Viral Respiratory Tract Infections

Question 1

What are the 6 main viruses that cause RTI and which one is the most common?

Answer 1

Rhinovirus (most common), coronavirus (2nd most common), parainfluenza virus, adenovirus, enterovirus, respiratory syncytial virus, influenza virus

Question 2

What are the 3 consequences of viral RTIs in immunocompromised individuals?

Answer 2

1) same range of viruses that can infect healthy people plus more opportunistic viruses
2) hospitalization with more severe disease and mortality
3) viruses shed for longer periods of time

Question 3

What are the best specimen collection methods for uRTIs and lRTIs? What is the name of the media required to transport them?

Answer 3

URTIs: nasopharyngeal swabs or aspirates
LRTIs: bronchial alveolar lavages
Must be placed and transported in Universal Transport Medium

Question 4

What is the most effective laboratory method for respiratory virus detection?

Answer 4

Molecular methods such as RT-PCR

Question 5

Describe the morphology and characteristics of Rhinovirus (4)

Answer 5

(+)ssRNA, non-enveloped, most common viral RTI, over 100 serotypes making it difficult to develop a vaccine

Question 6

Describe the morphology and characteristics of corona virus (3)

Answer 6

(+)ssRNA, enveloped, capacity to cause sever disease such as SARS and MERS-CoV

Question 7

Describe the morphology and characteristics of enterovirus (4)

Answer 7

(+)ssRNA, enveloped, over 100 serotypes, usually mild illness, can cause aseptic meningitis, myocarditis and acute flaccid paralysis

Question 8

Describe the morphology and characteristics of respiratory syncytial virus (RSV) (5)

Answer 8

(-)ssRNA, enveloped, most common cause of bronchiolitis in children, severe infections may be fatal, passive immunization with palvizumab (humanized monoclonal IgG)

Question 9

Describe the morphology and characteristics of adenovirus

Answer 9

dsDNA, non-enveloped, more than 60 types, wide renage of diseases

Question 10

Describe the morphology and characteristics of influenza virus

Answer 10

(-)ssRNA, segmented genome, A, B or C (A and B cause the seasonal flu), Flu A is the most important because it has pandemic potential and causes the most severe disease of all the flu types, subtyping is based on surface hemagglutinin and neuraminidase

Question 11

what are the 2 targets of influenza antiviral drugs and what are the drug names for each target?

Answer 11

M2 channel inhibitors (amantidine), neuraminidase inhibitors (oseltamavir and zanamivir)

Question 12

What is the basic mechanism of how neuraminidase inhibitors work?

Answer 12

Prevent viral release from host cell, preventing infection of other cells

Question 13

How has influenza virus developed resistance to antivirals?

Answer 13

Resistance to amantidine through mutations in the M2 channel (all human H3N2 strains are resistant)
Resistance to neuraminidase inhibitors through mutations in NA or HA

Question 14

what type of vaccines are available for the flu? why do they need to be updated every year?

Answer 14

either a trivalent or quadruvalent. need to be updated every year because antigenic drift of surface glycoproteins or antigen shift between avian, swine and human flu viruses

Question 15

What is the morphological characteristic of flu viruses that allows antigenic shift to occur?

Answer 15

Segmented genomes allows for genetic reassortments between different strains of flu A in a co-infected host (ex: avian + human = swine flu)

Question 16

Describe the characteristics of avian influenza A

Answer 16

transmitted through direct contact with poultry or objects contaminated with feces
slow spreading but often fatal
human infection with H5N1 remains rare, though