Iahi: 3.06 - Respiratory Viruses

Front 1

What viruses cause respiratory infections and diseases?

Back 1

- Influenza virus
- Rhinovirus
- Coronavirus
- Parainfluenza Virus
- Respiratory Syncytial Virus (RSV)
- Metapneumovirus
- Adenovirus (sometimes)

Front 2

What causes influenza epidemics? Pandemics?

Back 2

- Epidemics - genetic drift (mutations)
- Pandemics - genetic shift (reassortment)

Front 3

What cells are infected by influenza virus? How are these cells destroyed/damaged?

Back 3

- Ciliated epithelial cells lining upper resp. tract, trachea, and bronchi
- Virus replication and cytotoxic T lymphocytes damage and destroy respiratory epithelium

Front 4

How long is the incubation period for influenza virus?

Back 4

Short ~24 hours

Front 5

What are the symptoms of influenza virus infection in adults?

Back 5

- Rapid onset of fever
- Malaise
- Myalgia
- Sore throat
- Non-productive cough

Front 6

What are the symptoms of influenza virus infection in children?

Back 6

- Similar to adults
- Higher fever
- GI symptoms (abdominal pain and vomiting)
- Otitis media
- Myositis
- Croup

Front 7

What are the complications of influenza virus infection?

Back 7

- Primary viral pneumonia
- Secondary bacterial pneumonia
- Myositis and cardiac involvement
- Neurological syndromes: Guillain-Barré Syndrome, Encephalopathy, Encephalitis, Reye Syndrome

Front 8

How do you diagnose influenza infection?

Back 8

- Rapid antigen capture (detects Nucleoprotein, NP, ~15 min.)
- RT-PCR

Front 9

Where does influenza virus replicate cellularly? What kind of genome?

Back 9

- Replicates, transcribes in nucleus (unusual)
- (-) ssRNA

Front 10

What kind of drugs are used to treat influenza infections?

Back 10

- Zanamivir and Oseltamivir (NA inhibitors)
- Previously Amantadine and Rimantadine (block M2 proteins - inhibits uncoating)
- Ribavirin (inhibits viral RNA synthesis)

Front 11

What kind of vaccines are used to prevent influenza infections?

Back 11

- Formalin inactivated (mix of prevalent antigenic types)
- Attenuated infectious viruses (intranasal and must be kept cold)

Front 12

What is the cause of 50% of common colds? Type - genome?

Back 12

Rhinovirus (Picornavirus = +ssRNA icosahedral)

Front 13

What causes the symptoms of Rhinoviruses?

Back 13

Inflammatory response - infected cells in nose release bradykinin and histamine --> nasal discharge, sore throat, cough, headache

Front 14

What are the temperature considerations of Rhinovirus? Coronoviruses?

Back 14

- Rhinoviruses - grow better at 33 degrees than 37 degrees (sensitive to fever)
- Coronoviruses - grow better at 33 degrees to 35 degrees

Front 15

What immune response is important for limiting re-infection of rhinoviruses?

Back 15

Secretory IgA

Front 16

How are Rhinoviruses transmitted between people?

Back 16

Directly from individual to individual via respiratory secretions (via fomites - door handle, silverware, etc)

Front 17

How do you treat / prevent Rhinoviruses?

Back 17

No effective prevention and control measures yet
(Experimental: IFN-α (induce antiviral resistance), soluble ICAM-1 (compete for attachment), viral protease inhibitors, WIN compounds (block uncoating by inserting in virus surface pore))

Front 18

What is the cause of 10-15% of common colds? Genome?

Back 18

Coronaviruses = +ssRNA (helical)

Front 19

What cells are affected by Coronaviruses? Symptoms?

Back 19

- Epithelial cells of upper respiratory tract
- Watery eyes, sneezing, nasal congestion, sore throat, sometimes fever, chills, headache, other aches, cough

Front 20

What is the cause of SARS?

Back 20

- Coronavirus - +ssRNA helical
- Originated from virus in horseshoe bats in China

Front 21

How was SARS (Coronavirus) spread?

Back 21

Face-to-face contact (virus in respiratory secretions and feces)

Front 22

How are Coronoviruses (common cold and SARS treated)?

Back 22

No vaccines available or efficacious therapies

Front 23

What diseases / viruses are caused by "Paramyxoviruses"? Way to remember? Genome?

Back 23

- Parainfluenza (croup)
- RSV (Respiratory Syncytial Virus)
- Mumps and Measles
PaRaMyxovirus
- (-)ssRNA helical

Front 24

What are the important surface proteins on Paramyxoviruses (Parainfluenza, RSV, Mumps, Measles)?

Back 24

- F = Fusion protein (for virus entry)
- HN = Hemagglutinin (viral attachment) and Neuraminidase (viral release)
** HN Not on RSV

Front 25

How are Parainfluenza viruses (Paramyxoviradae) spread? When are they more common?

