The main difference between vaccinia and variola virus is that the vaccinia virus is the modern source of the smallpox vaccine, whereas the variola virus causes the infectious disease smallpox.
Vaccinia and variola virus are two viruses that cause smallpox. The symptoms of the disease include fever and vomiting.
Key Areas Covered
1. What is the Vaccinia Virus
– Definition, Features, Importance
2. What is the Variola Virus
– Definition, Features, Importance
3. Similarities Between Vaccinia and Variola Virus
– Outline of Common Features
4. Difference Between Vaccinia and Variola Virus
– Comparison of Key Differences
Key Terms
Vaccinia Virus, Variola Virus
What is Vaccinia Virus
Vaccinia virus is a large, complex virus that belongs to the genus Orthopoxvirus. And it belongs to the poxvirus family. This virus contains an envelope. Also, the genome of the vaccinia virus contains linear, double-stranded DNA. Its size is around 190 kbp, and it contains around 250 genes. The dimension of the vaccinia virus is 360 × 270 × 250 nm. Importantly, vaccinia virus is the modern source of smallpox vaccine. World Health Organization (WHO) used the vaccinia virus to eradicate smallpox in a global vaccination program in 1958 -1977.
Figure 1: Vaccinia Virus
Furthermore, the vaccinia virus is closely related to the virus that causes cowpox. Therefore, a relatively mild infection with the cowpox virus confers immunity to smallpox. Vaccinia virus also causes smallpox, an endemic human disease with a 30% fatality rate.
What is Variola Virus
Variola virus is a virus that belongs to the poxvirus family. Therefore, it is also a large virus. Significantly, the viruses of the poxvirus family are large enough to observe under the microscope. The poxvirus family contains two subfamilies: Chordopoxvirinae and Entomopoxvirinae. Chordopoxvirinae infects vertebrates, while Entomopoxvirinae infects arthropods. However, variola is a human-specific virus. Also, the variola virus can be readily distinguished from other smallpox-forming viruses (Vaccinia, monkeypox, and cowpox) by the presence of characteristic small white pocks developed in the chorioallantoic membrane of 12-to 15-day-old chick embryos.
Figure 2: Smallpox
Moreover, the size of the variola virus is 400 × 200 nm. It contains a linear genome with double-stranded DNA. The genome size is around 190 kbp and can encode around 200 genes. Also, the indefinite virus maintenance in the population depends on three virus characteristics. They include 1. The capacity of the virus to undergo antigenic change, 2. Quality of infection, and 3. Characteristics of the population biology.
Similarities Between Vaccinia and Variola Virus
- Vaccinia and variola virus are two viruses that cause smallpox.
- Both are large viruses.
- They belong to the genus Orthopoxvirus.
- Their genome size is around 190 kbp.
- Also, their genomes are linear.
- The origin of both viruses is unknown.
Difference Between Vaccinia and Variola Virus
Definition
Vaccinia virus refers to a large, complex, enveloped virus belonging to the poxvirus family. On the other hand, variola virus is an extremely infectious disease that causes a fever, skin spots, and death.
Shape
Vaccinia virus is a membraned, slightly flattened, barrel-shaped particle with a complex internal structure featuring a biconcave core flanked by lateral bodies. In contrast, the variola virus has an ovoid or brick-like shape.
Size
The size of the vaccinia virus is 360 × 270 × 250 nm, while the size of the variola virus is 400 × 200 nm.
Function
Vaccinia virus is the modern source of the smallpox vaccine, while the variola virus causes the infectious disease, smallpox.
Conclusion
In brief, Vaccinia and variola virus are two viruses that cause smallpox. Also, they belong to the genus Orthopoxvirus. Vaccinia virus is a large, complex virus that belongs to the poxvirus family. Also, it has an envelope. Importantly, it is the modern source of smallpox vaccine. In comparison, the variola virus also causes smallpox, a disease that causes fever, spots on the skin, and often death. Therefore, the main difference between vaccinia and variola virus is their function.
References:
- Institute of Medicine (US) Committee on the Assessment of Future Scientific Needs for Live Variola Virus. Assessment of Future Scientific Needs for Live Variola Virus. Washington (DC): National Academies Press (US); 1999. 2, Variola Virus and Other Orthopoxviruses.
Image Courtesy:
- “Vaccinia virus PHIL 2143 lores” By CDC/Cynthia Goldsmith – Own work (Public Domain) via Commons Wikimedia
- “EM smallpox, grown via tissue, isolate by centrifuge ” By Dre at English Wikipedia – Own Work (CC-BY SA 3.0) via Commons Wikimedia
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