Smallpox Is An Acute Contagious Disease

1988 Words May 15th, 2015 8 Pages
SMALLPOX
Introduction
Smallpox is an acute contagious disease that is caused by the variola virus – which is a member of the Genus Orthopoxvirus family. It infects humans only as a result of its ability to escape the host immune system, and avoid any further activation (Koplow 2003). The virus is a two-stranded DNA virus. There exist two forms of the variola virus namely the variola major and variola minor. Variola major is the one that is lethal, while variola minor is not lethal but a mere strain. The most common strain is the variola major, which produces the more severe symptoms and with a higher fatality rate of 20% to 40%, within a week of infection (Koplow 2003). Key features of the life cycle(s)
The initial step is whereby the virus attaches to the host cell and infects an individual. It normally enters through the respiratory system. It attaches to the mouth, trachea or lung mucosa. The cells forming the mucous membrane are loosely packed hence permitting penetration and movement into the saliva. Once the virus reaches the cell membrane, it penetrates through endocytosis. In the host cell, the main protein in released (Koplow 2003).
The virus replicates in the cytoplasm of the host cell. DNA replication and transcription may start immediately as the virus itself contains enzymes for replication and transcription. It does not rely on the host cell enzymes to begin replication (Koplow 2003). First, the DNA and RNA polymerase are made, along with other transcription…
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