3.6.2. Viral Upper Respiratory Infections Flashcards Preview

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Flashcards in 3.6.2. Viral Upper Respiratory Infections Deck (27)
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Describe the structure of Rhinovirus.

  1. Structure: non enveloped


Describe the characteristics of Rhinovirus

Characteristics:  +ssRNA genome (is infectious), >100 serotypes, ICAM-1 is primary cellular receptor; temperature sensitive (88-90 F; prefers the temperatures of the nose and lung


What are the target cells of the Rhinovirus?

  1. Target Cells: respiratory epithelial cells



Describe the life cycle of the rhinovirus.

Life Cycle: after entry to cell, viral mRNA directly binds to ribosomes to make polyproteins [encodes its own RNA polymerase]; these proteins are cleaved by viral proteases to generate structural proteins and replicate +ssRNA; proteins insert into genome and viral release achieved via cytolysis


Describe the structuve of respiratory syncytial virus

Structure: enveloped; two major envelope proteins - F (fusion) and G (attachment) proteins


Describe the characteristics of the respiratory syncytial virus.

Characteristics: -ssRNA genome, helical capsid, encodes its own RNA-dependent-RNA polymerase


What are the target cells of respiratory syncytial virus?

Target Cells: nasopharyngeal epithelium


Describe the life cycle of the respiratory syncytial virus.

Life Cycle: is absorbed/fused and inserts -ssRNA; undergoes transcription to produce viral mRNA and replicate RNA genome; forms surface glyco-proteins on epithelium cells and exocytoses genome with glycoproteins to develop syncytia


What is the structure of adenovirus?

Structure: largest, non-enveloped virus; at least 51 serotypes; icosahedral


Describe the characteristics of adenovirus?

Characteristics: ds linear DNA genome; replicates in the nucleus


What are the target cells of the adenovirus?

Target Cells: mucoepithelial cells in resp/GI tract and conjunctiva or cornea


Describe the life cycle of the adenovirus.

Life Cycle: replication is temporal, it encodes its own DNA polymerase; the virus will persist in lymphoid tissues; two outcomes following infection: lytic in mucoepithelial cells; latent in adenoid cells


What is the structure of the Epstein-Barr Virus (EBV)?

Structure: “gamma” herpesvirus; enveloped


What are the characteristics of EBV?

Characteristics: restricted host range; large genome; linear dsDNA; encodes its own DNA-dependent-DNA polymerase


What are the target cells of EBV?

Target Cells: epithelial cells and lymphocytes (may be latent in endothelial cells and lymphocytes)


What is the life cycle of EBV?

Life Cycle: attachment and penetration by fusion, immediate early protein synthesis, early protein synthesis and replication of genome inside the nucleus, late protein synthesis (structural) and exocytosis and release, eventual lysis and release


How is rhinovirus transmitted?

Rhinovirus - transmitted via aerosol droplets and direct contact with contaminated surfaces


What is the pathogensis, symptoms, and complications associated with rhinovirus?

  1. pathogenesis: short incubation, self-limiting

  2. symptoms: nasal discharge, congestion, sneezing, sore throat, myalgias, fatigue, edema of nasal mucosa, headache

complications: in rare cases, may cause bronchopneumonia in young children


What are the pathogensis, symptoms, and complications associated with respiratory syncytial virus?

  1. pathogenesis: entry via epithelia of nose and eyes (aerosoles, fomites); self limiting [7-10 days]

  2. symptoms: runny nose, fever, rapid breathing, wheezing/breathlessness, cough, lips turn blue; infection produces protective immunity that is NOT long lasting, resulting in repeated infection

complications: repeat infection; brochiolitis in infants


What are the pathogenesis, symptoms, and complications associated with adenovirus?

  1. pathogenesis: transmission by direct contact: fecal-oral, contaminated water, objects, aerosol; endemic for acute respiratory disease in military recruits - Ad4, 7

  2. symptoms: varies with the age and immune status of the host

  3. complications: acute respiratory disease, pharyngoconjunctival fever, pertussis-like syndrome (infants/young children), pneumonia


What are the pathogenesis, symptoms, and complications of EBV?

  1. pathogenesis: ubiquitous, >95% of adults are thought to be infected; “kissing disease”; glandular fever; transmission is primarily through the oral route; incubation lasts 6-8 weeks with symptoms for 2-3 weeks

  2. symptoms: soreness and reddening of the throat and tonsils, white patches may be seen on the tonsils; cervical lymphadenopathy; pharyngitis, sore throat, atypical lymphocytosis are the most prevalent symptoms

complications: Burkitts, Non-hodgkins, and Hodgkins lymphomas; nasopharyngeal carcinoma and oral hairy leukoplakia are all seen with latent EBV; usually due to decreased immunogenicity


Describe the diagnosis of rhinovirus, respiratory syncytium virus, adenovirus, and EBV.

  1. Rhinovirus

    1. Diagnosis: based on symptoms; virus culture, PCR of nasal samples

  2. Respiratory Syncytial Virus

    1. Diagnosis: nasal washings or swab samples for antigen detection; ELISA or DFA; viral cultures; molecular assays
  3. Adenovirus

    1. Diagnosis: detection of antigen from nasopharyngeal aspirates and throat washings; isolation of virus from aspirates, throat swabs, and feces; retrospective serology; PCR assays

  4. Epstein-Barr Virus

    1. Diagnosis: atypical lymphocytes (CD8 CTL); agglutination test for heterophile antibodies; EBV antibody ELISA; PCR for EBV



Describe the preventive measures of rhinovirus, respiratory syncytium virus, adenovirus, and EBV.

Rhinovirus: Preventative measures: sanitation and hygiene to prevent the spread

Respiratory Syncytium Virus: None listed

Adenovirus: Preventative measures: sanitation and hygiene

EBV: None listed


Describe the vaccination of rhinovirus, respiratory syncytium virus, adenovirus, and EBV.

Rhinovirus: Vaccination:  none available due to >100 serotypes; mucosal IgA is protective, type I interferons control viral spread but causes pathogenesis

Respiratory Syncytial Virus: Vaccination: no licensed vaccine currently available

Adenovirus: Vaccination: neutralizing antibodies are protective against same serotype; by age 10, most have antibodies against the endemic serotypes; difficult to vaccinate, because it encodes proteins that play a role in immune evasion (E3 protein) which down regulates MHC class I and inhibits TNF mediated lysis

EBV: Vaccination: none


Describe the treatment of rhinovirus, respiratory syncytium virus, adenovirus, and EBV.

Rhinovirus: Treatment: treat the symptoms

Respiratory Syncytium Virus: Treatment: ribavirin has had limited success; O2 treatment and hospitalization for infants with severe brochiolitis; RespiGam (polyclonal antibody) and Synagis (anti-F protein monoclonal antibody) for passive immunotherapy

Adenovirus: Treatment: treatment of symptoms; disease resolves in 7-10 days; vaccine no longer produced; live vaccine tablets being tested in military commands

EBV: Treatment: symptomatic; is self-limiting and rapidly controlled by the immune response


What does a nice summary slide of all of this look like?

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