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177 Cards in this Set
- Front
- Back
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A virus is the size of a eukaryotic _________?
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ribosome
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Virus with envelope in environment?
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inactivated, must be in aqueous environment, like blood, saliva, other body fluids
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Virus without envelopes (naked) in environment?
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stable, can survive for months
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Why are enveloped viruses unstable?
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envelope sticks to surfaces, clothing, viral structure destroyed
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Where does the viral envelope come from?
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host cell plasma membrane
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Viral envelope can be destroyed by?
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organic solvents like ether (chloroform), bile salts in GI tract
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Peplomers?
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transmembrane protein spikes
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Viruses can only replicate where?
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in host, never in test tube
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Helical viruses always have what?
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an envelope
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DNA viruses must?
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go to host nucleus, need DNA polymerase to replicate
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RNA viruses can replicate in?
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cytoplasm, have own polymerase
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All DNA viruses replicate in nucleus except?
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Poxvirus (smallpox)
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Viruses only make what kind of RNA?
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mRNA, not tRNA or rRNA
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Steps to DNA virus infection (4)?
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1) virus goes to host, 2) uses viral DNA polymerase to replicate 3) uses host DNA dependent DNA polymerase II to make viral mRNA 4) host ribosomes make viral proteins
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Drugs for DNA viruses target?
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Viral DNA polymerase, not host DNA polymerase
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Steps in RNA virus infection (3)?
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1)make RNA dependent RNA polymerase (RdRp) 2)RdRp makes mRNA 3)host ribosomes translate mRNA to viral protein
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Steps in Retroviral infection (3)?
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1) virus uses viral RNA dependent DNA polymerase to make DNA 2) DNA is transcribed with DNA dependent RNA polymerase II from host to make mRNA 3) host ribosomes translate mRNA to viral protein
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Steps in virus life cycle (5)?
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1- attach to cell, 2- genome replication and RNA synthesis, 3- make capsid proteins for RNA, 4- nucleocapsid assembly, 5- release of viral particles from host cell
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Most viruses have what type of genome?
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single stranded RNA
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mRNA must have 1 or more what?
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ORF (open reading frame)
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Viruses must make proteins at least how long?
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20 amino acids long
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mRNA can make protein, called?
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(+) sense
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No ORF, no protein made, called?
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(-) sense
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First step in (+) sense RNA virus infection?
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translation!
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Steps in (+) sense RNA (5)?
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1) enter cell, 2) translation to make RdRp, 3) replication to make (-) sense compliment, 4) compliment replication to make many (+) sense genome, 5) genomes translated to make proteins for assembly
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Injecting mRNA into a cell, will it cause disease?
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only if it is (+) sense, because it carries RdRp
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mRNA that codes for RdRp?
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(+) sense RNA
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RdRp?
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RNA Dependent RNA Polymerase, makes mRNA from RNA
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Steps in (-) sense RNA (5)?
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1) enter cell, 2) transcription of RNA to make mRNA, 3) each mRNA codes for different proteins including RdRp and assembly proteins, 4) replication to form (+) sense intermediate, 5)(+) sense used as template to make many mroe (-) sense genomes
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Transcription?
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synthesis of RNA
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Translation?
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protein synthesis
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Double stranded RNA synthesizes?
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(-) and (+) strands
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Double stranded RNA carries what?
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RdRp in particle
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Ambisense RNA viruses carry?
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RdRp in virus particle
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Ambisense genome?
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1/2 (+) sense, 1/2 (-) sense
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Retrovirus genome?
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diploid RNA (two + sense RNA)
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Retrovirus infection steps (5)?
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1)synthesis of (-) sense DNA from (+) sense RNA in cytoplasm, 2)digestion of (+)sense RNA by RNAse H in cytoplasm, 3)synthesis of (+)sense DNA from (-) sense DNA in cytoplasm, 4)entry of dsDNA to nucleus 5) transcription of viral mRNAs by host DNA dependent RNA polymerase II in nucleus
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DNA viruses replicate with?
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host DNA polymerase
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What receptor does HIV bind to?
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CD4
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What receptor does influenza bind to?
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Sialic acid
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What receptor does rhinovirus bind to?
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ICAM-1
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What receptor does rabies bind to?
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ACh receptor
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Cell fusion to form giant cells is called?
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Syncyticum formation
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Which viruses arise faster, DNA or RNA?
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RNA viruses arise faster
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How does a vaccine become virulent?
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spontaneous random RNA mistakes in genome
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How did the polio vaccine become virulent?
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usually injested, mutation allowed it to enter CNS to cause disease
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Flu pandemic happend due to what?
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genome reassortment (animal flu + human flu = new pathogenesis)
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Complementation?
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viral gene/protein rectifies defect in related virus
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Genome recombination?
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polymerase jumps from one genome to another
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In phenotypic masking/mixing, does the protein capsid matter?
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NO! the genome is always expressed, no matter the protein coating
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Growth curve-eclipse period?
