Chapter 24: DNA Viruses

What are viruses made of?

DNA or RNA surrounded by a protein coat

Which DNA viruses are single-stranded?

Parvoviruses

Which RNA viruses are double-stranded?

Reoviruses

Where do most DNA viruses replicate?

In the nucleus

Where do most RNA viruses replicate?

In the cytoplasm

What are two types of persistent viral infections?

Chronic and latent

What is a chronic viral infection?

Virus present and multiplying slowly; symptoms either mild or absent

What is a latent viral infection?

Virus dormant after lytic cycle; can reactivate.

What is a teratogenic virus?

A virus that crosses the placenta and causes developmental defects

What do poxviruses produce on the skin?

Pustules called pocks or pox

Where do poxviruses replicate?

In the cytoplasm (factory areas)

Which disease was the first eliminated by vaccination?

Smallpox

Which smallpox type is more severe (variola major or minor)?

Variola major

How is smallpox transmitted?

Inhalation or skin contact

What feature is shared by all herpesviruses?

Latency and recurrent infections

What is an episome?

Circular extrachromosomal viral DNA during latency

What does HSV-1 usually cause?

cold sores, fever blisters

What does HSV-2 usually cause?

Genital herpes

How are HSV infections transmitted?

Direct contact with secretions

What triggers HSV recurrence?

Stress, fever, and UV light

What is herpetic gingivostomatitis?

HSV-1 infection of the mouth/throat in children

What is herpetic keratitis?

HSV eye infection; can cause blindness

What is herpetic whitlow?

Painful HSV infection of a finger

What is neonatal herpes?

HSV infection during birth

What does Varicella-zoster virus (VZV) infection cause?

Chickenpox (primary) and shingles

Where does VZV remain latent?

Sensory neurons

What are shingles lesions distributed along?

Dermatomes

What vaccines exist for VZV?

Live attenuated

What is a key feature of Cytomegalovirus (CMV)?

Giant cells with nuclear inclusions

How is CMV transmitted?

saliva, urine, and breast milk.

What cells does Epstein-Barr virus (EBV) infect?

Lymphoid tissue and salivary glands

How is EBV transmitted?

Saliva (“kissing disease”)

What disease does EBV commonly cause?

Infectious mononucleosis

Name two cancers associated with EBV.

Burkitt lymphoma & nasopharyngeal carcinoma

What does HHV-6 cause in infants?

Roseola (high fever → rash)

What is unique about the HBV genome?

both single- and double-stranded DNA

Where does HBV multiply?

in the liver

How is HBV transmitted?

Blood, needles, and sex

What major cancer is linked to chronic HBV?

Hepatocellular carcinoma

Symptoms of HBV.

Jaundice and enlarged liver

What does HPV cause?

Papillomas (warts)

How is HPV transmitted?

Direct contact, contaminated fomites, and sexual contact

What type of wart is an STD?

Genital warts

Plantar warts

deeps sore on soles of the foot

Common seed warts

painless rough growth on fingers

Are parvoviruses enveloped or nonenveloped?

Nonenveloped

Are parvoviruses single- or double-stranded DNA?

Single-stranded DNA

What does human parvovirus B19 cause?

Erythema infectiosum (fifth disease)

What are symptoms of fifth disease?

rash on cheeks

What risk does B19 pose to fetuses?

fatal anemia

What is adeno-associated virus (AAV)?

A defective virus requiring adenovirus to replicate