Eradicated and Emerging Infectious Diseases Flashcards
Key features of diseases that could be eradicated
- Narrow host range
2. Must have a vaccine
Smallpox virus characteristics
linear ds DNA virus
Distinguish by barbell shape under electron microscope
Replicates in the cytoplasm (has no access to nucleus)
Doesn’t encode translational machinery
Smallpox symptoms
High fever (>100 degrees)
Rash will follow flu like symptoms
Firm, deep seeded rash vessicles
Headache and back pain may occur
How is smallpox different from chickenpox?
Small pox starts with vessicles on hands, face, and feet and the vesicles are in a synchronous stage of development
Chicken pox has most vesicles starting on the trunk and will be in various stages of development
Smallpox disease mechanisms
Enters the body via respiratory tract or skin invasion Goes to the lymph nodes and multiplies Becomes viremic in the blood stream Spleen and liver are infected Secondary viremic into the blood stream Goes out to the skin
Poliovirus characteristics
Postivie ss RNA virus No envelope high mutation rate Virus surface can't change so vaccine neutralizes the surface protein Genome similar to HCV
How does (+) ssRNA replicate
Virus builds replication factories in mitochondria
Viral RNA replicates inside (+ to - to +)
How are the replication houses not detected?
TLR-3 doesn’t detect them, which would normally recognize the d.s. DNA and kick off the innate immune system
How is poliovirus spread?
Fecal to oral transmission
Goes from the gut to the nerves to the spinal cord
Poliovirus mechanisms
Enters body and replicates in oropharynx and intestine
Goes to the lymph nodes then to the blood
Goes viremic to the skin, muscle, brain, or meninges
How many people become paralyzed by poliovirus?
1%
Why isn’t polio eradicated yet?
Hard to reach remote areas
War and political reasons
Key features of diseases that are emerging
- Large, probing host range
2. Reassortment
Retroviruses
RNA virues that replicate through a DNA intermediate
HIV characeteristics
Enveloped virus
+ s.s. RNA (2 copies in virion)
Contains reverse transcriptase (RNA to DNA)
tRNA molecules for primers
gag gene
encode structural proteins
pol gene
encodes reverse transcriptase and integrase
env
encodes envelope proteins
What does HIV look like?
Has a coffin shaped center
When viruses are budding they aren’t infectious right away. An enzyme must mature them from the spherical shape to the coffin like shape.
How and what does HIV attach to?
CD4+ is the target cell
attaches to CXCr4 or CCr5
Cells that are lysed during infection with HIV
CD4+ T lymphocytes
Cells that go through a prolonged period of infected and bud out virus
NK cells CD8 T cells macrophages cells of the nervous system dendritic cells
Where did HIV start?
Central/West Africa
HIV pathogenesis
Enters the body and first attacks macrophages
Can pass to CD4 T cells which goe to the lymph node where it spreads
The T cell loses function which causes the body to lose the adaptive immunity and the training for innate immunity
Nerve cells can be killed off leading to AIDS dementia
