Chapter 29. General Properties of Viruses
Some viruses are characterized by helical symmetry of the viral nucleocapsid. Which of the following statements about viruses with helical symmetry is most accurate?
(A) All enveloped viruses with helical symmetry are classified into the same virus family.
(B) Helical nucleocapsids are found primarily in DNA-containing viruses.
(C) All human viruses with helical nucleocapsids possess an envelope.
(D) Excess empty helical particles containing no nucleic acid are commonly produced in infected cells.
Virus-infected cells often develop morphologic changes referred to as cytopathic effects. Which of the following statements about virus-induced cytopathic changes is most accurate?
(A) They are pathognomonic for an infecting virus.
(B) They are rarely associated with cell death.
(C) They may include giant cell formation.
(D) They can only be seen with an electron microscope.
Viruses usually initiate infection by first interacting with receptors on the surface of cells. Which of the following statements is most accurate about cellular receptors for viruses?
(A) Cellular receptors for viruses have no known cellular function.
(B) All viruses within a given family use the same cellular receptor.
(C) All cells in a susceptible host express the viral receptor.
(D) Successful infection of a cell by a virus may involve interaction with more than one type of receptor.
Which of the following can be used to quantitate the titer of infectious viruses?
(D) Polymerase chain reaction
Which one of the following states a principle regarding viral nucleic acid?
(A) Viruses contain both RNA and DNA.
(B) Some viruses contain a segmented genome.
(C) Purified viral nucleic acid from any virus is usually infectious.
(D) Viral genome sizes are similar among known human viruses.
Two mutants of poliovirus have been isolated, one (MutX) with a mutation ...