Microbiology trans - DNA Viruses

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Questions and Answers

What is the recommended dosage of Acyclovir for immunosuppressed patients with zoster?

800 mg five times daily (correct)

1 g by mouth three times daily

500 mg three times daily

400 mg twice daily

When should antiviral therapy for zoster be initiated?

As soon as the rash appears

Within 5-7 days after symptoms

Within 24-48 hours of symptoms (correct)

Within 72 hours of symptoms

Which antiviral medication is taken three times daily for 7 days?

Ganciclovir

Famciclovir (correct)

Acyclovir

Valacyclovir

What is the duration of therapy for Valacyclovir when prescribed for zoster?

5-7 days Signup and view all the answers

What is another name for Epstein-Barr Virus?

HHV-4 Signup and view all the answers

How is Epstein-Barr Virus primarily spread?

Bodily fluids, primarily saliva Signup and view all the answers

What is the primary method used for identifying adenoviruses in infected cells?

Immunofluorescence test using anti hexon antibody Signup and view all the answers

Which sample type is NOT mentioned for adenovirus detection?

Saliva Signup and view all the answers

Which diagnostic method can identify any member of the adenovirus group?

Complement fixation test Signup and view all the answers

What type of virus structure does adenovirus have?

Naked virus with icosahedral nucleocapsid Signup and view all the answers

Which of the following methods can be used to directly detect viral antigens?

Staining of basal epithelial cells Signup and view all the answers

What is the significance of a four-fold or greater rise in complement fixing antibody titer?

Signifies recent infection Signup and view all the answers

What kind of DNA do adenoviruses possess?

Double-stranded linear DNA Signup and view all the answers

How is adenovirus primarily transmitted?

Direct contact with infected individuals and contaminated surfaces Signup and view all the answers

Which HPV types are responsible for the majority of cervical cancers?

Types 16 and 18 Signup and view all the answers

What is the primary feature of papillomaviruses in relation to their infection?

They exhibit great tissue and cell specificity. Signup and view all the answers

Which virus family is classified as non-enveloped DNA viruses?

Parvoviridae Signup and view all the answers

What is the replication location for parvoviruses?

Nucleus Signup and view all the answers

Which agent cannot inactivate viruses?

Ethanol Signup and view all the answers

What must happen for parvoviruses to use the host's DNA replication machinery?

The host must enter the S-phase. Signup and view all the answers

Which of the following viruses is known as Cytomegalovirus?

HHV-5 Signup and view all the answers

Which family of viruses is implicated in causing diseases similar to human herpesvirus?

Herpesviruses Signup and view all the answers

What mechanism do parvoviruses utilize to enter host cells?

Endocytosis Signup and view all the answers

Which of the following viruses does NOT belong to the Herpesviruses group?

Adenovirus Signup and view all the answers

Which phase of the host cell cycle is critical for parvovirus replication?

S phase Signup and view all the answers

What is a major clinical characteristic of varicella?

Generalized vesicular eruption of the skin and mucous membranes Signup and view all the answers

What is the most common source of herpes simplex virus infection in newborns?

The mother Signup and view all the answers

What distinguishes varicella from herpes zoster?

Varicella features successive crops of vesicles Signup and view all the answers

What is the greatest susceptibility for primary herpes infection in newborns?

Between 6 months to 2 years Signup and view all the answers

Which group is at higher risk for severe complications of varicella?

Adults and immunocompromised individuals Signup and view all the answers

What is a common complication of varicella in neonates, adults, and immunocompromised patients?

Varicella pneumonia Signup and view all the answers

How do newborns typically acquire herpes simplex virus?

In utero or during the birth process Signup and view all the answers

What is a common route of infection for a newborn during delivery?

Contact with herpetic lesions in the birth canal Signup and view all the answers

Which statement about neonatal varicella is true?

It can occur from maternal infection before or after birth. Signup and view all the answers

What is the mortality rate for varicella in normal children?

Very low, with complications being rare Signup and view all the answers

What is one potential benefit of antiviral drugs such as Acyclovir?

It shortens healing time and reduces recurrences Signup and view all the answers

What is a characteristic of how a newborn's immune response to HSV works?

Maternal antibodies are present but do not prevent infection Signup and view all the answers

What is a rare but possible life-threatening complication of varicella?

Encephalitis Signup and view all the answers

What does a cesarean section aim to prevent in mothers with genital herpes?

Transmission of the virus to the baby Signup and view all the answers

How are lesions of varicella and herpes zoster characterized?

Both result in vesicular lesions Signup and view all the answers

What type of pattern does varicella infection follow?

A centrifugal pattern Signup and view all the answers

What effect do maternal antibodies have on subsequent herpes infections in the newborn?

They may modify subsequent disease but cannot prevent reactivation Signup and view all the answers

What often follows varicella infection in survivors?

Permanent sequelae Signup and view all the answers

What is the primary role of antiviral therapy in patients with genital herpes?

To suppress symptoms and reduce risk of transmission Signup and view all the answers

Why is it significant for mothers with herpes to understand asymptomatic shedding?

It is a common source of transmission even when there are no visible symptoms Signup and view all the answers

Study Notes

Overview of DNA Viruses

DNA viruses categorized into two groups: non-enveloped and enveloped.
Non-enveloped DNA viruses include Parvoviridae, Adenoviruses, and Papovaviridae.
Enveloped DNA viruses include Herpesviruses, Poxviruses, and Hepatitis B Virus.

Parvoviridae

Parvoviruses depend on host cellular functions for replication.
Viral DNA replication occurs within the nucleus after endocytosis.
Cannot induce host cells into S-phase; await the host cell cycle to enter.

Adenoviruses

Detected in respiratory samples, conjunctiva, blood, stool, and urine; early sample collection enhances detection.
Diagnosis can employ immunofluorescence tests, hemagglutination inhibition tests, and polymerase chain reaction (PCR) assays.
Hexon protein is the primary structural protein of Adenovirus.
Transmission occurs via direct contact, sexual contact, or contaminated surfaces (fomites).

Human Papillomavirus (HPV)

Causes hyperplastic epithelial lesions across diverse host tissues.
Infection is tissue-specific, primarily affecting skin and mucous membranes.
Types 16 and 18 are linked to cervical carcinoma, contributing to over 70% of cases.

Herpes Simplex Virus (HSV)

Neonatal herpes can originate from infected mothers during birth or after birth.
Newborns are especially vulnerable; maternal antibodies offer temporary protection but do not prevent infection.
Antiviral treatments (Acyclovir, Valacyclovir) suppress symptoms, aid healing, and reduce recurrences.

Varicella Zoster Virus (VZV)

Causes Chickenpox (Varicella), characterized by a generalized vesicular skin eruption.
Complications are rare in children; more severe in adults and immunocompromised patients.
Diagnosis and treatment regimens involve antiviral medications like Acyclovir, Famciclovir, and Valacyclovir administered promptly within 24-48 hours of symptom onset.

Epstein-Barr Virus (EBV)

Known as Human herpesvirus-4, primarily transmitted through saliva.
In healthy individuals, most infected cells are effectively eliminated, reducing virus spread.

Clinical Notes

For genital herpes, antiviral therapy can reduce asymptomatic shedding and transmission risk.
Varicella pneumonia is a significant complication in neonates, adults, and immunocompromised individuals.

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Description

This quiz covers the topic of DNA viruses discussed in the Microbiology lecture held on September 13, 2024. It includes details on inactivation methods such as formalin and 𝛃-propiolactone. Test your understanding of the characteristics and classifications of non-enveloped DNA viruses.