FINAL Flashcards
the lag phase
This period of little or no cell division, called the lag phase, can last for or several days. During this time, the cells are not dormant; they are undergoing a period of intense metabolic activity
multiplication of DNA animal virus
❶–❷ Following attachment, entry, and uncoating, the viral DNA is released into the nucleus of the host cell.
❸ Transcription of a portion of the viral DNA—the “early” genes—occurs next. Translation follows. The products of these genes are enzymes that are required for the multiplication of viral DNA. In most DNA viruses, early transcription is carried out with the host’s transcriptase (RNA polymerase); poxviruses, however, contain their own transcriptase.
❹ Sometime after the initiation of DNA replication, transcription and translation of the remaining “late” viral genes occur. Late proteins include capsid and other structural proteins.
❺ This leads to the synthesis of capsid proteins, which occurs in the cytoplasm of the host cell.
❻ After the capsid proteins migrate into the nucleus of the host cell, maturation occurs; the viral DNA and capsid proteins assemble to form complete viruses.
❼ Complete viruses are then released from the host cell.
Major difference bw maturation of RNA virus and DNA
The multiplication of RNA viruses is essentially the same as that of DNA viruses, except RNA viruses multiply in the host cell’s cytoplasm.
steps of RNA virus replication
After uncoating, single-stranded RNA (ssRNA) viruses with a strand genome are able to synthesize proteins directly from their strand. Using the strand as a template, they transcribe strands to produce additional strands to serve as mRNA and be incorporated into capsid proteins as the viral genome. (b, blue arrow) The ssRNA viruses with a strand genome must transcribe a strand to serve as mRNA before they begin synthesizing proteins. The mRNA transcribes additional strands for incorporation into capsid protein. (c, yellow arrow) The dsRNA viruses transcribe a + strand in capsid proteins to protect dsRNA from cellular destruction.
Replication of retrovirus
Is actually a ssRNA(+) containing reverse transcriptase or RNA dependent DNA polymerase
Best description of parental route of entry
M/o deposited under the skin
Examples of infections using parental route of entry
HIV, hepatitis, tetanus
Salmonella typhi preferred portal of entry
GI tract (mucous membrane)
Streptococcus pneumonia: portal of entry
Resp tract (mucous membrane)
Yersinia pestis portal of entry
Black plague - parental route
Virulence often expressed as
ID50
Potency often expressed as
LD50
Bacteria forms of adherence to cells
Glycocalyx of Streptococcus mutans: surface of teeth
Fimbriae of enteropathogenic Escherichia coli: specific cells in small intestine
Fimbriae ofNeisseria gonorrhoeae: cells in genitourinary tract
Tapered end as a hook: Treponema pallidum
What does streptococcus use to adhere to host
Glycocalyx
How does N. Gonnorhoeae ahere to GI tract
finmbraie
How does treponema pallidum adhere to GI tract
Tapered end is hooked
Adhesins or ligands
glycoproteins or lipoproteins) on microbes bind to receptors (carbohydrates) on host cells; altering one can block adherence
Invasin
Invasins rearrange nearby host cell cytoskeleton and induce ruffling
How does a capsule contribute to a bacteria virulence (ex of bacteria)
impair phagocytosis
Streptococcus pneumoniae
How does having a waxy layer contribute to virulence plus example
Waxy layer: resist digestion by phagocytes
Mycobacterium tuberculosis
How is Coagulase used to evade host defenses
Coagulate the fibrinogen in blood
Staphylococcus aureus
How does kinase allow for evading host defenses
Digest fibrin clots
Streptococcus pyogenes, Staphylococcus aureus
Hyaluronidase use in virulence
Hydrolyses hyaluronic acid that holds together some cells in body (i.e. connective tissue)
Streptococcus spp, Clostridium spp
Collaginase purpose
Hydrolzyses collagen
Which bacteria uses IgA proteases
N. Gonnohoreae
What does a bacteria alter on itself to avoid detection and become a different strain
Antigens
2 ways that pathogens damage host cells
Siderophores and direct damage
Characteristics of Exotoxin
mostly Gram +ve (but found in both)
Yes neutralized by antigen
Does not cause fever
Small lethal dose
Characteristics of endotoxin
ONLY G-
Present in LPS of outer membrane
Causes fever
Unaffected by antitoxin
Large lethal dose (relatively)
During what phase of bacterial grwoth are exotoxins secreted?
Log phase
The primary function of the humoral,
AKA antibody-mediated, immune response is to control freely circulating pathogens.
