BIOM 250: Week 10,11 Notes
BIOM 250: Week 10,11 Notes BIOM 250
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This 9 page Class Notes was uploaded by Davis Notetaker on Friday April 22, 2016. The Class Notes belongs to BIOM 250 at Montana State University taught by Kari Cargill in Winter 2016. Since its upload, it has received 10 views. For similar materials see Micro Hlth Sci: Infect Disease in Biology at Montana State University.
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Date Created: 04/22/16
Mon 4/11 Innate Host Defenses Part 1 Terminology Innate host defenses nonspecific defenses Adaptive defenses specific defenses Host Defenses Overview The body has many types of mechanisms for defense. Host defense types include: Physical, chemical, cellular, inflammation, fever, molecular Barriers physical ● Skin & mucous membranes ○ Skin has layers to prevent pathogen invasion ○ Mucous membranes secrete mucus to trap pathogens ○ Cilia traps pathogens ● Washing actions clear out potential pathogens ○ E.g. tears, saliva, urine, vaginal secretions ● Reflexive actions dispel pathogens ○ Cough, sneeze, vomit, diarrhea ○ Pathogens also take advantage of these for spreading to a new host Barriers chemical ● Skin salt in perspiration, acidic sebum (from glands in skin) ● Stomach gastric acid ● Body secretions lysozyme (breaks down peptidoglycan) Cellular Defenses Blood ● 60% fluid “plasma” (antibodies, proteins) ● 40% formed elements ○ Erythrocytes (RBC’s) ○ Leukocytes (WBC’s) ○ Platelets/thrombocytes (for clotting) Leukocytes Neutrophils, aka polymorphonuclear leukocytes (PMN’s) ● Phagocytic (look & act like amoeba) ● Active during initial infection ● Can enter tissues to take care of an infection there ● # of PMN’s increases during bacterial infection ● Phagocytosis kill pathogens intracellularly (kind of like ‘ingestion’) Eosinophils ● “Somewhat” phagocytic ● See increase during parasitic invasion or if allergy is present Basophils ● Release histamine (triggers inflammation + allergy symptoms) Monocytes ● Mature into macrophages (phagocytic) Lymphocytes ● Involved in adaptive immunity: B & T cells ● Numbers increase during viral infection Extracellular killing Natural killer (NK) cells type of lymphocyte ● Kill cells infected with virus ● Excretes cytotoxic proteins (toxic to living cells) WBC Differential count (“Diff count”) Below shows normal levels of WBC presence, a Diff count measures how close/far from normal an individual’s count is, with a greater count indicating the presence of a pathogen ● Neutrophils 4075% ● Lymphocytes 2045% ● Monocytes 210% ● Eosinophils 16% ● Basophils 01% WBC mnemonic: Never Letonkeys tBananas: Neutrophils Lymphocytes Monocytes Eosinophils Basophils Fri 4/15 Innate Host Defenses Part 2 Disease: Tuberculosis TB is an ancient disease (tubercular decay has been found in remains of Egyptian mummies) Historically has gone by other names: “consumption”, “white plague” disease/infection Tuberculosis etiologic agent Mycobacterium tuberculosis (caused by: name, type of m/o, Acidfast bacteria other characteristics) reservoir (where it is harbored Has been in humans too long to determine a clear origin naturally) mode of transmission to Transmission: Respiratory droplets humans (& susceptible Risk groups: people) ● Those who have tested HIV + ● alcoholics ● Jailhouse inmates pathogenesis (progression of Pulmonary TB (Lungs) disease within body, virulence ● Mycobacteria replicate within macrophages factors) ● Granulomas form around bacteria these are walled off “tubercles” formed from aggregated WBC’s ● Can lead to Latent TB: mycobacteria is dormant, non infectious, many are asymptomatic ● Abnormal cell death develops ○ caseous necrosis of granulomas (interior looks like soft, white cheese) Extrapulmonary TB ● spreads beyond the lungs: bones, meningitis, urogenital, etc ● Problem in children , immunosuppressed Miliary TB ● systemic spread, usually fatal Virulence factors: Drug resistance ● Multiple Drug ResistantTB (MDRTB) resistant to top 2 drugs (rifampicin & isoniazid) ● Extreme Drug ResistanceTB (XDRTB) resistant to 3 of 6 drugs ● Total Drug ResistanceTB (TDRTB) resistant to ALL current drugs ● Lack of medication for TB has motivated a return to older, riskier drugs with dangerous side effects symptoms Many asymptomatic (latent TB) Fever Very bad cough for more than 3 weeks Pain in chest No appetite Weight loss Weakness or fatigue Eventually, coughing up blood or sputum treatment/prevention/control Control: ● Required Screening (Mantoux (tuberculin) test) ● Vaccine exists, bacillus CalmetteGuerin (BCG), but not available in US ○ commonly used in children in other parts of the world. Effectiveness varies per case per country Treatment: ● Antibiotics ● Requires months to complete Mantoux test 1. TB antigen is injected under the skin 2. If antibodies are present a reaction occurs that causes the injection site to swell, indicating the tested subject has been exposed to TB Tuberculosis Impact ● ⅓ people are infected worldwide (9 million new cases/year) ● TB is the leading killer of those afflicted with HIV ● Historically TB was a major killer in US & Europe: ○ ~10,000 new cases in US in 2013 TB Politics Continued TB problem in US is often more of a political problem than a problem of insufficient resources Political policies cut down TB funds Nonspecific Defenses: Fever ● Characterized by an increase in body temp ○ This is triggered by infection or tissue damage ● The benefits of a fever include: ○ Inhibition of microorganism ○ Speeds up defensive cells Molecular Defenses Interferons ● Viral infection of a cell triggers the production of an interferon ● Interferon signals “infection” to uninfected