliovirus existed in the United States as an endemic infection, spreading among humans via the fecal-oral pathway. Most children contracted poliovirus early in life, rarely manifested any symptoms, and recovered with lifelong immunity. However, this mode of infection was disrupted when sanitation measures improved water quality in the 20th century. Consequently, the frequency of poliovirus infections in children plummeted, leaving a pool of susceptible individuals. If infected later in life, these adults were at a greater risk of developing the devastating, paralytic version of polio. In this ironic turn of events, improvements in public health actually contributed to an increase in the occurrence of paralytic poliomyelitis.
Jonas Salk introduced the first polio vaccine in 1955. Before that, quarantine was the only way to prevent poliovirus from spreading.
posted by Jennifer S. Griffin @ 9:04 PM 2 comments links to this post
2 Comments:
At 9:15 PM, Anonymous said...
This website helped me out.... thanx.
At 7:43 AM, Anonymous said...
What is the full scientific name for Poliovirus? Poliovirus?
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Jennifer S. Griffin
I am a science writer and editor at a science consulting organization. I recently entered the working world after earning my Bachelor of Science in Cell Biology and Biochemistry from Bucknell and my Masters in Molecular Biology from Princeton. In addition to science writing, I'm also working on a second Masters in Environmental Engineering from the Worcester Polytechnic Institute (thanks to a grant from the National Science Foundation). This blog was mainly started to write about microbiology (virology in particular), but I also discuss careers in science beyond academia.
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