The type of immunity that results from introducing antibodies that have been produced either in another animal or by in vitro methods. Immunity is only temporary.
What did Beijerinck do?
Demonstrated that filterable causative agent of tobacco mosaic disease could reproduce in a susceptible host.
What did D’Herrelle do?
Firmly established the existence of bacterial viruses and developed a plaque assay for enumerating them.
What are viruses (and characteristics)?
Simple, acellular infectious agents; virions containing either RNA or DNA (not both); can only reproduce inside of a living host cell.
What types of nucleic acids (NA) are carried by viruses?
What is plaque assay used for?
To measure particle counts and infectivity of viral dose.
What is the size range of a virion?
Size ranges from 10nm to 400nm
What is the difference in the way virus are grown from bacteria?
Bacterial and archaeal viruses are usually cultivated in broth or agar cultures of suitable, young, actively growing host cells.
How are animal viruses cultured?
Suitable host animal, embryonated eggs, or tissue (cell) cultures.
What is the function of a viral protein coat?
Protects viral genetic material and aids in its transfer between host.
What are viral envelopes?
Membrane structures surrounding some (but not all) viruses.
What are viral envelopes composed of and what are their characteristics?
Some species of virus envelop themselves in a modified form of one of the cell membranes, either the outer membrane surrounding an infected host cell or internal membranes such as nuclear membrane or endoplasmic reticulum, thus gaining an outer lipid bilayer known as a viral envelope. This membrane is studded with proteins coded for by the viral genome and host genome; the lipid membrane itself and any carbohydrates present originate entirely from the host. The influenza virus and HIV use this strategy. Most enveloped viruses are dependent on the envelope for their infectivity.
Describe differential centrifugation?
Separates viruses according to size.
Describe gradient density centrifugation?
Separates according to buoyant density of to sedimentation rate (size and density), and is more sensitive to small differences among various viruses.
Describe self-assembly process?
Enzymatic activity is not required to link protomers together. However, noncapsid protein may be involved.
What criteria are used to classify animal viruses?
1. Nucleic acid type.2. Nuecleic acid strandedness (double or single stranded).3. The sense of ssRNA genomes.4. The presence of absence of an envelope.5. The host.
What type of Nucleic Acid (NA) viruses make up most of the plant viruses?
Most plant viruses are RNA, plus strand are most common.
What mechanisms do viruses use to cause cancer?
1. Viruses may carry one or more cancer-causing genes (Oncogenes).2. Viruses may produce a regulatory protein that activates cell division.3. Viruses may insert a promoter or enhancer nest to a cellular proto-oncogene (a cellular gene that regulates cell growth and reproduction), causing abnormal expression of this gene and thereby deregulating cell growth.4. Viruses may inhabit the activity of tumor suppressors that regulate cell cycling.
What virus has been associated with a form of liver cancer?
Hepatitis B virus
What are the facts about viroids?
Have circular single-stranded RNA molecules that lack a capsid and cause a variety of plant diseases.
What diseases are caused by prions?
Kuru (found only in the Fore, an eastern New Guinea tribe that practice ritual cannibalism),Creutfeldt-jakob disease (CJD), fatal familial insomnia, and Gerstmann-Strassler-Scheinker Syndrome (human diseases)
What is the most common functioning molecule of animal virus receptor?
What NA type of virus make up the plant viruses?
What type of virus causes T-cell leukemia?
T-cell lymphotropic viruses (HTLV-1 and HTLV-2)
What methods do viruses enter host cells?
1. Fusion of the viral envelope with the host cytoplasmic membrane results in deposition of the Nucleocapsid core within the cell.2. Endocytosis; lysosomal enzymes and low endosomal pH often trigger the uncoating process.
What are the mechanisms that viruses can cause cell damage to the host cell?
1. Inhibition of host DNA, RNA, and protein synthesis.2. Lysosome damage, leading to release of hydrolytic enzymes into the cell.3. Plasma membrane alteration, leading to host immune system attack on the cell or leading to cell fusion.4. Toxicity from high concentration of viral protein.5. Formation of inclusion bodies that may cause direct physical disruption of cell structure.6. Chromosomal disruptions.7. Malignant transformation to tumor cell.
What is the mechanism that prions use to cause abnormality?
PiP (proteinaceous infectious particles)
What are the characteristics of macrophage?
Larger than monocytes, have more organelles and possess receptors that allow them to discriminate self from nonself; surface molecules recognize common components of pathogens (LPS) respond to Opsonization (chemical enhancement of phagocytosis) Where are they derived? From monocytes.
