viruses associated with gastrointestial tract infections medical virology lecture 03/04 youjun feng...
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Viruses associated withgastrointestial tract infections
Medical VirologyLecture 03/04
Youjun Feng
Center for Infection & Immunity, Zhejiang University School of Medicine
Enterovirus of picornaviridae & acute gastroenterities virus
Viruses infected through gastrointestinal tract
Enteroviruses of picornaviridae Acute gastroenteritis viruses
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Polioviruses
Coxsackieviruses
Echoviruses
New enteroviruses
Parenteral disease
• Rotavirus
• Calicivilus
NorovirusSapovirus
• Astrovirus
• Enteric adenovirus
Viral gastroenteritis/viraldiarrhea
Enterovirus of picornaviridae
PICORNAVIRUSES
Small RNA Viruses
icosahedral symmetry
Non-enveloped
+ strand RNA
+ Strand RNA is infectious, serves as mRNA
Most are very cytolytic to cells
Members
Enterovirus
Virus
Poliovirus
Disease
Poliomyelitis
Rhinovirus
Heparnavirus
Coxsackie Virus A
Coxsackie B
Echovirus
other Enterovirus
100 serotypes
Hepatitis A virus
Herpangina, Hand Foot and Mouth disease
Myocarditis, Pericarditis
Common Cold
Hepatitis
PICORNAVIRUSES
Enterovirus of picornaviridae
parenteral disease
DISEASE MECHANISMS
Transmission route:Fecal-oral
Season:
summer
Viremia
DISEASE MECHANISMS
Enterovirus of picornaviridae
Poliovirus
Poliovirus
DiseasePoliomyelitis
Herpangina, Hand Foot
and Mouth disease
Myocarditis, Pericarditis
Serotypes1-3
1-22, 24
1-6
1-9, 11-27, 29-34
MembersPoliovirus
Coxsackie Virus A
Coxsackie B
Echovirus
other Enterovirus
Poliovirus & poliomyelitis
Poliovirus & poliomyelitis
In spinal paralysis one or more limbsmay be affected or complete flaccid
paralysis may occur.
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In bulbar paralysis cranial nerves and therespiratory center in the medulla areaffected leading to paralysis of neck andrespiratory muscles.
no sensory loss
Iron lung
Polio vaccines
Decline in Poliomyelitis
World Polio Map
World Polio Map
World Polio Map
In 2011, only four countries (Afghanistan, India, Nigeria and
Pakistan) remain polio-endemic, down from more than 125
in 1988.
Current situation
In 2012, only three countries (Afghanistan,
Nigeria and
Pakistan) remain polio-endemic, down from more than
125
in 1988.
Current situation
http://www.who.int/csr/don/2011_09_01/en/index.html
Enterovirus of picornaviridae
Coxsackieviruses
Echoviruses &New Enteroviruses
Other enteroviruses & diseases
PATHOGENESIS
Fecal-Oral route trasmission
Spread in the body like polioviruses
Disease AssociationsParalytic Disease
Meningitis Encephalitis
Undifferentiated febrile illnessHand foot mouth disease.
HerpanginaEpidemic Pleurodynia (Bornholm disease)
MyocarditisRespiratory InfectionsRubelliform rashes.Neonatal Infection
ConjunctivitisPancreatitis/Diabetes
Exanthems- Rubelliform rashes
- EV leading cause in summer & fall. All types of rash
•Herpangina – usually coxackie A• acute onset, fever, sore throat,
dysphagia• lesions – posterior pharynx• no gingivitis
Herpangina/
• Hand-foot-and-mouth
disease:
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mostly coxackie A 14, HEV71
– fever, malaise, sore throat,vesicles on bucal mucosa,tongue, hands, feet, buttocks
highly infectious
resolution – 1w
Hand-foot-and-mouth disease
Hand food and mouth disease(HFMD)
Typical lesions around theMouth of an 11 month old male
Management and Prevention
• no specific antiviral therapyavailable
• no vaccine available mainly becauseof the multiplicity of serotypes
Viruses infected through gastrointestinal tract
Enteroviruses of picornaviridae Acute gastroenteritis viruses
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Polioviruses
Coxsackieviruses
Echoviruses
New enteroviruses
parenteral disease
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Rotavirus
Calicivilus
Norovirussapovirus
Astrovirus
Enteric adenovirus
viral gastroenteritis/viraldiarrhea
Viruses infected through gastrointestinal tract
rotavirus
Rotavirus Pathogenesis
• Universal disease– All children are exposed and acquire
antibodies by age 5
• Leading cause of severe dehydratingdiarrhea in infants and young children
• Sudden onset of watery diarrhea, feverand vomiting
• Recovery in 4-5 days
Rotavirus Transmission
• Fecal-oral?– Improvements in water, sanitation, hygiene
have not decreased incidence
Diagnosis
• Rapid diagnosis - antigen detection in stool byELISA (uses a monoclonal antibody).
