Lecture 16: Paramyxovirus, Orthomyxovirus, (Rhabo,Filo,Borna) Chap 48, 49, 50s

Question 1

What type of genome do Paramyxoviruses have?

Answer 1

Single-stranded, negative-sense RNA

Question 2

Describe the structure of Paramyxoviruses.

Answer 2

Helical nucleocapsid with an envelope; includes F, HN, H, or G proteins depending on the virus

Question 3

Which protein is responsible for syncytia formation in Paramyxoviruses?

Answer 3

Fusion (F) protein

Question 4

How do Paramyxoviruses typically evade immune detection?

Answer 4

Forming syncytia for cell-to-cell spread, avoiding antibody detection

Question 5

What diseases are caused by Paramyxoviruses?

Answer 5

Measles, mumps, respiratory syncytial virus (RSV) infections, and parainfluenza

Question 6

What is the primary transmission route for Measles?

Answer 6

Respiratory droplets

Question 7

Describe the life cycle of Paramyxoviruses.

Answer 7

1) Attachment via surface proteins, 2) Fusion at plasma membrane, 3) Replication in cytoplasm, 4) Budding from host cell

Question 8

What are the hallmark symptoms of Measles?

Answer 8

High fever, cough, conjunctivitis, coryza, and maculopapular rash

Question 9

Which receptors does Measles virus bind to on host cells?

Answer 9

CD46, nectin-4, and CD150 (SLAM)

Question 10

How is RSV different from other Paramyxoviruses in disease mechanism?

Answer 10

RSV causes localized respiratory infections without systemic spread

Question 11

What immune response primarily controls Paramyxovirus infections?

Answer 11

Cell-mediated immunity

Question 12

What type of genome do Orthomyxoviruses have?

Answer 12

Segmented, negative-sense RNA

Question 13

Describe the structure of Orthomyxoviruses.

Answer 13

Enveloped with 8 RNA segments and surface proteins hemagglutinin (HA) and neuraminidase (NA)

Question 14

Where does Orthomyxovirus replication take place, and why is it unique?

Answer 14

In the nucleus, which is rare for RNA viruses

Question 15

Explain antigenic drift and shift in Orthomyxoviruses.

Answer 15

Drift: minor mutations; Shift: major genome reassortment, both enhancing immune evasion

Question 16

What is the main disease caused by Orthomyxoviruses?

Answer 16

Influenza (flu)

Question 17

Describe the symptoms and complications of Influenza.

Answer 17

Fever, cough, body aches; complications include pneumonia and secondary bacterial infections

Question 18

Which protein facilitates Influenza virus entry into host cells?

Answer 18

Hemagglutinin (HA) binds to sialic acid receptors

Question 19

How does neuraminidase (NA) aid in Influenza virus spread?

Answer 19

Cleaves sialic acid to release new virions from infected cells

Question 20

What seasonal pattern does Influenza follow, and why?

Answer 20

Winter seasonality due to cooler, less humid conditions that stabilize the virus

Question 21

What diagnostic tests are used for Influenza?

Answer 21

PCR, antigen tests, and viral culture from respiratory samples

Question 22

How is Influenza typically treated?

Answer 22

Antivirals (e.g., oseltamivir), supportive care, and annual vaccination

Question 23

What type of genome do Rhabdoviruses have?

Answer 23

Single-stranded, negative-sense RNA

Question 24

Describe the shape and structure of Rhabdoviruses.

Answer 24

Bullet-shaped with an envelope; helical nucleocapsid

Question 25

What disease is most commonly associated with Rhabdoviruses?

Answer 25

Rabies

Question 26

Describe the Rabies virus lifecycle in the host.

Answer 26

1) Entry via animal bite, 2) Replication near entry site, 3) Ascends nerves to CNS, 4) Spreads to salivary glands

Question 27

What are hallmark symptoms of Rabies?

Answer 27

Hydrophobia, agitation, paralysis, and coma

Question 28

How is Rabies virus transmitted?

Answer 28

Through saliva, typically via animal bites

Question 29

What is the incubation period for Rabies, and what factors influence it?

Answer 29

Weeks to months; depends on bite location and viral load

Question 30

How is Rabies diagnosed?

Answer 30

Skin biopsy, saliva PCR, and direct fluorescent antibody tests

Question 31

What treatments are available for Rabies post-exposure?

Answer 31

Wound cleaning, rabies immunoglobulin (HRIG), and vaccination

Question 32

What vaccines are available for Paramyxovirus diseases?

