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75 Cards in this Set
- Front
- Back
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Incidence
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new cases/period of time
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prevalence
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total cases/area
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Subclasses of picornoviruses
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enterovirus and rhinovirus
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inclusion bodies
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sites of viral replication or assembly
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window period
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temporary interval where antibody or viral infection should be detected but is not yet detectable by the available test
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nucleocapsid
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virion structure containing nucleic acid and protein
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What are the general characteristics of RNA viruses with simple nucleocapsids?
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Icosahedral, assembled in cytoplasm, and make crystals there
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What are the general characteristics of DNA viruses that are simple nucleocapsids?
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Icosahedral, assembled in nucleus, and make crystals there
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Is direct person to person contact required for transmission of simple nucleocapsid viruses?
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No
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Where does polio's RNA-dependent RNA polymerase come from?
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viral RNA acts as mRNA with cellular ribosomes to form polysomes
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Does polio make proteins in one large piece or in 8 small pieces?
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One large piece
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How does RNA-dependent RNA polymerase use RNA of infecting virus?
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As template to make negative sense RNA which can then be template for positive sense RNA
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What is the replicative intermediate?
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Negative strand with several "growing" strands of viral RNA attached to it.
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What type of virus is polio?
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Positive stranded RNA virus
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What type of genetic material do picornaviruses have?
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ssRNA
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What is spinal polio?
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Destruction of motor neurons
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What is bulbar polio?
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Destruction of respiratory centers in medulla and cranial nerves.
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What is the incubation period of polio?
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2-3 weeks
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How many polio serotypes are there?
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3
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What type of virus is polio?
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enterovirus
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What virus causes neonatal myocarditis? And what is it?
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Coxsackie group B; Generalized infection
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What are the types of enteroviruses?
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Coxsackie, ECHO, all picornaviruses
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What do enteroviruses cause?
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aseptic meningitis, common cold, system infection with rash, paralytic disease in rare cases
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What causes epidemic pleurodynia and what is it?
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Group B Coxsackie; viral attack on intercostal muscles
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What causes herpangina and what is it?
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Group A Coxsackie; acute sore throat with characteristic ulcerating vesicles in throat
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What causes HFM and what is it?
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Group A Coxsackie; vesicular lesions and fever occur about the same time
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How are rhinoviruses and enteroviruses different?
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Rhinoviruses grow poorly at pH 3 and core temperature
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What are the characteristics of reoviruses?
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Icosahedral, 10 segments of dsRNA, polymerase is part of virion
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What type of virus is rotavirus?
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Reovirus
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What are the characteristics of adenovirus?
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icosahedral with spikes, dsDNA, viral mRNA and protein synthesis are regulated, 30 types, stable when dried
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What causes epidemic keratoconjunctivitis?
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adenovirus
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What is norovirus?
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enteric adenovirus
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What are the primary viral causes of gastroenteritis?
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rotavirus, enteric andenovirus, norovirus, other calciviruses.
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Are enveloped viruses destroyed by ether?
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Yes
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What are the important classes of enveloped viruses?
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paramyxo-, herpes-, toga-, flavi-, rhabdo-, orthomyxo-, hepadna-, retro-, pox-
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What type of virus is influenza?
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Orthomyxovirus (enveloped)
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What is the genetic material of influenza?
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8 segments of ssRNA with each segment enclosed in a separate helical nucleocapsid
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Does influenza virion contain virus-specific RNA polymerase?
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Yes--uses virion RNA as template to make mRNA
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What is the H antigen?
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functions early in infection--required for adsorption of virions to cells--antibodies to this are important
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What is the N antigen?
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Enzyme that functions late in infection--releases newly formed virions from final point of attachment to infected host cell
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Will antibodies to influenza H antigen cause hemagglutination?
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Yes
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Will antibodies to influenza N antigen cause hemagglutination?
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No
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How many types of influenza virus are there?
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3
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Which is more severe: influenza A or influenza B?
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A
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What is antigenic drift?
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minor variation by mutation within existing RNA segments
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Antigenic shift
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major antigenic differentiation resulting from genetic recombination or direct transmission between species
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Phenotypic mixing
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phenotype may not correspond to genotype
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What does amantadine do?
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Only type A influenza--affects penetration-uncoding step of growth
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What do oseltamivir and zanamivir do?
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inhibit neuramidase--act against influenza A and B to reduce symptomatic period
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What are paramyxoviruses?
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ssRNA with helical nucleocapsid. Negative sense. One piece. Polymerase present in virion.
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Will paramyxoviruses agglutinate RBCs?
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yes
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What is effective in preventing severe RSV pneumonia?
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passive immunization with high doses of monoclonal antibody against RSV [palivizumab]
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What causes SARS?
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SARS-associated coronavirus
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What are the characteristics of SARS-associated coronavirus?
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single molecule of positive RNA, enveloped with helical nucleocapsid
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What is the incubation period of SARS?
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2-10 days
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What does 2-5-A synthase do?
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makes 2-5-A which activates ribonuclease that destroys mRNA
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What does specific protein kinase do?
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specifically phosphorylates IF-2 which is essential to start of protein synthesis--when phosphorylated it is not active
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Is the interferon system short or long term?
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short term
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What type of virus is hepatits A?
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picornavirus
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What is the incubation period of hepatitis A?
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30 days
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Does hep A cause viremia?
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Yes
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Is the hep A vaccine live or killed?
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killed
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What type of virus causes hep B?
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hepadnavirus--circular DNA that is mostly ds but has some ss regions
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What does hep B virion contain?
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reverse transcriptase
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Does hep b virus have an envelope?
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yes
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Incubation period of hep b?
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70 days
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What is HBeAg correlated with?
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presence of infectious HBV and progression to hepatic carcinoma.
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What percentage of hep B infections result in chornic disease?
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5%
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What type of vaccine is used for hep b?
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subunit
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What type of virus causes hep c?
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flavivirus--enveloped positive RNA
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what is the incubation period of hep c?
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60 days
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Characteristics of hep e
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unenveloped positive RNA transmitted fecal-oral
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Shared characteristics of Hep A & E
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fecal-oral with acute disease only and short incubation (30 days)
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Shared characteristics of Hep B, C, & D
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transferred by blood, venereally, and perinatally and can cause chronic disease with liver damage; long incubation
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Shared characteristics of chronic B & C infection
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hepatocellular carcinoma
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