BLS 113_CAT 2_2022

SOKOINE UNIVERSITY OF AGRICULTURE
College of Veterinary Medicine and Biomedical Sciences

BLS 113: Virology CAT 2 Total Marks: 90 Date: 21st June 2022 Time: 45 minutes

1. Select the best answer among the alternative statements given for each question and circle it (30 marks)

i. The process whereby progeny viruses acquire their envelope:
A) Fusion B) Viropexis C) Budding
D) Engulfment

ii. Poxviruses replicate:
A) On a plasmid B) In the cytoplasm
C) Nucleus D) Within the nucleus

iii. Replication of RNA viruses typically occurs in the:
A) Nucleus B) Golgi
C) Endoplasmic reticulum D) Cytoplasm

iv. Replication of DNA viruses typically occurs in the:
A) Golgi B) Cytoplasm
C) Nucleus D) Endoplasmic reticulum

v. Which of the following internalization method is mostly used by enveloped viruses to enter a cell:
A) fusion B) endocytosis
C) integration D) pore formation

vi. In order for a virus to replicate inside a cell, what component of the virus must enter the cell?
A) the genome B) the capsid
C) capsid D) envelope

vii. Which viruses always have an RNA genome that acts as a template for DNA synthesis?
A) reoviruses B) retroviruses
C) hepadnaviruses D) influenza A virus

viii. Which viruses appear to be hypermutable?
A) DNA viruses B) ‘Emerging’ viruses C) Influenza and HIV D) RNA viruses

ix. Viruses largely lack metabolic machinery of their own to generate energy or to synthesize….
A) protein B) carbohydrate
C) capsid D) nucleic acids

x. Reverse transcriptase is a useful enzyme to have when
A) an RNA virus converts its RNA to DNA
B) a DNA virus converts its DNA to RNA
C) an RNA virus converts its DNA to RNA
D) a virus lacks metabolic machinery

xi. When a virus enters a cell but does not replicate immediately, the situation is called
A) lysogeny B) latent C) symbiosis
D) synergism E) incubation F) lytic

xii. The first step in infection of a host cells by a virus is called
A) adsorption B) absorption C) abruption D) penetration E) replication F) fusion

xiii. In the one-step growth curve, the time from infection until lysis is known as
A) eclipse period B) rise period
C) latent period D) burst size

xiv. Inclusion bodies of rabies virus are called:
A) intracytoplasmic B) intranuclear
C) Negri bodies C) both (a) and (b)
D) none of the above

xv. All negative sense RNA viruses have:
A) no envelope
B) envelope
C) segmented genomes only
D) non-segmented genomes only
E) no RNA-dependent RNA polymerase

 

2. Indicate whether the following statements are TRUE or FALSE (4 marks)

i. The synthesis of viral proteins for all viruses is carried out in the cytoplasm using the virus machinery…………………………………………………………………………………………….
ii. Enveloped viruses acquire envelopes by generating it themselves during replication in the cell……………………
iii. In the (-) sense RNA genomes, the (+) strands and mRNA are the same…………………………….
iv. All DNA viruses replicate in the nucleus except retrovirus replicate in the cytoplasm……………….

 

3. Select the answer among the alternatives given in list B that best matches with the statement in list A, then write the letter of the correct response in spaces provided in list A (20 marks)

LIST A

LIST B

i.      Internalization mechanism used by most enveloped viruses………………… ii.    A form of a virus when outside the cell…………………………………….. iii.    The mechanism used by most of the non-enveloped viruses to leave the cell after replication……………………………………………………………… iv.    The process of bringing viral envelope and cellular plasma membrane into intimate contact and then merging them into one…………………………… v.      In HIV replication, the cellular RNA polymerase II copies the …………. to make mRNA for viral proteins and full length viral RNAs vi.    The process whereby a virus capsid is completely or partially removed and the virus genome exposed…………………………………………………… vii.  The enzyme that MUST be packaged by -ssRNA viruses within their virion for replication and transcription…………………………………………….. viii.  Viral proteins such as enzymes or transcription factors for virus replication which are not incorporated in the virus are called…………………………………… ix.    A cell with the capacity to replicate the virus is called……………………… x.      The integrated retroviral DNA genome is called……………………………

A. Fusion B. Permissive C. Penetration D. RdDp E. Proviral RNA F. Provirus G. Uncoating H. Non-structural proteins I. Viral DNA J.  Lysis K. Susceptible L. Core M. Prion N. RdRp O. Virion P. Viropexis Q. Budding

 

4. By filling in the table provided below (Each 1 mark, Total 36 marks);
a) Name the virus groups based on Baltimore classification
b) Provide the sites where replication of the genome and transcription takes place
c) State whether the virus group packages any enzyme within the virion or not

Baltimore Class	Virus group	Site for genome replication	Site for transcription	Package enzyme (s) or not
Class I (smaller)
Class I (larger)
Class II
Class II
Class IV
Class V (segmented)
Class V (non-segmented)
Class VI
Class VII

 

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