Medical Microbiology: Human Herpes Virus 5 (Cytomegalovirus)
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Questions and Answers

What is the characteristic of valganciclovir that makes it a better option than ganciclovir?

  • It is only available for intravenous use.
  • It is less effective against CMV.
  • It has better bioavailability. (correct)
  • It is only used to treat CMV in immunosuppressed individuals.

    • How is CMV primarily spread?

  • Through contaminated food and water.
  • Through respiratory droplets.
  • Through sexual contact, tissue transplantation, and transfusion. (correct)
  • Through casual contact with an infected individual.

    • What is the name of the disease caused by HHV-6 or HHV-7?

  • Roseola infantum.
  • Fifth disease.
  • Exanthem subitum. (correct)
  • Measles.

    • What type of cells are primarily infected by HHV-6?

    <p>Lymphocytes.</p> Signup and view all the answers

    What is the primary mode of transmission of HHV-6?

    <p>Through saliva.</p> Signup and view all the answers

    What is the primary immune response controlling HHV-6 replication?

    <p>Cell-mediated immunity.</p> Signup and view all the answers

    What is a common complication of HHV-6 infection in childhood?

    <p>Febrile seizures.</p> Signup and view all the answers

    What is the outcome of HHV-6 infection in individuals with AIDS or other immunosuppressive disorders?

    <p>Opportunistic disease.</p> Signup and view all the answers

    What is the common outcome in immunosuppressed patients if CMV disease is not treated?

    <p>Fatal lung disease</p> Signup and view all the answers

    What is the histologic hallmark of CMV infection?

    <p>Owl’s eye</p> Signup and view all the answers

    What is the mechanism of action of Ganciclovir?

    <p>Inhibits viral DNA polymerase</p> Signup and view all the answers

    What is the primary method of laboratory diagnosis of CMV infection?

    <p>Detection of viral antigen or genome</p> Signup and view all the answers

    What is the significance of serology in CMV infection?

    <p>It is useful for screening blood donations</p> Signup and view all the answers

    What is the common feature of CMV infection in immunocompromised patients?

    <p>Symptomatic primary or recurrent disease</p> Signup and view all the answers

    What is the characteristic feature of CMV inclusions?

    <p>They are readily seen with Papanicolaou or hematoxylin-eosin staining</p> Signup and view all the answers

    Which of the following FDA-approved medications is activated by a CMV-encoded protein kinase?

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

    What is the primary mode of transmission of CMV in utero?

    <p>Vertically from mother to fetus</p> Signup and view all the answers

    Which cell type is permissive for CMV replication?

    <p>Epithelial cells</p> Signup and view all the answers

    What is the primary reason why CMV is a significant pathogen in immunocompromised patients?

    <p>It can cause opportunistic infections in immunocompromised patients</p> Signup and view all the answers

    Which of the following is a common clinical presentation of CMV infection in fetuses?

    <p>Congenital defects</p> Signup and view all the answers

    What is the primary characteristic of CMV's ability to evade the host's immune system?

    <p>It establishes persistent and latent infections</p> Signup and view all the answers

    Which group of people is at high risk for CMV infection due to their lifestyle?

    <p>Sexually active people</p> Signup and view all the answers

    What is the primary reason why CMV is a concerning pathogen in blood and organ recipients?

    <p>It can be transmitted through blood transfusions and organ transplants</p> Signup and view all the answers

    What is the primary difference between CMV and HHV6&7 in terms of transmission?

    <p>CMV is transmitted through sexual contact, while HHV6&amp;7 are transmitted through close contact</p> Signup and view all the answers

    Where does CMV establish latency?

    <p>In hematopoietic progenitor cells in the bone marrow and monocytes</p> Signup and view all the answers

    How is CMV typically spread?

    <p>Through contact with infected bodily secretions</p> Signup and view all the answers

    What is essential for resolving and controlling CMV infection?

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

    What is a common consequence of congenital CMV infection?

    <p>Hearing loss</p> Signup and view all the answers

    In which population is CMV disease most severe?

    <p>Immunosuppressed individuals</p> Signup and view all the answers

    How can CMV be transmitted?

    <p>Through sexual contact</p> Signup and view all the answers

    What is a characteristic of CMV infection?

    <p>It is shed sporadically throughout life</p> Signup and view all the answers

    What is a common disease caused by CMV?

