Virology Flashcards
Name 3 Enteroviruses
- Coxsakie A and B
- Echoviruses
- Polioviruses
What as the sensivitiy of CSF culture for enteroviral meningitis?
50-70%
Due to low titres of virus in the CSF and coxsackie A virus may not grow in culture
How long does it take for CSF culture for enterovirus to become positive?
3-4 days, can take up to 7-10 days
What is enterovirus season?
Summer/Fall
Why is serology not useful for enterovirus diagnosis? (3 reasons)
- Antigenic diversity of the enteroviruses
- A rise in Ab titers may take several weeks before convalescent serum is available
- IgM Ab assays are not widely available
What is the target for enterovirus PCR?
5’ noncoding region, conserved among most serotypes
What % of viral meningitis is caused by HSV?
1-5%
List 3 differences between HSV meningitis and HSV encephalitis
- HSV meningitis is usually HSV-2, encephalitis is usually HSV-1
- Meningitis is self limited, encephalitis is necrotizing
- HSV can sometimes be cultured from CSF in meningitis, but rarely in encephalitis
True or False: VZV meningitis can occur as a complication of varicella or zoster?
True
Name 2 viruses in the Arenaviridae family.
- Lassa fever virus
2. Lymphocytic choriomeningitis virus (LCM)
How are humans infected with Lymphocytic choriomeningitis virus?
Contact with mice or hamsters
4 viruses associated with acute transverse myelitis.
- CMV
- EBV
- VZV
- Enteroviruses
4 viruses associated with Guillain-Barre syndrome.
- CMV
- EBV
- VZV
- HIV
What is the triad of ‘spongiform change’ on brain tissue when diagnosing CJD prion disease?
- Neuronal loss
- Reactive gliosis
- Neuronal vaculation
What protein is detected in the diagnosis of CJD?
14-3-3
What is SSPE?
Subacute sclerosing panecephalitis, caused by measles virus but presents years after infection. Caused by defective measle virus in the brain leading to production of nucleocapsid.
2 most common clinical syndromes caused by adenovirus
- Respiratory illness
- Childhood diarrhea
(Don’t forget pharyngoconjunctival fever and keratoconjunctivitis too)
Adenovirus:
RNA or DNA?
Envelope?
Morphology?
dsDNA
Nonenveloped
Icosahedral
What receptor does Adenovirus use to gain entry into cells and what other virus uses the same receptor?
CAR receptor (Coxsackie Adenovirus Receptor)
Also used by Coxsackie B virus
Infects corneal epithelium, upper and lower respiratory epithelium, urinary tract epithelium.
Can persist chronically in lymphocytes. Can find in many tissues and blood during disseminated disease.
What are the 2 most common serotypes of Adenovirus that cause gastroenteritis?
40 and 41
These infections can be asymptomatic
What age are Adenovirus infections most common?
6 months - 5 years
Many kids have seen 3 or 4 different Adeno infectious in this time
Who is at increased risk for severe Adenovirus infections?
Impaired cell-mediated immunity
Neonates, congenital immunodeficiencies, HSCT, HIV
How is adenovirus transmitted?
Direct contact, small droplet aerosols, fecal-oral, water
How long is adenovirus excreted after initial infection?
5-10 days in nasopharyngeal secretions
Weeks - months in stool
1-14 days with gastroenteritis from 40 or 41
What is the incubation period of adenovirus?
2-21 days (average 7-13 days)
How do laboratory values differ for Adenovirus compared to Flu and RSV?
In Adenovirus there is high WBC, ESR, and CRP.
Also they have high and persistent fever
What the most common cause of acute febrile tonsillitis?
Adenovirus
Which viral infection predisposes children to more severe adenovirus disease?
Measles, due to temporary suppression of cell mediated immunity during measles
Clinical symptoms of adenovirus gastroenteritis
Watery, nonbloody diarrhea lasting 3-11 days (longer than rota)
Fever and vomiting are common
Type 41 diarrhea lasts longer than type 40
What adenovirus serotype casues hemorrhagic cystitis?
11
Hematuria can last from 2 days to 2 weeks
How long after transplantation do adenoviral infections tend to occur
Peds - 30 days
Adults - 90 days
Thought to be due to latent virus
What cell lines can adenovirus be cultured from?
A549, HeLa, HEp-2, KP, MRC5
Serotypes 40 and 41 do not grow well in most cell lines
Can use shell vials
At CHEO they will grow it in HFL, RMK, MRC5
Is there a vaccine for Adenovirus?
Yes, it is approved for military recruits aged 17-50.
A tablet form, live oral vaccine for types 4 and 7. However now seeing more type 14
What is the treatment of Adenovirus?
There is not good treatment.
Ribavirin, ganciclovir, and cidofovir have variable activity
What parvoviruses cause infections in humans?
- Parvovirus B19 (genus Erythrovirus)
- Human bocavirus (genus Bocavirus)
- Adeno Associated Viruses (genus Dependovirus)
- PARV4 and PARV5 (no genus)
Parvovirus:
RNA or DNA?
Envelope?
Morphology?
ssDNA
Nonenveloped
Icosahedral
What is the receptor for parvovirus B19?
Globoside or P antigen
What tissues does parvovirus B19 infect?
Bone marrow, erythroid precursor cells
Also fetal liver in utero
In what cell lines can Parvoviruses grow?
B19 - Human leukemic cell lines as it needs erythropoietin
Bocavirus - no cell lines
AAV - many lines as long as it has the appropriate helper virus
What is the rash associated with parvovirus B19 called?
Erythema infectiosum (fifths disease)
Asymptomatic infections are common
The rash comes at the end of the illness
What season are parvovirus infections most common?
Late winter and spring
What is the frequency of vertical transmission when a mother is infected during pregnancy?
25-50%
2-10% lead to fetal death
If the fetus survives there is no increased risk for birth defects
How is parvovirus B19 infection acquired?
Respiratory, close contacts, droplets, fomites
What is the incubation period of parvovirus B19?
1-2 weeks
Signs and symptoms of parvovirus B19 infection?
Fever, malaise, rash, arthritis
Decreased Hb, WBC, Platlets and neutrophils
When do IgM and IgG appear for parvovirus B19?
IgM - 10-14 days after innoculation
IgG - 14 days after innoculation
What illness does human bocavirus cause?
Respiratory illness