viruses & prions Flashcards
can viruses survive by their own?
no, they need another cell to survive, they are acellular
what does it mean when an organism is obligate?
it needs to grow in another cell
can viruses switch between the 2 nucelic acids?
yes, between dna and rna
what is the protein coat of viruses called? and what is it made of?
the protein coat is called capsid, made up of capsomeres
what does the core of the viruses contain?
nucleic acids
what are the 2 forms viruses exist in? shape wise
isocahedral, helical
do all viruses have envelopes and tails?
no, only some
what is a naked virus?
a virus without an envelope
what does the nucleocapsid consist of?
nucleic acid and capsid
what is the icosohedral shape
same repeating units over and over again in traingular surfaces
what is a bacteriophage?
a virus that infects bacteria
is a bacteriphage an icosohedral shape?
it has an icosohedral head and a helical body, and its got a tail
what happens when a bacteriophage attaches itself onto a virus?
the dna inside the middle part of the bacteriophage injects itself into the cell, and then the viral DNA is in the bacteria cell
what is a lawn?
bacterial cells in solution
how does viral replication happen?
virus attaches to the host, the viral DNA penetrates into the host, inside the host will be the synthesis of nucleic acid and protein, then the viruses are assembled and packaged. then they are released
how can viruses be transmitted?
respiratory transmission, feacal oral transmission, blood borne transmission, sexual transmission, animal or insect vectors
what does tissue tropism?
targeting of the virus to specific tissue and cell types
can viruses change gene epression?
yes
are viral infections localised?
yes, they are localised to a specific site of body
what is viraemia?
the presence of viruses in the blood - widespread infection of tissues
what is an enveloped virus with RNA?
influenza A virus
how is the influenza A virus infection spread?
by respiratory route, the virus infects cells of the respiratory tract, it destructs the respiratory epithelium
what does the influenza A virus do to cause hayfever?
alteres the cytokine expression, leading to fever
what characteristics must an antiviral have?
- must be able to enter the cells infected with virus
- must be able to interfere with viral nucleic acid synthesis and/or regulation
- able to interfere with ability of virus to bind to cells
- must be able to stimulate the body’s immune system
which patients have the best response to antiviral drugs?
patients with competent immune systems
can antivirals treat infections caused by HIV?
no, antiretroviral drugs are used to treat infections caused by HIV
what does HSV-1 cause?
oral herpes
what does HSV-2 cause?
genital herpes
what does the varicella zoster virus cause?
chickenpox and shingles
when is the antiviral drug, nonretroviral Amantadine used?
used prophylactically when vaccine is not available or cannot be given
what is the disadvantage of the antiviral drug, nonretroviral Amantadine?
it has a narrow antiviral spectrum - active against influenza A
what are the CNS effects of Amantadine (Symmetrel)?
insomnia, nervousness, lightheadedness
what are the GI effects of Amantadine (Symmetrel)?
anorexia, nausea, others
name 2 antiviral drugs
Acyclovir (Zovirax)
Amantadine (Symmetrel)
name 2 antiviral Neuraminidase Inhibitors
Oseltamivir (Tamiflu) and Zanamivir (Relenza)
what are Oseltamivir (Tamiflu) and Zanamivir (Relenza)
active against?
influenza types A & B , they reduce duration of illness
when should the treatment for influenza types A &B be started?
within 2 days of influenza symptom onset
what does HAART stand for?
what does it include?
Highly active antiretroviral therapy
-includes at least 3 medications - it is a cocktail. these medications ork in different ways to reduce the viral load
what do reverse transcriptase inhibitors (RTIs) do?
they block the activity of the enzyme reverse transcriptase, preventing the production of new viral DNA
what are the 3 types of TSEs?
infectious, sporadic, familial
how are infectious TSEs spread?
by consumption of infected material, organ transplant, transfusion
what is the cause of familial TSEs?
Due to autosomal dominant mutation of PrP
what are some characteristics of TSEs?
they are transmissible, inevitably fatal, long incubation periods, no antibody response, no inflammatory reponse, afebrile (not fever causing), accumulation of PrP protein
what is a prion?
Proteinaceous infectious particle. they are smaller than the smallest known virus
what is the most accepted theory for prions?
that prion are mutated proteins
what is the difference between a normal and an abnormal protein?
in a normal protein, the secondary structure is dominated by alpha helices, whereas in an abnormal protein, the secondary structure is dominated by beta conformation.
both proteins have the same amino acid sequence and primary structure
how is the abnormal form of a protein formed?
When the abnormal protein comes in contact with the normal protein (PrPC) it converts the normal protein to the abnormal form.
are abnormal proteins insoluble?
yes, theyre insoluble in all but strongest solvents, they are highly resistant to digestion by proteases, they are extremely resistant to heat, normal sterilization processes, sunlight, has no detectable immune response
what are the initial symptoms of vCJD?
Depression, anxiety, insomnia, social withdrawal, persistent painful sensory symptoms
Schizophrenia-like psychosis
Neurological signs
at progression, person becomes completely immobile and mute.
what is the treatment of vCJD?
there is no effective treatment available? , so we just offer symptomatic treatment and supportive care
how do you disinfect from prions?
To physically inactivate the prion, the best option is porous load autoclaving at 134-138oC for 18 minu