Helper T cell
Activated by two signals
- Binding of T cell receptor to processed antigen
- Costimulatory cytokine
Cell mostly responsible for enhanced secondary response to an antigen
Memory cells
This type of immunity is acquired via injection of antibodies from an individual or host that has immunological memory to the specific pathogen or antigen.
artificially acquired passive immunity
This type of immunity is acquired when a person is vaccinated for a specific type of infection via the introduction of antigens. These antigens normally have undergone some type of modification and may not confer the same type of long-lasting memory that would occur with unmodified antigens
artificially acquired active immunity
What type of defenses are the first line defenses?
External
Secretions: Skin pH 3-5 (inhibit microbes)
Lysozyme: Enzyme in skin, saliva and tear secretions
Fungistatic fatty acid in sebum (oily skin)
Lactic acid bacteria in vagina:
Produce lactic acid (acidic pH)
Stomach acid is lethal to most bacteria:
Helicobacter pylori survives stomach pH
Normal Microflora:
Complement systems
An antimircrobial substance produced by the body composed of Special proteins that attack and lyse microbes
Interferons
Antimicrobial substance of proteins secreted by virus infected cells that inhibit viral multiplication
Defensins
Antimicrobial proteins secreted by activated macrophages to destroy pathogens
Ag
Antigen
Ab
Antibody
Describe physical differences bw mature T cell and Mature B cell
B cell
Y shaped with two IDENTICAL light chains and two IDENTICAL heavy chains
Two differnt (straight) chains
CD antigens stands for
Clusters of differentiation
Most T cells are
Helper (65%)`
What MHC class do T cells
MHC 1 or MHC 2
Most osre throats can be treated by
Penecillum
Analytical epidimology
Comparing healthy individuals to sick (florence nightinggale)
Descriptive epidemiolgy
Gathering information of all sorts
Streptococcus Pyogenes
Low G+C Lactobacillus
First step In DNA virus multiplication
Synthesis of DNA
Differnce bw vehicle transmission and vector
Vehicle is air, water, food
Vector is biological (animal) or passive (FLy on food)
How can botulism ingestion be easily avoided
Boiling food
Cornebacterium diptheria
High G+C G+ producing exotoxins
Salmonella produces toxins?
Endotoxins
Vibrio cholera produces toxins?q
Exotoxins
Do phagocytes use complements or lysozumes?
COmplements but no lysozymes
Neutrophils with a defextive lysozyme are unable to do what to a pathogen
Digest it
Normal microbiota of the skin
Micrococci
M. luteus
M. roseus
Staphylococci
S. epidermidis
S. aureus
Diphtheroids (pleomorphic rods)
Corynebacterium xerosis (aerobic)
Propionibacterium acnes (anaerobic)
Ampicillin
Semisynthetic (penecilin)
Extended-spectrum
beta lactam antibiotic
Cephalosporins does whar
Inhibits cell wall synthesis
Bacitracin, Colistin, and vancomyosin are
Polypeptide antibiotics that inhibit cell wall synthesis
isonicotinylhydrazine and ethambutol are
Antimycobacterial antibiotics inhibitors of cell wall synthessi
mycolic acid synthesis
Pseudonomas are
G- Gamma proteobacteria
Tetracyclines
Macrolides (e.g. Erythromycin)
Chloramphenicol
Aminoglycoside
are all
Broad spectrum Inhibitors of Protein Synthesis
Rifamycin, Quinolones and fluoroquinolones
Nalidixic acid, Ciprofloxacin (CIPRO)
- Inhibitors of DNA/RNA Synthesis and treatment for antrhax
Polymyxin B
- Injury to the Plasma Membrane
effective against g- like psudonomonas
Sulfonamides, Trimethoprim, and SXT –
Competitive Inhibitors of Enzymes
2 major bacteria genera involved in diseases of the skin
Staphylococcus
Streptococcus
Describe S.Epidermis
Very common on skin (90%)
Opportunistic infection (broken skin or catheter)
Produce biofilm
`
What bacteria CAN be found on the skin, is not NORMAL skin flora, and causees a wide range of diseases?
Streptococci
P. aeruginosa. resists antibiotics
Pump out drug
Efflux pumps
How does S.aureus resist antibiotics
Prevents entrance
How is MRSA durg resistant
Alteration of target enzyme or organellec (Binding proteins of penicillin)
M protein or Capsule prevents adherence to macrophage
Streptococcus pyogenes, S. pneumoniae
Leukocidins kill mcrophages:
Staphylococcus aureus
Lysis of phagolysosome
Listeria monocytogenes
Escape from the phagosome
Shigella
Prevent fusion of phagosome with lysosome
HIV and M. tuberculosis
Survive in phagolysosome (advantage?)
Coxiella bunetii
