Human Herpesvirus 6 - HHV6

Human herpesvirus 6 (HHV6), a member of the β-herpesvirus subfamily, exists as two closely related variants, HHV6A and HHV6B. A large portion (>90%) of the population is infected with HHV early in life, at which time the virus can cause a mild, self-limited syndrome called roseola. In immunocompromised patients, HHV6 reactivation can cause life-threatening diseases such as myocarditis, liver failure, and encephalitis. Reactivated HHV6 can also facilitate activation of other viruses and allow the spread of fungal infection.

Tabs Content

Clinical Overview

Diagnosis

Indications for Testing

Severe viral illness in immunocompromised patients

Laboratory Testing

Immunocompromised patients
- Polymerase chain reaction (PCR)
  - More rapid and sensitive than antibody testing
  - Use in patients with suspected meningitis – cerebrospinal fluid (CSF) sample
  - Quantitative PCR may help identify acute vs. previous disease
  - Not useful for inherited chromosomally integrated human herpesvirus 6 (iciHHV6) – always positive
- Antibody testing – traditional testing of paired acute and convalescent antibody testing samples
  - Indirect fluorescent antibody (IFA) – recommended
    - Provides quantitative testing
    - Allows for evaluation of change over time
  - Enzyme-linked immunosorbent assay (ELISA) – qualitative testing; less useful
  - Not as useful as PCR in immunocompromised diagnoses
- Culture – not recommended due to difficulty and extended turnaround times
Young children – testing typically not performed; diagnosis based on clinical presentation
Concurrent testing for other viral etiologies based on symptoms
- Epstein-Barr virus
- Meningitis – arbovirus, lymphocytic choriomeningitis (LCM)
- Hepatitis – hepatitis A, B, C, cytomegalovirus (CMV)
- Bone marrow suppression – parvovirus
- Pneumonitis – herpes simplex virus (HSV), adenovirus

Differential Diagnosis

Exanthem
- Measles
- Rubella
- Parvovirus B19
Meningitis
- Other viral
  - HSV
  - Arbovirus
  - LCM
  - Mycobacterium tuberculosis
- Bacterial
- Parasitic
- Fungal
Viral fever/flulike illness
- Mononucleosis
- Hepatitis
- HIV
Seizures

Background

Epidemiology

Prevalence – most children >2 years are seropositive
Transmission
- Oral droplets
- Transfusion
- Organ transplantation
- Congenital

Organism

DNA virus – human herpesvirus 6 (HHV6) and human herpesvirus 7 (HHV7) together constitute Roseolovirus of the Herpesviridae family
- HHV6B – most common agent
- HHV6A – may be responsible for neuromeningitis
Isolated in 1986 from patients with AIDS and lymphoproliferative disease
- Virus originally named human B-lymphotropic virus; now identified as T-lymphotropic
Following primary infection, the virus becomes latent in lymphocytes and monocytes
- May persist in various tissues with a low level of replication
Evidence suggests HHV6 may act as an opportunistic agent with reactivation found in
- Immunodeficient patients – after bone marrow or organ transplants
- HIV-infected patients – as primary infection, reactivation of latent infection, or persistent infection
- Other immunosuppressed patients

Clinical Presentation

Primary infection in children
- Fever ≥40°C persisting for 3-5 days
- Exanthem subitum (roseola infantum or sixth disease) – develops on trunk and spreads to extremities
- Diarrhea
- Respiratory symptoms
Primary infection or reactivation in immunocompromised patients (particularly in organ transplant patients)
- Meningitis/encephalitis – posttransplantation acute limbic encephalitis
- Fulminant or chronic hepatitis, gastritis, colitis
- Bone marrow suppression, hemophagocytosis syndrome
- Pneumonitis
- Organ transplant rejection
- Arthritis
- In transplant patient, increases risk for (Razonable, 2013)
  - Allograft dysfunction
  - Cytomegalovirus (CMV) disease after kidney or liver transplantation
  - Fungal disease
  - Higher mortality

ARUP Lab Tests

Tests generally appear in the order most useful for common clinical situations. Click on number for test-specific information in the ARUP Laboratory Test Directory.

