Difference between revisions of "Host invasion by microorganisms"

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<big><big><center>[[WikiBlood|'''BACK TO WikiBlood''']]</center></big></big>
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===Introduction===
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<br>
 
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<big><center>[[Immunology - WikiBlood|'''BACK TO IMMUNOLOGY''']]</center></big>
 
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=Introduction=
 
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[[Image:Routes of Infection.jpg|thumb|right|150px|Routes of Infection - B. Catchpole, RVC 2008]]
 
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Infection is a primary cause of disease.  Three pathways of infection are identified: bacterial, viral, and parasitic.  In all three cases, microorganisms can display similar characteristics.  They can manifest as '''primary (obligate) pathogens''' or '''secondary (opportunistic) pathogens''', the former of which always corresponds to disease, and the latter of which depends on prerequisites being fulfilled before causing disease.  As such, secondary pathogens can be found in healthy animals, but they lie in wait until a primary cause compromises the immune system and then manifest symptoms.  Secondary pathogens can even masquerade as '''commensal''' organisms, or those which operate in harmony with the animal, until they become pathogenic.
 
  
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Microorganisms can enter the body by three routes: '''contact''' (typically dermatological infection), '''aerosol''' (typically respiratory infection), or '''orofecal''' (typically enteric infection).  Infection can be either '''exogenous''' (via entry to epithelial surfaces) or '''endogenous''' (intracellular, extracellular, or vesicular).
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One of the main causes of disease is infection by microorganisms, with four types so far identified:
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*[[Viruses]]
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*[[Bacteria]]
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*[[Fungi]]
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*[[Parasites]]- comprising [[protozoa]] and [[helminths]]
  
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=[[Viruses - WikiBlood|Viruses]]=
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A fifth controversial type are Pirons, which are infectious proteins that are believed to be the cause of bovine spongiform encephalopathy (BSE) and the human variant Creutzfeldt–Jakob disease (vCJD).<br />
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[[Image:Virus structure.jpg|thumb|right|150px|Virus Structure - B. Catchpole, RVC 2008]]
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<br />
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==Structure==
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All exist as either:
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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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*Primary pathogens ('''obligate'''): presence always corresponds with disease
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*Genetic material, which consists solely of viral RNA
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*Secondary ('''opportunistic'''): prerequisites must be fulfilled before disease occurs
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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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==Replication==
 
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[[Image:Viral replication.jpg|thumb|right|150px|Viral Replication - B. Catchpole, RVC 2008]]
 
  
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==Routes of infection==
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Microorganisms can enter the body by three routes:
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==Prevention and control==
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*'''Contact''': typically seen in dermatological infections
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*'''Aerosol''': typically respiratory infections
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*'''Orofecal''':typically enteric infections
  
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*[[Vaccines - WikiBlood|Vaccines]]
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{{Learning
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|flashcards = [[Host Invasion by Microorganisms Flashcards|Host Invasion Flashcards]]
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}}
  
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=[[Bacteria - WikiBlood|Bacteria]]=
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===References===
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*<div id="Janeway">{{citation|initiallast = Murphy|initialfirst = K|2last = Travers|2first = P|finallast = Walport|finalfirst = M|year = 2008|title = Janeway's Immunobiology|ed = 7th |city = New York|pub = Garland Science Publishing}}</div>
  
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==Structure==
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*http://www.cellsalive.com
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==Replication==
 
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==Routes of infection==
 
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==Prevention and control==
 
  
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=[[Parasites - WikiBlood|Parasites]]=
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{{review}}
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<br><br>
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{{Jim Bee 2007}}
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[[Category:Immunology]]

Latest revision as of 09:28, 24 May 2012

Introduction

One of the main causes of disease is infection by microorganisms, with four types so far identified:

A fifth controversial type are Pirons, which are infectious proteins that are believed to be the cause of bovine spongiform encephalopathy (BSE) and the human variant Creutzfeldt–Jakob disease (vCJD).

All exist as either:

  • Primary pathogens (obligate): presence always corresponds with disease
  • Secondary (opportunistic): prerequisites must be fulfilled before disease occurs

Microorganisms can enter the body by three routes:

  • Contact: typically seen in dermatological infections
  • Aerosol: typically respiratory infections
  • Orofecal:typically enteric infections


Host invasion by microorganisms Learning Resources
FlashcardsFlashcards logo.png
Flashcards
Test your knowledge using flashcard type questions 		Host Invasion Flashcards


References

  • Murphy, K., Travers, P. and Walport, M. (2008) Janeway's Immunobiology. 7th ed. New York: Garland Science Publishing.


This article has been peer reviewed but is awaiting expert review. If you would like to help with this, please see more information about expert reviewing.




LIVE logo Originally funded by the RVC Jim Bee Award 2007
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