MMG301 1nd Edition Lecture 31Outline of Last Lecture I. Human microbe interactionsOutline of Current Lecture II. VirulenceIII. Pathogenesis Current Lecture-Adherence: aided by several bacterial adherence factors that are specific to cells of certain tissues; most often these are epithelial cells-Glycocalyx – aids adherence and biofilm formation-Adherence proteins – bind bacteria to specific host receptors (glycoproteins, polysaccharides); “adhesins”-Fimbriae and pili – bind to specific receptors on host cells-Lipoteichoic acidd – aid in attachment-Invasion – entry of the pathogen through the epithelium; enzymes can aid this process-Usually occurs through breaks or lesions of the mucosa or skin-Invasion is not required to cause some diseases – some bacteria produce harmful toxins; examples: botulism-Colonization and growth – multiplication and growth of microbes after entry into host tissues that have a suitable environment with proper nutrients, pH, trace minerals, and temperature.-ID50- infective dose of a pathogen that makes 50% of a population sick-LD50- lethal dose that kills 50%-Virulence factor: a pathogen-produced substance (usually a protein, enzyme, adherence factor, or toxin) that promotes the establishment and maintenance of diseaseThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.-Virulence genes (genes that encode a virulence factor) are sometimes lost upon prolonged cultivation of cultures in the laboratory-Exotoxins – bacterially-produced toxins are proteins or enzymes that are released from the bacterial cell into the surrounding environment (extracellular toxins)-Cytolytic toxins – degrade host cells resulting in lysis; cyto=cell, lytic=lysis-Some examples of bacterial cytolytic exotoxins:-Staphylococcus α-toxin-Proteins bind to host cell membrane creating a two-way pore-Host cell dies due to loss of cell contents and loss of proton gradient-Hemolysins- originally discovered because of lysis of red blood cells, but also lyse other cell types-AB toxins – consist of two subunits: B binds to host surface, A crosses into cell.-Superantigens – hyperstimulate immune cells, resulting in tissue inflammation and
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