RNA viruses - picornaviridae

Question 1

What are the subgroups of picornaviruses?

Answer 1

Polio, Echovirus, Rhinovirus, Coxsackie viruses, and HAV.

Question 2

What of the picornaviruses are enteroviruses?

Answer 2

All except HAV. Polio, echo, rhino, coxsackie.

Question 3

What is the genetic structure of picornaviruses? How are proteins made?

Answer 3

All small RNA viruses, + single strand. RNA is transported into one long polypeptide, then cleaved by protease into function viral proteins.

Question 4

Where do picorna entero viruses replicate and spread?

Answer 4

Infect intestinal epitheliod and lymphoid (tonsils, peyer’s patches) cells. Excreted in feces, spread by fecal oral. Replication in tonsils also results in viral shedding from pharyngeal secretions.

Question 5

What two cell types does poliovirus infect?

Answer 5

1) Peyer’s patches of the intenstine (fecal oral tx)
- spreads via blood, crosses blood/brain barrier, gets at anterior horn of spinal cord…
2) Motor neurons (paralytic poliomyelitis).

Question 6

What are the three clinical presentations of poliovirus?

Answer 6

1) Mild illness
2) Aseptic meningitis - recovery complete in 1 week
3) Paralytic poliomyeltitis

Question 7

How is paralytic poliovirus caused?

Answer 7

Viral infection destroys presynpatic and post synaptic motor neurons - causes both central and peripheral motor neuron defects.
ASYMMETRIC generally, but can be paraplegia/quadriplegia, even respiratory dysfunction.

Question 8

What are the two types of polio vaccines?

Answer 8

Salk vaccine, Sabin vaccine.
SalK = killed, subQ.
Sabin = oral polio, live attenuated. Better because can confer herd immunity through shedding, but worse because there were a bunch of cases of vaccine associated paralytic poliomyelitis.

Question 9

What symptoms can coxsackie A and B, echoviruses and “new enteroviruses” cause?

Answer 9

1) Asx or mild febrile infection
2) Respiratory symptoms (“cold”)
3) Rashes
4) aseptic meningitis - enteroviruses are most common cause of non-bacterial meningitis.

Question 10

What does coxsackie virus A cause?

Answer 10

Herpangina - fever, sore throat, red based vesicles over back of throat
Hand/foot/mouth - small children, fever, oral vesicles and small tender lesions on hands/feet/butt
Severe infection in mice

Question 11

What does coxsackie virus B cause?

Answer 11

Pleurodynia, myocarditis/pericarditis, can result in arrythmias or cardiomyopathy/HF.