What complement pathway depends upon the formation of antigen-antibody complexes?
How does the complement system aid the defensive response of an organism?
Lysis of target cells, attraction of phagocytic cells, activation of phagocytic cells
What types of immunity does the alternate complement pathway play an important part?
What is the function and characteristics of dendritic cells?
Kills viruses, by secreting interferon-a; mature Dendritic cells migrate to blood stream or lymphatic system where they interact with B-cells, natural killer cells, and present foreign antigens to T cells.
What must opsonizing antibodies do to stimulate phagocytosis?
Prepare organism by coating it with a serum, binding proteins, or glycoprotein that prepare them for recognition and ingestion by phagocytic cells
What triggers a fever response?
A disruption in the hypothalamic regulatory control, leading to increase of thermal “set point”.
Fever helps host’s defense by doing what?
Stimulating leukocytes to destroy microorganisms, Enhances specific activity of the immune system, and enhances microbiostatsis (growth inhibition) by decreasing available iron to the microorganism.
Where do T-cells undergo maturation?
What do T-cells attack?
Foreign cells, malignant cells, and cells infected with microorganisms.
How does humoral immune response differ from cell-mediated immune response?
Humoral immunity action antibodies by tagging and marking bacteria, toxins and viruses for destruction. Cell-mediated immunity T-cells directly attack infected cells.
Where are lymph nodes located?
Throughout the body in the junction of the lymphatic vessels.
What do lymph nodes do?
Filter and remove foreign antigens, and the activation and proliferation of lymphocytes.
What type of cells release histamine?
What type of cells makeup the lymphocytes?
T-cells, B-cells, and Null-cells.
What causes a granuloma to form?
When Neutrophils and macrophages are unable to destroy the microorganism during inflammation, it starts to wall off and isolate the site causing granuloma.
What is the key role(s) or functions of cytokines?
Stimulate cells to mature and differentiate, produce new efector products, and cause some cells to die.
How do super antigens exert their damage?
Trick T-cells into activation with no specific triggering agent, causing massive quantities of cytokines CD4+T-cells, leading to organ failure and suppression of specific immune responses.
What is the microbiota of the skin found?
On any anatomical site of the body.
How are mictobiota of the skin checked?
The skin provides a mechanical barrier to microbial invasions, due to its thick closely packed cells; frequent shedding, and being acidic and salty.
What causes the skin to be a not favorable place for bacteria growth?
Slightly acidic pH, periodic drying, and hyperosmotic (salt produced by sweat glands)
What are the most numerous bacteria of skin glands?
How are the lungs protected from microorganisms?
1. Aerodynamic filtration (mucociliary blanket).2. Activity of ciliated epithelial cells (mucociliary escalator) cough, sneeze, salivation etc..3. Alveolar macrophages destroy pathogens that get to the alveoli.
What is the role of complement in the immunity process?
Serum proteins that act in a cascade fashion and play a major role in an animal’s immune response.
What are characteristics of gnotobiotic colonies or organisms?
Animals that are germfree or that associate with one or more known species of microorganisms.
What do “natural killer” cells kill?
Malignant cells, and cells infected with microorganisms
What is the most prevalent bacterium found in the colon? Duodenum?
What is the most prevalent bacterium found in the duodenum?
Where is the largest microbial population found?
The external ear flora resembles what other type of flora?
What are the main organisms found in adult pre-menopausal female reproductive tract?
Why do females have more UTI’s then males?
The urethra is much shorter and closer to the anus.
Which complement pathway is important in innate immunity, but not effective of bacteria and fungi invasion?
Alternative complement pathways.
How does fever augment the host’s defenses?
Stimulating leukocytes to destroy microorganisms, Enhances specific activity of the immune system, and enhances microbiostatsis (growth inhibition) by decreasing available iron to the microorganism. How is fever response triggered? Endogenous pyrogen is released by macrophages during infection.
What happens to the immune system with aging?
Autoimmune disease- activation of T & B cells, that lead to tissue damage.
What are normally the sterile environments of organs in humans?
Kidneys, ureter, and urinary bladder.
How do tears protect the eyes?
Keep eye moist by continuous flushing, tears contain the chemicals Lysozyme, lactoferrin, and sIgA that protects the eye.
What does humoral immune response defend against?
Microorganisms, toxins, and extracellular viruses.
What classes of proteins are directed by MHC?
HLA in humans and H-2 in mice
What are the functions and characteristic of mast cells?
Found in connective tissue; contain granules with histamine and other chemicals that contribute to immune/inflammatory response.
