Micro Topics Flashcards
III.11 Adenovirus characteristics
- dsDNA
- Icosahedral capsid
- Naked
- Fiber antigens for attachment to receptor and agglutination of RBCs
- Human adenovirus has 57 serotypes (number 14 most severe), differentiated by hemagglutinin inhibition
III.11 Adenovirus Transmission
Contact, respiratory droplets, feces and aerosol
III.11 Adenovirus Pathogenesis
Pentons of the icosahedral capsid contains fibers that acts as hemagglutinin (toxic to cells)
- In permissive cells: virus is lytic – production occurs/replication
- In non-permissive cells: can be chronic of oncogenic (transformation occurs)
III.11 Adenovirus Clinical
a) Respiratory diseases: Tonsillitis (#1 cause), pharyngitis, pharyngoconjunctival fever, pneumonia, pertussis-like symptoms
b) Enteric infection: Watery diarrhea
c) Eye infection: Epidemic keratoconjunctivitis, follicular conjunctivitis
d) UTI: Acute hemorrhagic cystitis
e) Immune suppressed patients: Pneumonia, hepatitis, encephalitis
* Reactivation can occur in case of immunosuppressed patients
III.11 Adenovirus Ddx
Serology, cultivation on HeLA, epithelial cell culture –> strong CPE (cytopathic effect), rapid test for diarrhea
III.11 Adenovirus treatment
none - supportive
III.11 Adenovirus vaccine
Live attenuated (serotype 4 and 7) –> only for military recruits
III.12 Herepesvirus : HSV1 and HSV2 characteristics
- dsDNA – linear
- Icosahedral capsid – Encode glycoproteins for attachment, fusion, immune escape
- Enveloped – Sensitive to acid, detergents etc.
- α-herpesvirus
III.12 Herepesvirus : HSV1 and HSV2 Transmission
Saliva, vaginal secretions, transcervical (perinatal), TORCH
III.12 Herepesvirus : HSV1 and HSV2 Pathogenesis
The virus targets Mucoepithelial cells:
Viral replication in site of infection –> local nerve ending invasion –> retrograde axonal transport to dorsal root ganglia –> latency
*Generally: acute infection (early proteins) –> latency (viral genome present, but no viral proteins produced – periodic reactivation i.e. due to UV, stress etc.
III.12 Herepesvirus : HSV1 clinical
- Herpes labialis (cold sores) and gingivostomatitis Keratoconjuntivitis
- Herpetic Whitlow – rash on fingers
- Erythema multiforme – back of hands/feet
- Encephalitis – due to necrosis and hemorrhage of neurons
III.12 Herepesvirus : HSV2 clinical
- Genital herpes – inguinal lymphadenopathy and painful genital lesion
- Neonatal herpes – transcervical or transplacental (liver involvement/encephalitis)
- Aseptic meningitis
III.12 Herepesvirus : HSV1 and HSV2 ddx
Scrapings of the base of lesions – cultivation on HeLA
PCR of CSF – for encephalitis
Serology to distinguish HSV-1 and HSV-2
Genital infections – virus isolation from vesicles –> Tzanck smear
*Tzanck smear - Cytology that will show multinucleated giant cells, intranuclear eosinophilic Cowdry type A inclusion bodies are also seen
III.12 Herepesvirus : HSV1 and HSV2 treatment
Acyclovir (inhibition of DNA synthesis) – does not prevent latent infection
III.13 Herpesvirus - VZV - Varicella Zoster Virus characteristics
- dsDNA
- Icosahedral capsid ~ 150nm
- Enveloped
- α-herpesvirus
III.13 Herpesvirus - VZV - Varicella Zoster Virus transmission
Respiratory droplets, contact(rare), TORCH
III.13 Herpesvirus - VZV - Varicella Zoster Virus Pathogenesis
Primary infection in mucosa of respiratory tract –>blood and lymphatics –> dissemination to skin –> dermal vesiculopapular rash –> chicken pox –> latency in sensory ganglia –> reactivation –> migrates along neural pathways to skin –> Shingles
III.13 Herpesvirus - VZV - Varicella Zoster Virus Clinical
Primary infection: Varicella (chicken pox)
- Asynchronous rash forms small, itchy blisters all over the body (different stages; Macula, vesicles, scabs).
- Presents with fever, headache, pharyngitis, malaise (general discomfort), rhinitis.
- Adults present with pneumonia, encephalitis. Highly contagious!
Secondary infection (recurrence): Zoster (Shingles)
- Pain in a given dermatome with rash limited to said dermatome.
- Develops in immunocompromised patients
- Can cause post-herpetic neuralgia (chronic pain that lasts for years due to damage of nerves addected by virus) *
Herpes Zoster ophthalmicus – Vision loss when CNV/I is affected
Congenital varicella syndrome –> Limb hypoplasia, cutaneous dermal scarring, blindness
III.13 Herpesvirus - VZV - Varicella Zoster Virus ddx
Serology –> Examine skin lesion scraping
Tzanck smear –> Will show multinucleated giant cells, Cowdry bodies
III.13 Herpesvirus - VZV - Varicella Zoster Virus treatment
Acyclovir
III.13 Herpesvirus - VZV - Varicella Zoster Virus Vaccine
Passive (VZ-Ig) – immunosuppressed patient, ineffective in active cases
Active; live, attenuated – cell mediated immunity
III.14 - Herpesvirus - Epstein-Barr Virus (HHV-4) characteristics
- large linear dsDNA
- Icosahedral capsid
- Enveloped
- gamma-herpesvirus
III.14 - Herpesvirus - Epstein-Barr Virus (HHV-4) transmission
Saliva and respiratory secretions (90% of population is seropositive)
III.14 - Herpesvirus - Epstein-Barr Virus (HHV-4) pathogenesis
Infects permissive nasopharyngeal epithelial cells, salivary and lymphoid tissues.
Latent infection in B-cells;
Binds CDRI and produce LMP1 (latent membrane protein 1) –>
a) NFKB activation and B-cell proliferation
b) Bcl2 ⊣ apoptosis
This causes production of atypical CD8+ T-cells – Downey cells against it