Introduction to viruses Flashcards
What size are viruses
Small: 20 – 400 nm diameter
What is the 3 structure of viruses
Icosahedral: 20 faces equilateral triangle
Helical: protein binds round DNA/RNA in a helical fashion
Complex: neither
What does it mean that viruses are Obligate intracellular pathogens
can only replicate inside host
What is the order of taxonomy
Order Family genus species (oh my freaking god sarah)
Viral families classified by
shape/symmetry
envelope
genetic structure
mode of replication
What do they spiral infections do for the virus
provide natural immunity
What is a virus composed of
nucleic acid
Lipid envelope
Protein capsid
Virion associated polymerase
Process of viral replication
attaches, uncoats RNA, replication of virus RNA in MRNA synthesis, virus protein synthesised, budding and related on the surface
What are the different viral transmissions
Blood borne Sexual Droplet Airborne Close contact Vector borne Zoonotic (Animals)
What isa droplet transmission; example
Large particle with small projection; Influenza,
What is a airborne transmission; example
Particle transferred in the air environment; Measels, chicken pox
What does coinfection of human and animal or bird lead to
may lead to recombination and generation of a new strain
Novel virus
Virus that has not be seen before
What does a clearance of viral infection mean
you don’t get any immunity e.g. influenza
What immunity does Measels have
Long term immunity
What infection is HIV, hepatitis B, hepatitis C
Chronic infection
What is viral latency
Virus lies dormant, then something triggers the virus
eg. immune system supresors/ stress etc.
What is viral transformation
long term viral infection that alters gene expression e.g. cancer
Example of viral infections that cause transformation i.e. cancer
Epstein-Barr Virus — glandular fever
Human Papillomavirus — causes cervical cancer
Hepatitis B/C : hepatocellular carcinoma
Human T-cell Lymphotropic Virus: Adult T-cell leukaemia/lymphoma
What viruses are latent
Herpes Simplex Virus (coldsore)
Varicella Zoster Virusm (chicken pox)
How does viral infections cause cancer
Modulate cell cycle control
Modulating apotosis
Promote oxidation
(some persistent viral infections can cause persistent inflammatory processes which lead to cancer)
How do you detect a whole virus organism
electron microscopy or grown in cell culture
How do you detect part of virus organism (antigen, nucleic acid)
antigen detection detected from viruses immune response
DNA/RNA replication from PCR
Amplification of region target organism genome
What is antiviral therapy
treating viruses by binding to cell and preventing viral replication
Antivirals are used for
Prophyaxis - prevent disease
Pre-emptive therapy - treat before symptoms
Overt disease
Suppressive therapy - keep viral replication below the rate that causes tissue damage in an asymptomatic infected patient
How do you prevent viral infection
immunisation - vaccination
Antenatal screening
Human virus passage to animal is called
coinfection
