Thirty Six Flashcards
What is rhinovirus like? Describe the life cycle of rhinoviruses. What is the pathogenesis/dissemination? What is the transmission like and how can it be prevented?
Single Positive strand RNA (non-enveloped)
- Virus enters in respiratory droplets
- Binds ICAM-1
- Infection ~damages respiratory epithelium and causes discharge
- IFN and antibodies speed control and recovery
- Lots of serotypes! Immunity is short-lived
Attachment (ICAM-1) Penetration Uncoating Translation (pos. strand) Processing Minus strand replication Plus strand replication virion assembly cell lysis
• Non-enveloped virion is stable, very resistant to
dessication
- Spread by aerosols and surface contact
- Wash hands frequently, and don’t touch your nose
Describe the symptoms/clinical progression of rhinoviruses. Treatment?
- The common cold: – sneezing, pharyngitis, rhinitis, nasal congestion, cough, itchy eyes (note ~no fever)
- Symptoms appear quickly; palliative Rx
- Recovery in 6-10 days
- Kids can have up to 12 colds per year (seasonal incidence)
- Some association with worsening asthma
What is the enterovirus D68? History? Transmission?
Rare respiratory virus in picorna family
• Responsible for recent clusters of severe
respiratory disease
• I.D.’d by PCR in Chicago, Kansas City,
and St. Louis
• Spread through respiratory secretions like
saliva and mucus
What is adenovirus like? Describe the basic scheme of non-enveloped DNA virus replication.
Double stranded non enveloped DNA virus
Virions enter by endocytosis (attachment, penetration), uncoat in endosomes, and genome is transported to the nucleus
early Viral transcription (nucleus)/translation
DNA replication (nucleus)
late viral transcription (nucleus)/translation
virus assembly (nucleus)
Cells lyse and virus particles are released
Describe the dissemination/infection with adenoviruses.
- 57 serotypes: different serotypes cause different infections
- Some serotypes cause upper
respiratory tract infections in
infants and young children and are
very common (50-90% incidence)
- Incubation period for respiratory infections is broad
- Some infections are asymptomatic
- Some serotypes form long-term persistent infections and can reactivate in immunosuppressed patients
What are some respiratory diseases caused by adenoviruses
endemic respiratory disease acute respiratory disease pharyngoconjuctival fever Disseminated adenovirus infections in immunosuppressed patients
Describe endemic respiratory disease and acute respiratory disease as they apply to adenovirus.
Endemic respiratory disease
- Pediatric respiratory disease
• 5% of “common cold” in children
• fever, pharyngitis, tonsillitis, cough, etc.
Acute respiratory disease (ARD)
• upper + lower respiratory disease seen in military recruits(not seen in comparable civilian adult populations)
• can be fatal or result in chronic lung damage
• A new vaccine has been approved for use in the military
What is PCF? How are infections acquired? What are they symptoms? What is the result? How can it be prevented?
- Pharyngoconjunctival Fever (PCF)
• Infections can be acquired by direct conjunctival
inoculation, or from inadequately chlorinated
swimming pools
• High fever, phayrngitis, conjunctivitis
• Disease is self-limiting and recovery is without
sequelae
Usually no need for definitive diagnosis
Prevention: Handwashing, refrain from touching
nose/face, chlorinated pools
When do Disseminated adenovirus infections in immunosuppressed patients occur? What symptoms do they cause? What causes them?
• Especially pediatric allogeneic stem cell
transplant patients
- ~1 in 5 get these infections, and about half die
- Caused by many serotypes, especially those that
commonly cause infections in children
- Pneumonia, also hepatic and GI damage
- Not known whether due to reactivation of latent
virus or to new infections
What is the structure of parvovirus B19? Describe its replication/pathogenesis/life cycle.
- single-stranded DNA genome
- Host cell must be in S-phase for virus replication
- Receptor for virion entry is limited to hematopoietic progenitor cells(erythroblasts)
- Major site of replication is adult bone marrow and fetal liver (site of erythropoiesis during development)
Attachment Penetration DNA genome released into nucleus synth of non structural proteins Synth of structural proteins Assembly and lysis
Describe the 2 phases of the childhood disease of parvovirus B19.
Phase I
- Common infection of childhood (30-60% have antibody)
- Intense viremia, sometimes accompanied by mild cold
symptoms
• Highly infectious at this time
Phase II
• At 10-14 days postinfection can
be accompanied by “fifth disease”
(erythemia infectiosum), due to
circulating immune complexes
• Not infectious
Describe the adult disease of parvovirus B19
• Infected adults, especially women, can get symmetrical
polyarthropathy that can last for weeks, mostly resulting
from immune response
• Transient aplastic crisis in patients with sickle cell disease
• Some fetal infections with mothers experiencing acute
infection, especially in the first half of pregnancy
• “hydrops fetalis” can be fatal to fetuses
