DNA viruses

DNA viruses

1. Herpesviridae

   • Simplexvirus (Herpes Simplex Virus)
     • asymptomatic shedding infection is lifelong
     • HSV-1
       • mostly transmitted orally
       • 50-80% adults
       • Herpes Keratitis
         • - HSV-1 - virus travels down opthalmic branch of trigeminal nerve ganglion
         • gritty feeling, conjunctivitis, sharp pain, visual blurring, discharge, and photophobia - chemosis, conjunctivitis, decreased corneal sensation, dendritic lesions of cornea
       • Unilateral conjunctivitis
       • Blepharitis
       • Herpes encephalitis
         • lesions usually limited to one temporal lobe destruction of temporal lobe can lead to: CSF, seizures, focal neurologic abnormalities Infection of CNS
       • Herpes gladiatorum
         • rash distributed by close contact lesions may be painful and can treated
     • HSV-2
       • mostly transmitted sexually
       • 20-40% adults
       • HSV meningitis
     • Structure
       • Icosahedral
       • dsDNA, linear
       • enveloped
         • Do not survive well in env
     • contagious
       • direct inoculation
         • mucus membranes, eye, genitals, respiratory tract, anus
         • leading infectious cause of blindness
       • Diagnosis
         • Case study
         • Viral culture & isolation
         • PCR for HSV DNA
         • Tzanck smear
           • look for epidermal multi-nucleared cells and eosinophilic intranuclear inclusions
       • Protect
         • wear gloves, wash hands, cover active lesions, stay away from babies/immunocompromised/burn victims/eczema patients
     • Latent or lytic
       • Avoids immune system through latency
         • neurons, reactivates later
     • Acute Retinal Necrosis (ARN)
       • decreased vision potentially blinding immunocompetent, pregnant females, and HIV-infected patients
     • Chorioretinitis
       • Posterior uveitis - can be seen in neonates - Give acyclovir to prevent dissemination to newborn during childbirth
     • Herpetic whitlow
       • Blister HSV infected autoinnoculation
     • Genital herpes
       • small red bump or blister, cluster of bumps will small red base
     • Eczema herpeticum
       • seen in patients with preexisting skin disorders or in immunocompromised patients clusters of dimpled blisters emerge over 7-10 days untreated- can be fatal
     • Treatment
       • Trifluridine (Viroptic)
         • Herpes keratitis preservative-free artifical tears help promote corneal healing STOPS DNA REPLICATION
       • Cidofovir
       • Acylcovir
         • encephalitis, acute meningitis, recurrent meningitis
   • Varicella zoster virus (VZV)
     • Alphaherpesvirinae Varicellovirus Human herpesvirus 3
     • Structure
       • Icosahedral
       • dsDNA, linear
       • enveloped
       • smallest genome of herpes viruses
     • Diseases
       • Chicken pox
         • rash appears 14 days post infection; more severe on trunk; itch; more severe in adults than children chicken pox primary, shingles secondary
         • shingles
       • Herpes zoster ophthalmicus (HZO)
         • sight-threatening linked to VZV reactivation in trigeminal gangliontopical steroid drops to reduce inflammation; intravenous acyclovir
         • infects along a single dermatome
     • Highly contagious
       • humans only known reservoir
       • respiratory droplets
       • direct contact with lesions
     • Protection
       • Antiviral drugs
         • acyclovir
         • famciclovir
         • valacyclovir
       • Live vaccine
         • Varivax
           • Live, attenuated prevents 70-90% prevents severity of infection in 95%
         • Zostavax
           • single dose for 50+ lower cases of shingles by 50%
     • Diagnosis
       • dewdrops on a rose petal
       • examination of vesicle scrapings shows Giant cells
         • intacnuclear inclusions and syncytial formation
   • Betaherpesvirinae
     • Cytomegalovirus
       • largest genome transplant problems may cause birth defects 70-75% of population may play role in cancer
       • Structure
         • Icosahedral
         • dsDNA, linear
         • enveloped
       • Causes
         • Heterophile negative infectious mononucleosis
           • mild mono
         • organ regection
         • AIDS patients, infect multiple organs
       • Diagnosis
         • owl's eye basophilic intranuclear inclusion body
         • viral culture
         • Serology
           • indirect ELISA; detect anti-CMV antibodies
         • direct detection antibodies in blood
         • Molecular techniques
           • PCR DNA hyrbiziation assays
       • Dangers
         • Guillain-Barre syndrome
           • rare nervous system disorder resulting from nerve damage caused by body responding to virus
         • babies, sexually active, immunocompromised, burn victims, blood/organ receipients
       • Contagious
         • saliva, urine, blood, throat washings, tears, breast milk, semen, stool, vaginal and cervical secretions, transplant tissues
       • Protection
         • prior vaccines failed
           • passive admin. of CMV serum immunoglobulins used for prevention in organ transplant
       • Treatment
         • acyclovir
         • ganciclovir
           • AIDS patients to treat CMV retinitis (implant)
         • valganciclovir
         • Cidofovir
         • Foscarnet
       • Largest genome!!!
   • Gammaherpesvirinae
     • Lymphocryptovirus
       • Epstein-Barr virus (Human herpesvirus 4)
         • Chronic in some people chronic tiredness and low-grade fever - infects B cells and epithelial cells of oropharynx - promotes shedding in saliva - cytotoxic T cells attack infected B cells - results in symptoms
         • Structure
           • Icosahedral
           • dsDNA, linear
           • enveloped
         • Causes
           • casually linked:  -African Burkitt's lumphoma (AfBL)  -nasopharyngeal carcinoma
           • Complications
           • Heterophile infection mononucleosis
         • Signs
           • mild in children
           • swollen lymph glands, fever, exudative pharyngitis, malaise, heptosplenomegaly, ampicillin-induced rash
           • 15-17 year olds
         • Treatment
           • self-limiting
             • acetaminophen sleep
         • Diagnosis
           • symptoms and blood work

