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I & I Part II > Respiratory Viruses II > Flashcards

Respiratory Viruses II Flashcards

1
Q

Parainfluenza Viruses

A
  • Paramyxovirus genus of Paramyxoviridae family
  • 4 serotypes
  • Significant antigenic drift or shift does not occur
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2
Q

Paramyxovirus Structure

A
  • Single-stranded (-) RNA (one linear piece)
  • Nucleoprotein covers RNA
  • M (matrix) protein surrounds nucleoprotein complex
  • envelope contains attachment protein that has both H and N and the fusion protein (F).
  • Pleomorphic
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3
Q

Paramyxovirus Replication

A
  • All events occur in the cytoplasm
  • Replicates like (-) RNA virus
  • Budding through cytoplasmic membranes
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4
Q

Paramyxovirus Clinical Disease

A
  • Infants and young children get more serious illness but older adults and people with weakened immune system also gets sick
  • Parainfluenza 1: Major cause of acute croup (laryngotracheitis) in infants and young children.
  • Parainfluenza 2: Croup in children
  • Parainfluenza 3: Severe bronchitis and/or pneumonia in infants under 1 year of age
  • Parainfluenza 4: Least common of the group, generally associated with mild upper respiratory illness.
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5
Q

Paramyxovirus Diagnosis

A

•Clinical picture, serology, virus isolation, RT - PCR

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6
Q

Paramyxovirus Treatment

A

•No specific treatment or prevention, serious cases may require supportive care

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7
Q

Paramyxovirus Vaccine

A

•Nasal spray vaccine under development

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8
Q

Respiratory Syncytial Virus (RSV)

A
  • Pneunovirus genus of Paramyxoviridae family
  • 2 serotypes (A and B)
  • forms syncytia in tissue culture
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9
Q

RSV Structure

A
  • Same as parainfluenza virus except the envelope glycoproteins are an attachment (G) glycoprotein and a fusion (F) glycoprotein.
  • Non segmented (-) ss RNA genome
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10
Q

RSV Replication

A

•same as Paramyxovirus

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11
Q

RSV Epidemiology

A

•RSV infection occurs annually from late fall to early spring

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12
Q

RSV Clinical Disease

A
  • Single most important agent of bronchiolitis and pneumonia in infants under 1 year of age
  • Can infects children and adults
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13
Q

RSV Transmission

A

•Transmission by contact with infective secretions incubation period 2-4 days

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14
Q

RSV Clinical Findings

A
  • Spreads from upper respiratory tract and goes down to bronchi, bronchioles, alveoli
  • Acute phase of cough, wheezing and respiratory distress lasts 1 to 3 weeks
  • hyperexpansion of lungs, hypoxemia, hypercapnia, interstitial infiltrates
  • Fatality: 0.5-1.0%
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15
Q

RSV Pathogenesis

A
  • Infection primarily in respiratory epithelium with progression to middle and lower airways
  • RSV F protein promotes fusion leading to syncytia formation
  • Major factors in pathogenesis:
  • Deficit in humoral response to RSV antigens
  • Antigen-antibody complex formation within respiratory tract results in complement activation
  • Excessive damage from inflammatory cytokines
  • TH2 cytokines associated with severe disease
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16
Q

RSV Immunity

A

•Immunity to reinfection is brief because recovered patients from a primary acute episode are reinfected with the virus

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17
Q

RSV Diagnosis

A

•immunofluorescence to detect viral antigen in nasal secretions, RT-PCR

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18
Q

RSV Treatment

A

•supportive, (aerosol ribavirin in selective circumstances)

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19
Q

RSV Prevention

A
  • No vaccine. A monoclonal antibody against F protein (palivizumab) used for prophylaxis in high-risk infants
  • Nasal spray vaccine under development
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20
Q

Human Metapneumovirus (hMPV)

A
  • Metapneumovirus genus of the Paramyxoviridae family
  • Accounts for 10% of the respiratory tract infection in infants and young children
  • Second to RSV to cause acute bronchiolitis with comparable severity and symptoms to those of RSV
  • Both RSV and hMPV can infect the same child
  • Infection with hMPV occurs in slightly older children compared with RSV
  • Diagnosis: RT-PCR (amplification of the viral genome)
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21
Q

