31. Viruses I

Question 1

Which of the following viruses are negative ssRNA?

A. Renoviruses
B. Orthomyxoviruses
C. Retroviruses
D. Arenaviruses
E. Bunyaviruses 

SZ

Answer 1

Ans. B Orthomyoxiruses

Orthomyoxiruses are segmented negative ssRNA. Renoviruses are positive dsRNA. Retroviruses are positive ssRNA. Arenaviruses and Bunyaviruses are both ambisense ssRNA (+/-)

Question 2

A 67 old man is rushed to the ICU he has been vomiting, hematochezia and hyphema. His blood pressure is 170/120 with a heart rate of 92 bpm, his O2 sat. is 86% percent. He has been showing these symptoms for 20 minutes. He is immediately put onto supplemental oxygen but dies within an hour. After investigation it is found that the patient had been infected with a bacteriophage. Which type of bacteriophage affected this patient?

A. Lytic
B. Lysogenic
C. Latent
D. Eclipse 
E. Temperate

RFA

Answer 2

Ans A .Lytic- a Lytic or “Virulent” infection is a bacteriophage that kills its host immediately

B & E Lysogenic & Temperate are different names for the other type of bacteriophage it occurs when the host is not immediately killed. The phage genome is integrated into the host genome.

C. Latent- is a phase of viral growth its is when the viral genome takes over the control of the host cell protein making production of it own viral components

D. Eclipse- is another phase of viral growth it follows the initial infection and is noted by a disappearance of the viral particles

Question 3

A 14 year old girl is kept home from school. She has a persistent cough and a soar throat and feels muscle aches. She is taken to the doctor by her parents and after test it is shown that she has influenza. Influenza is a member of the Orthomyxoviruses family. Which is true of this family of viruses.

A. It’s genome has monocistronic mRNA
B. Penetrates cells by directly crossing the plasma membrane
C. Has a Icosahedral structure
D. Is a positive sense RNA virus
E. It is able to be treated by Boceprevir

RFA

Answer 3

Ans. A. Has a genome for monocistronic mRNA- this characteristic is know as segmentation. Orthomyxoviruses is one of the 4 segmented viruses BOAR helps you remember them all
Bunya, Ortho, Arena,Reo

B. Orthomyxoviruses are negative sense RNA viruses and all are enveloped viruses, only non enveloped viruses cross the plasma membrane directly. Enveloped viruses use fusion or Endocytosis and acidification

C. All negative sense viruses are helical shaped

D. Orthomyxoviruses is negative sense

E. Boceprevir is protease inhibitor for Hep C

Question 4

An enveloped virus is found in the lab. Its capsids are open-ended and form around the genome. Which of the following forms describes the capsid?

A. Complex Capsid
B. Helical Capsid
C. Icosahedral Capsid
D. Cone-shaped Capsid

SZ

Answer 4

Ans. B Helical Capsid

DLA 17: Helical capsids are rod-like, filamentous structures. They must form around a genome, meaning they are “open-ended.”

Complex capids are often “spaceship-like” structures. They have a head, base, tail.

Icosahedral capsids are soccer ball-like in structure. Few proteins for a protomer, protomers assemble into a pentamer. They have a 5-3-2 axis of symmetry.

Cone shaped capsids are specific to retroviruses

Question 5

Which of the following viruses infect a host cell by means of fusion? (MG)

A. Influenza
B. Herpesvirus
C. Paramyxovirus
D. HIV
E. Poliovirus
F. Parvovirus

Answer 5

B. Herpesvirus
C. Paramyxovirus
D. HIV

All enveloped, all use fusion

Question 6

Non-enveloped viruses typically exit the host cell post-replication via what method? (MG)

A. Fusion
B. Exocytosis
C. Lysis
D. Endocytosis and acidification
E. Direct entry
F. Endocytosis followed by injection

Answer 6

C. Lysis