DNA Viruses Flashcards
Herpesviruses
Herpesviruses acquire their viral envelope from the:
Host’s nuclear membrane (not the plasma membrane, as is seen with other DNA viruses)
HSV1
- Vesicular rash
Primary Infection
* Gingivostomatitis
* Herpetic whitlow
Reactivation
* Herpes labialis
* Erythema multiforme
Immunocompromised (severe)
* Encephalitis
* Esophagitis (punched-out ulcers)
Dx
* Tzanck smear»_space; giant cells w/ intranuclear inclusions (“cowdry bodies”)
Rx
* Acyclovir, valacyclovir
Primary Infection
Virus replicates at the primary site of exposure
HSV-1 enters sensory neurons (sensory ganglia dormancy) after primary infection via:
Retrograde Transport. Then for reactivation it travels via anterograde transport to the epithelial cells.
Erythema Multiforme
Target-shaped lesions
CMV Esophagitis
Linear/long ulcers in the esophagus that run down length-wise
Acyclovir
Inhibits viral DNA Polymerase. Stops the cell from replicating.
- Does not have any impact on the dormant form of the virus
- Can be used to treat active cases, but the infection never really goes away
HSV-2
- vesicular rash on erythematous base
- Herpes genitalis
- extragenital manifestations are rare
Dx
* Tzanck smear»_space; giant cells w/ intranuclear inclusions (“cowdry bodies”)
Rx
* Acyclovir, valacyclovir
Is viral meningitis more common with HSV-1 or HSV-2?
HSV-2
HHV3 (VZV)
Transmission
* respiratory droplets
* infected lesions
Primary Infection
* Pruritic vesicular rash (chickenpox)
* Encephalitis»_space; cerebellar ataxia
* Pneumonia
Dormancy in sensory ganglia
* DRG or Trigeminal ganglia
Reactivation
* immunocompromised state
* Unilateral rash along single dermatome
* Postherpetic neuralgia (burning nerve pain)
* Blindness (rare)
Dx
* Tzanck smear»_space; giant cells w/ intranuclear inclusions (“cowdry bodies”) on wright-giemsa stain
Rx
* Chickenpox: symptomatic relief
* Shingles: acyclovir, famiyclovir, valacyclovir
- Acyclovir
- Famciclovir
- Valacyclovir
Guanosine analog that inhibits viral DNA polymerase
- Requires herpes viral thymidine kinases (phosphorylation) for conversion into their active form
EBV
Heterophile/monospot test
- Saliva “kissing disease”
- Infects B-cells through CD-21
Presentation (mononucleosis)
* Pharyngitis
* Lymphadenopathy (posterior cervical nodes)
* Splenomegaly/Splenic rupture risk»_space; avoidance of contact sports
* morbilliform rash with penicillin
Associated with
* Burkitt Lymphoma (& other B-cell lymphomas)
* Primary CNS Lymphoma
* Nasopharyngeal carcinoma
Dx
Peripheral blood smear
* Reactive cytotoxic T-cells (enlarged due to viral antigens)
Heterophile/monospot test
* highly specific to an EBV infection
Rx
* Supportive care
* Acyclovir & related drugs are NOT effective»_space; lack the viral thymidine kinase necessary for activation
CMV
Mononucleosis-like syndrome (immunocompetent)
No:
* pharyngitis/tonsil involvement
* heterophile antibodies (= negative Monospot test)
Yes:
* Morbilliform/maculopapular rash
Immunocompromised
* Retinitis
* Esophagitis w/ linear ulcers on biopsy
* Colitis
* Pneumonitis (lung transplant)
Congenital CMV
* chorioretinitis
* hearing loss (SSNHL)
* 10% of babies w/ symptomatic mother are affected
Dx - Histology
* Owl-eye inclusions
Rx
* Ganciclovir
* Foscarnet»_space; (2nd drug added for AIDS patients– CMV retinitis)
No pharmacotherapy is indicated in immunocompetent patients.
- HHV-6
- HHV-7
- Transmitted via saliva
- Causes Roseola
Dx
* Clinical
Rx
* Supportive care
Roseola Infantum
- Babies (7-13 months old)
-
High fever for 3-5 days (104 C+)
* Rash»_space; starts from neck and spreads outward»_space; presents right after the fever resolves
*
HHV-8
Kaposi Sarcoma
* Cancer of the blood vessels
* Immunocompromised patients
* AIDS, organ transplant recipients
* Discolored skin lesions
* Lymphedema
* B-symptoms
Tumor biopsy
* Whorled pattern of spindle cells
* Vessel proliferation
Rx
* HAART in AIDS-related disease
* Interferons may be helpful
Poxvirus
Mollusks have shells.
