Week 3 - Microbiology Viral Replication Flashcards
What are viral pathogens classified by?
Basis of virion structure, characteristics of nucleic acid, and replication strategy
What are viruses?
Obligate Intracellular parasites… must have host cell - if they don’t multiply they will not cause disease
Do viruses produce toxins?
NO. They must multiply to cause disease.
Why vaccinate?
Provide as many antiviral compounds so when virus enters body they do not multiply
Virion
Invections virus particle, what invades the body
What does a virion contain?
Nucleic acid genetic material surrouned by protein coat (capsid)
Some have lipid and glycoprotein envelope
Genomes can be?
DNA or RNA
Single stranded or double stranded
Can have same (+) polarity or complimentary (-) polarity as viral m-RNA
Circular or linear (some segmented)
Positive polarity in viral genomes
Same polarity as viral mRNA (+)
Negative polarity in viral genomes
It is complementary to viral mRNA
Viral genomes are haploid except for what?
Retroviruses.. They are diploid
DNA vs RNA virus genomes
DNA are single stranded, double stranded, or circular
RNA is Single stranded (polarity), segmented or double stranded segmented
Capsids/Nucleocapsids
Nucleocapsid if enveloped
They are composed of many copies of one or very few viral-encoated protein subunits
Their function is in packaging the nucleic acid in viral assembly and protection of the nucleic acid
Capsid Shape
Either cylindrical (helical form) or cubic shape (icosahedron from)
Viral attachment protein (VAP)
Capsids of naked viruses contain VAPs. They are used this to get into other cells
VAPs as drug targets
If an antibody targets and destruct the VAP the virus cant get into cell and cant replicate
Capsomer arrangement
Penton capsomer (surrounded by 5 capsomers) Hexon capsomer (surrounded by 6 capsomers)
Do all capsids contain enzymes?
No. Only some.
Glycoproteins on Nucleocapsids
Specific glycoproteins act as VAPs for enveloped helical nucleocapsids
What is the Envelope composed of?
Lipds, proteins and glycoproteins
The glycoproteins are acquired from viral modified cellular membranes during egress of virus from host cell
What is the viral envelope disrupted by?
Non-moist environments, heat, acid, and lipids solvents…
What is a Peplomer
A glycoprotein
Enveloped helical
Capsomere surrounds nucleic acid in helix form
How are viruses classified?
Nucleic acid, virion structure, replication strategy
How many families of viruses in human pathogens?
21 families, 7 families contain DNA. Viruses in same family don’t always produce same diesease.. Also different families can produce same disease…