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Category: Clinical Microbiology
Human Herpesviruses 6, 7, and 8, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555816728/9781555814632_Chap100-1.gif /docserver/preview/fulltext/10.1128/9781555816728/9781555814632_Chap100-2.gifAbstract:
The viruses discussed in this chapter are Human herpesvirus 6 variants A and B (HHV-6A and HHV-6B), Human herpesvirus 7 (HHV-7), and Human herpesvirus 8 (HHV-8; Kaposi's sarcoma [KS]-associated herpesvirus). These viruses cause diseases that are clinically significant primarily in small children and in immunocompromised patients. HHV-6A and HHV-6B, along with HHV-7, comprise the Roseolovirus genus of the betaherpesvirus subfamily. Roseoloviruses share many features of their genomic architecture and genetic content, the ability to replicate and establish latent infections in lymphocytes, and associations with febrile rash illnesses in young children, and they are opportunistic pathogens in immunocompromised patients. Collectively, HHV-6A and HHV-6B are highly prevalent, with seroprevalences in many populations exceeding 90%. During primary infection in young children in the United States, HHV-6A was found by polymerase chain reaction (PCR) in 2.5% of peripheral blood mononuclear cell (PBMC) and 17% of cerebrospinal fluid (CSF) specimens, while HHV-6B was found in 99% of PBMC and 86% of CSF specimens (some specimens were coinfected). HHV-6 primary infection causes roseola in approximately one-quarter of children. Less common but more severe forms of primary HHV-6 infection may include fever of >40°C, respiratory tract distress, tympanic inflammation, diarrhea, and convulsions. Antiviral susceptibility is evaluated by measuring the inhibition of viral replication by immunofluorescence, by antigen slot blots, and by inhibition of virus-induced cytotoxicity.
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Child with roseola during primary HHV-6B infection. Photo courtesy of Stephen Dewhurst, University of Rochester. Previously published in reference 44 .
Child with roseola during primary HHV-6B infection. Photo courtesy of Stephen Dewhurst, University of Rochester. Previously published in reference 44 .
Disease associations
Disease associations
Commercial sources of reagents and assays a
a DNA, purified DNA; qDNA, DNA for use as quantitative reference; qPCR, kit for quantitative PCR. No FDA-approved tests are available for any of these viruses.
Commercial sources of reagents and assays a
a DNA, purified DNA; qDNA, DNA for use as quantitative reference; qPCR, kit for quantitative PCR. No FDA-approved tests are available for any of these viruses.
Some commercial sources for HHV-6, HHV-7, and HHV-8 testing
a Q, quantitative PCR; q, qualitative PCR.
Some commercial sources for HHV-6, HHV-7, and HHV-8 testing
a Q, quantitative PCR; q, qualitative PCR.
Diagnostic methods for HHV-6, -7, and -8 a
a ACIF, anticomplement immunofluorescence; NT, neutralization test; RT-PCR, reverse transcriptase PCR. No FDA-approved tests are available for these viruses.
Diagnostic methods for HHV-6, -7, and -8 a
a ACIF, anticomplement immunofluorescence; NT, neutralization test; RT-PCR, reverse transcriptase PCR. No FDA-approved tests are available for these viruses.