Philip Pellett, Chair, Herpesvirales Working Group
Phil Pellet, the chair of the Herpesvirales Study Group of the International for Taxonomy of Viruses (ICTV, ictvonline.org), announced at the 7th International Conference on HHV-6 & 7 that the Study Group has recommended that HHV-6A and HHV-6B be recognized as two distinct viruses. The final decision will be made by the ICTV Committee this year.
The announcement came a year after a group of 18 leaders in the field of HHV-6 research petitioned the Study Group to officially recognize the two “variants” as separate species.
HHV-6B causes 97 – 100% of primary iHHV-6 infections in the USA and Japan and is responsible for a comparable percentage of transplant reactivation cases. HHV-6B, but not HHV-6 has been associated with febrile seizures, mesial temporal lobe epilepsy and status epilepticus
HHV-6A has been found more frequently in patients with neuroinflammatory diseases such as a patients with multiple sclerosis (MS) and children with rhomboencephalitis. HHV-6A is acquired later in life, usually without clinical symptoms, except in Sub-Saharan where HHV-6A is acquired earlier and causes roseola (instead of HHV-6B) in the majority of the pediatric population
HHV-6B is more prevalent than HHV-6A in the peripheral blood mononuclear cells of healthy adults and transplant patients, while HHV-6A is found more frequently in the plasma of HSCT patients. HHV-6B but not HHV-6A is commonly found in saliva. HHV-6A, but not HHV-6B can productively infect CD8+ T-cells, natural killer cells, and γ/δ (gamma/delta) T-cells.
HHV6-A will generally not infect cell lines readily infected by HHV-6 B and vice versa. There are also several monoclonal antibodies that will only interact with one or the other.
All HHV-6 isolates including those found in chromosomally integrated HHV-6 can be clearly designated either A or B. The IE1 gene shows 30% divergence between the two new species, but is very stable (>95%) within the clinical and laboratory isolates of each species.
Unfortunately, many HHV-6 publications do not specify which virus was used in the research. The authors of the petition on HHV-6A and HHV-6B, listed below, urge all of HHV-6 investigators to specify whether their research relates to HHV-6A or HHV-6B. Anyone interested in learning more details about the arguments to identify the two “variants” as two separate species, should contact the Committee Co-Chairs Dario Di Luca or Dharam Ablashi.
Ad Hoc Committee on HHV-6A & HHV-6B Genomic Divergence
Dharam Ablashi, DVM, HHV-6 Foundation, Santa Barbara, USA (Co-chair)
Henri Agut, MD, PhD, Hospital Pitie-Salpetriere, Paris, France
Yoshizo Asano, MD, PhD, Fujita Health University, Toyoake, Aichi, Japan
Roberto Alvarez-LaFuente, MD, Hospital Clinico San Carlos, Madrid, Spain
Don Carrigan, PhD, Wisconsin Viral Research Group, Milwaukee, USA
Duncan Clark, PhD, Royal Free & University College Medical School, London, UK
Dario Di Luca, PhD, University of Ferrara, Ferrara, Italy (Co-Chair)
Steve Dewhurst, PhD, University of Rochester, USA
Louis Flamand, PhD, University Laval, Quebec, Canada
Niza Frenkel, PhD, Tel Aviv University, Tel Aviv, Israel
Robert Gallo, MD, Institute of Virology, University of Maryland, USA
Ursula Gompels, PhD, London School of Tropical Medicine, London, UK
Caroline Hall, MD, University of Rochester, Rochester, USA
Steve Jacobson, PhD, National Institute of Neurological Disorders & Stroke/NIH, Bethesda, USA
Kazuhiro Kondo, MD, PhD, Jikei University School of Medicine, Tokyo, Japan
Mario Luppi, MD, PhD, University of Modena and Reggio Emilia, Modena, Italy
Paolo Lusso, MD, PhD, National Institute of Allergy and Infectious Diseases/NIH, Bethesda, USA
Yasauki Mori, MD, PhD, National Institute of Biomedical Innovation, Osaka, Japan
Koichi Yamanishi, MD, PhD, National Institute of Biomedical Innovation, Osaka, Japan
Tetsushi Yoshikawa, MD, Nagoya University School of Medicine, Toyoake Aichi, Japan
HHV-6A and HHV-6B to be recognized as two distinct viruses
Philip Pellett, Chair, Herpesvirales Working Group
Phil Pellet, the chair of the Herpesvirales Study Group of the International for Taxonomy of Viruses (ICTV, ictvonline.org), announced at the 7th International Conference on HHV-6 & 7 that the Study Group has recommended that HHV-6A and HHV-6B be recognized as two distinct viruses. The final decision will be made by the ICTV Committee this year.
