DNA & RNA Viruses: Structure, Transmission, and Prevention
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Questions and Answers

What is the structure of the DNA in a Parvovirus?

  • Double-stranded, linear
  • Double-stranded, circular, supercoiled
  • Single-stranded, circular
  • Single-stranded, linear (correct)

    • Which of the following viruses is NOT an example of a Herpesvirus?

  • HSV-2
  • VZV
  • JC virus (correct)
  • HSV-1

    • What is the usual site of latency for HSV-2?

  • Lumbar or sacral sensory ganglia (correct)
  • Cranial or thoracic sensory ganglia
  • Oropharynx
  • Liver

    • What is the route of transmission for HSV-1?

    <p>Via direct contact with virus vesicle and saliva</p> Signup and view all the answers

    What is the primary infection of VZV?

    <p>Varicella</p> Signup and view all the answers

    What type of vaccine contains HBsAg as immunogen?

    <p>Prevention vaccine</p> Signup and view all the answers

    What is the symmetry of the capsid of a Parvovirus?

    <p>Icosahedral</p> Signup and view all the answers

    What is the symmetry of the capsid of Picornavirus?

    <p>Icosahedral</p> Signup and view all the answers

    What is the DNA structure of an Adenovirus?

    <p>Double-stranded, linear</p> Signup and view all the answers

    Which virus is transmitted by the fecal-oral route?

    <p>Hepatitis A virus</p> Signup and view all the answers

    Which of the following viruses has an envelope?

    <p>Poxvirus</p> Signup and view all the answers

    What is the disease caused by Hepatitis B virus?

    <p>Hepatitis B</p> Signup and view all the answers

    What is the result of death of motor neurons in Poliovirus infection?

    <p>Paralytic poliomyelitis</p> Signup and view all the answers

    What is the primary infection of HSV-2?

    <p>Herpes genitalis</p> Signup and view all the answers

    What is the characteristic of the RNA structure of Reovirus?

    <p>Linear, 10 or 11 segments, positive polarity</p> Signup and view all the answers

    Which virus is destroyed by stomach acid?

    <p>Rhinovirus</p> Signup and view all the answers

    What is the antigenic shift in Influenza virus due to?

    <p>Reassortment of RNA segments</p> Signup and view all the answers

    What is the characteristic of the transmission of Measles virus?

    <p>Respiratory droplets</p> Signup and view all the answers

    What is the symmetry of the capsid of Orthomyxovirus?

    <p>Helical</p> Signup and view all the answers

    What is the characteristic of the replication of Rhinovirus?

    <p>Replicates best at low temperatures</p> Signup and view all the answers

    What is the initial site of measles virus infection?

    <p>Upper respiratory tract</p> Signup and view all the answers

    What is the cause of maculopapular rash in measles?

    <p>Cell-mediated immune attack</p> Signup and view all the answers

    What is the vaccine type for measles?

    <p>Live, attenuated virus</p> Signup and view all the answers

    What is the mode of transmission for mumps virus?

    <p>Respiratory droplets</p> Signup and view all the answers

    What is the rare complication of mumps virus infection?

    <p>Bilateral orchitis and sterility</p> Signup and view all the answers

    What is the mode of transmission for rubella virus?

    <p>Respiratory droplets</p> Signup and view all the answers

    What is the result of 50% of Hepatitis C Virus infections?

    <p>Chronic carrier state</p> Signup and view all the answers

    What is the mechanism of HIV transmission?

    <p>Body fluids and vertical transmission</p> Signup and view all the answers

    What is the function of NEF protein in HIV?

    <p>Reduces class I MHC protein synthesis</p> Signup and view all the answers

    What is the purpose of zidovudine in HIV-infected mothers and their newborns?

    <p>To prevent transmission</p> Signup and view all the answers

    What is the primary site of latency for EBV?

    <p>B lymphocytes</p> Signup and view all the answers

    What is the route of transmission for CMV?

    <p>Via sexual contact, transfusions, &amp; secretions</p> Signup and view all the answers

    What is the result of 5% of HBV infections?

    <p>Chronic carrier state</p> Signup and view all the answers

    What is the purpose of the laboratory diagnosis for HBV?

    <p>To detect the presence of HBsAg, HBsAb, &amp; HBcAb</p> Signup and view all the answers

    What is the result of the integration of part of viral DNA into hepatocyte DNA?

    <p>All of the above</p> Signup and view all the answers

    What is the mode of transmission for Adenovirus?

    <p>All of the above</p> Signup and view all the answers

    What is the function of two early viral genes, E6 & E7, in Papillomavirus?

    <p>They encode proteins that inhibit activity of proteins</p> Signup and view all the answers

    What is the mode of transmission for Papillomavirus?

    <p>Via direct contact of skin &amp; genital lesion</p> Signup and view all the answers

    What is the treatment for chronic hepatitis B?

    <p>Alpha interferon &amp; lamivudine</p> Signup and view all the answers

    What is the outcome of the 'window' phase in HBV infection?

