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Herpesviruses 5-8: Cytomegalovirus, others

Notes

Herpesviruses 5-8: Cytomegalovirus, others

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Human Herpesviruses 5-8

Key features of herpesviruses:

Large
Double-stranded DNA
Enveloped icosahedral capsids; vulnerable to acids, detergents, and drying

They cause lytic and latent infections; infection is lifelong

Human Herpesvirus 5: Cytomegalovirus

Infection is very common, and is present in over half of the adult population.

Causes persistent and latent infections, which are usually subclinical.

The virus is shed in urine and other bodily secretions.

Transmitted upon close contact (including sexual contact) and organ transplant; the virus can also be transmitted from mother to neonates

Replicates in epithelial cells, macrophages, fibroblasts, and other cells

Owl-eye basophilic inclusion bodies in kidney epithelial cells:

https://phil.cdc.gov/Details.aspx?pid=1155

The virus establishes latency in myeloid stem cells, monocytes, lymphocytes, bone marrow, and other cells.

Reactivation of the virus can occur in times of immunosuppression.

Infections:

Healthy individuals: Asymptomatic, Mononucleosis

Often asymptomatic infection.

Mononucleosis: In contrast to Epstein-Barr Virus mononucleosis, pharyngitis and swollen lymph glands are less pronounced, and, because cytomegalovirus is not a B cell infection, heterophile antibodies are not produced

More serious outcomes are possible, but rare

Immunocompromised individuals: Transplant recipients and HIV patients
Infection can produce multi-organ effects: Hepatitis, pneumonia, retinitis, colitis, and esophagitis

Neonates
Infection can lead to still birth or premature birth with congenital defects.

Complications are most likely when the mother experiences primary CMV infection during pregnancy.
CMV is associated with small size, microcephaly, petechial rash, jaundice, and mental retardation

Infection is also associated with specific neurological complications, including sensorineural hearing loss (SNHL), chorioretinitis, and periventricular calcifications.

Cytomegalovirus is one of the TORCHeS infections.

Human Herpesviruses 6 & 7

HHV-6b variant:
Commonly infects children.
Produces a rash called exanthema subitum, aka, roseola, which lasts 24-48 hours.
Some children may also experience febrile seizures or other problems.

The virus replicates and sheds in the salivary glands
In the histological sample, we can see examples of nuclear and cytoplasmic inclusion bodies in infected cells.

Following resolution of primary infection, HHV-6 produces latent infection in T-cells.

However, in immunocompromised patients, infection can have multi-organ effects and even lead to death
— It is also thought to be a co-factor in AIDS progression.

Human herpes virus 7

  • Common childhood infection, typically acquired later than HHV-6.
    Infection is typically asymptomatic; can present with rash like HHV-6

This virus is associated with Kaposi sarcoma, as well as primary effusion lymphoma, and Castleman's disease.

Kaposi Sarcoma occurs when viral genes promote the growth of infected cells.

As a result, tumors develop on the skin and mucosal surfaces.

We show characteristic spindle-shaped cells and branching vasculature of infected tissue, and lesions on the skin and gingivae.

Kaposi Sarcoma is an opportunistic AIDS infection.

Anti-viral drugs, such as ganciclovir, may prevent the development of Kaposi Sarcoma.

References

Al, G. Campadelli-Fiume et. "Human Herpesvirus 6: An Emerging Pathogen - Volume 5, Number 3—June 1999 - Emerging Infectious Disease Journal - CDC." Accessed July 11, 2018. https://doi.org/10.3201/eid0503.990306.

"Congenital Cytomegalovirus Infection: Clinical Features and Diagnosis - UpToDate." Accessed July 11, 2018. https://www-uptodate-com.proxy.medlib.uits.iu.edu/contents/congenital-cytomegalovirus-infection-clinical-features-and-diagnosis?search=cytomegalovirus&source=search_result&selectedTitle=8~150&usage_type=default&display_rank=8.

Crumpacker, Clyde S. "Valganciclovir and Human Herpesvirus-8." The Journal of Infectious Diseases 198, no. 1 (July 1, 2008): 6–7. https://doi.org/10.1086/588821.

"Cytomegalovirus (CMV) and Congenital CMV Infection | Home | CDC," June 15, 2018. https://www.cdc.gov/cmv/index.html.

Ganem, Don. "KSHV and the Pathogenesis of Kaposi Sarcoma: Listening to Human Biology and Medicine." The Journal of Clinical Investigation 120, no. 4 (April 1, 2010): 939–49. https://doi.org/10.1172/JCI40567.
Gantt, Soren, and Corey Casper. "Human Herpesvirus 8-Associated Neoplasms: The Roles of Viral Replication and Antiviral Treatment." Current Opinion in Infectious Diseases 24, no. 4 (August 2011): 295–301. https://doi.org/10.1097/QCO.0b013e3283486d04.

"HHV-8 Herpes Adult and Adolescent Opportunistic Infection." AIDSinfo. Accessed July 13, 2018. https://aidsinfo.nih.gov/guidelines/html/4/adult-and-adolescent-opportunistic-infection/342/hhv-8.

Mattes, F. M., J. E. McLaughlin, V. C. Emery, D. A. Clark, and P. D. Griffiths. "Histopathological Detection of Owl's Eye Inclusions Is Still Specific for Cytomegalovirus in the Era of Human Herpesviruses 6 and 7." Journal of Clinical Pathology 53, no. 8 (August 2000): 612–14.

Mesri, Enrique A., Ethel Cesarman, and Chris Boshoff. "Kaposi's Sarcoma Herpesvirus/ Human Herpesvirus-8 (KSHV/HHV8), and the Oncogenesis of Kaposi's Sarcoma." Nature Reviews. Cancer 10, no. 10 (October 2010): 707–19. https://doi.org/10.1038/nrc2888.

Wen, Kwun Wah, and Blossom Damania. "Kaposi Sarcoma-Associated Herpesvirus (KSHV): Molecular Biology and Oncogenesis." Cancer Letters 289, no. 2 (March 28, 2010): 140–50. https://doi.org/10.1016/j.canlet.2009.07.004.

Images:

CDC. This Transmission Electron Micrograph (TEM) Depicts a Number of Smallpox Virus Virions; Mag - Approximately 370,000x. 1975. This media comes from the Centers for Disease Control and Prevention's Public Health Image Library (PHIL), with identification number #1849. https://commons.wikimedia.org/wiki/File:Smallpox_virus_virions_TEM_PHIL_1849.JPG.

Haraszti, CDC/Dr. ID#: 1155. 1964. http://phil.cdc.gov/PHIL_Images/06011999/00016/09G0036_lores.jpg. https://commons.wikimedia.org/wiki/File:Histopathology_of_cytomegalovirus_infection_of_kidney_-_PHIL_09G0036_lores.jpg.

"Public Domain Picture | Histopathology of Cytomegalovirus Infection of Kidney Tubule Epithelial Cells. Lendrum Stain. | ID: 13521715811461 | PublicDomainFiles.Com." Accessed July 11, 2018. http://www.publicdomainfiles.com/show_file.php?id=13521715811461.

"Human Herpesvirus 6." Wikipedia, June 23, 2018. https://en.wikipedia.org/w/index.php?title=Human_herpesvirus_6&oldid=847252103.

"Kaposi's Sarcoma." Wikipedia, July 8, 2018. https://en.wikipedia.org/w/index.php?title=Kaposi%27s_sarcoma&oldid=849320525.