DNA viruses

Question 1

Nonenveloped, SS linear, icosahedral nucleocapsid DNA viruses

Answer 1

Paroviridae

• Parvovirus B19 - erythema infectiosum (immune complexes), transient aplastic anemia criiss (patients with sickle cell, thalassemia), hydrops fetalis

Question 2

Nonenveloped, DS circular, icosahedral nucleocapsid DNA viruses

Answer 2

Papovaviridae

• Papillomavirus - *HPV; *E6 (blocks p53), E7 (blocks Rb); 1% acetic acid turns lesions white
• Polyomavirus - JC virus (Progressive Multifocal Leukoencephalopathy in immunocompromised); BK virus (commonly targets kidney in transplant patients)

Question 3

Nonenveloped, DS linear, icosahedral nucleocapsid DNA viruses

Answer 3

Adenoviridae

• Mastadenovirus - Adenoviruses (conjunctivitis, URI, hemorrhagic cystitis, gastroenteritis); binds mucosal cells via hemagglutinin; latent viruses often remain in tonsillar adenoids following infection

Question 4

Enveloped, DS linear, icosahedral nucleocapsid DNA viruses

Answer 4

**Herpesviridae - **replicates in nucleus (eosinophilic Cowdry intranuclear inclusion bodies), only virus that obtains envelope by budding from nuclear membrane

• Simplexvirus - HSV-1/2 (temporal lobe encephalitis); multinucleate giant cells on Tzanck smear
• Varicellovirus - Varicella-Zoster virus; multinucleate giant cells on Tzanck smear
• Cytomegalovirus - congenital CMV (deafness, hepatosplenomegaly, microencaphly); giant cells with “owl’s eye” intranuclear inclusion bodies
• Lymphocryptovirus - EBV (mono); binds to and infects B cells via C3d complement receptor; monospot+ (vs. CMV); rash when treated with ampicillin
• HHV 6/7 - Roseola (high fever followed by rash on trunk)
• HHV 8 - *Kaposi sarcoma *(endothelial neoplasm)

Question 5

Enveloped, DS circular, icosahedral nucleocapsid DNA viruses

Answer 5

Hepadnaviridae

• Orthohepadnavirus - *Hepatitis B virus; *replicates in hepatocytes by first completing the partially dsDNA genoma via viral DNA polymerase

Question 6

Enveloped, DS linear, complex nucleocapsid DNA viruses

Answer 6

Poxviridae

• Orthopoxvirus - Smallpox (Variola) virus;
• Molluscipoxvirus - Molluscum contagiosum (flesh-colored pearly nodules with central craters); forms large eosinophilic inclusion bodies (molloscum bodies); limited to the epidermis and does not establish dormant state (unlike varicella or HSV infections)