Coronavirus

A
  • Coronavirus genus of the Coronaviridae family
  • alpha (human coronavirus) and beta (SARS Cov-1, MERS CoV SARS-CoV2 (COVID-19), bat, mouse hepatitis, bovine, human)
  • Cause respiratory, gastrointestinal, CNS diseases in human & animals
22
Q

Coronavirus Structure

A
  • Large, enveloped, (+) ssRNA, helical nucleocapsid virus
  • 125-150 nm in size
  • RNA genome size 27- 32kb
  • Envelope spike glycoprotein S1 binds to receptor (ACE2 for SARS), S2 helps in fusion
  • Other proteins: HA acetylesterase glycoprotein and Membrane glycoprotein
23
Q

Coronavirus Replication

A

i. Replicates in the cytoplasm like (+) RNA viruses
ii. Genomic and sub-genomic RNAs are made
iii. RNA dependent RNA polymerase and other proteins form the complex for transcription and replication
iv. Encodes an enzyme for proof reading of genome ability
v. Buds through endoplasmic reticulum or Golgi

24
Q

Coronavirus - human coronavirus

A

•229E, NL63, OC43, HKU1 – 10-30% of common cold; runny nose, sore throat, fever, headache, cough

25
Q

Coronavirus - SARS-CoV-1

A
  • Cause of SARS is a coronavirus
  • Transmission: direct contact, via the eyes, nose and mouth, with infectious respiratory droplet
  • SARS was first detected in China in Nov 2002, killed 774 people out of 8100 sickened worldwide
  • Risk of transmitting the disease to a person is greatest at around day 10 of illness, when maximum virus is shed from the respiratory tract
  • Older people are at higher risk than younger people/children
  • SARS virus genome has been sequenced
  • No treatment, no vaccine approved
26
Q

Coronavirus - MERS-CoV

A
  • New coronavirus 2012 causing MERS, MERS-CoV
  • Similar to coronavirus causing SARS-1
  • Fever, cough, shortness of breath, may lead to renal failure
  • About 30% people have died infected with MERS
  • First isolated in Saudi Arabia, has spread to other middle eastern countries
  • Person-to-person spread is still low
  • Imported cases in the U.S.
  • MERS virus has been found in camels and Egyptian tomb bat
27
Q

Coronavirus - SARS CoV-2 (COVID-19)

A
  • Novel coronavirus, SARS CoV-2 causing COVID-19, identified in Wuhan, China in December 2019
  • SARS CoV-2 probably jumped from bat to human, caused a severe disease,Covid-19, pneumonia and easily transmitted from person to person – perquisite for a pandemic pathogen
  • Spread in most countries starting early 2020 causing a pandemic infection: 37.8Mcases, 1.1M deaths globally, 7.8M infection, 215K deaths in the U.S. 10/12/20
  • It’s projected to infect a significant population in the U.S, including deaths
  • SARS CoV-2 likely to circulate in the next flu season
28
Q

Coronavirus - SARS CoV-2 (COVID-19) Transmission

A
  • Person-to-person transmission
  • Close contact (keep 6 feet distance)
  • Respiratory droplets when an infected person coughs and sneezes and the droplets lands on others face, nose, eyes
  • Respiratory droplets contaminated surfaces and hand to face, nose, eyes transfer
  • Through aerosol with some tiny droplets if too close
  • Many asymptomatic infected people transferring to others
29
Q
A
30
Q

Coronavirus - SARS-CoV-2 (Covid-19) Incubation

A

•2-14 days; median 5-6 (5.5) days, 97.5% of people who develop symptoms do so within 11.5 days

31
Q

Coronavirus - SARS-CoV-2 (Covid-19) Symptoms

A

•Fever or chills, Cough, Shortness of breath, fatigue, muscle or body aches, headache, new loss of taste or smell, sore throat, congestion or runny nose, nausea or vomiting, diarrhea.