How does the host have acquired immunity?
By being exposed to antigens or after transfer of antibodies or lymphocytes from an immune donor.
What are the characteristics and/or function of and between IgG-major Ig in human serum; monomeric protein;80% if Ig pool?
1. Antibacterial & antiviral.2. Enhances opsonization; neutralizes toxins.3. Only IgG is able to cross placenta (naturally acquired passive immunity for newborn).4. Activates the complement system by classical pathway.
What are the characteristics and/or function of and between IgD-monomeric protein; trace amounts in serum?
1. Does not activate the complement system and cannot cross placenta.2. Abundant on surface of b cells where it plays a role in signaling B cells to start antibody production.
What are the characteristics and/or function of and between IgM- pentameric protein joined with J chain at F ends; 10% of Ig pool?
1. First antibody made during B-cell maturation and first antibody secreted during primary antibody response.2. Never leaves the bloodstream.3. Agulates bacteria and activates complement by classical pathways; enhances phagocytosis of target cells.4. Up to 5% may be hexameric; hexameric form is better able to activate the complement system than pentameric IgM; bacterial cell wall antigens may directly stimulate b cells to produce hexameric form.
What are the characteristics and/or function of and between IgA- 15% of Ig pool?
1. Some monomeric forms in serum, but most is dimeric (using a J chain) and associates with protein called the secretory component (secretory IgA or sIgA)2. sIgA is primary Ig of mucosal-associated lymphoid tissue; also found in saliva. Tears and breast milk (protects nursing newborns); help rid the body of antigen-antibody complexes by excretion; functions in alternate complement pathway.
What does the immune system discriminate between antigens & antibodies?
Clonal selection; (self and non-self).
How are antibodies induced to be producers?Where are they produced?
Memory cells can initiate antibody-mediated immune response if they are stimulated by being bound to the antigen. Made by plasma cells.
What role do myeloma cells play in a special type of antibody production?
Produce large quantities of antibodies used for detection. Included in culture medium and can divide indefinitely but do not produce antibodies; a cancerous plasma cell.
What type of antigens does the immune system discriminate?
What are the characteristics associated with secondary antibody response?
Inflammation, fever, and phagocytosis.
Why is the secondary immune response stronger than the primary immune response
Because the primary response is not 100% effective.
What happens in the lag phase, log phase, plateau phase, and decline phase of immune response?
1. Lag phase- last several days.2. Log phase- antibodies titer rises logarithmically.3. Plateau phase- antibodies titer stabilizes.4.Decline phase- antibody titer decreases because the antibodies are metabolized or cleared from the circulation.
What immunoglobulin crosses the placental barrier?
What immunoglobulin transfers to infant during breast feeding?
What are signs of true food allergy?
Itching, vomiting, nausea, diarrhea.
What is an example of atopic allergy of the lower respiratory tract?
What are examples of type I, II, III, and hypersensitivity?
Type I- Includes allergic reactions (hives, hay fever, asthma).Type II- Generally cytolytic or cytotoxic reaction that destroys host cells. (Blood type, Rh factor)Type III- Involves formation of immune complexes, can cause inflammation and damage to blood vessels. (arthritis, glomerulonephritis, systemic lupus).
What is the function of body temperature?
The final outcome of most host-parasite relationships is dependent on what?
1. The number of pathogenic organisms present2. The virulence of the organism3. The host’s defenses or degree of resistance
What is the characteristic of endotoxin?
Usually capable of producing fever, shock, blood coagulation, weakness, diarrhea, inflammation, intestinal hemorrhage, and/or fibrinolysis. When is it released from pathogen? Only when the microorganism lyses or divides.
What are examples of ectoparasites?
Parasites that feed on the external surface of their host (e.g. fleas, lice, mites, mosquitoes, leeches, mildews, molds).
What are the results of viral infections?
Reproduces by entering a host cell and exploiting (killing) that cell to make copies of the virus, which then are released to infect other host cells. Can cause mild skin erruptions (warts, cold sore, chicken pox). Easily spread from one person to another.
What is required of a pathogen to possess in order for it to produce an infection?
It has to grow and multiply on/within a host.
What has effect on the outcome of the host-parasite relationship?
1. The number of pathogenic organisms present.2. The virulence of the organism.3. The host’s defenses or degree of resistance
What is a primary pathogen?
(Frank pathogen) organism that causes disease in a healthy host by direct interaction.
What are the characteristics of a pathogen that determines its virulence?
