2.3 - NAKED DNA VIRUSES
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How does the presence or absence of an envelope impact the entry mechanism of naked DNA viruses?

  • Naked viruses are directly injected into the host cell cytoplasm.
  • Naked viruses enter through specialized protein channels on the host cell surface.
  • Naked viruses utilize endocytosis followed by uncoating within the cell. (correct)
  • Naked viruses enter through direct fusion with the host cell membrane.

Parvovirus B19, a naked DNA virus, causes which of the following diseases?

  • Common cold
  • Genital warts
  • Hepatitis
  • Fifth disease (erythema infectiosum) (correct)

What role do the capsid proteins of naked DNA viruses play in the infection process?

  • They bind to specific receptors on the host cell surface for attachment. (correct)
  • They create channels for direct entry into the host cell cytoplasm.
  • They act as enzymes for viral genome replication within the host cell.
  • They facilitate fusion with the host cell membrane for entry.

Which statement accurately describes the process of uncoating for naked DNA viruses?

<p>The capsid undergoes disassembly, releasing the DNA genome into the cytoplasm. (D)</p> Signup and view all the answers

What are the characteristic features that distinguish naked DNA viruses from enveloped viruses?

<p>Naked DNA viruses lack an envelope, while enveloped viruses have a lipid bilayer membrane surrounding their capsid. (D)</p> Signup and view all the answers

What is the main difference between the DNA genome structure of parvoviruses and the other naked DNA viruses discussed?

<p>Parvoviruses have a single-stranded DNA genome, while the others have double-stranded DNA. (B)</p> Signup and view all the answers

Which of the following methods is NOT typically used for diagnosing infections caused by naked DNA viruses?

<p>Culture of viral isolates in a laboratory setting (B)</p> Signup and view all the answers

Which of these diseases is NOT caused by a naked DNA virus?

<p>Herpes simplex virus infection (B)</p> Signup and view all the answers

Which of these types of naked DNA viruses is LEAST likely to be associated with cancer development?

<p>Parvoviruses (D)</p> Signup and view all the answers

What is the time frame for symptoms to appear after a human infection with parvovirus B19?

<p>14 days (D)</p> Signup and view all the answers

Which symptom is NOT associated with adenovirus infections?

<p>Slapped cheek rash (D)</p> Signup and view all the answers

Which prevention method is specifically recommended for preventing adenovirus outbreaks in swimming pools?

<p>Proper chlorination (A)</p> Signup and view all the answers

Which strain of HPV is primarily associated with causing condyloma?

<p>HPV-6 (D)</p> Signup and view all the answers

What is a characteristic of the adenovirus vaccine developed for military personnel?

<p>Contains live adenovirus Type 4 and Type 7 (D)</p> Signup and view all the answers

Which step immediately follows the penetration of a virus into a target cell?

<p>Uncoating (C)</p> Signup and view all the answers

What is the final stage of viral replication for naked viruses?

<p>Lysis &amp; release (C)</p> Signup and view all the answers

Which of the following is NOT a step involved in the viral replication process?

<p>Recombination (C)</p> Signup and view all the answers

Which of the following processes represents how enveloped viruses typically release from a host cell?

<p>Budding (C)</p> Signup and view all the answers

In the context of naked DNA viruses, what does the mnemonic 'PAPPPA' represent?

<p>Classifications of naked DNA viruses (C)</p> Signup and view all the answers

Which of the following characteristics distinguishes enveloped DNA viruses from naked DNA viruses?

<p>Presence of a lipid membrane (D)</p> Signup and view all the answers

Which step in viral replication involves the production of viral proteins from the viral genome?

<p>Translation (D)</p> Signup and view all the answers

What role does 'Lysis' play in the lifecycle of naked DNA viruses?

<p>It facilitates the release of new virions. (D)</p> Signup and view all the answers

Which DNA viruses replicate in the nucleus using host cell's RNA polymerase for mRNA production?

<p>Adenovirus (D)</p> Signup and view all the answers

What process occurs after the capsid is removed from DNA viruses?

<p>Delivery to the nucleus for uncoating (D)</p> Signup and view all the answers

Which of the following is NOT a characteristic of double-stranded DNA viruses?

<p>Require reverse transcriptase for replication (A)</p> Signup and view all the answers

Which statement correctly describes the replication of single-stranded DNA viruses?

<p>They must first convert their genome to dsDNA for replication. (A)</p> Signup and view all the answers

How are progeny viral DNA and proteins assembled in DNA viruses?

