Dengue Virus (26)

Question 1

A feature of Arboviruses is:

a. They usually belong to the calciviridae, flaviviridae and filoviridae families
b. Humans are rarely just incidental hosts
c. Viruses replicate in blood sucking arthropod vectors
d. They are always DNA viruses

Answer 1

c. Viruses replicate in blood sucking arthropod vectors

Question 2

What is true about Dengue disease?

a. Infection always results in symptomatic infection
b. The four DENV strains are not antigenically cross reactive
c. Secondary dengue infections are more mild than the initial infection
d. Infection with one strain of dengue confers lifelong immunity to that strain only

Answer 2

d. Infection with one strain of dengue confers lifelong immunity to that strain only

Question 3

The intrinsic incubation period of an arbovirus:

a. Refers to the period of time for the virus to infect its host and become transmissible
b. Is not influenced by the dose or route of inoculum
c. Refers to the period of time for the virus to infect its vector and disseminate to the salivary glands
d. Is independent of environmental conditions

Answer 3

a. Refers to the period of time for the virus to infect its host and become transmissible

Question 4

What is correct about secondary dengue infection?

a. Antibody dependent enhancement can occur
b. There is a 20fold decreased risk of sever dengue
c. Virus titres usually remain low and the immune response is subdued
d. It results in decreased capillary permeability

Answer 4

a. Antibody dependent enhancement can occur

Question 5

How does the host immune response link to severe dengue infection?

a. Dengue virus represses the immune response by expressing IL-10 mimicry proteins
b. The inflammatory response peaks at day 4 and leads to an increase in capillary permeability
c. As dengue virus disseminates, blood vessels are damaged by apoptosis of infected cells
d. Dengue virus expresses a CrmA protein that prevents the activation of IL-1B

Answer 5

b. The inflammatory response peaks at day 4 and leads to an increase in capillary permeability

Question 6

What is correct about the CYD-TDV vaccine?

a. It is trivalent and contains the prM and E components of DENV1-3
b. It was designed using the Yellow Fever 17D attenuated vaccine strain as a backbone
c. It is most effective against DENV-2 infection
d. It is inefficient in those who are already seropositive for dengue virus

Answer 6

b. It was designed using the Yellow Fever 17D attenuated vaccine strain as a backbone

Question 7

• Each year there are 2.1million cases of severe dengue and 21,000 deaths.

Answer 7

T

Question 8

• Dengue infections are most often found in the older population due to the lack of cross-protection between differ strains.

Answer 8

F

Question 9

• Dengue virus fails to replicate in mosquitos infected with wolbachia.

Answer 9

T

Question 10

• The extrinsic incubation period of dengue virus is usually 7-14 days and this is half of the life of the mosquito.

Answer 10

T