Intro to Respiratory Viruses

Question 1

What are the different forms of upper respiratory infections (URI)?

Answer 1

rhinitis, pharyngitis, sinusitis and laryngitis

Question 2

What are the different forms of lower respiratory infections (LRI)?

Answer 2

bronchitis, bronchiolitis, pneumonia

Question 3

What is interstitial pneumonia?

Answer 3

infection involving alveolar septae and lining

Question 4

what is pleuritis?

Answer 4

disease of pleura

Question 5

What viruses cause the common cold?

Answer 5

rhinovirus (most common, URI, >100 serotypes, provoke asthma), Coronavirus (URI), Respiratory syncytial Virus (RSV, LRI, pneumonia= infants), Adenovirus (URI & LRI), Parainfluenza (URI but LRI if severe), cold symptoms= influenza, metapneumovirus (LRI), enterovirus (summer), EBV

Question 6

What are the different kinds of Parainfluenza viruses and their associated illnesses?

Answer 6

HPIV-1 and 2: childhood croup, more in fall; HPIV 3: usually spring and early summer, HPIV 4: less common; all= childhood croup, laryngeal-tracheal infection, URI, LRI

Question 7

What type of respiratory illness does HHV6 cause?

Answer 7

interstitial pneumonia, roseola (human herpes virus)

Question 8

Which respiratory viruses are more common January-March?

Answer 8

RSV, Influenza, Para Influenza

Question 9

Which respiratory viruses are more common July - September?

Answer 9

enterovirus, adenovirus, arbovirus

Question 10

How are respiratory viruses spread?

Answer 10

contact w/ respiratory secretions or aerosolized micro droplets, self inoculation via hands in eyes (tear duct into nasopharynx), inhalation, fomites (i.e. tissues)

Question 11

What are the three typical respiratory viral families?

Answer 11

Orthomyxovirus, paramyxovirus, adenovirus

Question 12

What are the features of the paramyxoviral family?

Answer 12

characteristic finding if multinucleated cells in culture, RNA, envelop, easily sterilized/disinfected, Para influenza 1-4, mumps, morbillivirus (measles), pneumovirus (RSV and metapneumovirus)

Question 13

What are some important clinical features of RSV?

Answer 13

most common respiratory virus in children and infants, extreme pathogenic effect on respiratory epithelium, recovery longer than bacterial

Question 14

What are some important clinical features of metapneumovirus?

Answer 14

second most common virus in children, similar to RSV, detection largely limited to molecular approaches

Question 15

What are some important features of adenovirus?

Answer 15

1-41 serotypes, aerosol enteric/respiratory, myocarditis in children (viremia), epidemic infections in close dense populations (military base), conjunctivitis or swimmer’s eye (pee in pool)

Question 16

How is influenza acquired? What does it cause?

Answer 16

through respiratory tract; widespread disease including fever, myalgia, and headache

Question 17

What are the identifying features of orthomyxoviruses?

Answer 17

influenza; Hemagglutination protein (attach to cells, serotyping H Ag), Neurominidase protein (release of new viral particles from cells, RNA w/ 8 segments, facilitates rearrangement, serotyping N Ag

Question 18

What are the clinical features of orthomyxoviruses?

Answer 18

influenza A: pandemic and seasonal, birds, humans, pigs, LRI; influenza B: seasonal, humans and seals, LRI and GI; influenza C: mild illness, URI rarely LRI, limited outbreaks

Question 19

What are the replicative features of influenza?

Answer 19

(-) RNA, requires viral proteins w/ nuclear host proteins to produce mRNA and genome, in cytoplasm mRNA translated to produce viral proteins, assembly at plasma membrane, neurominidase required for bud separation from cell

Question 20

What is the importance of influenza H and N antigens?

Answer 20

used to serogroup influenza A (16H and 9N), Ab made to these, basis for flu vaccines, allows binding with host cell, H- fusion of viral envelope with endosome when acidified, N allows budding out from cell.

Question 21

What is antigenic drift?

Answer 21

RNA viruses make more mutations than DNA viruses, serogroups spread in population and have new mutations, gradually drift into new antigenic shape, now unrecognizable by immune system

Question 22

Why do we have seasonal epidemics of influenza?

Answer 22

antigenic drift, small changes in H and N, how it eludes immune system, why we vaccinate yearly and vaccine updated for predicted changes

Question 23

What impact does seasonal influenza have in US?

Answer 23

> 36K deaths (85% over 65) and 200K hospitalizations, 5-20% attack rate in gen pop and ~60% in nursing home, 10 bil. in lost productivity and medical cost

Question 24

What is antigenic shift?

Answer 24

wild birds have different type of influenza A than humans, pig infected with human and bird virus (in same cell), virus segments combine creating new serotype which infects people who lack immunity

Question 25

What caused H1N1 virus of 2009?

Answer 25

antigenic drift and shift

Question 26

What typically causes pandemic influenza A? What is the recipe for a pandemic?

Answer 26

antigenic shifted virus entering human population; novel virus (pop little or no immunity), capable of replication in humans, pathogenic and virulent in humans, and capable of human-human transmission

Question 27

Which viruses are being watched for the next pandemic? Why?

Answer 27

H5N1 and H7N9; rapid mutation, tendency to acquire genes from viruses infecting other animals, cause severe disease in birds and humans, birds that survive shed virus in feces for weeks, ~70% fatal in humans (minimal person to person spread, not well adapted yet)

Question 28

what are key features of bird influenza?

Answer 28

not commonly transmitted between humans, high morbidity and mortality for humans

Question 29

What were the notable influenza pandemics of the 20th century?

Answer 29

1918 Spanish flu (H1N1) ~20-40mil deaths (675K in US); Asian flu (H2N2) ~ 1-4 mil deaths (70K US); and Hong Kong Flu (H3N2) deaths 1-4 mil (34K US)

Question 30

why does influenza spread so quickly?

Answer 30

incubation: 2 days (1-4), viral shedding: begin 1 day before onset of symptoms, peak shedding first 3 days (correlates w/ fever), subsides by 5-7 days but up to 10+ in kids

Question 31

How can flu droplet spread be minimized?

Answer 31

limited study but: masks and respirators (N95), contact, droplet and droplet nuclei (airborne) can all occur, droplet most important (cover cough, sneeze, talk- increase coail distance, can be on surfaces)

Question 32

What determines vaccine for the year?

Answer 32

WHO makes recommendations based on surveillance data

Question 33

What is the site of action of antivirals for influenza?

Answer 33

amantadine and rimantadine proton transport into endosome preventing acidification; zanamivir and oseltamivir- neurominidase

Question 34

Flu Vaccine vs Antivirals?

Answer 34

V: best prevention, limited supply, 6-9mo to produce, manufacturing limited, efficacy dependent on prediction of strains (midseason shifts!); AViral: best at stopping spread, effective treatment/prophylaxis, valuable adjunct to vaccine, limited supply

Question 35

How do we treat colds?

Answer 35

can’t really test to find culprit (too many options takes too long to matter), fluids and rest (no AB unless evidence of B infection)