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| | =[[Viruses - WikiBlood|Viruses]]= | | =[[Viruses - WikiBlood|Viruses]]= |
| − | [[Image:Virus structure.jpg|thumb|right|150px|Virus Structure - B. Catchpole, RVC 2008]]
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| − | [[Image:Viral replication.jpg|thumb|right|150px|Viral Replication - B. Catchpole, RVC 2008]]
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| − | [[Image:B Cell viral response.jpg|thumb|right|150px|B Cell Immunity to Viruses - B. Catchpole, RVC 2008]]
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| − | [[Image:T Cell viral response.jpg|thumb|right|150px|T Cell Immunity to Viruses - B. Catchpole, RVC 2008]]
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| − | ==Structure==
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| − | Viruses are very simple structures that do not carry any cellular machinery of their own. They depend on host cells to replicate and flourish. As such, their structure is streamlined, containing only:
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| − | *Genetic material, which consists solely of viral RNA
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| − | *Capsid proteins surrounding the RNA
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| − | *A lipid envelope
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| − | *Envelope glycoproteins (or spike proteins)
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| − | All of these elements can be recognized by the host as foreign material, and will provoke an immune response. Viruses have an advantage if they are able to penetrate host cell walls in that they are then capable of masquerading as host cells. The immune system must then counter by killing off host cells it recognizes as infected.
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| − | ==Pathogenesis==
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| − | ==Replication==
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| − | Viral lifespans have three distinct phases:
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| − | *Infectious (extracellular): as they seek out a host target
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| − | *Replicative (intracellular): as they overtake the host cell's utilities to multiply
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| − | *Dissemination (extracellular): as they leave the host cell and migrate to those surrounding
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| − | ==Immunity to Viruses==
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| − | *Viral evasion of immunity
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| − | **Latency: Viruses can "hide" in host cells until the immune system is suppressed
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| − | **Transformation: the virus incorporates into the host genome, activating an '''oncogene''', which causes cells to become neoplastic
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| − |
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| − | *[[The innate immune system - WikiBlood#Innate Immunity to Viruses|Innate Immunity to Viruses]]
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| − | *Adaptive Immunity to Viruses
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| − | **The adaptive immune system has two main ways of dealing with viral infection: the first targets viruses in its initial extracellular phase, the second targets infected host cells:
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| − | ***'''B-lymphocytes''' are capable of producing Antibody to neutralize the spike proteins of the viral lipid envelope, preventing the virus from attaching to host cells
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| − | ***'''Cytotoxic (CD8+) T cells''' target infected cells, which present any number of danger signals
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| − | ==Prevention and control==
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| − | *[[Vaccines - WikiBlood|Vaccines]]
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| − | Antibiotics cannot treat viral infection. While anti-viral therapies do exist, they are costly and often ineffective. The alternatives, therefore, include '''vaccination''' (priming the immune response to create memory lymphocytes for a particular virus) or '''eradication'''.
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| | =[[Bacteria - WikiBlood|Bacteria]]= | | =[[Bacteria - WikiBlood|Bacteria]]= |