Week 3 - Microbiology Vial, Fungal, and Parasite Pathogensis Flashcards
what should we know?
viruses - influenza virus* single stranded RNA virus with segmented genome
Whats the only diploid virus?
Retroviruses..
phsutomones (poster)
Herpes virus
Virulence factors on how bacterial cause disease
Viruses and how they cause disease
and just because infection dont necessary get a disease
injectosomes
enzymes that are secreted
toxins that are produced..
Slide on staffolacaucus.. not individual things but emphazid.. how they get there is very complex.. immune system repsonse to it.. Innoculation dose of bacteria…
Infection does not ALWAYS…
Cause disease
Subclinical infection
is the rule (only way you can tell a person has been infected is to do an antibody study*) Even if pt says they’ve had chx pox… still check antibodies..
Target organ
All viruses have a target organ
Hep B is liver
influenza is lungs
IMportant: the immune system can
play an active role in development of symptoms (rash) .. the rash is due to immune response to virus replicating in skin!
Vesicular rashes
The fluid in them contains infections virus that can be transferred
Just skin rashes do not hvae this (macular..something)
Localized infections
result from virus replication at the site of virus entry
-influenze. breath it in it targets lungs
Systemic or Disseminated infections
Take longer to take becuase the virus has to travel to target organ…
Rabies.. virus has to get from bite to the brain.. takes a while. Dont see clinical disease at bite.. see it in the brain. if bite in neck vs leg… have much longer time to treat pt if bite is in leg (neck is close to target organ!)
Acute viral disease
Symptoms occur shortly after viral infection (days to a week) Rabies
Persistent or chronic viral disease
Symptoms take months or years to occur.. Hep B
Steps in viral patholoties
No lipopolysaccharides (no endotoxins) or no exotoxins associated with viral infections
If you stop virus form multiplying - dont get diseases
Viruses only need to alter cells.. not kill cells
Bodies response to infectoin is inflammation, tissure damage… etc play significant role in severety of disease.
Latency is a common property
Steps continued
Entry and primary replication
routes are specific per virus
Most entery through mucous, resp or GI
Some inoculated into blood by needles (HIV HEPB) or insect vectors (arboviruses from moisquee or tics)
Most replicate at site of entry and some produce the disease there (flu and rotavirus) and dont spread
Spreading of viruses
free in plasma
White blood cells - sensitized T cells..
important - if have a disease like epsteen bar or measles. cause mono.. those viruses multiply and travel through body in WBC’s.. then they alter the normal properties of cells.. WBC are supposed to rid body of other infections.. so pts who have these are immunosuppressed…
RBCs
Nerve fibers
IF they are in the nerver fibers they are hidden by body. When they get to the neurons they can go latent.. body doen’t know they are there. (chicken pox - reactivated causes shingles.. )(chicken pox disease is live attenuated vaccine)(shingles vaccine is an increased level of virus in vaccine to increase immune system response). so can only repress the virus is when it in the periferial and active (like in the skin…)
Direct spread
Repiratory tract infections (flu virus) and
resperiatory TO GI infections (adenovirus)
**Naked viruses cause GI problems.. If you have enveloped virus going thorugh GI tract the envelope gets removed and the virus is killed.
Trophism and target organs
Spread from site of infecdtion to other area
Replicate only in tissue with cells having necessary receptors and host factors
*TIssue which shows most prominant clinical symptoms is the target organ.. chicken pox.. resides in neurons but rash is the clniica symptom so SKIN is the target organ.
Epstein bar causing mono.. Blood cells is target organ**
When virus gets to cell
Get cell injury
cell could lyse if naked virus
if enveloped virus will tranform cells…
Mechanisms of cytopathogensis
Add pic.
A LOT of viruses alter cell membrane structure
NET result of mechanisms is to create inclusion bodies in infected cells..
Inclusion bodies
Accumulations of virus specific proteins in the cell..
All herpes viruses cause
All cytomegalovirus
Cowdry’s typ a incluseion bodies
Owl’s eye inclusions (intranuclear)
Need to ask question.. :
Is it due to physiological issue or is it cause by an infections disease?
Toxicity of virion components
ONLY 2 viruses cause toxins…
Fibers of adenovirus
GI invection rotvirus (naked virus - they lyse cell - proteins in cell are released and one of the proteins is toxic)
Desease that you see?
and insensitive indicator of virus infection since inapparent or subclinical infections are extremeley common with some viruses
Circumstances and events that can result in disease from virus..
Inoculum size Competence of immune system Immune and health status of host Genetic constitution of host Age and nutritional condition of host
Hepatitis is very important to study for boards
… lots of questions will be on these.. and AIDS
Transmission Routes of viruses
Respiratory Intestinal Urogenital Oropharynx Skin and skin glands Blood (tattoo needles)
