Fenger- GI Viruses- Melissa**

Question 1

List the 4 viruses in the Reoviridae family

Answer 1

• Rotavirus
• OrthoReovirus
• Orbovirus
• Coltivirus

ORTHO’s ROTAte and COLlect OuRBOnes

Question 2

Describe the replication process for Rotavirus

Reoviridae Family

Answer 2

• Attachment–>
• Outer Capsid removed–>
• RNA-D RNAP activated in CORE–>
• Genomic AND mRNA synthesized **IN CORE**–>
• 11 mRNAproducts –> cytoplasm via TUBULES–>
• Translation of mRNA by host ribosomes–>
• Genomic dsRNA sent to cytoplasm–>
• New capsid proteins + Genomic dsRNA–> new virus

**Capping enzyme in core caps 5’ end of mRNA and (+) strand of dsRNA

Question 3

Describe the structure of viruses within the Reoviridae family: 
genome? 
capsid? 
envelope?
accessories?
acid: stabile or labile?
enzymes in core?

Answer 3

Segmented dsRNA (10-12segments: L,M,S)
2 icosahedral capsids (inner = core)
Naked!
Tubules: core--> capsid
Acid stable 
Core: RNA dep RNAP; capping enzymes

Question 4

Describe OrthoReovirus:
What kind of virus is this?
How does infection manifest?
What patient population gets infected?

Answer 4

OrthoReovirus

• Orphan virus: 3 types found in healthy kids
• Minor pediatric febrile illness and diarrhea/ enteritis

Question 5

Orbovirus: What two infections does this virus cause?

Answer 5

Orbovirus (ARBOvirus; tick borne)

• Bluetongue virus in sheep; African horse sickness
• *No human illness (These can “spread” to humans per Fenger, though I have never heard of such a thing).

Question 6

Coltivirus:

What kind of infection does this virus cause? How is the infection spread?

Answer 6

Coltivirus
(Arbovirus: Dermacentor andersoni tick)
-Colorado Tick Fever: myalgia + arthralgia, ocular pain, N/V w diphasic fever and full recovery

Question 7

Rotavirus: 
What kind of infection does this virus cause? 
Describe the symptoms.
How virulent is is? How common is it?
Does this virus grow well in culture?

Answer 7

Rotavirus

• Winter infantile diarrhea; highly infectious
• Sx: fever, belly pain, N/V, dehydration; fatal w/o tx

#1 cause of death kiddos under 2 yoa in dvlpng. Countries
Does not grow well in culture

Question 8

How does Rota cause disease?

How do we dx rotavirus?

Answer 8

-2-4 day incubation –> infects tips of villi in small intestine; cells lyse –> poor absorption –> osmotic diarrhea

Dx: ELISA, EM of stool, PCR

Question 9

How do we prevent rotavirus?

Answer 9

Px: Vaccines Oral, live attenuated (IgA&raquo_space;>IgG)
1) Rotarix: monovalent
RotaRIX is a ONE valence FIX!
2) Rotateq: Pentavalent

3 doses:

• *Start vaccinations b/w 6-12 wks old
• • Ideal: vaccinate @ 2, 4, 6 mos

Question 10

Calciviridae:

• what characterizes the family?
• which enteric virus is in this family?
• structure?

Answer 10

-not able to grow well in culture 
(NOROom for CALCI viruses on cultures!) 
-Norovirus 
(4 genera total)
-+ssRNA, icosahedral

Question 11

Does norovirus grow well in culture?

What patient population is immune to infection by this virus and why?

Answer 11

Does not grow well in culture (rep. not understood)

• Attachment—ABO RBC antigens are cell surface receptors
• AB, B blood types are IMMUNE

Question 12

Which two strains of norovirus infect humans? How many are there?
In what season are they particularly virulent?
Which circumstances increase likelihood of infection?
How does infection manifest (sx)?
How is infection diagnosed?

Answer 12

Norovirus/ Norwalk virus

• (4 genera– only G1, G2 infect adults and kids in winter)*
• Common in closed quarters (cruise ships, nosocomial, etc.)
• Sx: Flu Sx + N/V/D, belly pain
• Dx: ELISA, EM, PCR

Question 13

List 5 factors that make norovirus particularly virulent.

Answer 13

1) Small viral load (requires less than 100)
2) prolonged shedding after recovery
3) resists alcohol/ detergents
4) stabile in many environments
5) no long lasting immunity
(only short lived IgA)

Question 14

Coronavirus: describe the structure (genome, capsid, envelope?)

**One important factor about its replication?

Answer 14

(+) ssRNA
Helical nucleocapsid
Envelope w peplomers
Cytoplasmic replication + budding

Replicates with little to no cytoplasmic effect in tissue, otherwise typical for +ssRNA virus…

Question 15

Coronavirus:
What are the two reservoirs?
How does the disease manifest in adults?
How does the disease manifest in infants? **

Answer 15

Coronavirus

• Humans, Rodents = reservoir
• Infectious bronchitis in adults
• SARS droplet spread; lower RT infection +/- GI sx
• Necrotizing entercolitis in newborns

Question 16

Astroviridae: Which enteric viruses are in this family?

Answer 16

• Mamastovirus**
• Avastrovirus

MAMA AVA is an ASTROnaut.

Question 17

Describe the structure of astroviruses: genome, capsid, envelope, appearance on EM?

Answer 17

(+) ssRNA; nonsegmented
Icosahedral
Naked
*Looks like star on EM

Question 18

Which two species can mamastovirus infect?
How does infection typically manifest in humans?
How common is infection?
Is long lasting immunity established?

Answer 18

Mamastovirus

• Infect birds and mammals
• Asx or Gastroenteritis in young kids most often (MILD)
• Ubiquitous Ab in young kids
• long term immunity through adulthood

Question 19

Adenoviridae: which adenoviruses are enteric viruses?

How does infection manifest?

Answer 19

40, 41–gastroenteritis (dsDNA)

Question 20

Picornaviridae: which picornaviruses are enteric viruses?

How does infection manifest?

Answer 20

Enterovirus, Coxsackie A–gastroenteritis ((+) ssRNA)

Question 21

Most viruses in this lecture are +ssRNA.

Which family is not?

Answer 21

-Reoviridae = dsRNA, segmented

(Also note that adenovirus is vaguely mentioned in the chart. It is DSDNA).

All others= ssRNA!