Viruses Flashcards
Test 4
T/F: viruses are living organisms
F
Lack nucleus, mitochondria, cell membrane, ribosomes
We want to ______ an active virus
inactivate
Viruses are either _____ or ______
Active or inactive
Why are viruses considered intracellular parasites?
They cannot multiply –> have to invade a specific host cell
after invasion, instructs host cell to make and release new viruses
Differentiate between the lysogenic cycle in the lytic cycle
Give examples
Lysogenic cycle: virus slowly pinches off the cell
-lasts years/decades
Ex) HIV
Lytic cycle: Burst host cell r/t acute infections
-clears out fast
Ex) Flu
T/F: Virus have no effects on animals & plants
F
Plants effected the worst actually
What are the 3 main parts of a virus?
- external coating (outer coat/Capsid): repeating proteins that bind & form a capsid
- core containing nucleic acids (DNA/RNA)
- spikes: target specific cell that it’s going to infect
Are DNA strands mostly single or double stranded? RNA?
DNA: double
RNA: Single
But DNA/RNA could be either
Single stranded DNA = Parvo
What does retrovirus mean? What are examples
Starts off as RNA but changes to DNA & then put into nucleus of host cell
-All these viruses can be reactivated
Ex) HIV, Herpes, HPV16/18
T/F: retroviruses can be reactivated
T
What is the enzyme used in retroviruses to convert RNA to DNA?
Reverse transcriptase
T/F: all viruses have an antiviral therapy
F
What is the difference between a naked & enveloped virus?
Naked: Has capsid, nucleic acid, & spike
Enveloped: In addition to things listed naked virus; has an enveloped “outer cell membrane”
What does the outer cell membrane come from in an enveloped virus? What type of cycle do you see this in?
part of the cell host that it has infected
lysogenic cycle
What is the viral spike in HIV? What does it target?
GP120
CP4(+) proteins on T cells & marcophages
What are the 5 steps for Viral replication? Describe them. Why are they important?
- Absortion: attachment of virus to host cell; viral spike recognizes & attaches to protein target on host cell
- Penetration: entry of virion/genome into host cell
-some viruses have to uncoat (shed its outer membrane) to enter the cell or they inject the nucleic acid directly - Synthesis: new nucleic acid, capsid proteins, & other viral components (ex. reverse transcriptase)
This is where the host cell now becomes the factory for making new viruses - Maturation: assembly of newly synthesized viral components into complete virion
-moves virus to cell surface - Release: departure of nre virion from host cell
Antivirals target these steps
What are some viral infections that only occur in certain regions?
Dengue fever
rift valley fever
yellow fever
Why are viruses difficult to design a vaccine or antiviral for?
Mutate at rapid rate
Drugs: Acyclovir
Class: Antiviral; Chain terminator
Prototype
MOA: inhibit DNA synthesis
-very similar structure to DNA but missing part of sugar & hydroxyl group “Chain termination”
-another base cannot be added
Uses: Herpes, HSV, VSV
-reduces viral shedding
SE: mild; Renal insufficiency related to crystalization when given IV
-Can be reversed after d/c with hydration
What causes AIDS? How do you usually die from AIDS?
HIV
Opportunistic infection d/t failure of the immune system
Drugs: Azidothymidine, Lamivudine
Class: Antiviral
MOA: Azidothymidine: inhibits reverse transcriptase
-Lamivudine: inhibits DNA polymerase & reverse transcriptase
Azidothymidine is primary
Uses: HIV (Part of HAART cocktail)
-reduces viral shedding
Drugs: Cabotegrovir (PrEP)
Class: Antiviral
MOA: Blocks integration/absorption
Take this before exposure to HIV to prevent from getting infected in the first place
Drugs: Recombinent Interferon
Class: Antiviral
MOA: Activates MHC-1 receptors on cell surface that target CD8(+) T cells (Killer cells)
- CD8+ T cells fire cytokines at host cell to kill off host cell
We can produce this endogenously within the host cell
What are the killer cell? What do they do?
CD8+ T cells
Once on the MHC-1 receptor, they fire cytokines at virus host cells
How many different types of interferons are there?
20
Who is supposed to get their flu vaccine & how often?
Above 6 months old
every year
Differentiate between the 2 types of flu
Type A: Are a combo of 2 different subtypes
Hemagglutinin (role in absorption): H1, H2, H3 or
Neuraminidase (role in release): N1, N2
-Effects everything
-Moderate to severe cases
Type B: milder cases
-Only effects humans & seals
What is the most common target site for antivirals with the flu?
Neuraminidase which has a role in release
Drugs: Oseltamivir phosphate (Tamiflu)
Baloxivir marboxil (Xofluza)
Class: Antivirals - Flu
MOA: Tamiflu: targets Neuraminidase
Xofluza: targets polymerase enzyne
Need to take within 1st 48 hrs of symtpoms
Xofluza: not recommended for pregnant/breastfeeding or complicated illness pts
Drugs: Zanamivir (Relenza)
Class: Antivirals - Flu
MOA: targets Neuraminidase
Powder inhalant
Not for people with COPD or asthma
Have to be taken when you’ve been exposed to the flu BEFOREEEE symptoms occur
What are different types of Coronaviruses?
SARS
MERS
COVID-19
Drugs: Paxlovid, Remdesivir, COVID Mabs, Dexamethasone
Class: Antivirals - Covid
MOA: Remdesivir: chain terminator
-COVID Mabs: Block absorptoon of COVID into host cells
-Dexamethasone: Suppress immune system to suppress cytokines to prevent cytokine storm in severe covid cases
-Paxlovid- 2 antivirals combined (experimental medication
What is the #1 CDC recommendation for COVID?
Vaccination
