1、Gastrointestinal Viruses急性胃肠炎病毒1Viral GastroenteritisnIt is thought that viruses are responsible for up to 3/4 of all infective diarrhoeas.nViral gastroenteritis is the second most common viral illness after upper respiratory tract infection.nIn developing countries,viral gastroenteritis is a major
2、killer of infants who are undernourished.Rotaviruses are responsible for half a million deaths a year.nMany different types of viruses are found in the gut but only some are associated with gastroenteritis.急性胃肠炎病毒2Associated with gastroenteritisnRotavirusesnAdenoviruses 40 41nCaliciviruses嵌杯病毒nNorwa
3、lk like viruses or SRSV(Small Round Structured Viruses)nAstrovirusesnSRV(Small Round Viruses)nCoronavirusesnToroviruses急性胃肠炎病毒3Found in the gut,not normally associated with gastroenteritisnPolionCoxsackie AnCoxsackie BnEchonEnteroviruses 68-71nHepatitis AnHepatitis EnAdenoviruses 1-39nReoviruses急性胃肠
4、炎病毒4Found in the gut as opportunistic infectionnCMVnHSVnVZVnHIV急性胃肠炎病毒5Gastrointestinal VirusesVirusGenomeTypical diseaseincubationDuration Rotaviruses:Group A,B,Cds-segmented RNA Major cause of diarrhea in children1-3 days24-56 h5-8 days3-7 daysCalicivirusesNorwalk agentsssRNAInfects adults and chi
5、ldrenEpidemic viral gastroenteritis1-3 days18-24 h1-3 days12-48 hEAd 40,41Linear dsRNA diarrhea in children 7-8 days 8-12 d Astrovirus+ssRNAInfects mainly children and elderly1-4 days1-4 d急性胃肠炎病毒6Gastrointestinal VirusesnInfants:Rotavirus A;Adenovirus 40,41;Coxsackie A24 virusnInfants,children,and a
6、dults Norwalk virus;Calicivirus嵌杯病毒;astrovirus;Rotavirus B;Reovirus.急性胃肠炎病毒7Human Rotavirus急性胃肠炎病毒8Important Characteristicsn70 nm round,double shelled,enclosing a genome of 11 segments of double stranded RNA.急性胃肠炎病毒9急性胃肠炎病毒10Groups of Rotaviruses nGroup A subtypes 1,2,3,4(main human pathogens)(Furt
7、her 7 subtypes)also infect animals(monkey,calf,mouse)nGroup B Infects pigs and ratsFound to cause extensive outbreaks in China in past decade nGroup C Infects Pigs(Occasionally Man)nGroup D Infects birds nGroup E Infects pigs 急性胃肠炎病毒11急性胃肠炎病毒12PathogenesisnEssentially an ingestion disease(faecal-ora
8、l route)nIncubation is short:1 to 3 daysnIllness:Sudden onset watery diarrhoea,with or without vomiting.May last up to 6 days(or longer if immunocompromised).The disease is self limiting.nComplications:Dehydration may result,this can be severe and life threatening in young children.急性胃肠炎病毒13Pathogen
9、esisnGroup A:Main pathogen of infantile diarrheanGroup B:Cause epidemic adult diarrheanGroup C:Cause human or animal sporadic diarrhea急性胃肠炎病毒14急性胃肠炎病毒15Immunity:sIgALab.DiagnosisnIEM,nCell culture,nPAGE of RNA segments,nPCRnLatex agglutination nELISA 急性胃肠炎病毒16Treatmentntreatment of dehydration by or
10、al and/or intravenous fluids and electrolytes急性胃肠炎病毒17PreventionnNon specific factors:improved hygiene,education,clean waterSpecific-Breast feeding helps to provide passive immunity in the newborn(from maternal antibodies),Vaccination is still experimental.急性胃肠炎病毒18Enteric AdenovirusesnNaked DNA vir
11、uses,75 nm in diameter.nFastidious enteric adenovirus types 40 and 41 are associated with gastroenteritis.nAssociated with cases of endemic gastroenteritis,usually in young children and neonates.Can cause occasional outbreaks.nPossibly the second most common viral cause of gastroenteritis(7-15%of al
12、l endemic cases).nSimilar disease to rotavirusesnMost people have antibodies against enteric adenoviruses by the age of three.nDiagnosed by electron microscopy or by the detection of adenovirus antigens in faeces by ELISA or other assays.急性胃肠炎病毒19AstrovirusesnSmall RNA viruses,named because of star-
13、shaped surface morphology,28 nm in diameter.nAssociated with cases of endemic gastroenteritis,usually in young children and neonates.Can cause occasional outbreaks.nR e s p o n s i b l e f o r u p t o 1 0%o f c a s e s o f gastroenteritis.nSimilar disease to rota and adenoviruses.nMost people have a
14、ntibodies by the age of three.nDiagnosed by electron microscopy only,often very difficult because of small size.急性胃肠炎病毒20CalicivirusesnSmall RNA viruses,characteristic surface morphology consisting of hollows.particles 35 nm in diameter.nAssociated mainly with epidemic outbreaks of gastroenteritis,a
15、lthough occasionally responsible for endemic cases.nLike Norwalk type viruses,vomiting is the prominent feature of disease.nMajority of children have antibodies against caliciviruses by the age of three.nDiagnosed by electron microscopy only,often difficult to diagnose because of small size.急性胃肠炎病毒2
16、1Norwalk-like VirusesnSmall RNA viruses,with ragged surface,35 nm in diameter,now classified as caliciviruses.nAlways associated with epidemic outbreaks of gastroenteritis,adults more commonly affected than children.nAssociated with consumption of shellfish and other contaminated foods.Aerosol sprea
17、d possible as well as faecal-oral spread.nAlso named winter vomiting disease,with vomiting being the prominent symptom,diarrhoea usually mild.nAntibodies acquired later in life,in the US,only 50%of adults are seropositive by the age of 50.nDiagnosis is made by electron microscopy and by PCR.急性胃肠炎病毒2
18、2急性胃肠炎病毒23Other Possible Diarrhoeal VirusesCoronavirusesnRNA viruses with a crown-like appearancenNot convincing associated with gastroenteritis at presentSmall Round VirusesnSmall virus-like particles with a smooth surface,22-28nm in diameternMay possibly be parvoviruses,enteroviruses,or cubic bact
19、eriophagesnOccasionally seen in the faeces of endemic or epidemic cases of gastroenteritis急性胃肠炎病毒24Gastrointestinal VirusesVirusGenomeTypical diseaseincubationDuration Rotaviruses:Group A,B,Cds-segmented RNA Major cause of diarrhea in children1-3 days24-56 h5-8 days3-7 daysCalicivirusesNorwalk agentsssRNAInfects adults and childrenEpidemic viral gastroenteritis1-3 days18-24 h1-3 days12-48 hEAd 40,41Linear dsRNA diarrhea in children 7-8 days 8-12 d Astrovirus+ssRNAInfects mainly children and elderly1-4 days1-4 d急性胃肠炎病毒25
