MIC 301/PHM301/NUR301/MIC301V PICORNAVIRIDAE, RHABDOVIRIDAE AND REOVIRIDAEINTRODUCTION VIRUSES BELONGING TO THREE FAMILIESPICORNAVIRUSESPICORNAVIRIDAEPicornavirus PathogenesisPOLIOVIRUSPOLIOVIRUSSlide 8Slide 9THE POWER OF A VACCINEPoliovirus eradicationCOXSACKIEVIRUSES (cause a variety of diseases)HerpanginaHand, foot and mouth diseaseRHABDOVIRUSESRHABDOVIRIDAE bullet-shaped particleRABIESRabies in Wild and Domestic Animals (US)Pathogenesis of rabies virus infectionRabies (cont’d)Laboratory diagnosisRabies cont’d Treatment and ProphylaxisHuman Rabies VaccinePREVENTION OF HUMAN RABIESViral diarrheaVIRAL DIARRHEAROTAVIRUSESROTAVIRUSESROTAVIRUSES Clinical syndrome and diagnosisROTAVIRUSES course of diseaseROTAVIRUS TREATMENTS AND VACCINESSummaryP,R & R virusesMIC 301/PHM301/NUR301/MIC301VPICORNAVIRIDAE, RHABDOVIRIDAE AND REOVIRIDAEDr. John HayDepartment of Microbiology and [email protected] BELONGING TO THREE FAMILIESPICORNAVIRIDAE: transmission via fecal/oral routepoliovirus and coxsackie (A and B) virusesRHABDOVIRIDAE: transmission via bite of rabid animal (zoonotic) rabies virusREOVIRIDAE: transmission via fecal/oral routerotavirusPICORNAVIRUSESPICORNAVIRIDAE One of the largest families of small ss-RNA positive-sense virusesHuman pathogens include the following:Enteroviruses: poliovirus, coxsackie viruses Rhinoviruses: common-cold (>100 types) Heparnavirus: hepatitis A virusPicornavirus PathogenesisPOLIOVIRUSTransmission: fecal-oral route (poor hygiene)Four outcomes of poliovirus infection:(1) Asymptomatic infections: 90% infections(2) Abortive polio (minor illness): 5% infections3-4 days after infection- fever, headache, malaise, sorethroat, vomiting-self limiting (full recovery) in days(3) Nonparalytic polio: 1-2% infectionsVirus infects the CNS and meninges, causing back pain,muscle spasm and "minor illness" symptomsPOLIOVIRUS (4) PARALYTIC POLIOMYELITIS: 0.1-2.0% infectionsAfter the "minor illness"- viremia occurs and virusinfects: 1. the spinal cord (anterior horn cells)2. the motor cortex of the brainParalysis based on extent of neural infectionOne or all 4 extremities affectedParalysis may result in complete recovery, residual paralysis or deathPOLIOVIRUS BULBAR POLIOMYELITIS: severest form of paralytic poliomyelitis-involves muscles of the pharynx, vocal cords, respiration- mortality 75%IRON LUNG CHAMBERS - in 1950’sPOSTPOLIO SYNDROME:-may occur later in life (30-40 yrs later) in 20-80% of original victims. -deterioration of neurons -> originally affected muscles-no poliovirus is detected in these individualsPOLIOVIRUS POLIO VACCINATION: USES TRIVALENT VACCINE:includes serotypes 1, 2, 3KILLED-Salk inactivated vaccine (IPV)LIVE- Sabin live, attenuated, oral vaccine (OPV)In USA: ONLY IPV is recommended Recommended 4 doses At ages 2, 4, 6-18 months and at 4-6 yearsTHE POWER OF A VACCINEPoliovirus eradication•The WHO is currently pursuing a GLOBAL ERADICATION strategy for poliomyelitis•In 2010, there were 1300 cases worldwide•In 2011, 650 and in 2014, 358•Endemic countries include Pakistan, Afghanistan and Nigeria•MOST OF THE WORLD IS NOW FREE OF POLIO•Travellers’ vaccination?COXSACKIEVIRUSES(cause a variety of diseases)Coxsackie virus A: self limiting, no specific treatmentHERPANGINAvesicular lesions in throat region, fever, soar throatHAND-FOOT-AND-MOUTH DISEASEvesicular lesions on hands, feet, mouth and tongue Coxsackie virus B: PLEURODYNIA (BORNHOLM'S DISEASE)severe pleuritic chest pain (4 days), fever, vomitingMYOCARDIAL AND PERICARDIAL INFECTIONScardiomegaly, hepatomegaly, tachycardia(fast heart rate), fever VACCINE: none available for all the above diseasesHerpanginaHand, foot and mouth diseaseRHABDOVIRUSESRHABDOVIRIDAEbullet-shaped particleRABIESVirus is ss-RNA, negative sense, bullet-shaped and is the most important human pathogen in the familyRabies is a zoonotic infection: spread from animal to human no human to human transmissionReservoir= wild animals, unvaccinated dogs/catsSource of virus:Major= saliva in bite/lick of rabid animalMinor= aerosols in bat (rabid) cavesRabies inWild and Domestic Animals (US)Pathogenesis of rabies virus infectionRabies (cont’d)Clinical SymptomsLong incubation period- weeks/months, during whichvirus replicates at site of bite, in muscle tissue Prodrome stage (2-10 days): virus infects peripheralnerves and travels via spinal cord to brain(fever, headache, pain at site of bite, fatigue etc)Neurologic stage (2 to 10 days): virus spreads toeyes (cornea), salivary glands, skin and other organs(hydrophobia, seizures, disorientation, hallucination)Comatose stage and death:The neurologic stage almost always leads to death dueto neurologic and respiratory failureLaboratory diagnosis Once the neurologic symptoms begin in a person bitten byan animal, it is too late for intervention – death is inevitableLab tests are performed to confirm clinical diagnosis inpatient or if animal was rabid (post mortem)Viral antigen detection by immunofluorescence in brain or skinbiopsy material is widely used in animalsELISA assays are also used, for example to check the vaccination status of an individualRabies case was found (4/2012) in Toronto; virus typed by PCR. Strain from Dominican RepublicRabies cont’dTreatment and ProphylaxisPOST-EXPOSURE PROPHYLAXIS:1. Wash wound immediately with soap and water2. Immunization with vaccine (one arm) in combination with administration of one dose of human rabies immunoglobulin (HRIG) (the other arm). Passive immunization (HRIG) provides antibodies untilpatient produces antibodies in response to vaccinationHuman Rabies VaccineVaccine made in human diploid cells (HDCV) and virus is chemically inactivated (also can be made in chick cells [PCECV])Current vaccine is safe and effectivePost-exposure vaccinationHDCV is administered intramuscularly on day of exposure, and then on days 3, 7, 14 (+RIG, d0)Pre-exposure vaccinationDays 0, 7, 21/28 (no RIG)PREVENTION OF HUMAN RABIES1. Key to prevention in humans is effectivecontrol of rabies in domestic (all cats and dogs must be vaccinated) and wild animals.2. A live recombinant vaccinia virusvaccine expressing rabies virus G protein(envelope spike) is approved for use withwild animals.Vaccine is injected in a bait and parachuted intoforest, successfully immunizes raccoons, foxesand other wild animals.Viral diarrheaRotavirusesVIRAL DIARRHEAMany viruses cause diarrheaRotaviruses are the major cause of