Human Herpesvirus 6 (HHV-6A and HHV-6B) by Quantitative PCR 0060071
Method: Quantitative Polymerase Chain Reaction

Recommended Use

Detect and quantify HHV6 subtypes A and B in immunocompromised patients

Limitations

The limit of quantification for this DNA assay is 3.0 log copies/mL (1,000 copies/mL)

If no virus is detected, result will be reported as “<3.0 log copies/mL (<1,000 copies/mL)”; if assay detects the presence of the virus but is not able to accurately quantify the number of copies, result will be reported as “Not Quantified”

Herpesvirus 6 Antibody, IgG 2013423
Method: Quantitative Indirect Fluorescent Antibody

Recommended Use

Use in conjunction with HHV6, IgM screen with reflex to titer for diagnosis of HHV6 disease in immunocompromised adults

Consider HHV6 (HHV6A and HHV6B) by polymerase chain reaction (PCR) as an alternative, especially in cases of suspected meningitis

Herpesvirus 6 Antibody, IgM Screen with Reflex to Titer by IFA (Temporary Referral as of 10/19/17) 2011420
Method: Semi-Quantitative Immunofluorescence

Recommended Use

Use in conjunction with HHV6, IgG, for diagnosis of HHV6 disease in immunocompromised adults

Consider HHV6A and HHV6B by PCR as an alternative, especially in cases of suspected meningitis

Reflex pattern – if HHV6 IgM is detected at 1:10, a titer will be added

Medical Reviewers

Couturier, Marc Roger, PhD, D(ABMM), Medical Director, Microbial Immunology, Parasitology and Fecal Testing, and Infectious Disease Antigen Testing at ARUP Laboratories; Associate Professor of Clinical Pathology, University of Utah

Hillyard, David R., MD, Medical Director, Molecular Infectious Diseases at ARUP Laboratories; Professor of Clinical Pathology, Adjunct Professor of Biology, University of Utah

References

General References

Agut H, Bonnafous P, Gautheret-Dejean A. Human herpesviruses 6A, 6B, and 7. Microbiol Spectr. 2016; 4(3): PubMed

Agut H, Bonnafous P, Gautheret-Dejean A. Laboratory and clinical aspects of human herpesvirus 6 infections. Clin Microbiol Rev. 2015; 28(2): 313-35. PubMed

Flamand L, Komaroff AL, Arbuckle JH, Medveczky PG, Ablashi DV. Review, part 1: Human herpesvirus-6-basic biology, diagnostic testing, and antiviral efficacy. J Med Virol. 2010; 82(9): 1560-8. PubMed

Pantry SN, Medveczky PG. Latency, integration, and reactivation of human herpesvirus-6. Viruses. 2017; 9(7): PubMed

Prober CG. Human herpesvirus 6. Adv Exp Med Biol. 2011; 697: 87-90. PubMed

Razonable RR. Human herpesviruses 6, 7 and 8 in solid organ transplant recipients. Am J Transplant. 2013; 13 Suppl 3: 67-77; quiz 77-8. PubMed

Tyler KL. Emerging viral infections of the central nervous system: part 1. Arch Neurol. 2009; 66(8): 939-48. PubMed

Yao K, Crawford JR, Komaroff AL, Ablashi DV, Jacobson S. Review part 2: Human herpesvirus-6 in central nervous system diseases. J Med Virol. 2010; 82(10): 1669-78. PubMed

Zamora MR. DNA viruses (CMV, EBV, and the herpesviruses). Semin Respir Crit Care Med. 2011; 32(4): 454-70. PubMed

References from the ARUP Institute for Clinical and Experimental Pathology^®

Herrmann MG, Durtschi JD, Bromley K, Wittwer CT, Voelkerding KV. Amplicon DNA melting analysis for mutation scanning and genotyping: cross-platform comparison of instruments and dyes. Clin Chem. 2006; 52(3): 494-503. PubMed

Hymas W, Stevenson J, Taggart EW, Hillyard D. Use of lyophilized standards for the calibration of a newly developed real time PCR assay for human herpes type six (HHV6) variants A and B. J Virol Methods. 2005; 128(1-2): 143-50. PubMed

Rentz AC, Stevenson J, Hymas W, Hillyard D, Stoddard GJ, Taggart EW, Byington CL. Human herpesvirus 6 in the newborn intensive care unit. Eur J Clin Microbiol Infect Dis. 2007; 26(4): 297-9. PubMed

Content Review:

November 2017

Last Update: March 2018


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	Human Herpesvirus 6 - HHV6. ARUP Consult^©. Retrieved May 14, 2018, from: https://arupconsult.com/content/human-herpesvirus-6

Human Herpesvirus 6 - HHV6

Diagnosis

Indications for Testing

Laboratory Testing

Differential Diagnosis

Background

Epidemiology

Organism

Clinical Presentation

ARUP Lab Tests

Medical Reviewers

References

General References

References from the ARUP Institute for Clinical and Experimental Pathology®

References from the ARUP Institute for Clinical and Experimental Pathology^®