Herpesvirus Biology Flashcards
what are the 3 alpha herpes viruses
latent cell = NEURONS
1. herpes simplex type 1 (HSV1)
2. herpes simplex type 2 (HSV2)
3. varicella-zoster virus (VZV)
what are the 3 beta herpes viruses
latent cell = LYMPHOCYTES
1. cytomegalovirus (CMV)
2. human herpesvirus 6
3. human herpesvirus 7
what are the 2 gamma herpes viruses
*cause CANCER
1. epstein-barre virus
2. Kaposi’s sarcoma (associated with HHV-8)
herpesvirus structure - capsid
icosahedral + envelope
important enzyme made by herpes viruses
thymidine kinase (they make their own)
ALL herpes viruses establish what kind of infections?
lytic AND latent
what is responsible for maintaining latency of herpes viruses
cellular immunity (T cells)
what are the latent cells for HSV 1/2 ?
SENSORY neurons
what are the latent cells for varicella-zoster virus (VZV / HHV-3) ?
dorsal root ganglia of sensory nerves
what are factors that govern reactivation of latent alpha herpes virus infections
*IMMUNE SUPPRESSION
-UV-B radiation
-hyperthermia
-emotional stress
-physical stress
-menstruation
transmission of HSV 1/2
-close personal contact (kissing, sexual contact)
-vertical (TORCH infection)
clinical course of HSV 1
gingivostomatitis/cold sores
**latent in TRIGEMINAL ganglion
*can also cause encephalitis with focal TEMPORAL lesions
clinical course of HSV 2
painful genital vesicles with fever/malaise
**latent in SACRAL nerve ganglia
*can also cause encephalitis with focal TEMPORAL lesions
testing for HSV 1/2
*genital/skin lesions: immunofluorescent staining or PCR (Tzanck smear of vesicle)
*encephalitis: PCR of CSF
treatment for HSV 1/2
ACYCLOVIR (oral prodrug = valacyclovir)
how does acyclovir work to treat HSV 1/2
*in the virally infected cells, the VIRAL thymidine kinase converts acyclovir into a “false nucleotide” to BLOCK DNA synthesis (inducing chain termination)
*cellular thymidine kinase won’t do this
which nucleoside is acyclovir an analog for
guanosine
transmission of VZV (varicella-zoster virus)
*respiratory droplets from patients with chicken pox
*contact with lesions from patients with shingles
clinical course of VZV: chicken pox
*ASYNCHRONOUS vesicular rash (lesions in different stages)
*fever
*pharyngitis
*malaise
*rhinitis
clinical course of VZV: shingles
*REACTIVATION of latent VZV
*pain/vesicles in a DERMATOMAL DISTRIBUTION
treatment for VZV
ACYLOVIR (oral drug = valacyclovir)
vaccine for VZV (for children)
Varivax: LIVE ATTENUATED VACCINE
vaccine for VZV (for adults 50+)
Shingrix: SUBUNIT VACCINE
cytomegalovirus (CMV) appearance upon biopsy
“owl eye” inclusions in infected cells
latent cells for cytomegalovirus (CMV / HHV-5)
mononuclear cells
cytomegalovirus (CMV) transmission
-saliva, sexual, parenteral
-in utero (vertical transmission)
what cells are infected by CMV
salivary gland epithelial cells
(LATENT in mononuclear cells though)
clinical course of cytomegalovirus (CMV)
*mononucleosis but heterophile (monospot) negative
*“blueberry muffin” babies if congenital
*in immunocompromised pts, can cause retinitis, interstitial pneumonitis, GI disease
testing for CMV
PCR of blood
urine test in babies
treatment for CMV
GANCYCLOVIR (oral prodrug = valgancyclovir)
latent cells for HHV 6/7
mononuclear cells
clinical course for HHV 6/7
ROSEOLA: fever for 5 days FOLLOWED BY lacy body rash
*high fever can cause seizures (febrile seizures)
treatment for HHV 6/7 (roseola)
supportive care only
entry for Epstein-Barr Virus (EBV)
binds receptor CD21 (complement receptor 2)
latent cells for Epstein-Barr Virus (EBV)
B cells
transmission of Epstein-Barr Virus (EBV)
respiratory secretions and saliva (“kissing disease”)
clinical course for Epstein-Barr Virus (EBV) (immune COMPETENT patient)
mononucleosis (heterophile test +):
-fatigue
-fever
-sore throat
-lymphadenopathy
-splenomegaly
clinical course for Epstein-Barr Virus (EBV) (reactivation / cancer)
-lymphoma (endemic Burkitt)
-nasopharyngeal carcinoma (Asian adults especially)
Epstein-Barr Virus (EBV) testing
*antibody test or serology is best
*monospot (heterophile) test is easiest
*EBV blood PCR
Kaposi sarcoma-associated herpesvirus (HHV-8) latent cells
B cells and glandular epithelial cells
Kaposi sarcoma clinical course
-neoplasm of endothelial cells
-seen in HIV/AIDS and transplant patients
-dark/violaceous plaques or nodules
herpesvirus structure - nucleic acid
dsDNA
