Intro to Virus, Lytic, Lysogenic Flashcards
ALL viruses rely on host [2 things] and have an ______ and an ______ phase.
- Metabolic machinery
- Protein biosynthesis (NEED HOST RIBOSOMES)
- intracellular
- extracellular
Virus taxonomy is _____, meaning that it is based on a collection of individual properties. Name 5 of these properties. Which one is usually used primarily? What is this classification system called?
- polythetic
- particle type, tissue tropism, disease etiology, serology, genome type** (used the most)
- Baltimore classification (based on genome type)
____ is an example of an icosahedral, naked virus. _____ is an example of an icosahedral, enveloped virus. ____ is an example of a helical, enveloped virus. Enveloped viruses have _____ proteins under their envelope to provide structure.
- Adenovirus (DNA virus)
- Herpes Simplex Virus
- Paramyxovirus (measles)
- Matrix
Name the following types of genetic material in each Baltimore classification and if the virus uses reverse transcriptase: Class I Class II Class III Class IV Class V Class VI
Class I = dsDNA [Parvovirus; HPV]
Class II = +ssDNA [Poxvirus, Herpesvirus]
Class III = dsRNA **have RT [Reovirus–Rotavirus]
Class IV = +ssRNA –> –ssRNA **have RT [Picornavirus, Hepatitis E]
Class V = -ssRNA **have RT; [influenza, Paramyxovirus]
Class VI = +ssRNA –> –ssDNA **have RT [HIV]
Define the following:
- Virion
- Virus
- MOI
- CPE
- Viremia
- Egress
- viral particle
- infectious particle
- multiplicity of infection (how many viruses in cell)
- cytopathic effect
- spread of virus throughout body/bloodstream
- viral release from cells
DIAGNOSIS:
- How are viruses seen?
- Define the following (a) Plaque assay (b) Focus-forming assay (c) Single-step growth curve
- Electron microscopy
(a) titration of number of infectious progeny (pfu); count cell DEATH
(b) for oncology purposes; viruses promoting cell GROWTH
(c) quantification of burst size (single cell growth curve)
Where does the envelope of enveloped viruses come from?
nucleus, ER, golgi, vesicles, PM
Viruses replicate by ______. Viral genome and proteins must be ______, which happens via “zipcodes” on viral components.
- xeroxing
- selectively encapsulated
Naked viruses enter the cell via ______ and exit via ____. Enveloped viruses enter the cell via ___________ or ___________ and exit via _____.
- endocytosis
- cell lysis
- inducing fusion of virus and cell membrane (capsid in cytoplasm)
- endocytosis and fusion with acidic endosome (capsid in endosome)
- budding
Define the following:
(a) Productive infection
(b) Latent infection
(c) Persistent infection
(d) Abortive infection
(a) Productive infection = cytopathic effect due to lysis mostly (acute): form syncytia (RSV), shut off host metabolism, apoptosis, necrosis
(b) Latent infection = no production of infectious virus particles but genetic info remains and can be reactivated
(c) Persistent infection = chronic virus production
(d) Abortive infection = virus life cycle incomplete and virus lost
Name 4 important factors for host tropism for viruses.
- receptor type (influenza human {2,6} vs avian {2,3})
- tissue-specific cellular components (Hep C host miRNAs)
- tissue-specific restriction factors (retroviruses)
- temperature/pH/activating proteases
Name 3 ways viruses cause disease.
- destruction of infected cells
- modification of cell function/tropism (HPV)
- immune and inflammatory responses to infection (Hepatitis, influenza)
Defending the host:
- The innate immune response uses _____ and _____
- The humoral adaptive immune response uses _____ and _____
- The cell-mediated adaptive response use _______
- The memory response (B and T cells) use _____
- soluble mediators (IFNs, chemokines, cytokines for recruitment); apoptosis
- neutralizing antibodies; complement-fixing antibodies
- MHC presentation of viral peptides
- elicit response
What is the eclipse period of viral replication?
Post-infection, virus is not detectable; inside the cell and replicating; has not yet elicited an immune response
Picornavirus [LYTIC] properties:
- Morphology: _____
- Nucleic acid: _____
- Tegument? ____
- Enteroviruses stable at pH ___ whereas Rhinoviruses stable above pH ____
- icosahedral
- +ssRNA
- NO
- 3-9
- 6
What disease type is associated with each picornavirus [LYTIC]?
(a) Enteroviruses
(b) Rhinoviruses
(c) Hepatoviruses
(d) Parchovirus
(e) Kobuvirus
(a) Enteroviruses = paralysis (polio), hand-foot-and-mouth Dz [fecal-oral transmission]
(b) Rhinoviruses = common cold
(c) Hepatoviruses = Hep A
(d) Parchovirus = gastroenteritis, myocarditis
(e) Kobuvirus = gastroenteritis
Polio [LYTIC]:
- Subclinical (asymptomatic) infections are present in _____% of patients, usually because infection stays in oropharynx/gut.
- Mild illnesses, like a cole, are present in _____% of patients
- Aseptic meningitis (nonparalytic polio) is present in _____% of patients and lasts 2-10 days with _____ recovery
- Paralytic poliomyelitis occurs in ____% of patients; due to asymmetric ___ paralysis, usually more in lower extremities
- 90-95%
- 4-8%
- 1-2%; full
- 0.1-2%; flaccid
In poliomyelitis [LYTIC], _____ involves the cranial nerves, medulla and respiratory compromise (think iron lung); this causes a 5% death toll overall. Poliomyelitis has a ___ recovery and usually ____ paralysis.
- bulbar paralysis
- slow (2 years)
- residual
Polio [LYTIC] is exclusively a _____ disease and is known for its _____ epidemics. Patients that are _____ have a higher incidence of getting paralytic polio; _____ is one invention that has increased our risk for paralytic polio.
- human
- summer
- OLDER
- improved hygiene
Picornaviruses (polio) don’t need to cap-snatch like influenza because they have _______ on their 5’ mRNA. When translating, a _____ is made.
- a hydrophobic structure that better “grabs” ribosomes than host mRNAs.
- polyprotein
Picornaviruses [LYTIC] have capsid proteins that bind host PM and convert into an _______ that inject their _____ into the cytoplasm. First ____ are made and then more ____ is made.
- injector (VP1)
- +ssRNA
- –ssRNA templates
- +ssRNA
Name the type of antivirals that can inhibit picornaviruses [LYTIC].
- virus attachment (antibodies–WIN 52035/chemicals)
- entry/genome release (Pleconaril)
- protease processing (ruprintrivir)
- RNA-dependent RNA polymerase inhibitors (ribavirin)
____ make the inactivated polio virus vaccine and ___ make the live attenuated polio virus vaccine. New cases of polio are mostly due to ____.
- Salk
- Sabin
- live attenuated polio vaccine transformation
Viruses with segmented genomes must transcribe each genome separately to produce _____ mRNAs.
monocistronic (containing coding sequence for ONE protein)
