Intro to Viruses Flashcards
What is the definition of a virus?
An obligate intracellular pathogen
Name the different type of virus structures?
Icodshedral, helical and complex
Describe the icosehedral structure of a virus?
It has 20 faces, each being an equilateral triangle
12 verticre and 30 edges
Describe the helical structure of a virus?
The protein binds around the DNA/RNA in a helical fashion
Describe the complex structure of a virus?
It is neither icodahedral or helical
Give an overview of a virus?
Small between 20-400nm and is non-cellular and so its genetic element cant replicate independently
What are virions?
The extracellular form of a virus, which exists outside of the host and facilitates transmission
It also contains nucleic acid surrounded by a protein coat
How are viruses grouped into taxonomic groups?
Virion shape/symmetry
Presence or absence of envelope
Genome structure
Mode of replication
Name the key parts of the virion structure?
Lipid envelope Protein capsid Spike projections Virion associated polymerase Nucleic acid
What is the process of virus replication?
Virion attahcedment to the cell Uncoating Replciation of genomic nucleic acid mRNA synthesis Protein synthesis using the host machinery Newly synthesised viral proteins Genomic nucleic acid synthesis Insertion of viral proteins into membrane Virion assembly Budding Release Maturation
Name each method of transmission with an example?
Blood-bourne - HIV and hepatitis B Sexual - HIV Vertical - HIV and Hep B Faecal-oral - Hep A/E and polio Droplet - influenza Airborne - measles and chickenpox Close contact - herpes simplex and EBV Vector - dengue and yellow fever Zoontic - rabies and ebola
What is the definition of zoonotic?
Spread between animals and humans
What do influenza, measles and chickenpox have in common?
Respiratory syndrome
What do enterovirus, polio, rabies, HSV and VZV have in common?
Neurological syndrome
What do norovirus, rotavirus and adenovirus have in common?
Gastroenteritis
What causes hepatitis?
ABCDE, CMV, EBV and yellow fever
What clinical signs does HSV and enterovirus show?
Skin infections
What clinicall signs does HSV, VZV and adenovirus present?
Eye infections
What causes congenital abnormalities?
CMV, rubella, VZV and parvovirus
What clinical signs does dengue, rubella and parvovirus present?
Arthralgia
What causes lymphadenopathy
HIV, CMV and EBV
What are the different consequences of viral infection?
Clearance can lead to no, short or long term immunity
Or other viruses can lead to chronic infection such as HIV, hep B/C
Some viruses lay dormant (Herpes)
Other viruses transform and can cause cancer (EBV and HPV)
Describe viral latency?
The viral genome is retained in the host cell, but expression is restricted
Later, reactivation can occur being more aggressive
Herpes simplex
What are the methods in which viruses cause cancer?
Modulation if the cell cycle
Modulation of apoptosis
ROS mediated damaged (inflammation)
What are examples of viruses which cause cancer and what are they?
EBV - Burkitt's and Hodgkin's lymphoma Herpes 8 - Kaposi's sarcoma HTLV - Adult T-cell leukemia/lymphoma HPV - cervical and oropharyngeal cancers Hep B/C - hepatocellular carcinoma
How to detect viruses?
From the whole organism - microscopy
Part of the organism - ELISA and PCR
Antibodies - immuniflouresence
What immuniglobulins are present after infection?
Acute IgM
Past infection IgG
What is the aim if antiviral therapy?
They target the host machinery to disable protein and genetic synthesis
But have toxic side effects
What are the timings if therapy?
Prophylaxis - before infection
Pre-emptive therapy - evidence of infection but no clinical signs
Overt disease - infected
Suppressive - reduce viral load and replication
Name different ways of viral infection prevention?
Immunisation - passive and active Prophylactic treatment Infection conton - PPE, isolation and disposal Screening Antenatal screening
What are the properties a virus must have to be potentially able to be eradicated?
Specific to a species Clearly identifiable with a diagnostic tool No chronic state Efficient and practical prevention Support
