ICL 1.8: Respiratory Viruses Flashcards
which virus family is RSV?
pneumoviridae = enveloped (-)ssRNA
how does RSV replicate?
like rabies
what is a major characteristic of RSV?
syncytia = giant multinucleated cell during infection
what are the main clinical symptoms of RSV?
low grade fever
wheezing
rhinorrhea
what is the pathogenesis of RSV?
in the lung, tissue damage
generalized infection, replicates in mononuclear cells, upper and lower respiratory tract, children under 2 yrs, 1-2 days of incubation
how do you treat RSV?
supportive care
Palivizumab - monoclonal antibody against F protein
RSV vingette
A 5-month-old girl was brought to the pediatric clinic of a local general hospital in February with a 2-day history of cough, respiratory difficulty with nasal discharge, and low-grade fever. She had begun attending a day care center 4 weeks before. All of her immunizations were up to date, and no one else at home was ill.
PIV vingette
A 3-year-old boy is brought to the ER by his mother who is concerned about a “barking cough,” mild fever, and hoarse voice. She reports that he had a runny nose last week that has since resolved. Physical exam reveals an inspiratory stridor.
what does PIV stand for?
parainfluenza virus
what virus family is PIV?
paramyxoviridae family
what are the characteristics of the PIV genome?
paramyxoviridae family = enveloped (-) ssRNA
what population is PIV most common in?
Kids below 5-years are victims
how do you treat PIV?
no vaccines, no treatments
rhinovirus vingette
A 66-year-old man was examined by the physician at the community center where he volunteers. He had rhinorrhea, low-grade fever, headache and cough during the last two days. He is not feeling well and worries that he may be putting other seniors at risk of becoming sick
which virus family is rhinovirus?
picornaviridae
what are the characteristics of the rhinovirus?
picornaviridae = naked, icosahedral (+) ssRNA
what temperature is best for rhinovirus?
low temperatures
adaptation to
cool environment of the nasal mucosa
what are the clinical features of rhinovirus?
2-3 day incubation
upper respiratory tract infection
nasal congestion, sneezing, sore throat, headache and cough. There may be fever
what population is more susceptible to rhinovirus?
children
what is the pathogenesis of rhinovirus?
inflammation and abundant exudation from the upper respiratory tract
cytopathology is minimal, but nose becomes engorged with blood (hyperemic) and edematous. This is likely due to the presence of bradykinin
how do you treat rhinovirus?
no prophylaxis or treatment
high degree of variation limit treatments.
what are complications related to rhinovirus?
patients with chronic bronchitis or asthma may get exacerbated
rhinovirus virus, pathogenesis, clinical, diagnosis, treatment, prevention
Virus: Picornaviridae, +ve ss RNA genome, naked virion, icosahedral capsid
Pathogenesis: Upper respiratory tract infection, 2-3 days of incubation, low optimum temp for replication (nasal mucosa)
Clinical: Nasal congestion, sneezing, sore throat, headache and cough.
Diagnosis: Not done
Treatment and Prevention: None due to high degree of variability (many serotypes)
coronavirus vingette
a 44-year-old female presented to the emergency department with complaints of fever, myalgias, and mild shortness of breath for 2 days. She also has a moderate headache and had experienced several episodes of diarrhea in the last 24 hours. She is a nurseʼs aid and had been working in a busy medical unit of a hospital. She had taken care of a patient with severe respiratory illness 4 days before feeling ill. She did not have underlying disease
what are the coronavirus genome characteristics?
enveloped (+) ssRNA
RNA is 5’-capped and 3’-polyadenylated and it is infectious
what does a coronavirus look like?
Club-shaped spike (S) protein
Transmembrane matrix protein (M)
looks like a spiky ball
how do coronaviruses spread?
spread readily by aerosol and contact
what are the coronavirus virus types?
- human coronaviruses
- SARS
- MERS
what do human coronaviruses do?
Can replicate exclusively in humans, causing upper respiratory tract infections. They spread readily by aerosol and contact
Causes common colds – not much to worry about
what do MERS do?
Cause atypical pneumonia
Original reservoirs of these two viruses are ‘bats’
what are the coronavirus virus, pathogenesis, clinical, diagnosis, treatment and prevention?