    <p>HBV-infected person has neither detectable HBs antigen nor HBs antibody</p> Signup and view all the answers

    Study Notes

    Classification of DNA Viruses

    • DNA viruses can be classified into several families based on their characteristics:
      • Parvovirus: small, non-enveloped, icosahedral, single-stranded DNA, e.g., B19 virus
      • Polyomavirus: small, non-enveloped, icosahedral, double-stranded DNA, e.g., JC virus, BK virus
      • Papillomavirus: small, non-enveloped, icosahedral, double-stranded DNA, e.g., human papilloma virus
      • Adenovirus: medium-sized, non-enveloped, icosahedral, double-stranded DNA, e.g., adenovirus
      • Hepadnavirus: enveloped, icosahedral, double-stranded DNA, e.g., hepatitis B virus
      • Herpesvirus: enveloped, icosahedral, double-stranded DNA, e.g., herpes simplex virus, varicella-zoster virus, cytomegalovirus, Epstein-Barr virus
      • Poxvirus: large, enveloped, complex, double-stranded DNA, e.g., smallpox virus, molluscum contagiosum virus

    Herpesviruses

    • Herpesviruses can cause a range of diseases, including:
      • HSV-1: gingivostomatitis, herpes labialis, encephalitis, keratitis
      • HSV-2: herpes genitalis, perinatal disseminated disease
      • VZV: varicella, zoster
      • EBV: infectious mononucleosis, none (no recurrent infection)
      • CMV: congenital infection, mononucleosis in transfusion recipients, pneumonia and hepatitis in immunocompromised patients
      • HSV-8: Kaposi's sarcoma in AIDS patients

    Adenovirus

    • Adenovirus can cause:
      • Upper and lower respiratory tract disease (pharyngitis and pneumonia)
      • Enteric strains cause diarrhea
      • Transmitted by respiratory droplets, iatrogenic in eye disease, and fecal-oral with enteric strains
      • Live vaccine against types 3, 4, and 7 is used in the military to prevent pneumonia

    Papillomavirus

    • Papillomavirus can cause:
      • Papillomas (warts)
      • Condylomata acuminata (genital warts)
      • Carcinoma of the cervix and penis
      • Transmitted by direct contact of skin and genital lesions
      • Two early viral genes, E6 and E7, encode proteins that inhibit activity of proteins encoded by tumor suppressor genes, p53 gene and retinoblastoma gene, respectively
      • Vaccine containing capsid proteins of four HPV types (6, 11, 16, and 18) is available

    Hepadnavirus: Hepatitis B Virus

    • Hepatitis B virus can cause:
      • Hepatitis B and hepatocellular carcinoma
      • Transmitted by blood, during birth, and sexual intercourse
      • Hepatocellular injury due to immune attack by cytotoxic (CD8) T cells
      • Antigen-antibody complexes cause arthritis, rash, and glomerulonephritis
      • 5% of HBV infections result in a chronic carrier
      • Chronic hepatitis, cirrhosis, and hepatocellular carcinoma can occur (integration of part of viral DNA into hepatocyte DNA)

    Laboratory Diagnosis of Hepatitis B Virus

    • Three serologic tests are commonly used:
      • Surface antigen (HBsAg)
      • Surface antibody (HBsAb)
      • Core antibody (HBcAb)
    • Detection of HbsAg ≥6 months chronic carrier
    • Presence of e antigen infectious chronic carrier
    • "Window" phase: HBV-infected person has neither detectable HBs antigen nor HBs antibody and is diagnosed by detecting HB core antibody

    Treatment and Prevention of Hepatitis B Virus

    • Alpha interferon and lamivudine reduce inflammation associated with chronic hepatitis B but does not cure carrier state
    • Prevention:
      • Vaccine that contains HBsAg as immunogen
      • Hyperimmune serum globulins obtained from donors with high titers of HBsAb

    Classification of RNA Viruses

    • RNA viruses can be classified into several families based on their characteristics:
      • Picornavirus: small, non-enveloped, icosahedral, single-stranded RNA, positive polarity, e.g., poliovirus, rhinovirus, hepatitis A virus
      • Hepevirus: small, non-enveloped, icosahedral, single-stranded RNA, positive polarity, e.g., hepatitis E virus
      • Calicivirus: small, non-enveloped, icosahedral, single-stranded RNA, positive polarity, e.g., norwalk virus
      • Reovirus: small, non-enveloped, icosahedral, double-stranded RNA, e.g., rotavirus
      • Flavivirus: small, enveloped, icosahedral, single-stranded RNA, positive polarity, e.g., yellow fever virus, dengue virus, West Nile virus, hepatitis C virus
      • Togavirus: small, enveloped, icosahedral, single-stranded RNA, positive polarity, e.g., rubella virus
      • Retrovirus: enveloped, icosahedral, single-stranded RNA, positive polarity, e.g., HIV, human T-cell leukemia virus
      • Orthomyxovirus: small, enveloped, helical, single-stranded RNA, negative polarity, e.g., influenza virus
      • Paramyxovirus: small, enveloped, helical, single-stranded RNA, negative polarity, e.g., measles virus, mumps virus, respiratory syncytial virus
      • Rhabdovirus: small, enveloped, helical, single-stranded RNA, negative polarity, e.g., rabies virus
      • Filovirus: small, enveloped, helical, single-stranded RNA, negative polarity, e.g., Ebola virus, Marburg virus

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    Test your knowledge of DNA and RNA viruses, including their structure, transmission, and prevention methods. Learn about medically important viruses such as Parvovirus, Polyomavirus, and Adenovirus. Assess your understanding of virus classification and disease prevention.

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