Viral infections, oncoviruses & antiviral chemotherapy Flashcards
1
Q
Dynamic viral infections
A
- Virus to cause disease
- Infect specific host cell
- Replicate efficiently with host
- Damage target tissue
2
Q
Viral pathogenesis
A
- ## The process of a virus producing disease
3
Q
3 Requirements for sucessful infection
A
- Enough virus
- Accessible Cells that permits the viral replication
- Local antiviral defense/immune system absent or overcome
4
Q
Asimptomatic infection
A
- Evidence of disease that can be observed by others - sign
- Apparent only to patient
5
Q
Acute infection
A
- Display short incubation periods upon virus entry
into the host. - Rapid onset of disease
- Brief period of sympthoms
- Quick resolution
6
Q
Acute viral infections
A
- Genetic factors
- Age
- Comorbidity (other diseases)
- Individual immune response
- It is possible reinfection as the immune response triggered is not long-lasting and the virus
rapidly change
7
Q
Latent infection
A
- Latent virus remains in asymptomatic
host cell for long periods - No symptoms or viruses are detectable/active
- May reactivate due to changes in immunity
- Cold sores and herpes
8
Q
Persistent infection
A
- A persistent viral infection occurs
gradually over a long period - Where the virus continue to replicate over time a low level Hep B
- Not always becoming chronic
9
Q
Herpesvirus
A
- Remain latent in a quiescent but persistent form in neutral ganglia cells
- Primary infection - Cold sores HSV-1 and chicken pox for vzv
- Innervating sensory neurons, and viruses are transported to the neuronal cell body.
10
Q
Viral DNA episomal state
A
- Released into the neuronal nucleus
and circularizes
11
Q
Circular viral DNA
A
- Persists in the neuronal cell
nucleus
12
Q
Reactivation of herpes virus HSV-1
A
- Periodically reactivate to cause cold sores, in response exposure to sunlight, psychological stress, fever, menstruation and surgical resection
- Reactivation in the neuronal cell body
- Newly formed capsids are transported to the axonal termini
- Infectious virus is released from the axon and infects epithelial cells, resulting in recurrent infection and virus shedding
13
Q
Varicella Zooster Virus
A
- VZV after years of inactivity may produce skin disease shingles
- Localised and painful
- One or two adjacent dermatomes, usually on the trunk
14
Q
Cancers caused by virus (oncoviruses)
A
- Non contagious occour later in time
- Become integrated into the host cell’s DNA
and induce tumours
15
Q
Oncoviruses Mechanisms
A
- Encode proteins that act as oncogenes themselves
- Activate cellular proto-oncogenes (normal) to oncogenes
- Inactivate tumour suppressor genes
- Cell cycles are no longer regulated at checkpoints
- Unregulated cell proliferation
- Chromosome instability - Mutation accumulation
16
Q
Examples of viruses that caus cancer
A
- Hep-B and C
- HIV and HPV
- Human T-cell
17
Q
Isolation and Cultivation of Viruses
A
- The study and isolation of viruses
- Propagated using different systems in laboratory settings
- Animals
- Embryonated eggs
- Cell cultures
18
Q
Continuous eukaryotic cell lines
A
- Cells commercially available
to divide in a laboratory
19
Q
Isolation and Cultivation of Viruses
A
- Grow in plates sample containing viruses are added to allow virus to attach to the cells and then removed
- Cell are then covered with Agar block diffusion of viruses. Virions infect surrounding cells
- Localised area of cell destroyed
- Detected by using a dye to stain just the viable
cell. The dead cells of the plaque do not retain the dye - Each plaque corresponds to an area of cells infected and dead by single virus
20
Q
Vaccinations
A
- Prevent viral infections
- Protection from possible infection illness when coming into contact with respective pathogen
- Attenuated viruses or proteins or mRNA to trigger a specific immune response
- Viral diseases, often deadly have been eradicated or almost eradicated
21
Q
Antiviral drugs
A
- Antiviral chemotherapy to treat specific viral infectionsselectively
- Virus replication with low effects on the host cell activity
- Inhibiting intital viral life cycle
- Target machanism of action to treat infections
22
Q
HIV
A
- Retroviridae family - subtypes HIV-1 and HIV-2
- Insert a copy of its RNA genome into the host
cell’s genome
23
Q
HIV turning into AIDS
A
- Causes acquired immunodeficiency syndrome - progressive failure of immune system
- Decrease CD4+ and T-lyphocyte life-threatening opportunistic infections and cancers
24
Q
Acute HIV
A
- Flu-like symptoms that occur
days to weeks after contracting HIV
25
Q
Chronic HIV
A
- The latent and asymptomatic
stage that can last several years
26
Q
AIDS
A
- Occurs when CD4 cell count falls
below 200 cell/mm3. This makes people
vulnerable to opportunistic infections and
AIDS-defining conditions
27
Q
HIV Combinational therapy
A
- The highly active antiretroviral therapy regimene typically a combination of two/three antiretroviral drugs with different mechanisms of action
- Different mutations are required to develop drug resistance to all drugs
- Reduced risk of drug resistance
28
Q
Principle of combination therapy
A
- Different antiviral drugs with distinct mechanisms of action having a proved synergistic activity against HIV
29
Q
HIV Combinational therapy goals
A
- Reduce plasma viral RNA to an undetectable level
- Prevent or reduce drug resistance
- Reduce morbidity and mortality
- Prevent HIV transmission - Undetectable therefore untransmittable