Virus: Enveloped virion, +ve sense RNA genome (largest RNA genome), pleomorphic, human coronavirus, SARS and MERS
Pathogenesis: Upper respiratory tract infection for human coronavirus, SARS and MERS cause lower respiratory infection and extensive pneumonia
Clinical: Common cold similar to rhinovirus, unpleasant nasal discharge, malaise
Diagnosis: RT-PCR, ELISA, viral culture for SARS and MERS
Treatment and Prevention: Supportive care
adenovirus vingette
A 14-year-old girl presented to the emergency department with a 2-day history of fever, sore throat, and a red left eye, which felt like there was “sand” in it. She had been at a summer camp for the past two weeks where several other children had a similar illness. Activities in the camp included swimming in a local pool. The patient has no significant past medical history and denied being sexually active. Family history was unremarkable.
what is the adnovirus genome?
naked, icosahedral linear dsDNA
how many adenovirus serotypes are there
51
what are the adenovirus virus, pathogenesis, clinical, diagnosis, treatment, prevention?
Virus: Naked icosahedral virion, linear dsDNA genome, 51 serotypes
Pathogenesis: usually benign, persistence possible in adenoids
Clinical: Cold, keratoconjunctivitis
Diagnosis: Immunofluorescence, viral culture on human cells
Treatment and Prevention: No treatment, oral, live attenuated vaccine (serotypes 4 and 7) in military
influenza vingette
In December, a 71-year-old man from a nursing home was brought to the hospital in acute respiratory distress. He had been in his usual state of health until 10 a.m. the previous day, when he suddenly developed fever, chills, muscle aches, cough, and prostration. Several other nursing home residents had developed similar illness during the previous week.
His past medical history was unremarkable, and he had not seen a physician in the past year
which virus family is influenza?
orthomyxoviridae
what are the characteristics of the influenza genome?
orthomyxoviridae = 8 segmented (-) ssRNA
what are the immunogenic influenza proteins?
HA
NA
how many influenza strains are there?
A,B,C
16 HA serotypes
9 NA serotypes
what part of influenza replication cycle do neutralizing antibodies stop?
attachment
what part of influenza replication cycle do NA inhibitors stop?
release
what type of vaccine is the influenza vaccine?
two types of commercialized vaccines - inactivated vaccines and live attenuated vaccines
what is the composition of the inactivated influenza vaccine?
Two A (H3N2 and H1N1) and one B serotypes.
appropriate strains are grown in chicken eggs, the allantoic fluids are harvested and the HA and NA are purified by ultracentrifugation.
what is the immunization schedule for the inactivated influenza vaccine?
Annual dose.
for previously unvaccinated children, the first time they should receive two doses, one month apart.
what are some adverse effects of the inactivated influenza vaccine?
most common: soreness at vaccination site, fever, malaise, allergy
when should you not give someone the inactivated infleunza vaccine?
- Allergy to eggs or other vaccine components
2. Patients with acute febrile illness
which groups of people are at risk for influenza?
- People >50 years of age
- People with preexisting disorders
- Women after the first trimester of pregnancy
- Health care and school workers
- Household contacts of groups at high risk of complications
- Children under 24 months of age
- Immunosuppressed patients
- Travelers
- People working in community services
what is the composition of the live attenuated influenza vaccine?
aka flumist
live-attenuated intranasal vaccine
what are the differences between the live attenuated vaccine and killed vaccine for influenza?
potentially better at producing broad mucosal and systemic immunity
when should you not give someone the live attenuated influenza vaccine?
- Children under 5 years of age.
- Adults 50 years of age or older
- Known or suspected immune deficiency disease
- History of asthma or reactive airways disease
- With medical conditions such as chronic disorders of the lungs and heart, chronic metabolic diseases (including diabetes), kidney dysfunction, or a hemoglobinopathy such as sickle cell disease
- Pregnant women
- Due to the possible transmission of vaccine virus, FluMist recipients should avoid being in close contact with immunocompromised individuals for 3 weeks following vaccination
what is the influenza virus, pathogenesis, clinical, diagnosis, treatment, prevention?
Virus: Orthomyxoviridae, -ve ss segmented RNA genome, enveloped virion, cap stealing in nucleus
Pathogenesis: Upper and lower respiratory tract infection, 2-3 days of incubation pneumonia, often causes secondary bacterial infection
Clinical: Shivering, malaise, headache, fever of about 390C, myalgia and backache and often sore throat.
