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51 Cards in this Set
- Front
- Back
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What etiological agents are primarily responsible for Bronchiolitis in children? |
RSV
hMPV PIV adenovirus |
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What etiological agents are primarily responsible for croup in children? |
parainfluenza virus (PIV) |
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What etiological agents are primarily responsible for pneumonia in children? |
Influenza, Streptococcuspneumonia, Mycoplasma pneumonia, PIV, adenovirus, RSV
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What etiological agents are primarily responsible for pneumonia in transplant patients? |
RSV, PIV, influenza virus, hMPV
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What virus is the primary cause of croup (laryngotracheobronchitis)? |
HPIV 1 and 2 |
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What are the pathological effects of croup? |
increased epithelial cell shedding/replacement, increased mucous production and inhibition of ciliary motility
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What are the pathological effects of acute bronchitis? |
inflammation of the large airways with epithelial cell-shedding lining the large airways
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What is the leading cause of infant hospitalization in the U.S.? |
Bronchiolitis |
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What is the primary etiological cause of bronchiolitis? |
RSV |
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What are the pathological effects of bronchiolitis? |
characterized by destruction of epithelial cells lining the small airways
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What are the pathological effects of pneumonia? |
inflammation and tissue destruction in the lungs mainly affecting the alveoli; fluid in the alveoli
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What is the difference between typical and atypical pneumonia? |
typical pneumonia is caused by bacteria; while atypical pneumonia is caused by viruses |
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What are the main etiologic agents of acute respiratory tract infections? |
Human Rhinoviruses (HRVs) and Coronaviruses (CoVs) |
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What family and genus do Human Rhinoviruses (HRVs) belong to? |
Family: Picornaviridae
Genus: Enterovirus |
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How many species are associated with Human Rhinoviruses (HRVs)? How many serotypes? |
There are 3 HRV species (A, B and C) representing >100 serotypes (species C has not been serotyped because it cannot be easily propagated by cell culture). |
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What is unique about Human Rhinoviruses (HRVs) being classified as an enterovirus? |
Human Rhinoviruses (HRVs) are in the enterovirus genus even though they do not infect the GI tract because the virus is acid-labile. |
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What is the genome of Human Rhinoviruses (HRVs)? |
non-segmented, (+) ssRNA with VPg protein at the 5' end and a poly-A tail (3' end) |
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What is the structure of Human Rhinoviruses (HRVs)? |
non-enveloped, icosahedral |
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What is the major cell surface receptor for Human Rhinoviruses (HRVs)? |
ICAM-1 |
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Where does the replication of Human Rhinoviruses (HRVs) take place within the cell? |
cytoplasm |
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What is the ideal temperature for Human Rhinoviruses (HRVs) replication? |
33°C |
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What is the primary cause of "cold" symptoms associated with Human Rhinoviruses (HRVs)? |
Cold symptoms are mainly caused by an inflammatory immune response (innate immune response). Secretion of chemokines and cytokines from infected epithelial cells results in the recruitment of mononuclear cells (mainly neutrophils) to the infection. The inflammatory response causes an increased airway hyperresponsiveness (due to secretion of vasoactive kinins) and an increased mucous secretion (due to activation of goblet cells in nasal epithelium). |
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What is responsible for clearing Human Rhinovirus (HRV) infection? |
Innate immunity is responsible for clearing HRV infections.
a. Neutralizing antibodies appear in the serum often only after the infection. b. Neutralizing antibodies may hinder reinfection of an HRV with the same serotype,but not a different serotype. |
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How is Human Rhinovirus (HRV) infection diagnosed? |
The season and the presence of common cold symptoms |
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How is Human Rhinovirus (HRV) infection treated? |
Symptoms can be treated with analgesics and antipyretics. Get lots of rest, and drink lots of fluids[Some fluids (chicken broth) serve as temporary decongestants.] |
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What is the family and genus of coronavirus? |
Family: Coronaviridae Genus: Coronavirus (enteric coronaviruses are members of the Torovirus genus) |
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What is the second leading cause of the common cold? |
Coronaviruses (primarily HCV-229E and HCV-OC43) |
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Which has a longer incubation period Human Rhinovirus (HRV) or Coronavirus? |
Coronavirus |
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What is SARS? |
SARS is a coronavirus and is the etiologic agent of Severe Acute Respiratory Syndrome (SARS). |
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What is MERS? |
MERS is a coronavirus and is the etiologic agent of Acute Respiratory Distress Syndrome (ARDS). |
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What is the structure of Coronavirus? |
eveloped, pleomorphic (different shapes) |
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What is the genome of the Coronavirus? |
non-segmented, linear, (+) ssRNA with a 5' methylguanosine cap (for translation) |
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What is the spike protein of the coronavirus? |
Spike protein (E2) is used for receptor-binding and protects the virion from harsh environmental conditions. |
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How is polyprotein 1ab formed? |
A frameshift occurs at the end of ORF1 (open reading frame 1), which causes the ribosome to shift back one space then continue translating forming pp1ab. |
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What is the role of the nucleocapsid and the envelope of coronaviruses? |
Nucleocapsid (N) protects the RNA and prevents cellular detection of the RNA.