32
Q

Coronavirus - SARS-CoV-2 (Covid-19) Symptoms Severe

A
  • trouble breathing, persistent pain or pressure in the chest, new confusion, inability to wake or stay wake, bluish lips or face and many more.
  • Majority (~80%) of the people have mild to moderate symptoms. Some people (~14%) have severe disease such as pneumonia, ~5% have critical illness such as respiratory failure, shock or multiorgan dysfunction, death rate is around 2%.
33
Q

Coronavirus - SARS-CoV-2 (Covid-19) Risk Factors for Severe Illness

A
  • Individuals of any age can be infected, middle age are most commonly affected, and older individuals are most likely to have severe disease
  • Other conditions associated with severe illness:
  • Immunocompromised, Severe obesity
  • Cardiovascular disease, diabetes, hypertension, chronic lung disease, cancer, chronic kidney disease
34
Q

Coronavirus - SARS-CoV-2 Pathogenesis

A
  • Both viral and proinflammatory cytokines induced pathologic changes in the lung
  • SARS-CoV-2 targets cells through the viral structural spike (S) protein that binds to the angiotensin converting enzyme 2 (ACE2) receptor
  • The serine protease type 2 transmembrane serine protease (TMPRSS2) in the host cell further promotes viral uptake by cleaving ACE2 and activating the SARS-CoV-2 S protein
  • In the early stage, viral copy numbers can be high in the lower respiratory tract, Inflammatory signaling molecules are released by infected cells and alveolar macrophages in addition to recruited T lymphocytes, monocytes, and neutrophils.
  • In the late stage, pulmonary edema can fill the alveolar spaces with hyaline membrane formation, compatible with early-phase acute respiratory distress syndrome
35
Q

Coronavirus - SARS-CoV-2 Diagnosis

A
  • Viral genome by RT-PCR and viral antigen test,
  • For seroconversion (antibody test)
36
Q

Coronavirus - SARS-CoV-2 Treatment

A

•supportive, antiviral Remdesivir and dexamethasone have shown some benefits, convalescent plasma, monoclonal antibodies show promising results

37
Q

Coronavirus - SARS-CoV-2 Prevention

A

•social distancing, wearing masks, frequent hand washing with soap and water, using sanitizers with 70% alcohol.

38
Q

Coronavirus - SARS-CoV-2 Vaccines

A

•Several newer vaccines platforms such as mRNA, DNA, adenovirus-vector based DNA, protein subunit and others

39
Q

Adenoviruses

A

•several genera of the Adenoviridae family

40
Q

Adenovirus Structure

A
  • naked capsid virus (icosahedral)
  • double-stranded linear DNA
41
Q

Adenovirus Replication

A
  • replication and assembly occur in the nucleus
  • virions are released by cell destruction
42
Q

Adenovirus Clinical Disease

A
  • Persist in host cells from days to years
  • Subclinical
  • Latent
  • Febrile childhood respiratory disease
  • Pharyngoconjunctival fever
  • Pertussis-like (Whooping Cough) disease in children
  • Conjunctivitis
  • Cystitis
  • Gastroenteritis
  • May be linked to obesity (preliminary results)
43
Q

Adenovirus Diagnosis

A

•isolate virus (confusing because of healthy carriers), clinical picture, PCR

44
Q

Adenovirus Treatment

A

•suppportive

45
Q

Adenovirus Prevention

A

•enteric coated live vaccine

46
Q

Common Cold - Rhinovirus

A
  • Enterovirus genus of the Picornaviridae family
  • 125 serotypes 20-30nm
  • (+) ss RNA, cubic-naked
  • Optimum growth at 33oC
  • no treatment, no prevention
  • Common Cold!
47
Q

Common Cold - Coronaviruses

A
  • Coronavirus of the Coronaviridae family
  • (+) ssRNA, helical enveloped
  • replicate in cytoplasm
  • bud through endoplasmic reticulum or Golg
48
Q

Common Cold - Reoviruses

A
  • Reovirus genus of the Reoviridae family
  • 4 serotypes, dsRNA, segmented, small icosahedral, naked
  • most infections are asymptomatic
49
Q

Common Cold Syndrome

A

•Common colds are associated with:

  • no fever
  • sneezing, congestion, nasal secretions
  • short duration (2-4 days)

•Treatment and prevention

  • Kleenex, Kleenex (anti-viral)
  • No vaccines
  • New drug BIRR-4 (nasal spray) reduces the severity of the common cold (rhinoviruses)
50
Q

Bocavirus

A
  • Bocavirus of the Parvoviridae family
  • Single stranded DNA virus, naked capsid
  • Replication in the nucleus.
  • Primarily implicated as a cause of wheezing and other respiratory illnesses in children.
  • Diagnosis: PCR

I & I Part II (25 decks)

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