Poxviridae, Parvoviridae, Adenoviridae, Papillomaviridae, and Polyomaviridae Flashcards
What are the morphologic features of the family Poxviridae?
- Double-stranded DNA
- Enveloped
- Large in size
Where in the cell do Poxviridae members replicate?
The cytoplasm
What disease does the variola virus cause?
Smallpox
Which virus causes smallpox?
Variola virus
When was the last naturally recorded case of smallpox cured?
The 1970s
When was the most recent outbreak of monkeypox infection?
2022
What disease does molluscum contagiosum virus cause?
Skin infection
What were the factors that lead to the successful eradication of smallpox?
- Variola virus is a DNA virus that is antigenically stable
- The live attenuated vaccine was effective and gave long-term immunity
- The disease affected humans only with no animal reservoir
- All cases were symptomatic, with no subclinical infections or carrier states, meaning the chain of infection could be broken quickly
- The disease had a high mortality rate and survivors were left with permanent scars, so people were willing to participate in vaccination efforts
What are the morphologic features of the family Parvoviridae?
- Single-stranded DNA
- Non-enveloped
- Very small in size
Where in the cell do Parvoviridae members replicate?
The nucleus
Which family of viruses constitutes the smallest DNA viruses?
Parvoviridae
Which family of viruses constitutes the smallest RNA viruses?
Picornaviridae
How are parvovirus 19 and the bocaviruses transmitted?
- Respiratory secretions
- Vertical transmission
What is the tropism of parvovirus B19?
Erythroid progenitor cells
Why does parvovirus B19 not infect mature RBCs?
They lack a nucleus, which is where parvovirus B19 replicates
What is the tropism of bocaviruses?
Respiratory cells
What are the clinical diseases caused by bocavirus?
Upper and lower respiratory infections
What are the diseases commonly caused by parvovirus B19?
- In children: fever and rash (erythema infection; fifth disease; slapped cheek syndrome)
- In adults: arthritis
What diseases can parvovirus B19 cause in special groups of patients?
- Immunosuppressed patients: pure red cell aplasia (chronic anemia)
- In patients with underlying chronic anemia: transient aplastic crisis (severe acute anemia)
- In congenitally infected neonates: hydrops fetalis (potentially fatal anemia)
How are Parvoviridae members diagnosed?
- Clinical presentation
- PCR
- Serology: IgM for primary infection, IgG for past infection
Are there vaccines for members of Parvoviridae?
No
What is the epidemiology of Parvoviridae?
- Infection is common
- There is no latency state
What are the morphological features of the family Adenoviridae?
- Double-stranded DNA
- Non-enveloped
Where in the cell do Adenoviridae members replicate?
In the nucleus
How are Adenoviridae members transmitted?
- Respiratory secretions
- Fecal–oral route
- Direct contact
What is the tropism of Adenoviridae?
Epithelial cells of the:
- respiratory tract,
- eyes,
- GI tract, and
- urinary tract
What are the clinical features of Adenoviridae infections?
- Upper and lower respiratory tract infections: pneumonia and pharyngitis (most common cause of pharyngitis)
- Gastroenteritis
- Conjunctivitis
- Cystitis (infection of the urinary bladder)
How are Adenoviridae members diagnosed?
- Antigen detection
- PCR
How are Adenoviridae infections treated?
Supportive therapy
How are Parvoviridae infections treated?
Supportive therapy
Are there vaccines for members of Adenoviridae?
Live attenuated vaccine is available for a few serotypes (Ad4, Ad7) that cause pneumonia
What is the epidemiology of Adenoviridae?
Infection occurs year-round without seasonality
To which family do the human papillomaviruses (HPV) belong?
Papillomaviridae
What are the morphologic features of the family Papillomaviridae?
- Double-stranded DNA
- Non-enveloped
Where in the cell do Papillomaviridae members replicate?
The nucleus
How are Papillomaviridae infections transmitted?
- Direct contact
- Sexual transmission
What is the course of HPV infections?
- Most infections resolve spontaneously within 2–3 years
- Many infections are totally asymptomatic
- Some HPV types are benign, some have a low risk of causing cancer, and some are high-risk for cancer
How does HPV cause cancer?
The virus has transforming proteins that are related to carcinogenesis
What kinds of cancer can HPV cause?
- Cervical
- Penile
- Anal
- Oropharyngeal
- Vulvar cancer
What is the tropism of Papillomaviridae?
Epithelial cells of the skin and mucous membranes
What are the clinical diseases caused by Papillomaviridae?
- Common warts
- Condyloma acuminata (genital warts), caused mainly by HPV-6 and -11
- Laryngeal papilloma
- Cervical cancer, caused mainly by HPV-16 and -18
- Other cancers (penile, anal, oropharyngeal, vulvar), caused by HPV-16 and -18
Which HPV types are low risk for cancer?
- HPV-6
- HPV-11
Which HPV types are high risk for cancer?
- HPV-16
- HPV-18
How are HPV infections diagnosed?
- Clinical presentation
- Papanicolaou smear (pap smear), a cytology method that looks for precancerous lesions in the cervix
- PCR
How are HPV infections treated?
Mostly do not require treatment
- Surgical excision
- Laser therapy
- Chemical agents (e.g. podophyllotoxin and podophyllin, imiquimod)
Is there a vaccine for HPV?
- Cervarix (bivalent for HPV-16 and -18)
- Gardasil (quadrivalent for HPV-6, -11, -16, and -18)
- A nonavalent vaccine (6, 11, 16, 18, and five other types)
What is the epidemiology of HPV?
- The most common STI
- The global prevalence is about 10%
What are the morpholobic features of Polyomaviridae?
- Double-stranded DNA
- Non-enveloped
Where in the cell do Polyomaviridae members replicate?
The nucleus
What are the members of Polyomaviridae?
- JC virus
- BK virus
- Merkel cell polyomavirus
What is the typical outcome of infection with a Polyomaviridae virus?
Latency in the body without symptoms
How are Polyomaviridae viruses transmitted?
Unknown
What are the clinical diseases caused by BK virus?
Cystitis in bone marrow transplant patients
What are the clinical diseases caused by JC virus?
Progressive multifocal leukoencephalopathy (PML; neurodegenrative disease of the white matter) in AIDS patients
What are the clinical diseases caused by Merkel cell polyomavirus?
Merkel cell carcinoma (a rare skin cancer)
How are Polyomaviridae infections diagnosed?
- PCR
- Radiology
- Histopathology
How are Polyomaviridae infections treated?
No specific treatment
Are there vaccines for members of Polyomaviridae?
No
What is the epidemiology of Polyomaviridae?
- Widely spread
- The majority of humans have been infected by BK virus and JC virus
