Ch. 10 - Micro/HIV Flashcards
Pathogenic
Causes or produces a disease state in the host usually by:
a) direct damage to the cells
b) release of toxins
c) interfere with cellular metabolism
Infectivity
Ability of a microbe to invade and multiply in a host
Virulence
Potency of a pathogen. The number of microbes or the concentration of a toxin required to kill a host.
Immunogenicity
Ability to induce an immune response
Toxigenicity
Related to degree of virulence, ability to produce
a) Soluble Toxins - soluble on water, blood, body fluids
b) Exotoxins - released during bacterial growth, usually enzymes that have specific effects
–> neurotoxins
–> enterotoxins
–> cytotoxins
–> peumotoxins
React with cell membranes and disrupt homeostasis
React with adhesion proteins and allows penetration
Vaccinations can be made for exotoxins
c) Endotoxins - released upon bacterial death
–> LPS in the bacterial cell walls of G- bacteria
–> Cause the release of vasoactive peptides and trigger release of inflammatory cytokines (TNF, IL-1, IL-6, NO, PAF)
which reduce blood pressure by vasodilation but also increase capillary permeability
THIS IMPEDES O2 DELIVERY AND LEADS TO SHOCK
–> Can trigger clotting cascade through PAF and lead to DIC
VACCINES AREN’T EFFECTIVE BECAUSE IT’S IN THE BACTERIA
Define and differentiate : Endotoxins vs Exotoxins and their role in Septicemia, Inflammation and
shock.
Endotoxins - these are in G- bacteria cell wall also known as LPS
- -> Released upon Phagocyte death
- -> Cause release of inflammatory cytokines (TNF, IL-1, IL-6, PAF, NO)
- -> All these cause increased capillary permeability and vasodilation
- -> Leads to decreased O2 delivery and leads to shock
- -> Can trigger clotting cascade through PAF and lead to DIC
VACCINES ARE NOT EFFECTIVE BECAUSE IT’S IN THE BACTERIA
Exotoxins - released during bacterial growth
- -> release enzymes with specific effects (neurotoxins, enterotoxins, cytotoxins)
- -> React with cell membranes and disrupt homeostasis
- -> React with adhesion proteins and allows penetration
VACCINATIONS ARE EFFECTIVE HERE
Septicemia: presence of bacteria in the blood due to failure of body defenses
Barriers: innate and specific immune response
Endotoxins really cause the shock and septicemia due to increased capillary permeability however, exotoxins allow penetration of the bacteria and release enzymes with specific effects
Be prepared to discuss all of the following about the HIV virus. A. Type of virus and mechanism by which it gains access to human cells.
A. It is an RNA retrovirus, reverse transcriptase
Gains access through:
1) sexually contact
2) sharing needles
3) health care setting –> exposure to body fluids
4) blood products
5) breast milk
6) vaginal birth
7. ) placental barrier
Be prepared to discuss all of the following about the HIV virus. B. Which cells in humans are the primary targets of the HIV virus. (CD-4 receptors)
Any cell with CD4 receptor is a target of HIV virus
–> PRIMARILY TH CELL AND DENDRITIC CELL
NK cell, macrophage, and neural cells have small amount of CD4
Be prepared to discuss all of the following about the HIV virus. C. How HIV viruses cause acquired immune deficiency syndrome (AIDS).
Causes AIDS by binding to Th and reverse transcripting. It completely blocks Th cell function and thus the cell mediated immune response.
–> reverse transcriptase and places its double stranded DNA into your host cell (the helper T cell); YOU HAVE AIDS AT THIS POINT
–> T cells dropping below 300 = AIDS
–> Infects CNS leading to dementia
Be prepared to discuss all of the following about the HIV virus. D. The reason vaccination has not been a successful treatment for HIV and AIDS.
The reason the vaccination has not been successful is because it is an RNA virus that is rapidly changing all the time. It is always mutating.
–> Antigens are constantly changing and person may have simultaneous infections with virus with different antigens
–> Circulating antibodies aren’t protective and show no effect against virus or slow progress of AIDS
–> Virus can go from cell to cell without being exposed to immune system so a vaccine wouldn’t be helpful; no antibodies would be created against it
–> Activation of memory cells against virus requires IL simulation by Th cell which is absent
