51 Questions
What is the process by which an infection leads to disease called?
Pathogenesis
What are the pathogenic mechanisms of viral disease?
Implantation of virus at the portal of entry
What factors affect the pathogenic mechanisms of viral disease?
Accessibility of virus to tissue, cell
What does natural selection favor in terms of virus strains?
Low-virulence virus strains
What happens when several viruses infect the same type of tissue?
They usually cause the same type of disease
What is the percentage of subclinical viral infections, suggesting that body defenses arrest most infections before disease symptoms become manifest?
90%
How can viral pathogenesis be viewed on two distinct levels?
Cellular and tissue/systemic pathogenesis
What is the hallmark of viral infection of the cell?
Rounding and darkening of the cell
Which effect of virus infection on the cell is characterized by prolonged survival and unrestrained growth?
Malignant transformation
What is a common result of direct cell damage and death from viral infection?
Competition of viral mRNA for cellular ribosomes
What is a hallmark of viral infection of the cell that aids in the clinical diagnosis of herpesvirus skin infections?
Multinucleated giant cells with eosinophilic intranuclear inclusions
What can result from integration of the viral genome into the host genome?
Malignant transformation
What method is frequently used for quantifying the amount of virus in a sample based on the appearance of cytopathic effect (CPE) in cell culture?
Plaque assay
What happens during the incubation period of a typical viral infection?
Local multiplication and spread occur
What is a common indirect result of virus infection on cells?
Induction of inflammation
What is a common outcome when infected cells contain inclusion bodies?
Death of the infected cells
What is a characteristic of viral infection accompanied by virus production but without morphologic or gross functional changes?
Focal areas of rounded, piled-up cells
Which stage of a typical viral infection involves nonspecific symptoms?
Prodromal period
What are the four main effects of virus infection on the cell?
Death, fusion of cells to form multinucleated cells, malignant transformation, no apparent morphologic or functional change
How do most virus types spread among cells?
Extracellularly
What is the most common route of systemic spread from the portal of entry?
Circulation
How may the virus enter the target organs from the capillaries?
All of the above
What is dissemination via nerves usually associated with?
All of the above
What determines the final outcome of infection?
Virus dose and location, as well as its infectivity and virulence
In which route can viruses implant onto living cells?
Gastrointestinal
What may lead to localized disease and localized shedding of virus?
Local replication and local spread
Where does multiplication in the target organ occur?
In endothelial cells or fixed macrophages
Which factor determines the viral affinity for specific body tissues?
Local temperature and oxygen tension
What refers to people who produce virus for long periods of time and can serve as a source of infection for others?
Persistent viral infections
What characteristic is associated with latent infections?
Not producing virus at the present time but can be reactivated at a subsequent time
What is one of the barriers that the virus must traverse when infecting the fetus?
Developing first-trimester fetal organs
What is the medically important example associated with slow virus infections?
HIV infection
Which stage of a typical viral infection involves nonspecific symptoms?
Incubation period
What are the characteristics of slow virus infections?
Long incubation period, often measured in years
What does carrier state refer to in the context of viral infections?
"People who produce virus for long periods of time and can serve as a source of infection for others"
Which of the following viruses is associated with cancer of the cervix?
Epstein Barrvirus (EBV)
Which virus is known to cause liver cancer?
Hepatitis B virus (HBV)
Which RNA virus causes liver cancer?
Hepatitis C virus
Which type of virus is associated with Burkitt’s lymphoma and nasopharyngeal carcinoma?
Epstein Barrvirus (EBV)
What is the known viral agent of cancers associated with nasopharyngeal carcinoma?
Epstein Barrvirus (EBV)
Which virus is associated with Adult T-cell lymphocytic leukaemia?
Human T-cell leukaemia virus type 1
Which of the following viruses is NOT associated with cancer?
Poxvirus
Which type of immunity is present in all normal individuals and does not discriminate amongst microorganisms?
Innate immunity
Which components are part of the innate resistance in the immune system?
Physical barriers, Phagocytic cells, Proteins, and Antibodies
Which activity is NOT a major activity of the immune response?
Evasion
What type of immunity is acquired through immunization or clinical/subclinical infection?
Active immunity
Which physiological conditions regulate innate immunity?
Nutrition, Age, Hormones
Which cells are part of the innate immune system's phagocytic cells?
Neutrophils, Macrophages, Natural Killer cells
Which type of infection involves immunization with live or killed infectious agents or their antigens?
Acquired immunity
Which proteins are part of innate resistance in the immune system?
Complement, Lysozyme, Interferon
Which type of infection involves transfer of antibodies from another individual?
Passive immunity
Test your knowledge of the pathogenic mechanisms of viral diseases with this quiz. Explore topics such as implantation of the virus, local replication, evasion of host immunity, and spread to target organs and shedding sites. Also, learn about the factors that affect pathogenic mechanisms and natural selection.
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