The announcement came a year after a group of 18 leaders in the field of HHV-6 research petitioned the Study Group to officially recognize the two “variants” as separate species.
HHV-6B causes 97 – 100% of primary iHHV-6 infections in the USA and Japan and is responsible for a comparable percentage of transplant reactivation cases. HHV-6B, but not HHV-6 has been associated with febrile seizures, mesial temporal lobe epilepsy and status epilepticus
HHV-6A has been found more frequently in patients with neuroinflammatory diseases such as a patients with multiple sclerosis (MS) and children with rhomboencephalitis. HHV-6A is acquired later in life, usually without clinical symptoms, except in Sub-Saharan where HHV-6A is acquired earlier and causes roseola (instead of HHV-6B) in the majority of the pediatric population
HHV-6B is more prevalent than HHV-6A in the peripheral blood mononuclear cells of healthy adults and transplant patients, while HHV-6A is found more frequently in the plasma of HSCT patients. HHV-6B but not HHV-6A is commonly found in saliva. HHV-6A, but not HHV-6B can productively infect CD8+ T-cells, natural killer cells, and γ/δ (gamma/delta) T-cells.
HHV6-A will generally not infect cell lines readily infected by HHV-6 B and vice versa. There are also several monoclonal antibodies that will only interact with one or the other.
All HHV-6 isolates including those found in chromosomally integrated HHV-6 can be clearly designated either A or B. The IE1 gene shows 30% divergence between the two new species, but is very stable (>95%) within the clinical and laboratory isolates of each species.
Unfortunately, many HHV-6 publications do not specify which virus was used in the research. The authors of the petition on HHV-6A and HHV-6B, listed below, urge all of HHV-6 investigators to specify whether their research relates to HHV-6A or HHV-6B. Anyone interested in learning more details about the arguments to identify the two “variants” as two separate species, should contact the Committee Co-Chairs Dario Di Luca or Dharam Ablashi.
Ad Hoc Committee on HHV-6A & HHV-6B Genomic Divergence
Dharam Ablashi, DVM, HHV-6 Foundation, Santa Barbara, USA (Co-chair)
Henri Agut, MD, PhD, Hospital Pitie-Salpetriere, Paris, France
Yoshizo Asano, MD, PhD, Fujita Health University, Toyoake, Aichi, Japan
Roberto Alvarez-LaFuente, MD, Hospital Clinico San Carlos, Madrid, Spain
Don Carrigan, PhD, Wisconsin Viral Research Group, Milwaukee, USA
Duncan Clark, PhD, Royal Free & University College Medical School, London, UK
Dario Di Luca, PhD, University of Ferrara, Ferrara, Italy (Co-Chair)
Steve Dewhurst, PhD, University of Rochester, USA
Louis Flamand, PhD, University Laval, Quebec, Canada
Niza Frenkel, PhD, Tel Aviv University, Tel Aviv, Israel
Robert Gallo, MD, Institute of Virology, University of Maryland, USA
Ursula Gompels, PhD, London School of Tropical Medicine, London, UK
Caroline Hall, MD, University of Rochester, Rochester, USA
Steve Jacobson, PhD, National Institute of Neurological Disorders & Stroke/NIH, Bethesda, USA
Kazuhiro Kondo, MD, PhD, Jikei University School of Medicine, Tokyo, Japan
Mario Luppi, MD, PhD, University of Modena and Reggio Emilia, Modena, Italy
Paolo Lusso, MD, PhD, National Institute of Allergy and Infectious Diseases/NIH, Bethesda, USA
Yasauki Mori, MD, PhD, National Institute of Biomedical Innovation, Osaka, Japan
Koichi Yamanishi, MD, PhD, National Institute of Biomedical Innovation, Osaka, Japan
Tetsushi Yoshikawa, MD, Nagoya University School of Medicine, Toyoake Aichi, Japan