RNA Viruses

Question 1

All non-enveloped viruses are what structure??

Answer 1

Icosahedral

Question 2

All RNA viruses replicate in the cytoplasm except??

Answer 2

Orthomyxoviridae (influenza virus) & Retroviridae (HIV; DNA provirus goes to the nucleus)

Question 3

All RNA viruses are single stranded except??

Answer 3

Reoviridae (rotavirus)

Question 4

Reoviridae (rotavirus) - char

Answer 4

REO – Respiratory Enteric Orphan virus,
* naked, icosahedral
* dsDNA, segmented (important 4 vaccines)
* double/triple layer capsid

Question 5

Reoviridae (rotavirus) - proteins

Answer 5

Outer shell proteins: VP7 (G) & VP4 (P)
* neutralizes antibodies
* vaccine components
NSP4 (nonstructural protein 4)
* promotes Ca 2+ influx
* acts like enterotoxin

Question 6

Reoviridae (rotavirus) - transmission and management

Answer 6

Fecal/oral - most common cause of gastroenteritis in infant to age 5
2 live virus vaccines:
* RV5 - human bovine assortment - attenuated
* RV5 - human monovalent attenuated

Question 7

Reoviridae (Coltivirus)

Answer 7

Colorado tick fever!
Infects RBCs and causes leaky capillaries -> rash
* Lethargy, myalgia for months
* No vaccine, antivirals

Question 8

Picornavirdiae family contains which viruses?

Answer 8

Enterovirus (poliovirus, coxsachie virus and echovirus), Hepatovirus, rhinovirus

Question 9

Enteroviruses - characteristics and examples

Answer 9

• Stable at acidic pH
• Replicates pharynx & GI tract
• Transmission - respiratory & fecal/oral
• Coxsackie A6= Hand-foot-mouth
• Coxsackie B= Myocarditis, pericarditis
• Meningitis caused by polio, coxsackie and echo

Question 10

Enterovirus CNS diseases

Answer 10

Polio
*Enterovirus 71 -most virulent next to poliovirus
- Hand-foot-mouth disease
Poliomyelitis-like paralytic disease, meningitis
- Enterovirus D68 – associated with acute flaccid myelitis
- Coxsackie B1 - myocarditis along with meningitis + neonatal disease

Question 11

Poliovirus - transmission and dissemination

Answer 11

respiratory or fecal/oral transmission
- Tonsils; lymph nodes; small intestine; Peyer patches
- crosses the blood/brain barrier
- Spreads to the CNS in ~1% of cases

Question 12

Polio - CNS diseases

Answer 12

Nonparalytic poliomyelitis (aseptic meningitis):
* fever, malaise, drowsiness, headache
* stiffness & pain in the back & neck
* 2-10 days complete recovery
Paralytic poliomyelitis:
* Loss of reflexes; flaccid paralysis (reduced muscle tone)
* Spinal poliomyelitis (most common) damages anterior horn cells

Question 13

Polio - vaccination/treatment

Answer 13

Salk vaccine - Trivalent, formalin inactivated, no VAPP, given to immunocomp..
Sabin Vaccine - OPV, live attenuated vaccine, risk of VAPP lowww
Polio type 2 & 3 slight circulation