Assessment of Future Scientific Needs for Live Variola Virus (1999) / Chapter Skim
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2 Variola Virus and Other Orthopoxviruses
2 Variola Virus and Other Orthopoxviruses
Pages 17-24
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From page 17... ...
The latter process causes the virus to shed some of its outer components so its inner core of genetic material has access to components of the host cell in order to be transcribed and translated. The accepted classification of viruses is based primarily on Me morphology of the virion and the nature and structure of the viral nucleic acid.
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From page 18... ...
The external surface of the poxvirions is ridged in parallel rows that are sometimes arranged helically (see Figure 2-1~. As noted, He viral particles contain approximately 200 proteins, about half structural and half nonstructural.
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From page 19... ...
There are two different infectious forms of vaccinia virus-Intracellular Mature Virus (IMV) and Extracellular Enveloped Virus (EEV:whose virions differ in their role in the virus life cycle, their interaction with the immune system, and the way they bind to and enter cells.
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From page 20... ...
The basic question regarding the origin of a human-specific virus is how long ago, in terms of biological evolution, the viral species in question developed He capacity to be maintained indefinitely through human-to-human spread. Indefinite maintenance of a virus in populations of various sizes depends on three factors: (1)
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From page 21... ...
All present strains of vaccinia virus are genetically related, although they exhibit different biological properties in the laboratory. Most strains have a wide host range in experimental animals, and all exhibit rapid growth on the chorioallantoic membrane cultures.
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From page 22... ...
Prospective studies in Zaire between 1981 and 1986 have indicated that three-fourths of human monkeypox infections are attributable to direct contact with animals; the remainder can be traced to contact with infected persons. Whereas the person-to-person transmission rate to unvaccinated individuals in close contact ranges up to 70 percent for smallpox, it is about 8 percent for monkeypox.
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From page 23... ...
VARIOLA VIRUS AND OTHER ORTHOPOXVIRUSES 23 however, is not fully comparable to variola virus because the route of infection is usually skin abrasion rather than inhalation, and ectromelia is unique among the orthopoxviruses in that the spleen and liver are major target organs for viral replication.
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