Smallpox/Rabies

Question 1

Structure of Pox viruses

Answer 1

ds DNA
Contain RNA polymerase (not infectious genome)
no symmetry
unenveloped

Question 2

One thing that distinguishes Pox viruses from other DNA viruses

Answer 2

they contain a DNA-dep RNA pol: only DNA virus that does this. reason: they repl in the cytoplasm.

Question 3

Pox viruses form what in the cytoplasm?

Answer 3

INclusion bodies

Question 4

Which viruses form inclusion bodies in teh cytoplasm? which form inclusion bodies in the nucleus?

Answer 4

Cytoplasm: pox viruses.
Nucleus: herpes

Question 5

How is smallpx transmitted?

Answer 5

Resp

Question 6

How does smallpox manifest in the body?

Answer 6

First viremia: lungs, liver, spleen.

Second viremia: skin. x 10 days later

Question 7

Clinical presentation of smallpox/

Answer 7

papules, vesicles, pustules.

Question 8

What is an example of pantropic virus?

Answer 8

Measles, smallpox.

Question 9

What is the tropism of Hepatitis?

Answer 9

Liver

Question 10

What type of vaccine for smallpox?

Answer 10

Live, vaccinia virus (similar to but not identical to smallpox)

Question 11

Has smallpox been eradicated?

Answer 11

YES

Question 12

What is the strategy for dealing with isolated cases of smallpox that arise? Why did it work?

Answer 12

Ring vaccination. Worked because post-exposure vaccination works up to 4d post-exposure.

Question 13

Smallpox has how many serotypes?

Answer 13

ONE.

Question 14

Does smallpox have non-human reservoirs?

Answer 14

NO

Question 15

Does smallpox result in any asymptomatic infections?

Answer 15

NO.

Question 16

What is an example of a pox virus that we might see clinically?

Answer 16

Molluscum contagiosum

Question 17

How is molluscum contagiosum transmitted?

Answer 17

Cutanous contact

Question 18

How long is the incubation for mollusc. contag?

Answer 18

2-8 wks

Question 19

What is the clinical presentation of mollusc. contag?

Answer 19

after 2-8 weeks, pearly white papules appear.

Question 20

What type of virus is rabies?

Answer 20

Rhabdovirus.

Question 21

Characteristics of rhabdoviruses?

Answer 21

Bullet-shaped, enveloped, helical, -RNA (single molecule)

Question 22

Does the rabies/rhabdovirus bring along its own polymerase?

Answer 22

YES, brings in its own RNA-dep RNA pol.

Question 23

How is rabies transmitted?

Answer 23

Through the bite of an infected animal that has virus in its saliva.

Question 24

Tropism of rabies?

Answer 24

Nerve cells.

Question 25

Describe the replication of rabies virus in an infected animal.

Answer 25

wave of viral replication moves up peripheral nerves from the bite, infects CNS, and then down a neural route to the salivary glands. Virus can grow in sal glands of rabid animals, this providing virus in the bite that is transmissive.

Question 26

How long is the rabies incubation period?

Answer 26

Long: week to months.

Question 27

Rabies: fatal to what organisms?

Answer 27

Usually fatal for human, dog

Question 28

Initial and later sx of rabies?

Answer 28

Initial: fever, anorexia Later: hydrophobia due to pain with swallowing.

Question 29

How does herpes simplex infect the CNS?

Answer 29

Via neural pathway (same as rabies)

Question 30

How do most viruses infect the CNS?

Answer 30

via viremia. Ex: HSV, VZV are latent in sensory ganglia. when reactivated, move down sensory nerves to the cutaneous site at which lesions appear.

Question 31

Diagnosis or Rabies depends on what unique finding?

Answer 31

Negri bodies (cytoplasmic inclusions). Fluorescent Ab to rabies confirms that these bodies are from rabies virus.

Question 32

Review of inclusion bodies: Rabies have what? Pox viruses have what? Herpes have what:

Answer 32

Rabies: cytoplasmic Negri bodies Pox: cytoplasmic inclusions Herpes: nuclear inclusions

Question 33

What type of vaccine is used for rabies?

Answer 33

Killed. Cultured in diploid cells, then killed/inactivated.

Question 34

With rabies, can you immunize after infection?

Answer 34

Yes: the long incubation allows for this. however, once Sx are seen in the CNS, death will ensue. Generally the vaccine is given in 5 doses.

Question 35

What is special about rabies treatment after possible contact with the virus?

Answer 35

Combination of passive immunization (pooled donated human serum, which is given to delay symptoms) and killed vaccine is given.