• Electron microscopy
Rotavirus vaccines
• Wyeth - Rotashield (Sept. 1998)– Live, oral, tetravalent
– human/simian re-assortant viruses
– withdrawn in 1999 due to increasedincidence of intus-susception
• Merck - Rotateq (Feb. 2006)– Live, oral, penta-valent
– Bovine/human re-assortant viruses
Rotavirus vaccines
• GSK - Rotarix; not yet available in U.S.– Live, oral, attenuated, human
– Mono-valent
– Cross-protective, replicates well in GI
• TreatmentSupportive - rehydration (oral / intravenous)Antiviral agents not known to be effective
Treatment and prevention
• Prevention of spreadHand washing with good techniqueDisinfection of surfaces, toilets, toys
•First discovered in Norwalk, Ohio
•Has been at the root of several epidemics or outbreaks ofgastroenteritis across North America in hospital emergency rooms,schools and even on cruise ships
•There is a group of similar or related viruses that are referred to asNorwalk-like viruses or agents.
Norwalk virus
•Can infect people of any age and usually cause profuse watery diarrhea,vomiting and fatigue.
•The infection lasts a few days and there is no specific treatment.
•Most of the time, it spreads form one person to another through director indirect contact with infected feces or vomit.
•The infection develops within 1-2 days after contact with an infectedperson.
SUMMARY
1. Know the common viruses infected throughgastrointestial tract: Enterovirus ofpicornaviridae and acute gastroenteritis virus.
2. Understand the properties of picornaviruses.
3. Master the clinical findings as a result ofrotavirus infection.
1.Each of the following statements regarding rotavirus is correct EXCEPT:(A)the infection mainly affects children younger than 3 years(B)it is a major cause of death in children in developing countries
(C)a high viral concentration is necessary for a efficient transfer of the virus(D)in the northern hemisphere the virus is transmitted during the winter/springseason
Self control questions
2.Each of the following statements regarding norovirus is correct EXCEPT:(A)the infection mainly affects younger children and older people as well(B)epidemics occur every 2 to 3 years(C)the first line diagnostics is the detection of the virus by PCR from fecalsamples(D)a vaccine is available that protects people from norovirus infection
3. Each of the following statements regarding the mode of action of the viruses/bacteria iscorrect EXCEPT:
A. noroviruses possess an enzyme that inhibits proteinsynthesis of the host cellB. rotaviruses induce cell death (apoptosis) thereby causing diarrheaC. Shigella produces a N-glycosidase that has a specificity for 28S ribosomal RNA and upon
this action stops protein synthesis of the host cellD. Vibrio cholerae ADP-ribosylates G-proteins and thereby activates an adenylate cyclase
which indirectly affects the efflux of water
4. Each of the following statements regarding the treatment of severe diarrhea is correctEXCEPT:
A. if possible glucose should be given the oral way at a concentration of 20g/LB. Chloride and bicarbonate losses should be included in the glucose/electrolyte solution to
compensate anionic lossC. sodium and potassium losses should be included in the glucose/electrolyte solution to
compensate cationic lossD. coca cola contains all the electrolytes and the glucose to compensate the loss of glucose
and electrolytes that are lost during diarrhea
6. Please describe the general properties of picornaviruses.
7. What are the clinical findings as a result of rotavirus infection versus Norwalk virusinfection?
8. What causes poliomyelitis? What is the route of infection? What is the globalsituation of the disease? How about the vaccine?
A. noroviruses have an infectious dose lower than 100 particlesB. rotaviruses have an infectious dose higher than 1000 particlesC. campylobacter requires 1000 to 10.000 particles to become infectiveD. Vibrio cholerae requires > 1.000.000 particles to become infective
5. Each of the following statements regarding the infectious dose of the viruses/bacteria iscorrect EXCEPT: