enteric viruses

Question 1

Most common viral agent of severe diarrhea in infants and young children worldwide?

Answer 1

rotavirus

Question 2

Info on rotaviruses

Answer 2

• non-enveloped particles - segmented, ds RNA genome - high antigenic diversity with lots of G and P serotypes BUT only 4-G-P combos cause most of the disease in humans!

Question 3

Rotavirus/reovirus replication?

Answer 3

1) taken up by endocytosis and delivered to late endosomes or lysosomes where capsid proteins are proteolytically processed –> infectious sub viral particles.
**processing of capsid proteins can occur outside cell (when passing through gut) or after endocytosis in the late endosomes or lysosomes

2) **after penetration, enzymes in the core start making mRNA. **

     \*\* assymetric transcription 3) some capped mRNA are assembled into assortment complexes. capped + strand serve as template for synthesizing complementary - strand

4) Assembly of virus particles occur in cytoplasm in cytoplasmic viroplasms
5) progeny released via lysis of host cell

Question 4

Major cause of foodborne EPIDEMIC acute gastroenteritis in older children and adults?

Answer 4

• Norovirus/caliciviridae

Question 5

Info on norovirus

Answer 5

• nonenveloped, nonsegmented, + strand RNA virus

Question 6

Norovirus/caliciviridae replication?

Answer 6

not yet determined but similar to picornovirus replication cycle.

Question 7

How are rota and noroviruses transmitted?

Answer 7

via fecal-oral route aka contamination
- they are also both extremely stable in the environment

Question 8

Which virus is often linked to a single source? aka contaminated food (raw or steamed shellfish, cake frosting, salads) or contaminated water (cruise ship outbreaks)?

Answer 8

norovirus

Question 9

how do rota- and norovirus infections usually present?

Answer 9

These viruses in patients present with nausea, vomiting, diarrhea, fever, and dehydration

Question 10

Pathophysiology of rota- and norovirus

Answer 10

• they both initially infect villous epithelium of small intestine.
• virus replication and cell lysis cause LOSS OF CELLS IN LINING the SMALL AND LARGE intestine.
• Loss of cells cause FUNCTIONAL ALTERATION in SI villous epi cells
• glucose coupled Na transport IS IMPAIRED, BUT AC and cAMP are NOT stimulated like in cholera.

Question 11

Epidemiology of rotavirus?

Answer 11

• before 2007 lots of rotavirus diarrhea per year in US but very few deaths in US d/t to othis bc of availability of effective fluid and electrolyte replacement.
• worldwide though many children/infants die from rotavirus diarrhea each year. ~600k

Question 13

what is the difference between how antibody to rotavirus is obtained vs antibody to norovirus?

Answer 13

• antibody to rotavirus is obtained early in life
• ab to norovirus is acquired gradually in childhood and increase steadily over person’s lifetime!

Question 14

vaccines for rotavirus?

Answer 14

1) rotateq- pentavelnt bovine-human reassortment virus (serotypes g1-g4 and p8)
*rotateq is life, attenuated vax given oral at 2, 4, & 6 mo of age

2) rotarix- human derived monovalent (G1, p8) live attenuated vax
*rotarix is admin orally in 2 doses started @ 6 weeks of age

Question 15

vaccines for norovirus?

Answer 15

• no approved vax available yet

Question 16

most important preventitive measures for norovirus is?

Answer 16

1) careful handwash
2) effective disinfection of contaminated surfaces

3) proper food prep

Question 17

Info on astroviruses

Answer 17

nonenveloped, icosahedral, single stranded, + sense RNA virus

**characteristic star like appearance on EM

Question 18

What is the second most common cause of childhood diarrhea?

Answer 18

second to rotavirus is the astrovirus

Question 19

How is astrovirus transmitted?

Answer 19

-oral fecal route

Question 20

what is the vax for astrovirus?

Answer 20

no vax available yet

Question 21

describe astrovirus illness

Answer 21

• self limiting illness with short duration with a peak in winter months

Question 22

info on enteroviruses/picornoviridae

Answer 22

small, isosahedral, nonenveloped, + sense RNA virus
*picorna- small rna

Question 23

name 4 enteroviruses

Answer 23

poliovirus, coxsackievirus (group a and b), echovirus, and enterovirus
**echovirus followed by coxsackievirus group a has the most number of serotypes

Question 24

clinical manifestation of poliovirus?

Answer 24

flaccid paralysis (poliomyelitis)

Question 25

clinical manifestation of coxsakieviruses?

Answer 25

various illnesses such as hand food mouth disease, menangiocephhalitis, diarrhea, muscle pain, inflammation of myocardium and pericarium

Question 26

clinical manifestation of echoviruses and other enteroviruses?

Answer 26

mild gastroenteritis
**echo = enteric, cytopathic, human, orphan

Question 27

what is another enterovirus-like picornavirus?

Answer 27

hep A!

Question 28

how do you differentiate rhinoviruses from enteroviruses?

Answer 28

1) acid stabilty and
2) replication @ 37 degrees Celsius

Question 29

Transmission of enterovirus?

Answer 29

fecal-oral route

Question 30

enterovirus reservoir

Answer 30

humans are the only known reservoir

Question 31

vax for enterovirus

Answer 31

no vax except for polio

Question 32

Incubation time of enteroviruses?

Answer 32

short (7-14 days)
**initially enteroviruses replicate in lymphoid tissue of the URT and the gut so these are often isolated and cultred for diagnoses via throat swab

Question 33

clinical manifestation of enteroviruses?

Answer 33

asymptomatic infection is common
- can have malaise, fever, sore throat, headache, stiff neck
**viremia results in infection of target organs like spinal cord and brain, meninges, myocardium, and skin

Question 34

info on adenovirus/picornaviridae

Answer 34

large, nonenveloped, linear ds DNA virus

Question 35

what serotypes of adenovirus are associated with gastroenteritis?

Answer 35

• serotypes 40 and 41

Question 36

how is adenovirus transmitted?

Answer 36

via fecally contaminated water.
* foodborne transmission has not yet been documented

Question 37

epidemiology of adenovirus?

Answer 37

• generally seen in young children and infants like rotavirus and astrovirus
  **most ppl have antibodies vs enteric adenovirus by the age of 3