Negative Sense (-)RNA Viruses

Question 1

What is the difference between antigenic drift and shift?

Answer 1

Antigenic Drift – point mutations
Antigenic Shift – segments change from reassortment when multiple strains are together in a host (Much worse for pandemics)

Question 2

What are orthomyxoviruses and their classifications?

Answer 2

ss(-)RNA Viruses, 8-segment genome
– Influenza Viruses
Remember – has to bring machinery with it to convert (-)RNA into functional +RNA
–Replicate in the Nucleus

Question 3

What are the proteins responsible for the pathology of influenza?

Answer 3

Hemagluttinin – binds sialic acid in Upper resp tract
M2 Protein – influxes acid to uncoat the virus
Neuraminadase – cleaves the sialic acid to release the virions from the infected cell

Question 4

What pathway is being blocked by Oseltamivir and Anamivir?

Answer 4

– Neuraminadase, releasing of the virions is prevented

Question 5

What are complications of being infected with influenza?

Answer 5

Due to destruction of respiratory epithelial increases risk for bacterial infection – most commonly Strep/Staph

Question 6

What viruses are apart of the paramyxovirus family and their characteristics?

Answer 6

(-)ssRNA, encapsulated

• • Rubeola
• • Mumps
• • RSV
• • Parainfluenza Virus

Question 7

What are the unique clinical manifestations of Rubeola(Measles)?

Answer 7

– Cough
– Conjunctivitis
– Coryza (Runny Nose)
– Fever x4 days
*Koplik Spots in the buccal mucosa
Macular Rash – starts on the face and moves down the body.

Question 8

What are complications that can arise from measles (Rubeola) infection?

Answer 8

• -Pneumonia

- - subacute sclerosing panencephalitis –from chronic (generally immigrant and personality change)

Question 9

What can be given to someone with measles to reduce the mortality of children?

Answer 9

Vitamin A

Question 10

What virus can cause parotitis and orchitis?

Answer 10

Mumps – can cause sterility and aseptic meningitis

Question 11

What virus most commonly causes croup and what is the most indicative finding?

Answer 11

Parainfluenza Virus

• • upper airway stridor
• • Steeple Sign
• *Croup = laryngotracheobronchitis

Question 12

What is the most common cause of pneumonia and bronchiolitis in infants?

Answer 12

RSV – less than 6months, binds to resp epithelium via G-protein

Question 13

How can you classify Rhabdovirus (Rabies)?

Answer 13

(-)ssRNA, enveloped helical capsid

• *Bullet Shaped**
• -Nigri Bodies (intracellular inclusions)

Question 14

Who are at risk for Rabies?

Answer 14

– exposure to bats/caves, possible rabid other animals

Question 15

What is the pathology of Rabies virus and symptoms?

Answer 15

Initially affects the motor-end plate, but binds Nicotinic Acetylcholine Receptors (motor neurons) and progresses retrograde into the CNS/dorsal root ganglia.

• • Hippocampus / Purkinje cells
• • agitation, photophobia, hydrophobia, esophogeal spasms, death

Question 16

What classification is ebola / marburg virus?

Answer 16

Filovirus – (-)ssRNA

Question 17

What are clinical symptoms of Filovirus and who is at risk?

Answer 17

• Flu-like syndrome, petechiae rash, hemorrhagic fever, hypovolemic shock, death
• • Africans / Healthcare Workers

Question 18

What is unique about Reovirus, compared to other RNA viruses?

Answer 18

DOUBLE STRANDED RNA, naked

– Rotovirus

Question 19

What virus causes villous atrophy, watery secretory diarrhea, in children who are in daycare?

Answer 19

Rotovirus
-- NSP4 Toxin -- induces the secretion 
-- #1 cause of severe diarrhea in children, should get vaccinated
-- only supportive treatment
RISK for Intussuception

Question 20

What class of viruses have (-)ssRNA segmented and circular and enveloped, that is typically vector bourne?

Answer 20

Bunyavirus

• • Arbovirus
• • Hantavirus
• • Rift Valey Fever / California Encephalitis

Question 21

What are common syndrome from Hanta Virus?

Answer 21

• • from deer mice
• • Pulmonary Capillary Leak, pre-renal azotemia from fluid loss
• -pneumonia
• • hemorrhagic fever

Question 22

What is the vector of Rift Valley Fever / California Encephalitis?

Answer 22

Aedes Mosquito

– seizures and encephalitis

Question 23

What the causative agent that is responsible for lymphocytic choriomeningitis, how is it unique?

Answer 23

Arenavirus – Ambisense (-/+)RNA, 2 segments each is different

• • grainy on microscopy
• • from rodent
• • treat with heating and irradication