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virus disappears from host for certain period of time
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Growth curve-latent period?
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virus is inside of the cell, but isn't released, therefore not causing disease
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Horizontal spread?
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person to person
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Vertical spread?
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mother to child during delivery
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Iatrogenic?
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medical practice
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Causes of Cruetzfeldt-Jacob disease?
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corneal transplantation, growth hormone from cadaver pituitary glands, neurosurgery
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Inapparent/subclinical infection?
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active virus replication but no symptoms
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Acute infections?
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active replication and severe symptoms, then goes away
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Persistent infections?
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active infection, variable disease (no symptoms or pain)...mosquitos, mice
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Latent infections?
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inactive virus hiding in body
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Humoral immunity antibodies?
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IgM, IgG, IgA
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Virus neutralization by antibody?
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antibody binds to virus so it can't attach or enter cells
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Passive immunity available for what viruses (4)?
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rabies, hepatitis B, chickenpox, measles
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Cell-mediated immunity?
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Tc cells recognize MHC-II protein
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Antibody can only neutralize viruses with?
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envelopes and glycoprotein spikes
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How does AZT work?
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uses decoy nucleotides to stop peptide chain
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HIV retrovirals?
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inhibit reverse transcriptase, cause peptide termination
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Protease inhibitors?
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inhibit processing of translated proteins
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Interferons?
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inhibit protein synthesis in virus-infected cells
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Acyclovir?
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inhibits viral DNA polymerase, purine nucleoside analog, terminates chains
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Gancyclovir?
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inhibits viral DNA polymerase in CMV
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ELISA?
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Enzyme Linked Immunosorbent Assay, detects antigen-antibody reactions using enzymes and color
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Immunofluorescense?
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fluorsecent virus-specific antibody put into virus-infected tissues
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In Situ Hybridization?
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viral acids or antigens in tissue specimens detected with virus-specific probes
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Hemagglutination?
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virus particles attract RBC
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Hemagglutination inhibition?
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antibodies bind to viruses to prevent the attraction of RBC
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Complement Fixation?
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virus-specific antibodies fix complement, won't lyse RBC
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Plaque assay?
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put virus on agar and let it lyse the cells. the #of holes on the agar is the # of viral particles
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Plaque assay used for what kind of virus?
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viruses causing cell death
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Helical viruses always have?
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RNA
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DNA virus mnemonic?
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HHAPPPy
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DNA viruses (6)?
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Herpes, Hepadna, Adeno, Papova, Parvo, Pox
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Naked RNA viruses (3)?
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picorna, calici, reoviridae (PCR)
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Icosahedral RNA viruses (5)?
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Reo, Picorna, Toga, Flavi, Calici
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RNA viruses that replicate in the nucleus (2)?
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retro, orthomyxo
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7 live attenuated viruses?
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oral polio (Sabin), adenovirus, measles, mumps, rubella, yellow fever, varicella-zoster
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5 killed viruses?
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killed polio (Salk), influenza, rabies, Japanese encephalitis B, hep A
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Name the Togaviruses (2)?
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rubella, alpha
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Rubella causes?
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German measles
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Symptoms of German measles?
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blotchy 3 day rash, upper respiratory infection,
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How many RNA molecules found in the Togavirus family particles?
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2 molecules
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What is a rash?
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immune response causing RBC to leak into extra-cellular matrix
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Congenital Rubella Syndrome cause?
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pregnant woman gets Rubella infection during 1st trimester
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Congenital Rubella Syndrome symptoms?
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cataracts (blindness), ductus arteriousis, thrombocytopenia purpura (rash), meningitis, mental retardation, neurosensory deafness
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Treatment for German Measles?
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none...self limiting in weeks
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Vaccine for German Measles?
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MMR (live attenuated virus)
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Diagnosis of German Measles?
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ELISA
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Transmission of German Measles?
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humans, no mosquito infection
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All insect-transmitted viruses cause?
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viremia
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How do insect-transmitted viruses reach the CNS?
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cross the blood-brain barrier
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Transmission of Alphaviruses?
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mosquito-transmitted
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Symptoms of Alphavirus infection?
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encephalitis in horses, birds; usually subclinical in humans
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WEE?
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Western Equine Encephalitis, found in Western US and Canada
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EEE?
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Eastern Equine Encephalitis, found in Eastern US
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VEE?
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Venezuelan Equine Encephalitis, found in Southern US, South and Central America
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Chikungunya?
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arthropathy (joint swelling and pain)
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Alphavirus vaccine given to?
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horses
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Arboviruses include what families?
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toga, flavi, rhabdo, reo, bunya
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All Arboviruses are?
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RNA viruses
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Clues for Arbovirus infection?
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marshlands, forests, stagnant water, abandoned tires, summer/early fall
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All Flaviviruses are?
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enveloped RNA (+) sense
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St. Louis Encephalitis?
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in USA, mosquito borne
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Japanese Encephalitis?
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Asian countries, pigs, birds, mosquito borne, killed virus vaccine available
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Tick Borne Encephalitis?
