MIBO EXAM 5 WITH 100% CORRECT ANSWERS.

Secretory IgA is found in the secretions that coat mucus membranes, thereby preventing pathogens from colonizing mucosal surfaces. What are methods that bacteria have evolved to evade or inactivate these antibodies? -IgA proteases that cleaves the antibodies, so that they cannot bind to the pathogen -Antigenic variation, or altering the bacterial structures to which the antibodies bind -Rapid turnover of pili structures to shed any bound antibody How do pathogens penetrate the skin? they rely on injuries like cuts or wounds What mechanisms do pathogens use to penetrate the mucous membranes? -directed uptake by cells -exploiting antigen-sampling processes Directed uptake by cells pathogen attaches to cell and induces non-phagocytic cells to engulf them via endocytosis type III secretion system injectisome - drills holes in host cell and injects effector proteins which induces engulfment ruffling (result of rearranged actin molecules from the injectisome) ruffles on cell surface that enclose bacteria and bring them into the cell exploiting antigen-sampling processes M cells pass pathogens through intestinal barrier to macrophages, some pathogens can survive the macrophages and induce apoptosis then binds to epithelial cells to induce uptake What are the 4 ways bacteria avoid host defenses? -hiding within a host cell -avoiding destruction by phagocytes -avoiding killing by complement system proteins -avoiding recognition by antibodies hiding within a host cell pathogens enter host cells which allows them to avoid complement proteins, phagocytes, and antibodies (all outside the cell) avoiding destruction by phagocytes some pathogens can avoid being recognized altogether or have mechanisms to survive being engulfed by a phagocyte (C5a peptidase, membrane-damaging toxins, capsules, M-proteins, Fc receptors) avoiding killing by complement system proteins microbe hijacks the host cell's mechanism to prevent their surfaces from activating the complement system. microbe binds host cell's regulatory proteins to avoid activating the membrane attack complex (MAC) avoiding recognition by antibodies (bacteria) -IgA protease: splits IgA antibodies (in mucosal surfaces) -antigenic variation: alter surface antigens - stay ahead of antibody recognition -mimicking host molecules: mimic a host molecule/structure to appear as self instead of foreign (immune system does not attack "self" cells) direct damage to the host toxins indirect damage to the host immune response exotoxins proteins with specific damaging effects (gram-negative and gram-positive bacteria) endotoxins lipopolysaccharide components of the outer membrane of gram-negative bacteria (Lipid A is the toxic component) neurotoxins exotoxins that damage the nervous system enterotoxins exotoxins that disturb the intestines cytotoxins exotoxins that damage a variety of cells antitoxin antibodies against a specific toxin (neutralize toxin) 3 categories of exotoxins A-B toxins, membrane-damaging toxins, superantigens superantigens exotoxin - stimulates a high number of Th cells which causes an over release of cytokines (cytokine storm) - tricks Th cells into thinking all antigens are bad except for their "perfect match", T cells undergo apoptosis which suppresses the immune response example of superantigens toxic shock syndrome toxin, staphylococcus aureus exotoxins that cause food-borne intoxication damaging effects of the immune response -damage associated with inflammation -damage associated with adaptive immunity damage associated with inflammation phagocytes recruited to an area can release toxic products, damaging surrounding tissues inflammation in the lungs can cause a buildup of mucus which strains the lungs or fluid to collect in alveoli which interferes with gas exchange What are the 3 ways viruses avoid host defenses? -avoiding the antiviral effects of interferons -avoiding cell-mediated immune response -avoiding antibodies immune complexes antigen-antibody complexes form (clumps) and settle in joints or kidneys and cause damaging inflammation cross-reactive antibodies antibodies produced may bind to self cells - autoimmune response (body attacking itself) mechanisms of bacterial pathogenesis -colonization strategies -invading host tissues -avoiding host defenses -damage to the host mechanisms of viral pathogenesis -enter appropriate cell -use host machinery for replication -avoid host cell recognition and destruction -move to new hosts damage associated with adaptive immunity -immune complexes -cross-reactive antibodies avoiding the antiviral effects of interferons -coat RNA with virally encoded protein to avoid being recognized by PRRs -shut down host gene expression to prevent protein expression for interferon response -interfere with activation of enzymes that shut down infected cells avoiding cell-mediated immune response viruses interfere with antigen presentation by the MHC molecules, Tc cells unable to recognize the cell is infected avoiding antibodies (viruses) viruses jump to immediate neighbor cells or fuse neighboring cells to avoid antibodies, or rapidly change surface antigens to avoid effective antibodies immunization the process of inducing immunity natural immunity gaining adaptive immunity through natural events such as being exposed to an infectious agent artificial immunity gaining adaptive immunity through mimicking natural events such as vaccination or administration of immune globulin active immunity results from an immune response from the exposure to an antigen -produces memory cells -long lasting passive immunity results from the addition of antibodies from others -no memory cells -short lasting natural active immunity immunity from an immune response to the exposure of an infectious agent or illness artificial active immunity immunity from an immune response to a vaccine natural passive immunity immunity from antibodies being transferred from mother to child during pregnancy or breastfeeding artificial passive immunity immunity from antibodies injected from others (people or animal's serum) antiserum serum containing protective antibodies herd immunity Protection of an entire population based upon a concentration of immune hosts that prevents the spread of an infectious agent attenuated vaccine weakened form of pathogen, can replicate, strong immune response, can cause illness inactivated vaccine dead pathogen, cannot replicate, weak immune response, cannot cause illness adjuvant Substance that increases the immune response to antigens inactivated whole agent vaccine contains killed microorganisms or inactivated viruses ex. Influenza, Rabies, Hepatitis A toxoid vaccine inactivated toxins used to protect against diseases caused by toxins ex. Tetanus, Diphtheria subunit vaccine contain specific antigenic fragments or proteins of a pathogen that trigger an immune response ex. Pertussis virus-like particle (VLP) vaccine contain empty viral capsids but do not contain viral genetic material ex. human papillomavirus (HPV) polysaccharide vaccine contain polysaccharides from bacterial capsules ex. Pneumococcal conjugate vaccine polysaccharides linked to proteins ex. Streptococcus pneumoniae nucleic acid-based vaccine contains segments of naked DNA or RNA of an infectious agent ex. COVID-19 which vaccine type is not effective in young children? polysaccharide monoclonal antibodies (mAbs) antibodies produced from one B cell (cloned) that recognize a single specific epitope polyclonal antibodies antibodies produced from a collection of B cells, recognize multiple epitopes therapeutic antibodies self immune cells modified to target a specific pathogen/cell