DD Common Viral pathogens Ii More specific

Question 1

What types of viruses are: (DNA vs RNA)
Influenza
RSV
Ebola

Answer 1

Influenza: segmented ssRNA
RSV: ssRNA
Ebola: (-) strand RNA

(remember, HSV 1, HSV2, VZV, CMV, EBV were all dsDNA viruses)

Question 2

Which virus can replicate in cytoplasm?
Influenza
RSV
Ebola

Answer 2

Ebola

remember poxviridae can too!

Question 3

What glycoproteins are present in Influenza? Their purpose?

Answer 3

Hemaglutinin (H): involved in viral cell entry - attach to host cell

Neurominidase (N): releases virus from the cell

Question 4

What glycoproteins are present in RSV? Their purpose?

Answer 4

F protein: causes fusion of viral envelope to host cell (syncytia)

G protein: helps with initial binding of virus to host cell.

Question 5

What special proteins are present in Ebola? Their purpose?

Answer 5

1. VP40 matrix protein:
   
   • for assembly, budding, structure, stability
2. VP24 matrix protein:
   
   • for assembly, budding, nucleocapsid assembly, and immune defense
3. Nucleocapsid (VP30) and nucleoprotein:
   
   • form capsid
4. VP35 and L:
   
   • replication, RNA-dependent RNA polymerase.
5. Glycoprotein:
   
   • attachment and entry (key for pathogenicity)

Question 6

Characteristics of Type A Influenza

• severity
• epidemic or pandemic?
• rapidly changing or uniform?
• who is affected?

Answer 6

Potentially severe illness
Epidemics and pandemics
Rapidly changing
Birds, swine, dogs, cats, horses, seals, whales, humans

Question 7

Characteristics of Type B Influenza

• severity
• epidemic or pandemic?
• rapidly changing or uniform?
• who is affected?

Answer 7

Usually less severe illness
Epidemics, no pandemics
More uniform
Humans

Question 8

Is type A or B RSV more severe and prevalent in epidemiologic studies?

Answer 8

Type A

Type A influenza is also more severe

Question 9

How does the virus enter?

• Influenza
• RSV
• Ebola

Answer 9

• Influenza:
Enter through mucosal surfaces (eyes, nose, mouth), respiratory route. Also by contact with hands and fomites

• RSV:
Enter and invade through conjunctiva and nasopharynx. Can live on surfaces for hours

• Ebola:
From animal reservoirs (initially tied to hunters and slaughtering of animals)… now mainly entering through mucosal surfaces or cuts to skin, from fluid contact of infected humans

Question 10

How does ebola cause cells to die?

Answer 10

Initially enters phagocytic cells, →
Send for more to come to infect those ones too →
(induce massive cytokine storm and can induce DIC),

spreads efficiently until reaches lymph nodes to infect more immune cells! →

Then goes on to infect other organ cells (endothelial cells, liver, spleen and lungs) →
causes bystander immune cells to die …

Question 11

What two drugs is made to help against RSV? How is it made?

Answer 11

Respigam or Synagis (aka palivizmumab)

• made form pooled Ab with high RSV titer

Question 12

antigenic drift in virus

Answer 12

○ changes are gradual b/c the virus has to acquire many point mutations over time to become a new strain.

It represents an adaptation to its host antibodies.

Question 13

antigenetic shift in virus

Answer 13

§ This is the result of gene reassortment

• occurs when segmented genes are swapped (i.e. human strain swapped with an avian strain).
• And though the strain may be predominantly human, its avian H or N gene received, results in a new Type A. - Slower than antigenic drift, but the outcome can have a more dramatic impact.

Question 14

Which is faster? 
antigenic drift (point mutation) or
antigenic shift (reassortment of genome segments)

Answer 14

Antigenic drift is faster

Antigenic shift is slower (but more impact)

Question 15

origin of Pandemic H1N1 (influenza)

Answer 15

• Swine flu! 2009 and 2010 Pandemic H1N1 came from antigenic shift where genetic reassortments occurred between birds, pigs, and humans.

Question 16

What population of indiv did H1N1 predom. effect?

Answer 16

Children and young adults <24 y/o

spared the old bc of preexisting immunity against antigenetically similar viruses

Question 17

• For influenza, name three conditions to consider that pandemic of virus is happening:

Answer 17

1) Emergence of new influenza SUBTYPE (different H and/or N glycoproteins)
2) Virus has to cause infections in humans and cause serious illinesses
3) Virus can be spread easily between humans and remains that way.