MIC 205 1st EditionExam # 3 Study Guide Lectures: 15-21**Viruses, prions, infection, epidemiology, drugs, nonspecific/specific defense mechanismsViruses: - Nonliving, acellular, miniscule infectious agento Carry 1 or several pieces of DNA or RNAo Infect bacteria, plants, animals Not an organism, NO cytoplasmic membraneo Viruses ONLY infect ONE particular host Glycoproteins must be compatible with the hostStructure of Virus- If a virus is outside the host it is called a VIRIONo Viron = Made up of a protein capsid that carries the nucleic acid- If a virus is inside the host it is a naked nucleic acido Virus = Capsid is shedViral envelope- On some animal viruses, made of phospholipid bilayero Acquired from host cell during viral replicationCategorizing Viruses- Type of genetic material, kind of cells they attack, size/shape, capsid structure, envelope or noto If it has DNA/RNA, single/double, circular/linearViral Replicationo Lytic replication- Destructive mechanism that kills the host cell 5 stages:1. Attachment2. Entry3. Synthesis4. Assembly5. Release Replication cycle:o Burst time = period required to do the entire lytic process o burst size = total number of new virons released- Dormancy replication:o Lysogenic replication- extended dormancy replication in bacteriophages Lysogenic Replication (Bacteriophages): attaches and entry like lytic cycle,then enters dormancy1. Bacterial chromosome and viral genome combine into one loop (Prophage in chromosome)2. Replication of chromosome (copies viral genome at same time)3. Specific conditions allow the prophage to undergo induction, exits dormancy and enters the Lytic cycle at synthesis again- **Lysogenic phage must re-enter Lytic Replication in order to go infect a new host- Lytic replication of animal viruses-o Same pathway as lytic for bacteriophages with same 5 steps as above Differences result from:o Prescence of envelopeo Eukaryotic nature of animal cell hostso Lack of cell wall surrounding animal cell hosts- 3 entries of Attachment and Entry of Animal Viruseso Direct penetrationo Membrane fusiono Phagocytosis- Latent replication- dormancy in animal viruses, can be temporary OR permeant Dormancy can be temporary or permanent  Incorporated into the host chromosomes or just sit in the cell- Ex: chicken pox, HIV/AIDS, herpesViruses in Cancer:o Neoplasia- uncontrolled cell division in multicellular animalo A mass of these cells is a tumoro Benign vs. malignant tumorso Metastasis- sheds cells to migrate throughout the bodyo Oncogenes (copies of cell division genes) that are carried as part of the genomePrions- Infectious agent composed of a single protein (PrP)o Neural degenerative diseases- Has 2 forms:o Normal form- alpha helices (“cellular” PrP)o Disease causing form with beta sheets (“prion”PrP)- CAUSATIVE AGENT for human diseases- Only way to sterilize or destroy is: STERILIZATION Normal Microbiota- Normal flora/ indigenous microbiota- Organisms that colonize the body’s surfaces without normally causing diseaseo Acquired at birth- Two Typeso Resident microbiota Externally oriented features (skin, upper respiratory tract, lower digestive tract, upper digestive tract)o Transient microbiota Remain on body from hours to months Ones experienced in everyday lifeOpportunistic pathogens = normal microbiota than can cause disease in certain circumstances (when normal bacteria is in wrong places)Disease transmission:o Contact- direct/indirecto Vector- biological entityo Vehicle- non biological entityEtiology = study of the cause of a particular diseaseo Germ theory- diseases are caused by infections of pathogenic microorganisms (Koch’s Postulates)o Infection- results when the pathogen has evaded the external defenses, multiplied, and become established in host organismo Contamination- the presence of microbes on/in bodyo Disease (morbidity)- disease results only if the invading pathogen ALTERS the normal functions of the bodyo Portals of microbial entry: mouth, nose, ears, cut, eyes, anything with a hole Vehicle: water, dust Vector: insects, rats, lice Contact: fist bumpo Portals of exit: any portal of entryReservoirs of infection:o Sites where pathogens are maintained as sources of infectiono 3 types:  Animals- Zoonoses- diseases naturally spread from animal to humano acquired through direct contact with animal or waste, eating it or blood sucking arthropods Human carriers- Infected individuals who don’t have symptoms of the disease but are infective Nonliving reservoirs- Ex: soil, water, foodManifestations of Disease- Symptoms- subjective qualities of a disease felt by the patiento Ex: how bad does it hurt, how do you feel,- Signs- observable measureable things of a disease, objectiveo Ex: swelling, lab test results, body temp- Syndrome- group of symptoms and signs that characterize a disease- Asymptomatic- don’t have symptoms or signs that can be measures to determine if you have the disease or infectionStages of Infectious Diseases- 5 stage sequence called disease process 1. Incubation period- so signs/symptoms2. Prodromal period- vague, general symptoms3. Illness- most severe signs and symptoms4. Decline- declining signs and symptoms5. Convalescence- no signs/symptomsVirulence factors: degree of pathogenicity as determined by presence of virulence factorso Factors:- Adhesion factors- Extracellular enzymes- Toxins- Antiphagocytic factorsEpidemic= localized on one continentPandemic= across multiple continentsInfluenza Virus Structure- Envelope of an influenza virus contains 2 spikeso NA- breaks down mucus (opens door)o HA- allows influenza to bind to epithelial cells and triggers endocytosis (Entry)- Named off type of HA and NA present in envelopeo H1N1 = type 1 HA, type 1 NAo H5N1- bird flu, affects middle age individuals and young adultsDrugs: used to control microbial growtho Chemicals affect physiologyo History: Salvarsan 1910 Penicillin 1929 Suldanilamide 1932o Drugs target:o Cell wall synthesis (beta lactams target BACTERIAL cell wall)o Inhibition of protein synthesis (bacteria ribosomes are killed)o Disruption of cytoplasmic membrane (antifungal)o Inhibition of metabolic paths (antimetabolic- kill vegetative cells by stoping ATP production, DNA/RNA synthesis)o Efficacy of antimicrobial agents:o Kirby bauer disc diffusiono Minimum inhibitory concentration testso Minimum bactericidal concentration testsDrug administration:o Intravenous (IV)- direct