Viral Agents Flashcards
structure of a virus?
protein capsid surrounds DNA or RNA, never both. no enzymes.
Positive vs Negative strand RNA virus
positive strand is like mRNA and can be translated immediately.
Negative stand must be transcribed into a positive stand to be translated into protein. this is done by an RNA dependent RNA polymerase.
how do retroviruses replicate?
they use a reverse transcriptase to turn their RNA into DNA and add it to the host genome.
double stranded RNA virus
retrovirdae, including rotavirus is the only virus with double stranded RNA genome
Negative vs Positive strand in DNA viruses?
the negative strand is the strand that is transcribed inot mRNA and the pos strand is ignored.
explain how a capsid is made
a capsid is a made from capsomer building blocks. glue them together into a triangle, then add 20 triangles together and a capsid is formed!
naked for enveloped virus
enveloped has a plasma membrane surrounding it.
naked viruses don’t.
Name the DNA viruses
HHAPPPy: Herpes Hepandna Adeno Papova Parvo Pox
where do DNA viruses replicate vs RNA viruses?
DNA - nucleus
RNA - cytoplasm
Single stranded DNA Virus
Parvoviridae
very complex virus with double stranded DNA , coding for hundreds of proteins. it is surrounded by box proteins and replicates in the cytoplasm, not nucleus.
Poxviridae
DNA viruses with envelopes?
Herpes, Hepadna, Pox
three naked DNA viruses
Papova, Adeno, Parvo
four exceptions for RNA viruses
- reoviridae is double standed RNA
- three are enveloped : Picoma, Calici, revirdae
- five have icosahedral symmetry: Reo, Ricoma, Togo, Tlavi, Calici
- (Rhabdo has helical symmetry and its shaped like a bullet.
enzymes to replicate RNA
Replication:
POSITIVE RNA = have the RNA dependent RNA polymerase
NEGATIVE RNA = VIRON RNA POLYMERASE
steps in DNA transcription and translation of viral DNA
early vs late
early transcription = translation of proteins for DNA and replication
Late Transcription = translation of structural proteins and assembly.
possible host cell outcomes when Viral DNA replicates
Host cell outcomes:
- Death: shuts down the host cell and only does viron replications.
- Transformation: infection can induce oncogens resulting un uncontrolled and uninhibited cell growth.
- Latent infection: can sleep within the cell, making it clinically overt. varous factors can reactivate it later.
- Chronic Slow infection: can cause disease in many years, or decades, or indolent infection.
1-2 day incubation period.
Viral structure: spherical, with 8 segments on NEGATVIE stranded RNA put together with a protein called nucleocapsid protein (NP).
Orthomuxovirdae
outer proteins of influenza virus?
Outer proteins:
Hemaggultinin Activity (HA) - they attach to Silalic Acid receptors and cause heme-agglutination of RBC. needed for absorption in the upper respiratory tracts.
Neuraminidase (NA) - mucin is a part of the upper respiratory tract. NA cleaves neuramic acid and disrupts the mucin barrier, exposing the sialic acid binding sites beneath. NA then cleaves the sialic acid receptors when the virons are leaving the cells.
Influenza A vs B/C
Influenza A = mammals, Influenza B and C are in humans.
what is worse the flue or influenza?
who is at risk?
Influenza virus > The Flue; Pneumonia at risk groups, more severe risk groups.
define epidemic influenza
within the winter (Dec- Early March) is an outbreak in a city, state, or entire country. first sign is otitis media or pneumonia in children with secondary pneumonia in adults. this is followed by death in elderly and immunocompromised (chronic diseases).
high fever, chills (frank shaking chills), headache, malaise (feeling like shit), and myalgia (muscle aches)
the flu
dry cough, sore through, rhunorrhea (runny clogged nose), painful muscle aches, high fevers, and headaches set this apart from a mild cold.
URI