cells, which can then make antiviral proteins to prevent the spread of infection Limits: ● Doesn’t help the cell that has already been infected ● Short term (colds & influenza) ● Used clinically has side effects in high doses (clinically active dose) Complement Pathways Complement ● Series of 20 proteins in plasma ● Act in a “cascade” (or “bucket brigade”) Triggered in two ways: 1. Classical pathway Antibodies bound to microbes 2. Alternate pathway pathogen surface interaction with complement proteins Results: ● Opsonization ○ Enhancement of phagocytosis (process by which phagocytes ‘digest’ pathogens) ○ Plays a role in inflammation ● Membrane Attack Complex (MAC) destroys microbes via cytolysis Mon 4/18 Adaptive Host Defenses Types of Immunity ● Active immunity ○ Body makes antibodies after exposure to antigens ○ Memory a body mechanism for retaining information about (almost) every threat it has been exposed to ● Passive immunity ○ Premade antibodies are received from another source (e.g. from mother) ○ No memory but provides immediate protection Both types can be acquired naturally or artificially Active Passive Naturally ❖ Development of antibodies ❖ Antibodies transferred from Acquired after illness mother to baby via (via placenta ❖ Lasts years to a lifetime or breast milk) (memory) ❖ Only lasts as long as antibodies live (no memory): weeks to months Artificially ❖ Comes from ❖ Premade antibodies acquired by Acquired vaccination/immunization injection ❖ Won’t cause disease but still ❖ Immediate protection but provokes an immune protection is temporary (no response memory) ❖ Memory is longterm Vaccines All are made from nonvirulent antigens, but this can be done in several ways: Types of Vaccines ● Killed microorganisms, such as influenza, rabies, Salk polio ● “Attenuated” microorganisms these are live but weakened, examples include MMR, Sabin polio ● Toxoids inactivated toxins, such as tetanus, diphtheria ● Subunit vaccines only part of antigen is used, e.g. new pertussis vaccine, hep B vaccine ● DNA vaccines new, experimental method of using genetically engineered DNA to instruct cells to produce antigen Misconceptions about vaccines Misconception Fact Improvement of hygiene and sanitation had Diseases only disappeared after the use of already begun to suppress disease before vaccines vaccines were introduced The US has been virtually wiped of This threatens herd immunity, and does not vaccinepreventable diseases, so there is no protect against disease exposure from need for children to be vaccinated traveling, immigration, emerging diseases and other diseases that still circulate the US Children receiving multiple vaccinations for Vaccinations do have an associated risk, but different diseases at the same time is risks of vaccination have to be considered associated with an increased risk of harmful against the risk of disease. See Risk from side effects and can overload the immune Disease vs Risk from Vaccines below system Risk from Disease vs Risk from Vaccines Risk from Vaccine Risk from Disease MMR Measles ● Can cause encephalitis or severe ● Pneumonia occurs in 6/100 cases allergic reactions in 1/1,000,000 ● Encephalitis occurs in 1/1,000 cases cases ● Death occurs in 2/1,000 cases Rubella ● Congenital Rubella Syndrome: 1/4 cases DTaP Diphtheria ● Continuous crying, followed by full ● Death occurs 1/20 cases recovery occurs 1/1,000 cases Tetanus ● Convulsions or shock, followed by full ● Death occurs 2/10 cases recovery occurs 1/14,000 cases Pertussis ● Pneumonia occurs 1/8 cases ● Acute encephalopathy occurs 010.5 / ● Encephalitis occurs 1/20 cases 1,000,000 cases ● Death occurs 1/200 cases Vaccine > Autism “Hoax” ● 1998 paper by Wakefield was published linking MMR vaccine & autism in 12 UK children ● His experiments were not reproducible, and 10/12 coauthors retracted the published findings ● 2004 Wakefield was under investigation, and the investigation found that the paper was likely motivated by a conflict of interest, to support a patented single measles vaccine ● 2010 Wakefield was banned from medical practice in UK ● The paper was declared fraudulent in Feb 2011 Consequences ● Roughly 95% vaccination coverage is required to achieve herd immunity ● In 1988, up to 92% of UK pop had the MMR vaccination and measles was declared “under control”, with 56 measles cases each year ● After the paper, less than 80% of the population was receiving MMR vaccination ● Then in 2008 a measles endemic broke out with 1348 cases each year and resulting in 2 deaths Thimerosal Concern “Thimerosal is a mercurybased preservative that has been used for decades in the United States in multidose vials (vials containing more than one dose) of medicines and vaccines. There is no evidence of harm caused by the low doses of thimerosal in vaccines, except for minor reactions like redness and swelling at the injection site. However, in July 1999, the Public Health Service agencies, the American Academy of Pediatrics, and vaccine manufacturers agreed that thimerosal should be reduced or eliminated in vaccines as a precautionary measure.” CDC  Just a ‘nod’ to significant achievement: Maurice Hilleman (19192005): Accredited with major contributions to a safer society ● Behind the development/improvement of more than 40 vaccines: measles, mumps, rubella, hep A, hep B, chickenpox, meningitis, pneumonia, influenza, Marek’s disease (in chickens) ● Discovered the viruses hep A and rhinoviruses ● Discovered antigenic shift and drift in influenza  “Thimerosal in Vaccines Thimerosal | Concerns | Vaccine Safety | CDC.” [Online]. Availablehttp://www.cdc.gov/vaccinesafety/concerns/th [Accessed: 18Apr2016].
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