What is the definition of a virus?
Obligate intracellular 'parasites'
Replicate only in living susceptible cells
What virus families have double-stranded (ds) DNA genomes?
Which virus families have +ve RNA genomes?
Which virus families ahve -ve RNA genomes?
What do virion proteins do?
Protect nucleic acids
Attach to receptors on cells
Penetrate cell membrane
Replicate nucleic acid
Begin program for replication
Modify host cell
What three methods are used for virus cultivation?
Inoculation into embryonated eggs
What are the different types of cell culture?
Primary cell culture
Finite or diploid cell lines
Continuous cell lines
How are host cells generally damaged by viruses?
Accumulation of viral structural components
Formation of virion aggregates within the cell
Shutdown of cellular protein synthesis
What are some methods used for virus titration?
Quantal assays (TCID50, ID50, LD50)
What are some methods used for virus isolation and identification?
Films and smears
Biopsy or autopsy
What are some methods used to detect viral antigens?
What are some methods used to detect viral nucleic acid?
Southern blot hybridization
Northern blot hybridization
Polymerase chain reaction (PCR)
Nucleic acid sequencing
What are some methods used to identify viral isolates?
Hemagglutination and hemagglutination inhibition
Hemadosporin and hemadosporin inhibition
What are some limitations of using serology to detect a viral infection?
Detects exposure not when exposure occurred
For correlation with disease
IgM only produced early in infection
What substances can induce virus mutations?
What are some different types of mutations?
Plaque morphology mutations
Host range mutations
What are some different genetic interactions between viruses?
Recombination (breakage-reunion mechanism, copy-choice mechanism, reassortment)
What are some non-genetic interactions between viruses?
What are some possible interactions between a virus and it's host cell?
What are the main enzymes that viruses use for nucleic acid replication or mRNA synthesis?
DNA-dependent DNA polymerase
DNA-dependent RNA polymerase
RNA-dependent DNA polymerase
RNA-dependent RNA polymerase
What are some different ways that viruses penetrate a cell?
What viral genes encode for enzymes or factors that help in virus replication and are expressed before nucleic acid replication?
What viral genes encode for structural proteins and factors for virus assembly and are expressed after nucleic acid replication?
In which phase of viral reproduction does attachment, penetration, and uncoating take place?
What are some factors that defend against viral infection?
What are some defenses against viral infection that are present in the extracellular fluid?
Macrophages (B & T cells)
What are some defenses of viral infection that act on virus infected cells?
Helper T cells
What are some innate immune responses to viral invasion?
Phagocytic cells (neutrophils, monocytes, macrophages)
What host proteins are involved in immune responses to viral invasion?
MHC class I and II proteins
Proteins that cleave endogenous antigens
Transporter associated with antigen presentation (TAP)
T cell receptor (TCR) proteins
T cell accessory molecules
What are some ways that viruses can evade immune recognition?
Induction of immunosuppression
Induction of immune tolerance
Destruction of antigen presenting cells
Inhibition of recognition by antibodies
What are some ways that viruses can inhibit recogniton by CMI response?
Infection of cell lacking MHC class I antigen
Inhibition of MHC formation
Downregulation of viral protein expression
Induction of mutation in viral protein T cell epitopes
How can viruses induce an autoimmune disease?
Modulation of immune cells to present self antigens
What are the stages of viral pathogenesis?
What are some molecular determinants of viral virulence?
Envelope glycoproteins and capsid proteins
Viral polymerase and other proteins
Noncoding regions of viral genome
What are some mechanisms of viral virulence?
Modulation of host immune response
Modulation of growth factors and cytokines
Modulation of apoptosis
Disruption of intracellular Ca homeostasis
Production of reactive oxygen and nitrogen intermediates
Modulation of intracellular deoxynucleoside triphosphate pool
What are some ways that viral infections can persist for a long time?
Ability to infect host cells without being cytopathic
Integration into the host chromosomes
Inhibition of detection and elimination by the host immune responses
What factors can reactivate a herpesvirus infection?
What are some possible targets for antiviral action in the HIV replication cycle?
Viral Gene Expression
Post-transcriptional Processing and Assembly
Budding or release
What type of vaccines are considered conventional vaccines?
Live virus (Wild or Attenuated)
What are some novel approaches to vaccine development?
Subunit vaccines (peptides)
Gene deleted vaccines
Virus vectored vaccines
What are some different strategies used to develop live wild-type virus vaccines?
Unnatural time of year
What are some different strategies used to develop live attenuated virus vaccines?
Naturally occurring variant
Adaptation to natural host (animal passage and cell culture passage)
What are some different strategies used to develop Inactivated whole virus vaccines?
What are some different strategies used to develop inactivated virus subunit vaccines?
Naturally occurring subunits
What are some different strategies used to develop inactivated virus peptide vaccines?
In vitro chemical synthesis
What are some different strategies used to develop inactivated virus protein vaccines?
Recombinant DNA expression in bacteria
Recombinant DNA expression in yeast
Recombinant DNA expression in mammalian cells
Recombinant DNA expression in cell culture or insect cells
Recombinant DNA expression in heterologous virus
What term refers to the fact that protection is conferred on the unvaccinated in a population when a certain threshold number of individuals is vaccinated?
What is the study of the determinants, dynamics and distribution of disease in populations?
What is the measure of disease frequency in a population over a specific period of time?
What are some different types of studies done to investigate causation of an epidemic?
What are all the different modes a virus can be transmitted?
Iatrogenic (accidental transmission by professionals)
Nosocomial (hospital-derived infection)