<p>Progeny DNA, proteins, and capsid are assembled together. (D)</p> Signup and view all the answers

What typically occurs during the release of non-enveloped DNA viruses from the host cell?

<p>Lysis of the cell (D)</p> Signup and view all the answers

Which viral family is solely represented by single-stranded DNA?

<p>Parvoviridae (B)</p> Signup and view all the answers

What distinguishes the entry of DNA viruses into the nucleus from most RNA viruses?

<p>Most RNA viruses do not enter the nucleus. (D)</p> Signup and view all the answers

What is the primary risk factor for developing anogenital warts caused by human papillomavirus (HPV)?

<p>Number of sexual partners (D)</p> Signup and view all the answers

Which mechanism allows dsDNA viruses to perpetuate the viral life cycle without intact virions?

<p>Infectious purified nucleic acids (B)</p> Signup and view all the answers

Which HPV types are primarily associated with causing genital warts?

<p>HPV 6 and 11 (C)</p> Signup and view all the answers

Which of the following is NOT a diagnostic test for papillomavirus infections?

<p>Blood glucose test (C)</p> Signup and view all the answers

What is the suggested age range for receiving the Gardasil 9 vaccine?

<p>9 to 45 years (A)</p> Signup and view all the answers

What complication can occur with JC virus infections in immunocompromised individuals?

<p>Progressive multifocal leukoencephalopathy (PML) (A)</p> Signup and view all the answers

Which treatment is specifically prescribed for destroying genital wart tissue?

<p>Podofilox (C)</p> Signup and view all the answers

What is a common characteristic of BK virus infections?

<p>It is generally harmless unless the immune system is weakened (A)</p> Signup and view all the answers

Which treatment for warts is NOT a procedure performed in a doctor's office?

<p>Salicylic acid application (B)</p> Signup and view all the answers

What is the mechanism of the acetic acid test for identifying HPV lesions?

<p>It causes the lesions to change color to white (C)</p> Signup and view all the answers

Which preventive measure is recommended for cervical cancer aside from vaccination?

<p>Regular pap smears (D)</p> Signup and view all the answers

Flashcards

Viral Replication Steps

The process by which viruses reproduce, involving multiple stages.

Recognition of Target Cell

The first step where the virus identifies a suitable host cell to infect.

Attachment

The step where the virus attaches to the surface of the target cell.

Penetration

The process by which the virus enters the host cell after attachment.

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Uncoating

The removal of the viral capsid to release the viral genome into the host cell.

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Transcription & Translation

The processes of creating RNA from DNA and producing proteins respectively.

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Assembly of Virus

The stage where viral components are assembled into new virus particles.

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Lysis & Release

The final step where new viruses exit the host cell, often causing cell destruction.

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Parvovirus B19

A virus that primarily infects humans, causing Fifth Disease.

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Fifth Disease Symptoms

Includes slapped cheek rash, trunk rash, and joint pain, appearing ~14 days after infection.

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Adenovirus Overview

A virus causing symptoms like conjunctivitis, flu-like symptoms, and gastroenteritis; severe cases may require ribavirin.

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Adenovirus Prevention

No specific treatment; focus on symptom relief and proper swimming pool chlorination.

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HPV Detection Method

Developed by Eva Ramón Gallegos and Elizabeth Maldonado, allows for efficient HPV detection with 98% predictive value.

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Naked DNA viruses

Viruses without a lipid envelope; consist of only nucleic acid and capsid.

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Examples of naked DNA viruses

Includes Papillomavirus, Polyomavirus, Parvovirus, and Adenovirus.

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dsDNA

Double-stranded DNA, found in viruses like Papillomavirus and Adenovirus.

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ssDNA

Single-stranded DNA, characteristic of Parvovirus.

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Icosahedral capsid

A common virus shape; symmetrical 20-sided structure.

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Penetration process

The method viruses use to enter a host cell, includes endocytosis.

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Endocytosis

Process by which cells engulf material; a means of viral entry.

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Viropexis

Direct attachment and entry of a virus into a cell without engulfing.

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Receptors in virus entry

Specific molecules on host cell surfaces that viruses attach to.

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Capsid

The protein shell that encases the viral genome.

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Nucleocapsid

The combined structure of the viral genome and its capsid.

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Host cell RNA polymerase

An enzyme from the host cell used by viruses to transcribe their DNA into mRNA.

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Viral protein synthesis

The process where host or viral RNA polymerases create viral proteins from viral mRNA.