Envelope protein (E) and membrane glycoprotein (M) used for virion assembly and budding. |
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Describe the replication cycle of coronaviruses. |
1. Virion S binds specific cell surface receptors to trigger membrane fusion and entry. 2. The viral genome is released into the cytoplasm. 3. A 5’ methylguanosine cap on the viral genome (also on cellular mRNAs) allows for immediate translation of the 5’ portion of the genome. 4. Translation of ORF1a to pp1a, and translation of ORF1a/1b (frameshift) to pp1ab 5. Cleavage of pp1a and pp1ab into proteins that form the replicase complex. 6. The replicase complex synthesizes negative-sense genomic and subgenomic length RNAs using the original viral genome as a template. 7. Negative-sense genomic RNA is used to replicate the viral genome. 8. Replication & assembly occurs within specialized double membrane vesicles (DMVs), which are dervived from the cell's ER and Golgi. 9. Virus buds from the cell. |
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What is the SARS receptor? |
ACE2 (human angiotenin converting enzyme 2) |
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What type of polymerase is the replicase complex? |
The replicase complex is an RNA dependent RNA polymerase (RdRp). |
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Describe the synthesis of subgenomic (-) sense RNA in the coronavirus. |
Synthesis of subgenomic minus-sense RNA is discontinuous. It stops at transcription regulatory sequences (TRS), then transfers to leader TRS in RNA hairpin (LTH) where synthesis resumes. |
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What does the SARS use to evade the immune system? |
double-membrane vesicles shield the virus from pattern recognition receptors (PRRs) |
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What are the similarities and differences between HRV and Coronavirus? |
Similarities: Same mode of transmission, optimal replication temperatures in the URT (with occasional LRT infection), no viremia Differences: incubation period (longer in HRV), coronaviruses are not acid-labile (HRV are) |
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Where did the SARS virus originate? |
bats --> rodents --> humans |
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Where did MERS originate? |
Camels are known to be carriers of the virus with weak human-to-human transmission |
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How is SARS transmitted? |
Transmitted through infected aerosols, droplets and fomites.
Transmission may also occur through a fecal-oral route. Initially was transmitted through contact with rodents. |
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When does the viral load for SARS peak? |
Around day 10 post-infection |
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What is the site of initial SARS viral replication in the body? |
mucociliary epithelium |
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What is the cell surface receptor for MERS? |
dipeptidyl peptidase 4 (DPP4) surface protein |
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Which corona virus is associate with viremia? |
SARS is associated with viremia. Infection moves to the gastrointestinal tract, liver, kidney and brain. |
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Describe the pathology of SARS. |
a. Early event: destruction of brochial ciliated epithelial cells. b. Later event: diffuse damage to alveoli associated with an influx of macrophages and giant, multinucleated cells that stain as macrophages (syncytial formation). c. No damage to the intestinal tract (in lieu of diarrhea for 10-20% patients). d. Frequent lymphopenia (may facilitate disease progression). e. Delayed kinetics of adaptive immune response extended pro-inflammatory response --> cytokine storm. |
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How is SARS/MERS diagnosed? |
A SARS diagnosis correlates with the patients symptoms and whether the patient has traveled to, or been in contact with someone who has traveled to a region where SARS/MERS-CoV cases were recently documented. Chest x-rays may show lung infiltrates. PCR will confirm. |
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What is the treatment for SARS or MERS? |
Supportive |
