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Mature infectious particle
What are the characteristics of naked viruses?
- All are icosahedral
- R to organic solvents and chlorination
- Induce lysis of host cell
- Nucleocapsid proteins mediate attachment
- PAP PiCs Reo
What are the characteristics of enveloped viruses?
- Icosahedral, helical, or complex
- "Ether sensistive"
- Budding instead of lysis
- Chronic infections
- Envelope glycoproteins mediate attachment
Naked DNA viruses
- Papovaviruses (Papilloma & Polyoma)
- Parvoviruses (single-stranded)
Naked RNA viruses
- Picornaviruses (RNA +)
- Reoviruses (double capsid)(RNA +/-)
Double-Stranded DNA viruses
Enveloped RNA+ Viruses
Enveloped +RNA via DNA Viruses
Smallest DNA virus
Largest DNA virus
Smallest RNA virus
These require a "helper virus" to provide a function missing due to mutation (example: Hepatitis D)
Infectious particles composed solely of protein; "slow" diseases (transmissible spongiform encephalopathies)--> Creutzfeldt-Jakob disease, Scrapie in sheep; Resistant to inactivation by UV, heat, formaldehyde; Becomes infectious by conformational change; No immune or inflammatory response
Viral Life Cycle:
- Synthesis of Macromolecules
Early mRNAs are synthesized for what type of proteins?
Late mRNAs are synthesized for what type of proteins?
All DNA viruses replicate in the nucleus except _____?
Which viruses carry own RNA-dependent RNA polymerase in virion itself?
What occurs within the Eclipse Period of the Viral Growth Curve?
- Begins with uncoating
- No detectable virus
- NA replication and detection
- Detectable intracellular virus
What is the Rise Period of the Viral Growth Curve?
Time it takes to release all of the virus
This is the replication mode for phages; aka "temperate cycle"; "lytic" phase induced by UV light, etc.;
- (Lysogenic conversion-source of exotoxins)
True or False:
Disease often results as much from the immune response as from the pathogen's intrinsic virulence
Infection followed by resolution and temporary or lifetime immunity. (Example: Rhinovirus; Hep A)
What is an example of an acute infection?
Infection characterized by periods of latency and recrudescence (Example: Herpes)
Give an example of a chronic infection
- Varicella (chickenpox)
- Zoster (shingles)
Infection where there are no apparent periods of latency. Virus replication is detectable for life of the organism (Example: HIV-1; HCV)
Give an example of a persistent infection
______ of cells resulting in virus-induced tumors (Example: EBV, HTLV-1, HCV, HPV)
Give an example of a transformation of cells resulting in virus-induced tumors
What are the four major pathogenetic pathways induced by viral infections?
- Acute infection
- Chronic infection
- Persistent infection
- Transformation of cells resulting in virus-induced tumors
What are some human-specific viral infections?
- Yellow fever
Steps in Viral Pathogenesis (5):
- Entry and primary replication
- Viral dissemination and tissue tropism
- Cellular injury and clinical illness (direct and indirect effects)
- Virus shedding and host-host spread
- Host immune response and recovery from infection
True or False:
An initial round of replication usually occurs at the site of entry
By which route do most viruses enter?
List examples of viruses that enter through the respiratory (mucosal) route
What is the second most common route of entry for viruses?
Alimentary (mucosal) (gut)
Name some viruses that enter through the alimentary route
- Herpes simplex
List some viruses that enter through the genitourinary tract (mucosal)
List some viruses that enter through the Ocular (mucosal) route
By what methods can viruses enter through the skin?
- Trauma (herpes, HPV)
- Injection (hepatitis, HIV)
- Bites (Vectored) (rabies, arboviruses)
What is the most common mechanism of subject-caregiver or caregiver-subject transmission?
Parenteral or iatrogenic
What is a primary barrier to respiratory infection?
How do viruses that enter through the alimentary system generally spread?
As a result of fecal-oral contamination
What is the main immunoglobin found in mucosal secretions (tears, saliva, intestinal "juice", etc.)? It is resistant to degradation, so can survive in harsh environments (digestive and resp. tracts). Provides protection against microbes that multiply in body secretions. Can opsonize or neutralize virus
Secretory IgA (sIgA)
Tissue tropism is dictated by the presence of _________ for the virus
A virus which is capable of infecting nerve cells, or which does so preferentially. Often hematogenously spread to CNS (Polio, HIV-1)
Virus that is capable of entering or infecting the CNS but may or may not cause disease there (mumps paramyxovirus)
A virus that causes disease within the nervous system (rabies)
Consquence of an acute infection for the cell?
Progeny release, cell dies
Consequence for a persistent (chronic) infection for the cell?
Progeny release, cell lives --> may be associated with development of cancer
True or False:
Shedding is often via the route of initial exposure