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Viral life cycle perpetuation

The ability of dsDNA viruses to maintain infectivity even when nucleic acids are purified.

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Viral release mechanism

Process of viruses exiting host cells, often through cell lysis in non-enveloped viruses.

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Human Papillomavirus (HPV)

A virus with various strains causing warts and cervical cancer.

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HPV Types 1-4

These types mainly cause common skin warts, such as plantar and flat warts.

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HPV Types 6 & 11

Strains that cause genital warts known as condyloma.

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Signs of HPV Infection

Common signs include various types of warts and possibly cancer.

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Risk Factors for HPV

Factors include multiple sexual partners and immune system weakness.

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Acetic Acid Test

A diagnostic test where HPV lesions turn white when acetic acid is applied.

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Gardasil 9 Vaccine

Vaccine protecting against cervical cancer and genital warts, suitable for ages 9-45.

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JC Virus

A polyomavirus causing progressive multifocal leukoencephalopathy in immunocompromised patients.

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BK Virus

A polyomavirus that usually causes mild cold-like symptoms and can lead to kidney issues.

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Treatment for Warts

Includes salicylic acid, podofilox, and surgical options for removal.

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Study Notes

Naked DNA Viruses

  • Naked DNA viruses lack an envelope, unlike enveloped viruses.
  • These viruses replicate within the host cell's nucleus.
  • Viral recognition, attachment, penetration, uncoating, replication, assembly, and release are steps of viral replication.
  • Viral replication has both common steps and virus-specific differences.
  • Examples of naked DNA viruses include adenoviruses, papillomaviruses, polyomaviruses, and parvoviruses.

Viral Replication Steps

  • Recognition of target cell
  • Attachment
  • Penetration
  • Uncoating
  • Transcription & protein synthesis
  • Replication
  • Assembly of virus
  • Lysis & release (naked) or budding & release (enveloped)

Classification of DNA and RNA Viruses

  • Different viral classifications based on DNA or RNA, strand type, symmetry, and presence or absence of envelope.

Human Papillomavirus (HPV)

  • HPV infection is a highly common STI.
  • Certain HPV types can cause cervical cancer and other cancers.
  • Transmission occurs via skin-to-skin contact, and sexual contact, and inanimate objects.
  • HPV infections are typically diagnosed through history and physical examination.
  • HPV types 1-4 cause common warts.
  • HPV types 6 and 11 usually cause genital warts.

Polyomaviruses (JC, BK viruses)

  • BK Virus causes renal disease in patients with AIDS.
  • JC virus causes progressive multifocal leukoencephalopathy (PML).
  • Transmission of viruses is typically respiratory.
  • Infections are detected via PCR and blood/urine tests.
  • Treatments are supportive, due to a lack of effective and non-toxic antiviral drugs.

Parvovirus B19

  • Parvovirus B19 typically causes fifth disease in humans.
  • Symptoms include a red rash on the cheeks and body, swollen joints, and can lead to chronic anemia.
  • A 14-day infection period is usual.

Adenoviruses

  • Adenoviruses can be associated with respiratory and gastrointestinal infections.
  • Common symptoms include sore throat, fever, pink eye, and pneumonia.
  • Severe adenovirus infections may occur in immunocompromised individuals.
  • Adenovirus infections are diagnosed based on symptoms and possibly PCR tests.
  • Treatment involves managing symptoms with over-the-counter medications, and maintaining proper chlorination in public pools.

Viral Replication: Differences between DNA and RNA viruses

  • Replication method differs between DNA and RNA viruses
  • DNA viruses typically replicate in the host cell's nucleus.
  • Most RNA viruses replicate in the cytoplasm of the host cell.
  • Exception: Some RNA viruses (retroviruses) will go through an additional step called reverse transcription, where an RNA genome is transformed into DNA before integrating into the host's genome.

General Viral Replication

  • Viral entry through host cells
  • Viral genome replication
  • Synthesis of viral proteins, and assembly of new virions
  • Virus release from host cell

Viral Structure

  • Capsids, as examples of viral structures, are essential.
  • Icosahedral, helical, or complex structures often exist in capsids.
  • Most naked DNA viruses have icosahedral capsids.

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Naked DNA Viruses - Microbiology Block 2 - 2.3 PDF

Description

This quiz covers the characteristics of naked DNA viruses and the detailed steps involved in viral replication. Understand how these viruses, such as HPV and adenoviruses, differ from enveloped viruses. Test your knowledge on viral classifications and the implications of specific virus types on human health.

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