Molluscum contagiosum
* Enveloped, dS DNA, Linear chromosomes
- Replicates in cytoplasm»_space; carries its own DNA-dependent RNA polymerase
- Largest DNA virus
Transmitted via skin-to-skin contact
Presentation - skin
* Pearly papules w/ central umbilication
* healthy children or immunocompromised adults
Dx - Biopsy
* Eosinophlic cytoplasmic inclusions (“Molluscum bodies”)
Rx
* None b/c very benign
Hepnadnavirus
Hepatitis B virus
- Circular, enveloped, DNA virus, partially double stranded
- Replicates using Reverse Transcriptase
- Immune-mediated damage»_space; no direct cytotoxic effect of the virus
Presentation
* Acute hepatitis (ALT > AST) – most get resolved
* Chronic hepatitis»_space; cirrhosis or HCC
* Associated conditions: PAN, Membranous Nephropathy
Biopsy
* Eosinophilic “ground glass” appearance
* Pink apoptotic bodies (“councilman bodies”)
HBV Serologic Studies
HbeAg = bad news (active replication)
HBsAg
* Active infection
Anti-HBs
* Immunity to HBV»_space; prior infection/recovery or vaccination
Anti-HBc
IgM : acute (recent) infection (@ window period)
IgG: long past exposure (recovery)
HBeAg
* High infectivity»_space; active replication
HBV Vaccination
Contains HBsAg
- stimulates the production of anti-HBsAg in the host
- Serologies will be positive for Anti-HBs & negative for everything else after successful vaccination
Hepatocellular Carcinoma
- Integration of HBV DNA into the hepatocyte genome
- may cause inactivation of tumor suppressor genes
- higher risk of developing HCC with HBV than with HCV
Human Papillomavirus
- dsDNA, non-enveloped, circular chromosome
Pathogenesis & Presentation
Warts - low oncogenic potential
* 1,2»_space; cutaneous warts
* 6, 11»_space; condyloma acuminata (laryngeal & anogenital)
CIN/cervical cancer
* 16, 18, 31, 33
* E6 degrades p53
* E7 binds Rb
* Immunosuppression promotes oncogenesis
Dx
* PCR = gold standard
* pap smear
Rx
* self-resolving
* cryotherapy
Vaccination
* Gardasil 9»_space; targes low and high serotypes
Polyomavirus
JC- brain, BK- kidneys
Immunocompromised patients.
- non-enveloped, Circular, dsDNA genome
1. JC Virus
* PML – white matter degeneration in the brain (targets oligodendrocytes)
* neurological deficits
* dementia
* visual defects
2. BK Virus
* Transplant patients (take Rx for immunosuppression)
* Kidney injury (hemorrhagic cystitis, nephropathy)
Dx
* PCR
* biopsy – intranuclear inclusion bodies
Rx
* Supportive care
* PML is often fatal
* HIV/AIDS»_space; AVRT Tx
Parvovirus B19
“Parvovirus is part of a virus”
- ssDNA, non-enveloped, linear chromosome
- smallest DNAvirus
Pathogenesis
* infects RBC precursors in bone marrow and blood»_space; P-antigen (expressed on RBC’s, precursors)
Presentation
* Erythema infectiosum»_space; slapped cheek rash
* Aplastic anemia/Pancytopenia»_space; common in sickle cell disease… pure RBC aplasia (marrow failure) in adults also
* Hydrops fetalis
* Arthralgia/arthritis – knees, ankles, wrists, hands (stiffness & pain)
Dx
* Usually clinical, but can use IgM/IgG antibody assays to confirm (serology)
* PCR detection
Rx
* Supportive (self-limiting)
* NSAIDs for significant join pain
Adenovirus
- dsDNA, non-enveloped, linear chromosome
- seen in crowded/close quarters»_space; swimming pool/lake outbreaks
Clinical presentation
* Pharyngoconjunctival fever
* Acute hemorrhagic cystitis
* Pneumonia
* Gastroenteritis
Dx
* viral culture PCR
Rx
* supportive & self-limiting
