B4: ebola

Question 1

What virus family does Ebola belong to?

Answer 1

Filoviridae

Question 2

What are the key characteristics of filoviruses?

Answer 2

Filamentous morphology, highly pleomorphic, cause severe haemorrhagic fever

Question 3

When and where was Ebola virus first identified?

Answer 3

Zaire, 1976

Question 4

How many subtypes of Ebola virus exist?

Answer 4

Six: Zaire, Bundibugyo, Sudan, Taï Forest, Reston, Bombali

Question 5

Which Ebola strain is the most deadly?

Answer 5

Zaire (ZEBOV), with higher mortality than Sudan (SEBOV)

Question 6

How is Ebola virus transmitted?

Answer 6

Direct contact with bodily fluids of infected persons or animals

Question 7

What is the incubation period for Ebola?

Answer 7

3-16 days

Question 8

What are the initial symptoms of Ebola virus disease?

Answer 8

Flu-like symptoms: fever, headache, aches, pains

Question 9

What additional symptoms occur around days 5-7?

Answer 9

Maculopapular rash in ~50% of patients

Question 10

What are severe symptoms of Ebola virus infection?

Answer 10

Gastrointestinal bleeding, organ failure, shock, and death in 50-90% of cases

Question 11

What is the key approach to Ebola virus containment?

Answer 11

Barrier nursing, quarantine, and education

Question 12

What is the name of the Ebola vaccine?

Answer 12

Ervebo

Question 13

How is the Ervebo vaccine administered?

Answer 13

Dose 1: Zabdeno, Dose 2: Mvabea (8 weeks later)

Question 14

Is the Ebola vaccine used during outbreaks?

Answer 14

No, it is used prophylactically

Question 15

What is believed to be the primary reservoir of Ebola virus?

Answer 15

Fruit bats

Question 16

What evidence supports bats as an Ebola virus reservoir?

Answer 16

Leroy et al. (2005): fruit bats were either IgG or PCR positive but asymptomatic

Question 17

What animals have been linked to Ebola virus transmission but are not reservoirs?

Answer 17

Chimpanzees, gorillas, and antelope

Question 18

What is the genome structure of Ebola virus?

Answer 18

Negative-sense, single-stranded RNA (-ssRNA)

Question 19

What is the function of the L protein in Ebola virus?

Answer 19

It acts as the RNA-dependent RNA polymerase (RdRp)

Question 20

What is the shape of the Ebola virus nucleocapsid?

Answer 20

Helical

Question 21

How is Ebola virus related to other viruses?

Answer 21

It is closely related to rhabdoviruses (e.g. rabies) and paramyxoviruses (e.g. measles)

Question 22

What viral order does Ebola virus belong to?

Answer 22

Mononegavirales (-ve ssRNA genome)

Question 23

What is a pseudotype virus?

Answer 23

A modified virus used for studying viral entry, e.g., VSV with Ebola glycoprotein

Question 24

What is the role of the Ebola virus glycoprotein (GP)?

Answer 24

Mediates viral entry into host cells

Question 25

What does it mean that Ebola virus is pantropic?

Answer 25

It can infect and damage many different organs, particularly the liver and spleen

Question 26

Which immune cells does Ebola virus initially infect?

Answer 26

Monocytes, dendritic cells, macrophages

Question 27

Which cells does Ebola virus infect later in the disease?

Answer 27

Endothelial cells

Question 28

What is the estimated viral load in the blood during peak infection?

Answer 28

Up to 10¹⁰ virus particles/ml

Question 29

What are the major immune responses induced by Ebola virus infection?

Answer 29

Cytokine storm, suppression of interferons, and depletion of lymphocytes

Question 30

Which cytokines are involved in the Ebola virus-induced cytokine storm?

Answer 30

TNF-α, IFN-γ, but NOT IFN-α or IFN-β

Question 31

hat immune response does Ebola virus suppress?

Answer 31

Production and action of IFN-α and IFN-β

Question 32

What are the consequences of immune suppression by Ebola virus?

Answer 32

Decreased dendritic cell maturation, reduced T & B cell activation, and NK cell depletion

Question 33

How does Ebola virus cause coagulopathy?

Answer 33

Increased tissue factor (TF) expression on macrophages and endothelial cells

Question 34

What is the predominant coagulation defect in Ebola virus disease?

Answer 34

Inappropriate coagulation, rather than lack of coagulation

Question 35

What are some hypotheses for antibody-dependent enhancement of infection?

Answer 35

C1q/Ab/virus complex may contribute to hyperactivation of the immune system

Question 36

What are the two major components of Ebola virus pathogenesis?

Answer 36

1) Suppression of immune response, 2) Hyperactivation of immune response

Question 37

Why is Ebola virus highly contagious?

Answer 37

Transmitted in body fluids, remains infectious for long periods

Question 38

How does the Ebola vaccine help prevent infection?

Answer 38

It stimulates a strong immune response before exposure to the virus

Question 39

What factors contribute to the high mortality rate of Ebola virus?

Answer 39

Severe immune dysregulation, widespread organ damage, lack of effective treatment

Question 40

What is a key similarity between Ebola virus and measles virus in immune evasion?

Answer 40

Both suppress IFN-α & IFN-β responses

Question 41

Why are pseudotype viruses used in Ebola virus research?

Answer 41

They allow researchers to study Ebola virus entry and immune responses safely by replacing the Ebola glycoprotein in a non-lethal virus like VSV.

Question 42

How long can Ebola virus survive outside the body?

Answer 42

Ebola virus can remain viable for hours to days on surfaces, depending on environmental conditions like temperature and humidity.

Question 43

What are the differences between human-to-human and animal-to-human Ebola virus transmission?

Answer 43

Human-to-human occurs via direct contact with bodily fluids, while animal-to-human happens through handling infected wildlife (e.g., fruit bats, primates).

Question 44

What is the role of Ebola virus glycoprotein (GP)?

Answer 44

GP mediates virus entry by binding to host receptors and inducing membrane fusion. It also helps the virus evade immune detection.

Question 45

What are the functions of VP35 and VP40 in Ebola virus?

Answer 45

VP35 suppresses interferon production, helping the virus evade the immune response, while VP40 regulates virus assembly and budding.

Question 46

How does Ebola virus cause haemorrhagic symptoms?

Answer 46

The virus infects endothelial cells, triggering a cytokine storm and coagulation defects, leading to blood vessel leakage and internal bleeding.

Question 47

How do macrophages contribute to the spread of Ebola virus?

Answer 47

Infected macrophages travel through the bloodstream, spreading the virus to multiple organs, including the liver and spleen, leading to widespread damage.

Question 48

Why isn’t Ervebo used during Ebola outbreaks?

Answer 48

Ervebo is used prophylactically for high-risk individuals but not for immediate outbreak control, as it takes time for immunity to develop.

Question 49

What monoclonal antibody treatments exist for Ebola virus?

Answer 49

Inmazeb (REGN-EB3) and Ebanga are FDA-approved monoclonal antibody therapies that neutralize Ebola virus and improve survival rates.

Question 50

How does Ebola virus affect NK cells?

Answer 50

Ebola virus depletes NK cells, reducing the body's ability to clear infected cells and increasing viral spread.