Following an infection with an extracellular bacteria (for this example, the made up bacterium Streptocillia outsidica), we would predict that most optimal immune response would involve activation of humoral immunity. For

this example, let's assume that when wild type (WT) mice that have no known genetic mutations and a completely functional immune system are infected with S. outsidica, the infection establishes in the lungs and bacteria are able to overwhelm the standard innate immune response of rapid phagocytosis. Not to worry though-the adaptive immune response is initiated, producing antibodies specific to S. outsidica antigens that migrate to the site of infection. After 8-10 days, the infection is cleared and infected WT mice recover. In an experiment, you infect groups of the following genetically modified mice: 1. Mice that are deficient in (ie do not express) C3. 2. Mice that do not produce CD8 T cells. 3. Mice that are deficient in the Fc gamma receptor (FcR) (ie the protein on phagocytes that recognizes the constant region of IgG antibodies). Based on what you know about coordinated immune responses to infection, predict the outcomes of each mutant mouse line with the infection outcome. C3-deficient mice Fcgamma receptor-deficient mice CD8 T cell-deficient mice Previous Mice die by day 5 of the infection Mice survive, but take longer to clear the infection Mice clear the infection faster than WT Mice clear the infection just like WT Mice develop an overwhelming immune response that causes collateral damage to the lung that kills the mice 17 1 point Strep throat is commonly caused by group A Streptococcus bacteria. A common symptom of strep throat is the presence of swollen lymph nodes in the neck. This symptom usually peaks 2-4 days after the onset of the infection, and is due to: Damage to epithelial tissue in the throat Release of bacterial PAMPs leading to inflammatory cytokine production Activation of antigen-specific lymphocytes in the lymph nodes of the neck Recruitment of neutrophils and monocytes to the lymph nodes of the neck Recruitment of additional lymph nodes to the neck

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