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Chasing Jenner's vaccine: revisiting cowpox virus classification
Darin S Carroll1, Ginny L Emerson, Yu Li
1Poxvirus and Rabies Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America. DCarroll@cdc.gov
Plos One
|August 23, 2011
Summary
Cowpox virus (CPXV) is not a single species but a composite of up to five species. This finding reclassifies CPXV and impacts understanding of Vaccinia virus origins.
Area of Science:
- Virology
- Taxonomy
- Infectious Diseases
Background:
- Cowpox virus (CPXV) is historically recognized as the source of the first vaccine.
- CPXV belongs to the Orthopoxvirus genus, which includes smallpox and monkeypox viruses.
- Current literature often refers to cowpox as a singular disease entity with one causative agent.
Purpose of the Study:
- To investigate the species diversity within the traditional "cowpox" group.
- To clarify the taxonomic relationships of different CPXV isolates.
- To determine the evolutionary origins of CPXV and its relation to Vaccinia virus.
Main Methods:
- Genotypic analysis of CPXV isolates.
- Phylogenetic analysis of viral DNA sequences.
- Comparative genomics of Orthopoxviruses.
Main Results:
- Genotypic data reveal CPXV is a composite of up to five distinct species.
- These species infect a range of hosts including cows, humans, and other animals.
- Vaccinia virus strains are more closely related to continental European CPXV than UK strains.
Conclusions:
- The traditional classification of "cowpox" as a single species is inaccurate.
- Elevating four new species within the CPXV group is supported by the data.
- Vaccinia virus likely originated from continental European CPXV, challenging its historical association solely with the UK.
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