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)
Adenoviruses
Parvoviruses (single-stranded)
Naked RNA viruses
Picornaviruses (RNA +)
Reoviruses (double capsid)(RNA +/-)
Double-Stranded DNA viruses
Hepadnaviruses
Herpesviruses
Poxviruses
Enveloped RNA+ Viruses
Coronaviruses
Flaviviruses
Togaviruses
Enveloped +RNA via DNA Viruses
Retroviruses
Smallest DNA virus
Parvovirus
Largest DNA virus
Poxvirus
Smallest RNA virus
Picornavirus
These require a "helper virus" to provide a function missing due to mutation (example: Hepatitis D)
Defective Viruses
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
Prions
Viral Life Cycle:
Recognition
Attachment
Penetration
Uncoating
Synthesis of Macromolecules
Assembly
Release
Early mRNAs are synthesized for what type of proteins?
enzymes/control proteins
Late mRNAs are synthesized for what type of proteins?
Structural proteins
All DNA viruses replicate in the nucleus except _____?
Poxvirus
Which viruses carry own RNA-dependent RNA polymerase in virion itself?
Reovirus
Rhabdovirus
Paramyxovirus
Orthomyxovirus
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.;
Lysogeny
(Lysogenic conversion-source of exotoxins)
True or False:
Disease often results as much from the immune response as from the pathogen's intrinsic virulence
True
Infection followed by resolution and temporary or lifetime immunity. (Example: Rhinovirus; Hep A)
Acute Infection
What is an example of an acute infection?
Rhinovirus
Hep A
Measles
Infection characterized by periods of latency and recrudescence (Example: Herpes)
Chronic Infection
Give an example of a chronic infection
Herpes
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)
Persistent Infection
Give an example of a persistent infection
HIV-1
HCV
Herpes simplex
______ of cells resulting in virus-induced tumors (Example: EBV, HTLV-1, HCV, HPV)
Transformation
Give an example of a transformation of cells resulting in virus-induced tumors
EBV
HTLV-1
HCV
HPV
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
HIV
Measles
Polio
Smallpox
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
True
By which route do most viruses enter?
Respiratory (mucosal)
List examples of viruses that enter through the respiratory (mucosal) route
Influenza
Measles
Mumps
Rubella
What is the second most common route of entry for viruses?
Alimentary (mucosal) (gut)
Name some viruses that enter through the alimentary route
Rotavirus
Polio
Herpes simplex
List some viruses that enter through the genitourinary tract (mucosal)
Herpes
HIV
HPV
List some viruses that enter through the Ocular (mucosal) route
Herpes
Adenovirus
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?
Cilia
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
receptors
A virus which is capable of infecting nerve cells, or which does so preferentially. Often hematogenously spread to CNS (Polio, HIV-1)
Neurotropic Virus
Virus that is capable of entering or infecting the CNS but may or may not cause disease there (mumps paramyxovirus)
Neuroinvasive Virus
A virus that causes disease within the nervous system (rabies)
Neurovirulent Virus
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