2. Adenoviridae

   • Mastadenovirus
     • Human adenovirus (Adenovirus)
       • 100 serotypes 51 infectious for humans
       • interfrees with normal operation of cytotoxic T lymphocytes by blocking MHC-1 function produces protein that provides resistance to tumor necrosis factor (TNF) interfere w suppressive action of interferons; VA RNA molecules; shut down protein-synthesis
       • structure
         • Icosahedral
         • dsDNA, linear
         • naked
       • Causes
         • URT infections
         • conjunctivitis
         • hemorrhagic cystitis
         • gastroenteritis
         • EKC
           • Epidemic Keratoconjuctivitis - mucosa & palpebral conjunctiva become nodular and are inflammed Types 8, 19, & 37
       • Diagnosis
         • clinical presentation & history
         • immuno assays, PCR, DNA probe
       • Contagious
         • Fomites
         • fingers
         • contam. h2o
       • protection
         • handwashing
       • treatment
         • live, oral vaccine against adenovirus types 4 and 7
           • military use only
         • lubricating eyedrops or topical steriods

3. Papovaviridae

   • Papillomavirus
     • Human papilloma virus
       • Most common STD in USA
       • Causes
         • warts
           • common warts (HPV 2, 4, 27, 29)
             • painless elevated growths on fingers
           • Plantar warts (HPV 1)
             • painful deep papillomas on soles of feet
           • Flat warts (HPV 3, 10, 28, 49)
             • smooth skin-colored face, trunk, elbows, and knees
           • Anogenital warts (HPV 6, 11)
             • 17-33 common rarely cause discomfort/pain
         • Cervical cancer (HPV 16, 18, 31, 45
           • 16 & 18: - 70% of cervical cancer- 50% vaginal, vulvar, and penile16:- 85% anal cancer - 50% oropharnyx cancer
         • HPV 16, 18 cancers of genitals, anus, mouth, URT
       • Diagnosed visually
         • vinegar makes HPV-infected are turn white
         • PAP smears
           • vaginal and anal reveal koilcytotic (vacuolated cytoplam) squamous epithelial cells
         • DNA test
           • HPV DNA test detect DNA of 13 high risk HPVs (16 & 18) most helpful for PAPs minimally abnormal or inconclusive help separate those at high risk from low; only detects cancer causing HPVs
       • risk factors
         • smoking weakened immune system having children long-term oral contraceptive poor oral hygiene chronic inflammation
       • Contagious
         • direct contact
         • fomites
       • structure
         • naked
         • icosahedral
         • dsDNA, circular
       • Vaccines
         • 2vHPV (Cervarix)
           • HPV 16 & 18 routine vac. females 11/12 to 26r. 
         • 4vHPV (Gardasil)
           • HPV 6, 11, 16, 18 routine vac. females 11/12 to 26r. vac. males 11/12 to 21 gay men
         • 9vHPV (Gardasil)
           • 6, 11, 16, 18, 31, 33, 45, 52, 58 routine vac. females 11/12 to 26r. vac. males 11/12 to 21 gay men
       • treatments
         • cryotherapy electrocautery laser surgical excision chemical means interferon injected into warts imiquidmod pdophilox cidofovir topical

4. Poxviridae

   • Molluscipoxvirus (Molluscum contagiosum)
     • structure
       • brick shaped
       • dsDNA, linear
       • enveloped
     • Signs/Symptoms
       • lesions
         • papules vary in size central caseous plug common on trunk, fenitalia, promixma extremities alone of in clusters painless
     • contagious
       • sexual in adults
         • considered marker for sexual activity
       • face, neck, arms, hands in children
     • Diagnosis
       • large eosinophilic cytoplasmic inclusions
       • PCR
     • contagious
       • direct contact
       • fomites
     • Treatment
       • I.C. cidofovir
       • curettage
       • cantharidin
       • imiquimod
       • liquid nitrogen
       • laser therapy
       • Topical
         • imiquidmod
         • salicylic acid
         • glycolyic acid
         • tretinoin
         • sodium nitrate
         • potassium hydroxide

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