(-) Strand RNA Viruses

Question 1

Define the functions of the 2 glycoproteins spikes in Influenza virus.

Answer 1

1. Neuraminidase = cleaves receptor so that when viral progeny leave, they won’t infect same cell
2. Hemagglutinin = enables virus to attach and enter host cell (Antibodies to this neutralize influenza)

Question 2

List at least 3 helical (-) strand RNA viruses.

Answer 2

1. Filovirus
2. Rhabdovirus
3. Arenavirus

Question 3

List the helical (+) sense RNA viruses

Answer 3

1. Poliovirus - respiratory paralysis

2. Coronavirus -SARS and MerS-COV

Question 4

What are the 4 segmented RNA Viruses?

Answer 4

Bunyavirus, Orthomyxovirus (Influenza), Arenavirus, Reovirus

“BOAR”

Question 5

What are the 2 ways in which Influenza virus can mutate?

Answer 5

1. Antigenic Shift - reassortments responsible for PANDEMICS, responsible for recombination btw species (i.e. Avian, swine)
2. Antigenic Drift - point mutation that changes neuraminidase (NA) or hemagluttanin (HA) molecules, which is why we need a seasonal flu vaccine each year;
   Both associated with Influenza A

Question 6

Define hemagluttanin

Answer 6

Influenza glycoprotein that binds sialic acid on cell membranes of respiratory tract allowing them to enter the cell. HA also causes RBCs to aggregate in test tubes.

Question 7

Define neuramidase

Answer 7

Influenza glycoprotein that cleaves sialic acid residues within infected host cells to allow newly formed virions to exit (bud off).
Inhibited by Oseltamivir (Tamiflu)

Question 8

What is the significance of M2 protein in Influenza viruses?

Answer 8

Low pH (acidification) is needed to allow viral uncoating in endosome. Amantadine and Rimantadine inhibit viral uncoating (no longer useful).

Question 9

What are the antigenic components of the anti-Influenza vaccine currently used in the US?

Answer 9

Inactivated virions of currently-circulating serotypes of Influenza A and B viruses.

Question 10

What produces a pattern of worldwide Influenza epidemics at intervals every few decades? What is the significance?

Answer 10

Antigenic Shift = Genome segment re-assortment between human and avian-adapted viruses. These often produce more pathogenic, novel strains.

Question 11

What is the diagnostic feature of Rhabdovirus? What is the most reliable diagnostic test of CSF and serum in an Rabies-infected person?

Answer 11

Eosinophilia Negri bodies at cytoplasm of neurons (pyramidal cells of Hippocampus and Purkinje cells). It’s best to stain the cells with direct fluorescent antibody technique to detect rabies antigens.

Question 12

What are the treatment and prevention protocols for Rabies infection?

Answer 12

Human diploid cell culture KILLED vaccine and Active immunization via Human Rabies Immunoglobulin (HRIG)

Question 13

Describe Filoviruses (type, replication, symptoms)

Answer 13

Negative-sense, helical capsid ssRNA viruses with “pleomorphic” shapes. Replicates in the cytoplasm. Petechiae rash and hemorrhagic fever. Transmitted by monkeys and bats. Highly enveloped

Question 14

Describe Bunyavirus (type, transmission, symptoms)

Answer 14

Enveloped, segmented negative sense ssRNA virus.
Tsm: Mosquito (arthropod) vectors with wild rodent hosts (chipmunks, squirrels, rabbits).
Cx: Pulmonary capillary leak (edema)

Question 15

List 2 well known arboviruses that fall within the Bunyavirus family. What are some clinical symptoms and the transmission?

Answer 15

California encephalitis and Rift Valley Fever
Cx: seizures and encephalitis
Tsm: Aedes mosquito

Question 16

Describe Arenavirus (type, transmission, symptoms)

Answer 16

Segmented ssRNA virus, T-shaped glycoproteins but AMBISENSE genome. Rodent reservoir transmission. Lasso fever, Systemic Febrile illness, Lymphocytic Choriomeningitis Virus (LCV) = flu-like symptoms and self-limiting meningitis.

Question 17

Describe Reovirus (type, transmission, example)

Answer 17

The ONLY dsRNA virus (both +/- sense) with 2 icosahedral capsids.
Ex: Rotavirus = explosive, watery diarrhea in children (from NSP4 toxin = inc Cl permeability);
Live oral vaccine

Question 18

What do Mumps, Measles and Respiratory Syncytial Virus have in common?

Answer 18

These are Paramyxoviruses (with SEGMENTED genomes) that are form syncytial or multinucleated giant cells of the host cells they infect.

Question 19

This negative-sense ssRNA virus has the following diagnostic features: Koplik spots on lateral buccal mucosa, maculopapular rash, >101 F fever and sore throat. What is it?

Answer 19

Measles virus - with a >95% preventive MMR vaccine (live attenuated strain)!!! Viremia follows initial viral infection.

Question 20

This negative-sense ssRNA virus has the following features: #1 cause of viral LRT in infants/children, acute bronchialitis, results in multinucleated giant cells in mucus. What is it and how is it treated?

Answer 20

Respiratory Syncytial Virus - treated with RSV-IVIG, Palivizumab (IM monoclonal antibody) and Ribavirin aerosol

Question 21

This negative-sense ssRNA virus has the following features: bullet-shaped, helical nucleocapsid, results in prodromal fever, progresses to CNS dysfunction then respiratory arrest. What is it and how is it diagnosed? What of prophylactic treatment?

Answer 21

Rhabdovirus (Rabies);
Dx: Negri bodies in cytoplasm of neurons;
Tx: 4-dose Killed vaccine and Human Rabies immunoglobulin (HRIG for post-exposure)

Question 22

Define what occurs in Reye’s Syndrome (cause, effects)

Answer 22

Associated with children (aged 4-12) who take aspirin (instead of Tylenol) recently infected with Influenza B or Varicella. This results in acute brain damage and liver dysfunction.

Question 23

What is the live attenuated Flu vaccine and how does it work?

Answer 23

FluMist is the intranasal spray that ideally increases IgA’s in people who take it (aged 5-47 years old)

Question 24

Explain H1N1 (type, treatment)

Answer 24

Swine Influenza A (2009); novel strain with avian, swine and human subtypes; treated with oseltamivir (99%) and zanamirvir (100%);
Also occurred as the 1918 Spanish Flu

Question 25

What is the glycoprotein spike that enables paramyxoviruses to form multinucleated giant (infected) cells?

Answer 25

Fusion glycoprotein (F) - forms syncytial

Question 26

What negative-sense ss RNA virus has the following features: common LRT infections in children, causes syncytial formation, defined by a “croup” cough?

Answer 26

Parainfluenza (PIV 1-4) - transmitted by respiratory droplets.

Question 27

What negative-sense ss RNA virus has the following features: swelling of parotid glands, upper respiratory tract infection, painful swallowing, orchitis (painful gonads)?

Answer 27

Mumps virus - prophylactic MMR vaccine and hyper immunoglobulin, can result in deafness if not treated

Question 28

Describe the best way to reduce transmission of Ebola virus.

Answer 28

Use barrier methods to prevent contact with blood or body fluids of infected persons.

Question 29

Define the mode of transmission for Hantavirus.

Answer 29

Inhalation of aerosolized rodent urine/feces, or of material contaminated with these.

Question 30

Every RNA virus replicates in the ________ with the exception of _________ which replicates in _______

Answer 30

RNA viruses often replicate in cytoplasm; except Influenza (Orthomyxoviruses) that replicate in the nucleus.