Viral Agents and Structure (2,3,4) Flashcards
What is required for negative staining?
a. Compounds should be proton dense
b. The compounds should be able to crystallise
c. The compounds should be highly soluble
d. Calcium phosphotungstate
c. The compounds should be highly soluble
What is false about cryo-electron microscopy?
a. The sample is not distorted and allows the structure to be analysed
b. A negative stain must be applied first
c. Different 2D views can be reconstructed to form a 3D structure
d. A computer can be used to reconstruct the image of the virus
b. A negative stain must be applied first
The following does not have icosahedral capsid symmetry:
a. Herpesvirus
b. Papillomavirus
c. Adenovirus
d. Retrovirus
d. Retrovirus
What is false about Poxvirus?
a. It can possess either icosahedral or helical capsid symmetry depending on the species
b. It is the largest and most complex virus
c. IT has over 100 proteins in the virion
d. It has a 130-280 kb dsDNA genome
a. It can possess either icosahedral or helical capsid symmetry depending on the species
What is true about classifying viruses according to family and genus?
a. Family names end in virus and genus names end in viridae
b. The size of the genome and differences in sequence can distinguish a genus from other genera
c. The number and size of proteins is used to classify families
d. Viral replication strategies and morphology are used to distinguish between genera
b. The size of the genome and differences in sequence can distinguish a genus from other genera
What is false about determining if a virus has ssRNA or dsRNA?
a. RNase only digests ssRNA
b. TCA precipitates radioactive RNA polymers and the presence of precipitate demonstrates undigested RNA (double stranded)
c. ssRNA forms a precipitate when exposed to TCA
d. ssRNA would produce free uracil nucleotides when exposed to RNase and these remain in solution after treatment with TCA
c. ssRNA forms a precipitate when exposed to TCA
What is false about Hepatitis D?
a. It is a covalently closed circular RNA viroid element
b. It is dependent on hepatitis B for transmission and acts as a parasite of a virus
c. It can be considered an emerging infectious agent
d. It encodes RNA polymerase
d. It encodes RNA polymerase
• X ray diffraction can only be used on non-enveloped viruses.
T
• In a viral envelope, the phospholipids are virus-encoded whilst the glycoproteins and host encoded.
F
• Icosahedral capsid symmetry is only found in enveloped viruses.
F
• Enveloped viruses are less stable than naked viruses.
T
• Purified virions containing H suggest that the virus has an RNA genome whilst purified virions containing C suggest that the virus has a DNA genome.
T
• When extracting NA from viruses and cells, the upper aqueous phase contains protein and the lower phenol phase contains nucleic acids.
F
What sample would be taken to identify a virus from the following infections?
a. A faecal sample for a systemic fever
b. CSF for encephalitis
c. Nasal secretions for a vesicular rash
d. Blood for an enteric infection
b. CSF for encephalitis
What part of an embryonated chicken egg would be used to cultivate Poxvirus?
a. Chorioallantoic membrane
b. Yolk sac
c. Amniotic fluid
d. Allantoic fluid
a. Chorioallantoic membrane
What is false about mammalian cell culture methods?
a. Primary cells can only survive up to 10 divisions
b. Continuous cell lines are aneuploid
c. Diploid cell lines can survive up to 100 divisions
d. All modern vaccines are cultivated using continuous cell lines
d. All modern vaccines are cultivated using continuous cell lines