Diagnosis: Based on clinical picture, but ELISA, cell culture, immunofluorescence can be done
Treatment and Prevention: Inactivated and live-attenuated vaccines, rimantadine, amantadine (target M2), oseltamivir, zanamivir (target NA)
RSV:
1. genome
- pneumo
- lower RT infection
- incubation
- fever
- cough
- sore throat
- seasonality
- vaccine
RNA
pneumoviridae
no RT infection
3-5 day incubation
low fever
cough
sore throat
midwinter
no vaccine
rhinovirus:
1. genome
- pneumo
- lower RT infection
- incubation
- fever
- cough
- sore throat
- seasonality
- vaccine
RNA
picomaviridae
no RT infection
2-3 day incubation
maybe fever
cough
sore throat
no seasonality
no vaccine
coronavirus:
1. genome
- pneumo
- lower RT infection
- incubation
- fever
- cough
- sore throat
- seasonality
- vaccine
RNA
coronaviridae
no lower RT infection
3 day incubation
rarely fever
maybe cough
maybe sore throat
winter/spring seasonality
no vaccine
SARS and MERS
1. genome
- pneumo
- lower RT infection
- incubation
- fever
- cough
- sore throat
- seasonality
- vaccine
RNA
coronaviridae
there is a lower RT infection
few days incubation
fever
cough
sore throat
no vaccine
influenza
1. genome
- pneumo
- lower RT infection
- incubation
- fever
- cough
- sore throat
- seasonality
- vaccine
RNA
orthomyxoviridae
likely lower RT infection
2-3 incubation
high fever
cough
maybe sore throat
midwinter seasonality
vaccine available
adenovirus
1. genome
- pneumo
- lower RT infection
- incubation
- fever
- cough
- sore throat
- seasonality
- vaccine
DNA
adenoviridae
variable incubation
low fever
cough
sore throat
no seasonality
limited vaccine
what are the clinical features of coronavirus?
Common cold similar to that caused by rhinoviruses
Unpleasant nasal discharge and malaise
Diagnostic tests are not usually done.
SARS and MERS coronaviruses replicate in the lungs and cause extensive pneumonia
how do you diagnose coronaviruses?
Diagnosis of SARS and MERS can be done by nested RT-PCR, ELISA and viral culture
what is the pathogenesis of cornaviruses?
Only the upper respiratory tract supports human coronavirus replication.
Inflammation, oedema and exudation occur in the tract following days of cell destruction
how do you prevent coronaviruses?
no vaccines
how do you treat coronaviruses?
no antivirals to treat human coronavirus infection, treatment is limited to supportive care
SARS treatment is the same as for other serious pneumonias
Results from treatment with oseltamivir, ribavirin are unclear
what are the clinical features of adenovirus?
cause colds and a wide range of other illnesses, often with involvement of the eye
how do you diagnose adenoviruses?
diagnosis can be done by immunofluorescence on infected cells, by virus isolation, or by observation of cytopathic effect (cpe) on human cell lines
what’s the pathogenesis of adenoviruses?
Human infections are usually benign
Persistence is possible in the adenoids.
Vigorous immune responses account for the milder disease pathogenesis – may be lethal for immunocompromised patients
how do you prevent adenoviruses?
Oral, encapsulated, live attenuated vaccine (serotypes 4 & 7) used by the military
Widespread use of the vaccine may not be feasible due to the variety of circulating serotypes.
how do you treat adenovirus?
No specific treatment available
what are some of the complications of adenovirus?
Possible, but infrequent infection of the lower respiratory tract leading to pneumonia
what are the clinical features of influenza?
symptoms set up abruptly after an incubation period of 2-3 days
shivering, malaise, headache, fever of about 39°C, myalgia (myal – muscle, gia – pain) and backache and often sore throat.
how do you diagnose influenza?
Diagnosis is based on the clinical picture, but ELISA, cell culture, immunofluorescence tests can be also used
what’s the pathogenesis of influenza?
Upper respiratory tract infection, but it can spread to the lower tract and cause pneumonia.
Destruction of cilia, which are important element of respiratory system.
Strong host immune response against the virus, and is mediated by interferon, IL-6 and tumor necrosis factor (TNF).
what are some complications with influenza?
Secondary bacterial infections, particularly with S. aureus.
Reye’s syndrome, often fatal, is also associated with infection with influenza B in children (and aspirin)