Invasiveness- The ability of the organism to spread to adjacent tissue.Infectivity- the ability of the organism to establish a focal point of infection.Pathogenic potential- The degree to which the pathogen can cause morbid symptoms.
What are the mechanisms that allow pathogens to survive inside a phagocytic cell?
1. Inhibition of phagosome-lysosome fusion. The bacteria survive inside of phagosomes because they prevent the discharge of lysosomal contents into the phagosome environment (ex. strategy employed by Salmonella, M. tuberculosis, Legionella and the Chlamydiae.2. Survival inside the phagolysosome. With some intracellular parasites, phagosome-lysosome fusion occurs but the bacteria are resistant to inhibition and killing by the lysosomal constituents. Bacillus anthracis, Mycobacterium tuberculosis and Staphylococcus aureus all possess mechanisms to survive intracellular killing in macrophages.3. Escape from the phagosome. Early escape from the phagosome vacuole is essential for growth and virulence of some intracellular pathogens. Rickettsias produce a phospholipase enzyme that lyses the phagosome membrane within thirty seconds of after ingestion.
What are the differences between endotoxins and exotoxins?
Endotoxins- A lipid component of gram-negative bacterial cell wall (LPS) that is released from bacteria upon their death.Exotoxins- A heat labile, toxic protein produced by a bacterium as a result of its normal metabolism. It is usually released into the bacterium’s surroundings.
What methods are used to reduce or eliminate the source of an infection?
Quarantine and isolate cases & carriers; Destruction of animal reservoir; Treatment of sewage to reduce contamination of water; Therapy that reduces or eliminates infectivity of individuals
What contributes to the emergence of new diseases?
Rapid transportation systems and the mobility of the population; Ecological disruption such as loss of predators and/or rainforest destruction; Increased drug usage and sexual promiscuity
What percent of the hospital patients acquire some type of nosocomial infection?
5 – 10%
What nosocomial disease causes the most death?
What type of microorganism is the leading cause of nosocomial infections?
Bacteria (most noninvasive & part of normal microbiota)
What causes most nosocomial infections?
What is the most common nosocomial infection?
UTI (urinary tract infection)
What nosocomial infection is second in incidence?
pneumonia – Lower respiratory tract infection
What are most urinary tract infections related to?
What type of patient is most susceptible to nosocomial infections?
What are some functions of epidemiologist?
Disease detectives: conduct population surveys to determine who has a certain disease; identify infectious disease in a population; apply disease prevention and control, environmental health, and health promotion and education activities.
What are the mechanisms by which new susceptible individuals enter a population
-Birth of a new individual, migration of susceptible individuals into the population, evolution of disease-causing organisms to forms that are no longer recognized by host immune mechanisms.
What is septic shock the result of?
severe hypotension; endogenous mediators released from the patient’s own cells in response to bacterial endotoxins or exotoxins.
How are sepsis and septic shock categorized?
cannot be categorized under a specific mode of transmission
What virus causes chickenpox?
enveloped, DNA varicella-zoster virus (VZV); herpes family of viruses
What virus causes mumps
mump virus, a helical, enveloped negative-strand RNA rubulavirus in the family paramyxoviridae
What virus causes german measles?
rubella virus, an enveloped, ssRNA virus of family togaviridae
What virus causes yellow fever?
flavivirus; transmitted via mosquito (Aedes aegypti)
What virus causes mononucleosis?
epstein-barr virus (EBV), a herpesvirus (enveloped dsDNA virus)
What virus causes warts or verrucae?
What causes shingles?
herpes zoster; postherpetic neuralgia; reactivated form of chickenpox; adults who harbor the virus become compromised due to stress, age, and/or illness.
What is the common epidemic disease of childhood
viral chickenpox; influenza B
What type of influenza virus’s antigenic variation occurs almost yearly?
When does influenza a infection peak?
What group of people do most cases of measles occur?
What disease is koplic spots associated with?
What diseases or conditions do acute respiratory viruses cause?
(RSV) human disease- rhinitis, tonsillitis, laryngitis, bronchitis
What features of smallpox allowed it to be eradicated from the environment?
obvious clinical features; virtually no asymptomatic carriers; only human hosts as reservoirs & short period of infectivity (3-4 weeks).
What are some of the syndromes resulting from arthropod-borne virus?
undifferentiated fevers- with or without a rash; encephalitis- high fatality rate; hemorrhagic fevers- frequently severe and fatal (supportive treatment, no vaccines available)
How do you control and prevent yellow fever?
control of insect vectors; vaccination for endemic areas
What types of body fluids of transmit of AIDS virus?
