Viruses Flashcards
Why are viruses important in oral health
Cause infection in oral cavity
Easily spread
Hard to treat
Draw the structure of a virus
4 parts - capsid ( protein case )
- nucleic acid genome (DNA OR RNA -not both )
- envelope (lipid membrane - helps adhere to host cell)-NOT ALL VIRUSES HAVE
Lack organelles /enzymes
What is special regarding virus replication
Cannot reproduce themselves or use binary fusion
Must use another host cell to replicate
Name 5 steps in virus replication
- Recognise a host cell receptor and Attachment to host cell -
- Absorbing into cell - 3 ways
- fusing of virus and host cell membrane
- endocytosis of virus
- diffusion entire virus across the host cell
membrane - Nucleic acid replication - particles reach cytoplasm capsid sheds off and genome uses the host cells “machinery “to replicate viral genome into viral proteins ( via transcription/translation )
- Viral assembly - new viral proteins/genomes assemble into new viral particles
- Virus release - 3 mechanisms
- cell lysis -releases virus OR
if enveloped viruses -bud or exocytosis where the protein inserts itself into the host membrane
What is viral latency
After the primary infection the virus can lay “dormant” in a ganglion then become reactivated and cause active secondary infection
Give an example of a mouth virus and how it presents on its primary then secondary infection once its been latent
Herpes simplex virus type 1(most common mouth viral infection )
see. Primary stage - gingivostomatitis - asymptomatic or ulcers then it can …
Moves to trigeminal ganglion and lays in latent stage
Reactivation by stress/ sunlight /illness/ Trauma area etc
Reactivates - secondary HSV - cold sore - travels down peripheral nerve of trigeminal Nerve and causes ulceration on mucocutaneous area lip
What can cause reactivation of secondary virus infection in latent state
Stress
Sunlight
menstruation
illness
Trauma to the area
Name 2 oral viruses and their symptoms /complications
1.Herpes simplex type 1 virus - most common in mouth
gingivostomatitis - asymptomatic or ulcers
lays latent and secondary infection =cold sores
saliva transmitted
2.Epstein Barr virus ( ebv)- glandular fever
pharyngeal inflammation /tonsil large
saliva transmitted
children maybe subclinical
EBV CAN CAUSE BURKITTS lymphoma
How can you prevent virus infections
PPE/appropriate hygiene ( IMPT in oral health)
Vaccination - complicated
Antiviral medications
Name 2 antiviral medications and how they work
Amantadine ( influenza) - inhibits viral uncoating so genome not able be replicated
Acyclovir - inhibits DNA synthase - stops replication
Why is forming an antiviral difficult
high mutation rates
3 reasons Why a viral vaccination treatment is difficult
Antigenic shift
Antigenic drift
Low vaccination rates
All lead to increase in virus changes/mutations so vaccination then not effective )
What is antigenic shift
2 or more strains virus combine - so sudden genome changes causing new subtypes and infect more virulently or other organisms
What is antigenic drift
slow small mutations that accumulate overtime so eventually a new virus subtype emerges - vaccines then don’t work
Why do antibiotics not kill viruses
No peptidoglycan cell walls, no ribosomes, not replicate their own DNA
Need host cells to replicate not replicate by themselves