    <p>Cytomegalic inclusion disease</p> Signup and view all the answers

    Study Notes

    Overview of Human Herpes Virus 5 (HHV5)

    • HHV5 is a common human pathogen, also known as Cytomegalovirus (CMV)
    • Belongs to the herpesvirus family and is the most common viral cause of congenital defects
    • Usually causes mild or asymptomatic disease in children and adults, but is an opportunistic pathogen in immunocompromised patients

    Structure and Replication

    • CMV is a herpesvirus, an enveloped double-stranded DNA virus
    • Cells permissive for CMV replication: fibroblasts, epithelial cells, granulocytes, and macrophages

    Epidemiology

    • CMV is common worldwide
    • Virus is transmitted through:
      • Oral and sexual contact
      • Blood transfusions
      • Tissue transplants (especially kidneys and bone marrow)
      • In utero, at birth, and through breastfeeding
      • All secretions (urine, saliva, semen, cervical secretions, breast milk, and tears)

    Who Is at Risk?

    • Fetuses of mothers who get infected/reactivate during pregnancy
    • Sexually active people
    • Blood and organ recipients
    • Immunocompromised people

    Pathogenesis and Immunity

    • CMV establishes persistent and latent infections rather than extensive lytic infections
    • Highly cell-associated and spreads throughout the body within infected cells, especially lymphocytes and leukocytes
    • Virus establishes latency in hematopoietic progenitor cells in the bone marrow and monocytes
    • Reactivates on immunosuppression and possibly by allogeneic stimulation
    • CMV is shed sporadically throughout life

    Clinical Manifestations

    • CMV disease is an opportunistic disease, rarely causing symptoms in the immunocompetent host
    • Congenital infection:
      • May lead to hearing, eyesight, and intelligence deficits
      • Common infectious causes of congenital hearing loss
      • Vision loss and mental retardation are also common consequences
    • Infection in children and adults:
      • CMV is widely prevalent
      • Sexually transmitted
      • Asymptomatic, but may show a heterophile-negative mononucleosis syndrome
    • Infection in the immunocompromised host:
      • CMV is a prominent opportunistic infectious agent
      • Causes symptomatic primary or recurrent disease
      • CMV disease of the lung is a common outcome in immunosuppressed patients and can be fatal if not treated

    Laboratory Diagnosis

    • Histology:
      • Histologic hallmark of CMV infection is the “owl’s eye”
      • Found in any tissue and in urine
    • Serology:
      • Not reliable except if seroconversion is documented in primary infection
      • Useful for screening blood donations
    • Detection of viral antigen or genome:
      • Rapid, sensitive diagnosis can be obtained by detection of viral antigen or genome
      • Using immunofluorescence, ELISA, or PCR in cells of a biopsy, blood, bronchoalveolar lavage, or urine sample
    • Culture of virus in fibroblast cell lines and observation of the characteristic cytopathic effects

    Treatment

    • FDA approved for treatment of immunosuppressed patients:
      • Ganciclovir
      • Valganciclovir
      • Cidofovir
      • Foscarnet

    Control

    • CMV spreads through:
      • Sexual contact
      • Tissue transplantation
      • Transfusion
    • Spread by these means is preventable
    • Use of condoms or abstinence would limit viral spread
    • Screening of potential blood and organ donors for CMV seronegativity

    Human Herpesviruses 6 and 7

    • HHV-6 is a herpesvirus that was first isolated from the blood of patients with AIDS
    • Similar to CMV, HHV-6 is lymphotropic and ubiquitous
    • Causes a common disease of children, Exanthem Subitum (roseola)
    • HHV-7 was isolated from the T cells of a patient with AIDS who was also infected with HHV-6

    Pathogenesis and Immunity of HHV-6 and HHV-7

    • HHV-6 infection occurs very early in life
    • Virus replicates in the salivary gland, is shed, and is transmitted in saliva
    • HHV-6 primarily infects lymphocytes, especially CD4 T cells
    • Establishes a latent infection in hematopoietic progenitor cells and T cells
    • Replication of HHV-6 is controlled by cell-mediated immunity

    Clinical Syndromes of HHV-6 and HHV-7

    • Exanthem subitum, or roseola, is caused by either HHV-6 or HHV-7
    • Characterized by the rapid onset of high fever, followed by a rash on the trunk and face, and then spreads and lasts only 24 to 48 hours
    • Virus establishes a lifelong latent infection of T cells
    • HHV-6 is the most common cause of febrile seizures in childhood (aged 6 to 24 months)

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    Description

    This quiz covers the pathogenesis, transmission, and diagnosis of Cytomegalovirus (CMV) infections, as well as its prevention and control. Learn about the clinical syndromes associated with CMV and the lab tests required for diagnosis.

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