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Europe, tick borne
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Yellow Fever symptoms?
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hepatitis, jaundice, black vomit from stomach hemorrhaging
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Yellow Fever vaccine?
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17D live attenuated virus
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Dengue Fever symptoms?
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breakbone fever (flu-like, arthritis, rash), shock
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Hepatitis C is part of what family?
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flavi, NOT arbo
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Most common cause of transfusion associated, Non-A, Non-B hepatitis?
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Hepatitis C
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Hep C transmitted by?
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blood transfusion, IV drug use, sexual contact
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Hep C can cause?
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hepatocarcinoma (liver cancer)
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Treatment of Hep C?
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alpha interferon
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Coronavirus structure?
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enveloped, (+) sense RNA, with helical nucleocapsid
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Coronavirus causes?
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common cold, gastroenteritis
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Transmission of Coronavirus?
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aerosol, hand contact
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Structure of Picornaviridae?
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non-enveloped, (+) sense, viral protein on 5' end of genome
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Picornaviridae includes what species?
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polio, coxsackie, rhinovirus, Hep A
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Abortive poliomyelitis?
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no CNS involvement
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Aseptic meningitis?
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stiff neck, meningeal irritation
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Paralytic poliomyelitis?
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assymetric flaccid paralysis
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Bulbar polio?
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paralysis of pharynx and soft palate, dysphagia, hydrophobia, damaged CN9 and CN10
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Salk vaccine?
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killed, subcutaneous, includes 1, 2, 3 serotypes
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Sabin vaccine?
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oral
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Coxsackie A?
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foot-and-mouth disease, vesicular lesions on hands and face, hemorrhagic conjuncitivitis, pharyngitis, vesicles on soft palate
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Coxsackie B?
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pleurodynia, aseptic meningitis, myocardiopathy, myalgia
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Coxsackie A vesicles on soft palate look like?
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HSV-1
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Rhinovirus?
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#1 cause of common cold
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Rhinovirus transmitted mainly by?
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school children
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Hepatitis A structure?
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naked (+) sense RNA
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Hepatitis A transmission?
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raw seafood, fecal-oral transmission, contaminated water,
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Prevention of Hep A?
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inactivated vaccine for foreign travelers
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Calici viruses include?
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Norwalk (Noro), Hep E
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Noro virus structure?
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naked (+) sense RNA
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Symptoms of Norovirus infection?
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gastroenteritis, hepatitis
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Norovirus transmission?
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fecal-oral, contaminated water, raw shellfish
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Hep E structure?
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naked (+) sense RNA
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Hep E transmission?
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fecal-oral, raw seafood
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Hep E symptoms?
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gastroenteritis and hepatitis
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Astrovirus structure?
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naked (+) RNA virus
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Astrovirus symptoms?
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infantile diarrhea
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Astrovirus transmission?
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fecal-oral
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RNA (-) sense enveloped, bullet-shaped virus?
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Rhabdovirus
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Rhabdo causes?
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Rabies!
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Rhabdo multiplies where?
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muscle cells
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Rabies found only in?
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nervous system...NO viremia
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Highest concentration of Rhabdovirus in infected person?
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hippocampus
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How does rabies virus reach the CNS?
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enters nerves at the neuromuscular junction
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How does rabies virus reach the saliva?
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through autonomic nerves to the salivary gland
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Transmission of Rhabdovirus?
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bite of rabid animal: dogs, cats, bats, foxes, wolves, raccoons, skunks
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Rabies NOT transmitted by?
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mosquitos
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Symptoms of rabies arise in ____ mos?
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1 to 3 mos after bite
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Viruses found in saliva (3):
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EBV, mumps, rabies
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Symptoms of rabies?
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hyperexcitability, convulsions, hydrophobia (swallowing pain), paralysis, coma, death
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Rabies symptoms accelerated by?
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animal bite on face
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Negri bodies?
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cytoplasmic inclusion bodies in hippocampus and spinal cord
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Detection of rhabdovirus?
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fluorescent examination of animal brain
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Rabies vaccine?
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killed vaccine for high risk people (animal handlers)
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Paramyxo structure?
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enveloped, 1 segment of (-) sense RNA
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Paramyxo contains what protein?
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HN: Hemagglutinin-Nuraminidase, F protein
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All paramyxos cause?
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syncytia formation
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Members of paramyxo family?
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parainfluenza, RSV, mumps, measles
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Parainfluenza 1 symptoms?
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acute croup (laryngotracheobronchitis) in infants, upper respiratory
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Parainfluenza 2 symptoms?
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upper respiratory infection, sometimes lower respiratory infection
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Parainfluenza 3 symptoms?
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2nd major viral cause of bronchitis and pneumonia in children
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#1 cause of lower respiratory infection, pneumonia, bronchitis in infants?
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RSV (Respiratory Syncytial Virus)?
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RSV proteins?
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F protein, G protein
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F protein?
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mediates membrane fusion
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