113lecture2206 - BIOLOGY 113 - MICROBIOLOGY Lecture 22:...

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BIOLOGY 113 - MICROBIOLOGY Lecture 22: Mechanisms of Pathogenicity - Invasion, virulence factors, damage to host cells Pathogenic microorganisms gain entry into host tissues via several portals of entry - Many bacteria and viruses gain access to the body be penetrating mucous membranes lining the respiratory tract, gastrointestinal tract, and genitourinary tract - Though few microorganism are able to penetrate intact skin, entry to tissues through broken skin - The parenteral route of infection refers to direct access to deep tissues due to injury, surgery, etc - The ability of a microorganism to cause an infectious disease often depends on entry through a "preferred" portal of entry (Tortora et al., Table 15.1) - Different microorganisms vary in their virulence, sometimes expressed as ID50, or the number of cells necessary to cause infectious disease in 50% of exposed test animals - Adherence to host tissue is essential for pathogenicity (Tortora et al. Figure 15.1) = Adherence is accomplished through surface molecules - adhesions - that bind specifically to complementary surface receptors on host cells = The adhesins may determine which tissues a pathogen is able to colonize, since only certain cells are going to have the right receptors = Adhesins may be located on a glycocalyx, pili, or other surface structures
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This note was uploaded on 11/24/2011 for the course BIO 113 taught by Professor Staff during the Fall '09 term at Rutgers.

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113lecture2206 - BIOLOGY 113 - MICROBIOLOGY Lecture 22:...

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