ENVELOPED RNA VIRUSES (NEGATIVE SENSE)

Question 1

Under ORTHOMYXOVIRIDAE

Answer 1

Influenza Virus (A, B and C)

Question 2

Influenza Virus (A, B and C) The envelope is covered with two different types of spikes (which are also considered as the virus’ major antigens):

Answer 2

1. Hemagglutinin – bind to cell surface receptors
2. Neuraminidase – release progeny virus

Question 3

Worldwide epidemics (pandemics) each year
Has 16 antigenically distinct types of hemagglutinin
And 9 antigenically distinct types of neuraminidase
Some of these types cause disease in humans but most of the types typically cause disease in animals such as, birds, horses, and pigs

Answer 3

Influenza A

Question 4

Major outbreaks of influenza
Does not lead to pandemic

Answer 4

Influenza B

Question 5

Mild respiratory tract infection
Does not cause outbreaks of influenza

Answer 5

Influenza c

Question 6

Major changes based on the reassortment of segments of the genome RNA

Answer 6

ANTIGENIC SHIFT (Pandemics)

Question 7

Minor changes based on mutations in the genome RNA

Answer 7

ANTIGENIC DRIFT (Epidemics)

Question 8

Sudden change in the molecular structure of a microorganism → new strain → little or no acquired immunity to these NOVEL strains → new epidemics or pandemics

Answer 8

ANTIGENIC SHIFT (Pandemics)

Question 9

Slow and progressive change in the composition of microorganisms → altered immunological responses and susceptibility

Answer 9

ANTIGENIC DRIFT (Epidemics)

Question 10

Influenza Virus (A, B and C)

Transmission
Spectrum of disease
Treatment and Prevention

Answer 10

Transmission: respiratory droplets
Spectrum of disease: Influenza or Flu
Treatment and Prevention:
- Oseltamivir (DOC) and Zanamivir
- Amantadine and Rimantadine Vaccine (both influenza A & B)

Question 11

complications: fatal bacterial superinfection (S. aureus and
S. pneumoniae) and Reye’s syndrome

Answer 11

Influenza Virus (A, B and C)

Question 12

PARAMYXOVIRIDAE

Answer 12

Measles Virus
Mumps virus
Respiratory Syncytial virus (RSV)
Parainfluenza virus 1 and 2

Question 13

Measles Virus

Transmission
Disease
Features
Diagnosis
Cardinal Signs:

Answer 13

Transmission: respiratory droplets
Disease: red measles, rubeola, “first disease”
Features: Koplik’s spots
Diagnosis: Multinucleated giant cells (Warthin- Finkelday bodies)
Cardinal Signs: 3Cs: cough, coryza and conjunctivitis (+ fever), and Koplik spots

Question 14

Complications: otitis media, giant cell pneumonia, SSPE, bronchiolitis oblierans

Answer 14

Measles Virus

Question 15

Mumps virus

Transmission
Pathogenesis and Diseases: URT then spreads through the blood and infects the:
● parotid glands
● testes
● ovaries
● Meninges
● pancreas
Prevention

Answer 15

Transmission: respiratory droplet
Pathogenesis and Diseases
● parotid glands - Parotitis (increase in pain when drinking citrus juices)
● testes - Orchitis
● ovaries- Oophoritis
● Meninges - aseptic Meningitis
● pancreas - Pancreatitis
Prevention: MMR vaccine

Question 16

Respiratory Syncytial virus (RSV)

Transmission
Disease
Treatment and Prevention

Answer 16

Transmission: respiratory droplet
Disease: viral pneumonia (in infants)
Treatment and Prevention: Ribavirin and Palivizumab

Question 17

Parainfluenza virus 1 and 2

Transmission
Spectrum of Disease
Treatment

Answer 17

Transmission: respiratory droplet
Spectrum of Disease: laryngotracheobronchitis or croup
(“Steeple sign” on X-ray)
Treatment: Racemic epinephrine

Question 18

ENVELOPE SPIKES OF PARAMYXOVIRUSES

Hemagglutinin -> Neuraminidase -> Fusion Protein
Measles
Mumps
RSV
Parainfluenza

Answer 18

‼️Measles (+) (-) (+)
Mumps (+) (+) (+)
‼️ RSV (-) (-) (+)
Parainfluenza (+) (+) (+)

Question 19

RHABDOVIRIDAE

Answer 19

Rabies virus

Question 20

FILOVIRIDAE

Answer 20

Ebola virus

Question 21

Ebola virus

Natural host
Transmission
Pathogenesis and Disease
Diagnosis
Treatment and Prevention

Answer 21

Natural host: fruit bat (Pteropodidae family)
Transmission: direct contact, fomites, infected bats or primates
Pathogenesis and Disease:
- targets endothelial cells, phagocytes, hepatocytes
- Incubation period: 2- 21 days
Diagnosis: ELISA, antigen test and RT-PCR
Treatment and Prevention: supportive care; strict isolation

Question 22

Rabies virus

Transmission
Spectrum of Disease
Diagnosis

Answer 22

Transmission: animal bite (retrograde transmission)
Spectrum of Disease:
- incubation period
- prodome
- acute neurologic period
- cona
- death
Diagnosis: Negri bodies (HP) and immunofluorescent antibody test (IFAT)