Enteroviruses Flashcards
What is the genome of picornaviruses?
Positive strand single RNA
What diseases does poliovirus cause?
Entero c paralysis
Aseptic mengitis
What diseases does coxackieviruses lead to?
Hand foot and mouth, conjunctivitis, chronic fatigue syndrome
What does echovirus entero B lead to:
Aseptic meningitis guillan-bares syndrome
What shape are picornaviridae?
Icosahedral
How does genome organisation occur in picornaviridae?
Makes polyprotein then keeps cleaving it
Have P1 and P3 being cleaved into other proteins which are enzymes
Protease cleaves it up
What is poliovirus replication cycle?
Polio goes inside
Releases nucleic acid
Then through VPG it starts translating proteins straight away
Makes P1, P2, P3
Then makes proteins that cleave them into smaller proteins
The first set of proteins makes VP0, 1 and 3
Gets made into capsid
Genome that undergoes replication first makes a negative sense
Then makes positive sense
Then stuff the genome into pro capsid
Bursts out
What is attachment for poliovirus?
Virus binds receptor on cell
- glycoprotein e.g. CD155 (polio)
- ejection of VP4 -> structural changes to viral capsid
What happens in transcription and genome replication of poliovirus?
Makes a hole so RNA cna go through
Once RNA is thorugh, you get two things
Transcription
So you get positive sense and negative sense
Then replication
Negative sense to more positive sense
Making prodigy virions
What are the outcomes of poliovirus exposure?
Unapparent infection (95%)
Abortive or minor illness (4-8%)
Non-paralytic poliomyelitis (0.1-2%)
Paralytic poliomyelitis (0.1-2%)
What is the faecal oral route for poliovirus?
Virus enters the body thorugh the mouth and multiply in the intestine
What was the Francis field trial in 1954?
Three doses of inactivated polio vaccine given to 420,000 children
Controls included 200,000 placebo recipients and 1.2 million uninicualted children
Inactivated polio vaccine prevented paralysis at efficacy rate of 83%
What was the cutter incident?
Company meant to make poliovirus vaccine, they had much higher cases observed than expected because they didn’t properly inactivate the virus, they were giving people poliovirus
What was the initial strategy for eradication programme?
Use cheap , safe and effective and easy to administer vaccine
Follow proven campaign approach
Stop vaccinating when no more wild-type virus
What are key difficulties in successful vaccination program in endemic counties?
- Public health infrastructure
- Community health education
- Proper vaccine storage
- Vaccine provided at a convenient time and place
- Popular support, active participation of community leaders and the community itself