Back 25

- Respiratory secretions
- Fall and winter, common nosocomial infection (hospital acquired)

Front 26

What cells are affected by a Parainfluenza infection (Paramyxoviradae)? Symptoms?

Back 26

- Infect epithelial cells in upper respiratory tract
- Lower respiratory complications in infants and young children, CROUP, subglottal swelling may close airway

Front 27

What virus causes CROUP?

Back 27

Parainfluenza (Paramyxovirus)

Front 28

What are the types of Parainfluenza viruses? Differences?

Back 28

- Types 1, 2, 3 - resp. tract disease ranging from mild common colds to bronchiolitis an/or pneumonia
- Type 4 - usually mild

Front 29

What protects from Parainfluenza infection?

Back 29

IgA (against HN - hemagglutinin/neuraminidase) in nasal secretions (short-lived protection)

Front 30

What patient population is affected more severely by Parainfluenza infections?

Back 30

Children w/ T cell deficiencies

Front 31

What is the most common cause of fatal acute respiratory tract infection in infants and young children?

Back 31

RSV (Respiratory Syncytial Virus) - type of Paramyxovirus

Front 32

How common is RSV (Respiratory Syncytial Virus) - type of Paramyxovirus?

Back 32

Infects virtually everyone by age 2; re-infections occur throughout life and can be sever in elderly

Front 33

Where does RSV (Respiratory Syncytial Virus) - type of Paramyxovirus infect? Symptoms?

Back 33

- Localized infection of respiratory tract
- No viremia or systemic spread
- Pneumonia from cytopathologic spread of virus (syncytia), Bronchiolitis (by immune response), narrowing of airways (leads to obstruction)
- Typical "giant cells" lead to airway obstruction

Front 34

Can you be protected from RSV (Respiratory Syncytial Virus) - type of Paramyxovirus infection?

Back 34

- Maternal antibody does not protect infant (hence most common cause of fatal acute resp. tract infxn in infants and young children)
- Natural infection does not prevent re-infection

Front 35

What type of immune response to RSV (Respiratory Syncytial Virus) - type of Paramyxovirus is mediated by adults? Infants?

Back 35

- Adults - Th1 response --> IFN-γ --> activates macrophages, NK cells, CMI and B cells
- Infants - Th2 response --> IgG4, IgG1, IgE and IL-4 lead to mast cell degranulation, IL-5 leads to eosinophilia and wheezing

Front 36

What are the symptoms of RSV (Respiratory Syncytial Virus) - type of Paramyxovirus infection for children <1 yo, children, older children and adults?

Back 36

- <1 yo - fever, cough, dyspnea, cyanosis
- Children - febrile rhinitis and pharyngitis
- Older children and adults - common cold

Front 37

How do you treat healthy infants, premature or immunocompromised infants, and premature infants with RSV (Respiratory Syncytial Virus) - type of Paramyxovirus?

Back 37

- Healthy infant - supportive tx, oxygen, IV fluids, nebulized cold stream
- Premie or Immunocompromised - aerosolized ribavirin
- Premie - passive immunization w/ anti-RSV Ig and humanized monoclonal Abs
* NO vaccine *

Front 38

What are the symptoms and treatments for Metapneumovirus (Paramyxovirus)?

Back 38

- Acute respiratory illness similar to RSV (most severe cases seen in infants, elderly, and immunocompromised)
- Upper RTI - common cold, bronchitis, wheezing, pneumonia
- No vaccine or antiviral therapies
- Most children infected by 5 yo

Front 39

What are the two emerging respiratory viruses with high mortality rates?

Back 39

Hendra and Nipah virus - Paramyxoviruses (jumped from bats to people)

Front 40

What kind of viruses are Adenoviruses? Symptoms?

Back 40

- DS linear DNA virus
- Respiratory infection (pharyngitis), conjunctivitis (pink eye), GI infections, hemorrhagic cystitis (inflam. of urinary bladder)
- Resp. infections --> systemic infections (viremia) in immunocompromised

Front 41

What can happen to the respiratory tract when infected with Adenovirus?

Back 41

- Destructive productive infection
- Persistent infection w/ virus shedding
- Latent infections in lymphoid tissues like tonsils or adenoid tissue

Front 42

What populations of patients are Adenovirus infections associated with?

Back 42

- Military recruits - acute respiratory disease
- Children / bone marrow transplant recipients - acute hemorrhagic cystitis

Front 43

How are Adenoviruses spread?

Back 43

- Aerosol, close contact, or fecal-oral
- Fingers spread virus to eyes (conjunctivitis)

Front 44

What types of cells are affected by Adenoviruses?

Back 44

- Mucoepithelial cells in respiratory tract, GI tract, conjunctiva or cornea
- Persists in lymphoid tissue (e.g., tonsils, adenoids, Peyer patches)

Front 45

What immune responses are important for Adenoviruses?

Back 45

- Antibody is important for prophylaxis and resolution
- Cell-mediated immunity also important