Infected blood, semen, or vaginal secretion.
Why are colds common?
antigenic diversity of rhinovirus & lack of durable immunity; involvement of other respiratory viruses.
What activates the genital herpes virus?
sunlight; stress; sexual hormones
What diseases are associated with genital herpes?
miscarriages, cervical cancer, & congenital (neonatal) herpes
How are rabies virus transmitted to humans?
By bites of infected animals, aerosols in caves where bats roost or contamination of scratches, abrasions, open wounds & mucous membranes with saliva from infected animals.
Who should be vaccinated against rabies?
Veterinarians, laboratory personnel, or anyone spending more than a month in a country where rabies is common.
What are the control methods for hepatitis B?
excluding contact with contaminated materials, passive immunotherapy (within 7days of exposure) & vaccination of high risk groups.
What ways is hepatitis A transmitted to humans?
(Fecal/Oral) fecal contamination of food/drink or by infected shellfish.
What is the main rout of transmission for poliovirus?
Ingestion of infected food or water.
What most likely causes the german measles rash?
immunologic reaction to the virus; component of immunity development -not caused by virus infecting skin cells.
What reactivates cold sores?
stressful stimuli – excessive sunlight, fever, trauma, chilling, emotional stress, and hormonal changes
What is the typical mode of transmission for hepatitis C?
Intimate contact with virus-contaminated blood; mother to fetus (in utero); organ transplants (fecal/ oral route, sexually)
What type of virus causes human leukemias?
retroviruses: human T cell lymphotropic virus I & II (HTLV-I and HTLV-II)
What is the treatment for mononucleosis?
prevention and control (symptomatic/supportive therapy
What is the most common mode of transmission of the common cold?
contaminated hands or fomites; (hand-to-hand contact, followed by airborne droplets)
What is the prevention and control of rabies
Pre-exposure vaccination of dogs & cats, post exposure vaccination of humans, & pre-exposure vaccination of humans at special risk
What are the affects of protease inhibitor drugs on HIV infection?
Protease inhibitors (PIs) work by blocking the activity of the HIV protease and thus interfere with virion assembly
What other disease or conditions have been suspected in causing or being associated with viruses?
What disease occurs in more than 50% of aids patients?
Acute retroviral syndrome; Tuberculosis (TB) results in over 50% mortality in AIDS patients
How are most systemic mycoses acquired
Inhalation of spores from soil in which the mold-phase of the fungus resides
What systemic fungal agent infects more Americans than others put together?
Coccidioidomycosis (coccidioides immitis) – infects more americans than other systemic mycosis
What is the apparent source of infection of cryptococcus neoformans?
dried pigeon droppings
Why is the diagnosis of candidiasis difficult?
1) this fungus is a frequent secondary invader in diseased hosts (2) mixed microbiota is most often found in the diseased tissue (3) no immunologic procedures currently exist.
What is the leading organism responsible for death in AIDS patients?
human immunodeficiency virus (HIV) within the family retroviridae
What happens to entamoeba histolytica in the lower region of the small intestine? (Amebiasis -Amebic dysentery)
What do entamoeba histolytica feed on? (Amebiasis -Amebic dysentery)
bacteria, RBCs & yeasts; erythrocytes
What is the most common cause of epidemic waterborne diarrheal disease
How many species of plasmodium cause human malaria?
What is the diagnosis of leishmaniasis based on?
observation of parasite within infected macrophages; cultural & serological tests
What are the types of diseases caused by leishmaniasis organism?
mucocutaneous, cutaneous, and visceral
What are the types of subcutaneous mycosis
chromoblastomycosis, maduromycosis, sporotrichosis
Why are vaccines not effective against trypanosomiasis?
Because the parasite is able to change its protein coat (antigenic shift) & evade the immunologic response.
What is the major port of entry for aspergillus?
What is the intermediate host for leishmania?
canines & rodents
What is the carrier for histoplasmosis?
Birds- acquired by inhalation of airborne microconidia in bird droppings
How is pneumocystis carinii classified
As fungi (formerly classified as protists)
How is giardia removed from municipal water supplies
Slow sand filtration
Why does candida albicans normally not cause disease in the vagina
held in check because lactobacilli prevents overgrowth & keeps pH acidic
In what type of host does pneumocystsis pneumonia occur?
Immunocompromised; organism & disease localized in lungs
What test shows hypersensitive state to histoplasmosis?
histoplasmin skin test
Which gender is trichomoniasis asymptomatic
What is the characteristic of trichomonas disease
caused by protest flagellate (T. vaginalis) a common STD