del 6 Flashcards
The infectious prionic agents
a. Resistant to radiation and autoclaving temperature 121oC
b. Characterized by conversion of PrPSc to PrPc
c. Causative agent of diseases such as kuru and scrapie
d. Sensitive to nucleases and proteases
T: a, c
F: b, d
Scrapie:
a. Disease of cattle.
b. Seem to be a naturally occurring disease.
c. Only pathologic lesions occur in the CNS.
d. There is no significant horizontal spread.
e. There is never any fever.
T: b, c, e
F: a, d
41.Bovine spongiform encephalopathy (BSE):
a. Susceptible sheep have developed the disease in pastures previously occupid by scrapie-affected sheep.
b. Disease was caused by feeding cattle ruminant protein suppliments in the form of meat and bone meal produced by rendering animal waste.
c. There is no significant horizontal spread.
d. Transmission of BSE was associated with ritual cannibalism.
e. As the number of infected cattle increased, the infection rate may have been further amplified by inclusion in rendered products of waste from BSE-infected cattle.
T: b, c, e
F: a, d
General virus properties are
a. The basic structural unit of the virion is a capsid, which consists from capsomeres and protomers
b. Protomers are responsible for adsorption of the virus to the cell surface.
c. Peplomers are the smallest structural units of the virus.
d. Viruses differ from other living cells by their acellular organisation
T: a, d
F: b, c
All viruses:
a. Contain DNA.
b. Contain RNA.
c. Contain protein.
d. Are susceptible to antibiotics.
e. Are intracellular parasites.
T: c, e
F: a, b, d
Viruses:
a. Some viruses can survive in the soil or in fluids, that is how they can survive outside of the host cells, for a period of time.
b. Viruses are a unique group of infectious agents whose disinfectivness relies in their simple, cellular organization and pattern of reproduction.
c. Obligate intracellular parasites.
d. The nucleocapsid is composing of a nucleic acid, either DNA or RNA, held within a protein coat called capsid.
e. Capsid protects viral genetic material and aids its transfer between host cells.
T: a, c, d, e
F: b
The following statements are true:
a. Nucleocapsids of all viruses protect genome from nucleases.
b. Hemagglutination detect only infectious virons.
c. Virus is capable of „vertical transmission“.
d. Nucleocapsid is found in all infectious virions.
e. mRNA‘s must be present in an enveloped virus and absent in a naked or nonenvelope virus.
f. Enveloped virus is more virulent than non-enveloped virus.
g. Retroviruses have an RNA dependent DNA polymerase of revert transcriptase.
h. Mechanisms of virion release differ between naked and enveloped viruses.
i. Naked virions appear to be released more often by host cell lysis.
j. After synthesizing-DNA, the revert transcriptase copies this strand to produce a double-stranded DNA called proviral DNA.
T: a, c, d, g, h, i, j
F: b, e, f
Viruses are classified according to:
a. The host they infect (plant, animal or bacteria).
b. The presence of an envelope.
c. Number of capsid.
d. Type of nucleic acid.
e. Intracellular location of viral replication.
T: a, b, d, e
F: c
During the replication cycle of a virus, occured LAST:
a. Decrease in number of infectious particles.
b. Physical separation of nucleic acid from the nucleocapsid.
c. Release of mature viruses from cell (cell lyse, budding).
T: c
F: a, b
(1.adsorption 2.penetration 3.uncoating 4.eclipse 5.maturation 6.elution)
Replication and transcription in DNA viruses:
a. DNA replication with a virus specific RNA polymerase begins in the cell nucleus.
b. The DNA viruses are much more diverse in the reproductive strageties than are the RNA viruses.
c. Messenger RNA at least early mRNA is transcribed from DNA by host enzymes (except poxvirus).
d. DNA is transcribed by host DNA polymerase.
e. DNA replication usually occurs in the host cell nucleus (poxvirus are exception).
T: c, e
F: a, b, d
What is an example of a cytopathic effect:
a. Inhibition of viral attachment.
b. Alteration of membrane permability.
c. Alteration of host cell translation.
d. Degenerative changes in cells (especially in tissue culture) associated with the multiplication of certain viruses.
e. Lysis of the host cell.
T: b, c, d, e
F: a
The following are enveloped viruses:
a. Herpesviridae.
b. Adenoviridae.
c. Rotavirus.
d. Parvovirinae.
e. Bunyaviridae.
T: a, e
F: b, c, d
The following viruses replicate in the nucleus:
a. Herpesvirus.
b. Poxvirus.
c. Picornavirus.
d. Orthomyxovirus.
e. Paramyxovirus.
T: a, d
F: b, c, e
