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DNA Viruses

DNA Viruses. Samuel Aguazim MD Lange Chapters 37 & 38. Two types of DNA Viruses. 1. Naked: Parvovirus, Papovaviruses, Adenovirus 2. Enveloped: Hepadnaviruses, Herpesviruses, Poxviruses. Replication.

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DNA Viruses

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  1. DNA Viruses Samuel Aguazim MD Lange Chapters 37 & 38

  2. Two types of DNA Viruses 1. Naked: Parvovirus, Papovaviruses, Adenovirus 2. Enveloped: Hepadnaviruses, Herpesviruses, Poxviruses

  3. Replication • All DNA Viruses except hepatitis B duplicate their DNA by using it as a template to make more DNA • Hepatitis B’s DNA polymerase has reverse transcriptase activity.

  4. Parvoviruses • Parvovirus B19 is a naked, single stranded DNA virus that replicates in erythrocyte precursors. • Reservior: respiratory droplet • Transmission: resp droplet, formites, vertical transmission. Diseases • Fifth disease (erythema infectiosum, slapped cheek fever) • Chronic anemia in immunocompromised • Aplastic crises in sickle cell patients • Hydrops fetalis • Rash & arthralgias( adult predominantly)

  5. Papovaviruses (Papilloma virus) • Human Papillomavirus Diseases: • Cervical and Penile Carcinoma:HPV 16 and 18: Early proteins E6 and E7 inactivate tumor supressor functions of p53 and p110-Rb respectively. • Cutaneous warts(skin) HPV 2 & 4 • Plantar warts:HPV 1 • Anogenital Warts (condylomata acuminata)- may regrow after removal but are benign.

  6. Vaccine for HPV • Gardacil covers HPV 6,11,16 & 18 • DIAGNOSIS:Cutaneous- clinical ground • Genital: finding of Koilocytic cells( cells with perinuclearcytoplasmic vacuolization & nuclear enlargement) in pap smears. • Treatment: Imiquimod ( induced pro- inflammatory cytokines)

  7. Koilocytes

  8. Papovaviruses(Polyomaviruses) Diseases: • BK: • Reservior & transmission: respiratory • Pathogenesis: latent infection in kidney • Causes kidney disease and is often associated with kidney transplantation. • Diagnosis: ELISA, PCR • TREATMENT: SUPPORTIVE • VIRUS:JC • RESERVIOR AND TRANSMISSION: RESPIRATORY • PATHOGENESIS: Infect in oligodendrocytes= demyelination • Is associated with progressive multifocal leukoencephalopathy, a slow disease of immunocompromised patients • Diagnosis: ELISA, PCR • TREATMENT : SUPPORTIVE

  9. Adenoviruses • Naked, icosahedralds viruses with fibers projecting from the capsid’spenton subunits. Diseases: • Pharyngoconjunctivitis and keratoconjunctivitis:“pink eye” – conjuntivae are inflamed with a watery exudate • Acute respiratory diseases: military/vaccine serotypes 4,7 & 21 • Adenovirus 40 and 41: gastroenteritis • Acute hemorrhagic cystitis( boys 5-15) 11,15 • Gastro enteritis ( infantile): day care( 40-41)

  10. Adenovirus Fibers

  11. Hepadnavirus • We will have a separate lecture for the Hepatitis Viruses

  12. Herpesviruses

  13. Herpesviruses • Herpes simplex viruses I & II • Varicella-Zoster Virus • Cytomegalovirus • Epstein Barr Virus (EBV) • Human Herpes Viruses 6 &8 • Characteristics • Large, Ds DNA • Enveloped(derived envelop from nuclear membrane), icosahedral • Intranuclear inclusion bodies • Establishes latency

  14. Herpes Simplex Viruses I & II • Cause either acute or latent infections • Latent infections cannot be treated by acylovir: • reason: virus does not make thymidine kinase which is required to activate acyclovir by phosphorylation of acyclovir.

  15. HSV-1 & HSV II

  16. Herpes simplex virus can set up a primary infection in the lips, move to the trigeminal  ganglion where it can remain latent.

  17. Tzank smear

  18. Gingivostomatitis looks different from a cold sore

  19. Herpetic whitlow on the wrist

  20. Genital herpes on penis area

  21. Varicella Zoster Virus • Primary Infection: Varicella or Chicken pox • Lesions start as papular and then progress to vesicular and then pustular. • Asynchronous rash • Latent in neurons • Contagious for 6 days after all lesions have dried • Live attenuated vaccine reduces the incidence of chicken pox.

  22. Varicella Zoster Virus (VZV) 2. Secondary Infection: • Herpes Zoster or Shingles • Clusters of vesicular lesions, usually along a single sensory dermatome, accompanied by nerve pain • Tx: Varicella zoster immunoglobulin (VZIG) & Acyclovir • Both chicken pox and VZV are much more severe in immunocompromised patients

  23. Herpes Zoster following the dermatomal pattern

  24. Cytomegalovirus (CMV) • crosses the placenta, acquired during birth, mother’s milk, direct contact, sexual contact, blood transfusions or organ transplant. • When CMV replicates, it produces cells with typical large, purple intranuclear inclusion bodies surrounded by a halo (owl’s eyes)

  25. OWL’S EYE INCLUSION

  26. Cytomegalovirus (CMV) Diseases • Many are asymptomatic • Heterophile negative mononucleosis • Retinitis and interstitial pneumonitis in immunocompromised patients • Neonates: cytomegalic inclusion disease – hepatosplenomegaly with thrombocytopenic purpura, pneumonitis, CNS calcifications and microcephaly.

  27. Epstein Barr Virus • Infects oral epithelial cells and B-lymphocytes Diseases • Mononucleosis: - 15-25 year old: called the “kissing disease” - severe fatigue - pharyngitis/tonsillitis similar to strep throat. - postcervical lymphadenopathy - hepatomegaly and spenomegaly • Burkitt’s lymphoma -Oncogenic potential in Africa • Nasopharyngeal carcinoma – men from Southern China • Hairy Cell leukoplakia of the tongue • Interstitial pneumonitis in infants and lymphoma

  28. Oral hairy leukoplakia of tongue in AIDS due to Epstein-Barr virus

  29. Diagnosis of EBV Mononucleosis • Monospot test (Heterophile Antibody Test) - Heterophile antibodies react with animal red blood cell antigens rather than with the virus • Tests for specific EBV antibodies to EA (early antigens) or VCA (viral capsid antigens)

  30. Atypical Lymphocyte (Downey Cells): Mononucleosis

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