Answer 32

MMR vaccine for measles, mumps, rubella; RSV immunoprophylaxis for high-risk infants

Question 33

How is Rabies controlled in animal populations?

Answer 33

Vaccination of pets, bait vaccines for wildlife

Question 34

What is the function of the HA and NA proteins in Influenza?

Answer 34

HA: entry by binding sialic acid; NA: facilitates exit by cleaving sialic acid

Question 35

What complications can arise from Measles infection?

Answer 35

Pneumonia, encephalitis, and subacute sclerosing panencephalitis (SSPE)

Question 36

Question

Answer 36

Answer

Question 37

What is the structure of the Paramyxoviridae genome?

Answer 37

Single-stranded, negative-sense RNA.

Question 38

Which proteins mediate viral attachment in Paramyxoviridae?

Answer 38

HN (hemagglutinin-neuraminidase) for parainfluenza, H for measles, and G (glycoprotein) for RSV.

Question 39

How do Paramyxoviruses typically enter and exit host cells?

Answer 39

Enter via fusion with the plasma membrane; exit by budding.

Question 40

What is a defining cytopathic effect of Paramyxoviridae?

Answer 40

Formation of syncytia (multinucleated giant cells).

Question 41

How is the measles virus primarily transmitted?

Answer 41

Respiratory droplets.

Question 42

What receptors does the measles virus bind to on host cells?

Answer 42

CD46, CD150 (SLAM), and nectin-4.

Question 43

What are common symptoms of measles?

Answer 43

High fever, cough, conjunctivitis, and maculopapular rash.

Question 44

What characteristic sign is found in the mouth during measles?

Answer 44

Koplik spots.

Question 45

How does measles affect immunity?

Answer 45

Causes immunosuppression and weakens host defenses.

Question 46

How is mumps virus transmitted?

Answer 46

Large-droplet aerosols.

Question 47

What is a hallmark symptom of mumps?

Answer 47

Swelling of the parotid and salivary glands.

Question 48

What are common complications of mumps?

Answer 48

Orchitis, oophoritis, and meningitis.

Question 49

How is mumps diagnosed in the lab?

Answer 49

By RT-PCR, ELISA, or detection of giant cells in cell culture.

Question 50

What is the primary disease caused by Respiratory Syncytial Virus (RSV) in infants?

Answer 50

Bronchiolitis and pneumonia.

Question 51

How does RSV differ from measles in its spread within the body?

Answer 51

RSV causes localized respiratory infections without viremia.

Question 52

What treatment options exist for severe RSV infections?

Answer 52

Ribavirin aerosol and monoclonal antibodies (e.g., palivizumab).

Question 53

Describe the genome structure of Orthomyxoviruses (e.g., influenza).

Answer 53

Segmented, single-stranded, negative-sense RNA.

Question 54

How do Hemagglutinin (HA) and Neuraminidase (NA) proteins function in influenza?

Answer 54

HA facilitates entry; NA assists in viral exit.

Question 55

What are two mechanisms of genetic variation in influenza?

Answer 55

Antigenic drift (mutation) and antigenic shift (reassortment).

Question 56

How is influenza primarily transmitted?

Answer 56

Through inhalation of small aerosol droplets.

Question 57

What is the primary cell receptor used by rabies virus for neural infection?

Answer 57

Nicotinic acetylcholine receptor (AChR).

Question 58

Describe the progression of rabies after a bite.

Answer 58

Local replication, entry into neurons, CNS travel, and brain infection.

Question 59

What are characteristic symptoms of rabies?

Answer 59

Hydrophobia, hallucinations, and excessive salivation.

Question 60

What is a unique feature of Rhabdoviridae (e.g., rabies)?

Answer 60

Bullet-shaped virions.

Question 61

What are key zoonotic reservoirs for rabies?

Answer 61

Wild animals like bats, raccoons, and foxes.

Question 62

What is the primary treatment for rabies exposure?

Answer 62

Immediate wound cleaning, HRIG, and post-exposure vaccination.

Question 63

What is the structure of Filoviruses (e.g., Ebola)?

Answer 63

Filamentous, single-stranded, negative-sense RNA.

Question 64

How does Ebola cause tissue damage and shock?

Answer 64

By infecting multiple cell types, causing cytokine storms and vascular leakage.

Question 65

What are the main transmission routes for Ebola?

Answer 65

Contact with bodily fluids, contaminated needles, and funeral practices.

Question 66

What treatments are available for Ebola?

Answer 66

Antiviral antibodies (e.g., Inmazeb, Ebanga) and the Ervebo vaccine.