RT Book, Section A1 Schleiss, Mark R. A2 Rudolph, Colin D. A2 Rudolph, Abraham M. A2 Lister, George E. A2 First, Lewis R. A2 Gershon, Anne A. SR Print(0) ID 7030068 T1 Chapter 312. Human Herpesviruses 6 and 7 T2 Rudolph's Pediatrics, 22e YR 2011 FD 2011 PB The McGraw-Hill Companies PP New York, NY SN 978-0-07-149723-7 LK accesspediatrics.mhmedical.com/content.aspx?aid=7030068 RD 2024/10/14 AB Human herpesvirus 6 (HHV-6) was isolated in tissue culture in 1986 from peripheral blood leukocytes of patients with both lymphoproliferative disorders and HIV infection. It is the major etiologic agent of exanthem subitum and has also been implicated in other clinical syndromes. HHV-6 is a prototypical member of the betaherpesvirus family of herpesviruses, which also includes human herpesvirus 7 (HHV-7) and human cytomegalovirus (HCMV). The virus has a double- stranded DNA genome contained within an icosahedral capsid, surrounded by an outer envelope. HHV-6 is subclassified as either variant A or B, based on differences in nucleotide sequence, restriction enzyme profile, and reactivity with monoclonal antibodies. HHV-6B is the subtype associated with exanthem subitum.1 In contrast to the other human herpesviruses, which are maintained in a latent state in the host cell as circularized genomes.