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Questions and Answers
Why is a DNA-dependent RNA polymerase present within the poxvirus virion?
Why is a DNA-dependent RNA polymerase present within the poxvirus virion?
- To facilitate the breakdown of host cell DNA, providing nucleotides for viral replication.
- To enable viral mRNA transcription within the cytoplasm, independent of host nuclear enzymes. (correct)
- To initiate reverse transcription of the viral genome for integration into the host DNA.
- To protect the viral DNA genome from degradation by host cell restriction enzymes.
What is the most critical factor that led to the successful eradication of smallpox?
What is the most critical factor that led to the successful eradication of smallpox?
- The virus's strict zoonotic transmission cycle, which allowed for targeted interventions in animal reservoirs.
- The virus's complex antigenic structure, which elicited a broad and long-lasting immune response.
- The availability of antiviral drugs that specifically target variola virus.
- The existence of a single, stable serotype of the virus, facilitating effective vaccine development and deployment. (correct)
How does the rash distribution in smallpox (Variola) infection differ from that of varicella (chickenpox)?
How does the rash distribution in smallpox (Variola) infection differ from that of varicella (chickenpox)?
- Smallpox exhibits a centrifugal distribution, with lesions more prominent on the face and extremities, whereas varicella has lesions in various stages at the same time. (correct)
- Smallpox presents with lesions in all stages simultaneously, unlike varicella, which shows sequential development.
- Smallpox lesions appear predominantly on the palms and soles, while varicella spares these areas.
- Smallpox exhibits a centripetal distribution, with lesions concentrated on the trunk, whereas varicella has a centrifugal distribution.
If a patient presents with small, flesh-colored, painless papules with an umbilicated center, especially in the genital region, which virus is the most likely causative agent?
If a patient presents with small, flesh-colored, painless papules with an umbilicated center, especially in the genital region, which virus is the most likely causative agent?
What is the primary reason for the discontinuation of routine smallpox vaccination in the general population?
What is the primary reason for the discontinuation of routine smallpox vaccination in the general population?
Which aspect of M-pox (formerly monkeypox) poses the greatest challenge for its complete eradication, compared to smallpox?
Which aspect of M-pox (formerly monkeypox) poses the greatest challenge for its complete eradication, compared to smallpox?
A researcher is studying the pathogenesis of smallpox in a laboratory setting. What would be the most appropriate method to detect the presence of the virus in vesicular fluid?
A researcher is studying the pathogenesis of smallpox in a laboratory setting. What would be the most appropriate method to detect the presence of the virus in vesicular fluid?
How does M-pox differ clinically from smallpox?
How does M-pox differ clinically from smallpox?
What is the best approach to manage Molluscum contagiosum lesions in an immunocompetent adult?
What is the best approach to manage Molluscum contagiosum lesions in an immunocompetent adult?
Which population group is most likely to experience severe or disseminated Molluscum contagiosum infections?
Which population group is most likely to experience severe or disseminated Molluscum contagiosum infections?
Flashcards
Variola Virus
Variola Virus
Agent of smallpox, eradicated due to a single stable serotype.
Poxvirus Characteristics
Poxvirus Characteristics
Brick-shaped virus with linear, double-stranded DNA, replicates in cytoplasm, contains DNA-dependent RNA polymerase.
Smallpox Transmission
Smallpox Transmission
Respiratory aerosols and direct contact with skin lesions or fomites.
Smallpox Pathogenesis
Smallpox Pathogenesis
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Smallpox Clinical Symptoms
Smallpox Clinical Symptoms
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M-pox (Monkeypox)
M-pox (Monkeypox)
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Smallpox Vaccine
Smallpox Vaccine
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Molluscum Contagiosum Transmission and Lesions
Molluscum Contagiosum Transmission and Lesions
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Molluscum Contagiosum Lesion Characteristics
Molluscum Contagiosum Lesion Characteristics
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Molluscum Contagiosum Treatment
Molluscum Contagiosum Treatment
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Study Notes
- Poxviridae family includes smallpox (variola virus), M-pox, and molluscum contagiosum virus.
Smallpox (Variola Virus)
- Smallpox is caused by the variola virus.
- It is the only human disease eradicated worldwide.
- Eradication was possible due to the existence of a single, stable serotype.
Variola Virus Properties
- Poxviruses are brick-shaped with linear, double-stranded DNA.
- They feature a disc-shaped core within a double membrane and a lipoprotein envelope.
- The virion contains its own DNA-dependent RNA polymerase.
- The virus needs its own polymerase, as it replicates in the cytoplasm, not the nucleus.
Transmission and Pathogenesis
- Spread occurs through respiratory aerosols and direct contact with the virus.
- Contact can be from skin lesions or contaminated objects (fomites).
- Initial infection occurs in the upper respiratory tract and lymph nodes.
- Primary viremia occurs as the virus enters the bloodstream.
- Internal organs become infected, leading to secondary viremia.
- The virus spreads to the skin and replicates, causing a rash.
- The rash and related skin damage is the result of cytotoxic T cells attacking infected cells.
- All the above events occur during the incubation period where the patient is asymptomatic.
Clinical Symptoms
- Incubation lasts 7-14 days, followed by sudden prodromal symptoms like fever and malaise.
- Rash appears, more severe on the face and extremities (centrifugal distribution).
- Rash evolves through stages: macules, papules, vesicles, pustules, and crusts over 2-3 weeks.
- Unlike varicella (chickenpox), lesions are not all in the same stage at the same time.
Diagnosis and Prevention
- Historically diagnosed by growing the virus in cell culture or chick embryos.
- Alternatively, viral antigens could be detected in vesicular fluid via immunofluorescence.
- Eradication was achieved through global vaccination efforts.
- The vaccine contained a live, attenuated vaccine virus similar to smallpox.
- Routine vaccination of civilians has been discontinued because of eradication.
M-pox
- M-pox, formerly known as monkeypox virus, is caused by the M-pox virus
- Likely harbored by African rodents and non-human primates, which can infect humans.
- Symptoms are similar to smallpox, but milder, and M-pox is rarely fatal.
- M-pox is not related to chickenpox.
- The mortality rate is about 11%.
- Higher risk of severe illness or death for those with weakened immune systems, children under one year, people with a history of eczema, and pregnant/breastfeeding individuals.
Molluscum Contagiosum Virus
- A distinct member of the poxvirus family.
Transmission and Symptoms
- Spread through close personal contact, including sexual contact.
- Common in children, with lesions often around the eye and on the trunk.
- Adults often have lesions in the genital area.
- Lesions are small, 2-5 mm, flesh-colored papules on the skin or mucous membrane.
- Lesions are typically painless, non-itchy, and non-inflamed.
- Lesions display a characteristic cup-shaped or umbilicated crater with a white core.
Risk Groups and Treatment
- Children, people with AIDS, and immunocompetent individuals are most at risk.
- Immunocompetent patients typically experience self-limited infections lasting months.
- Patients with reduced cell-mediated immunity (e.g., AIDS) may develop large, numerous lesions.
- Lesion removal via curettage or liquid nitrogen can be effective.
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