Controlled study of human herpesvirus 6 detection in acquired immunodeficiency syndrome‐associated non‐Hodgkin's lymphoma

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Abstract
Human herpesvirus 6 (HHV‐6) is a recently identified lymphotropic herpesvirus, which has been isolated from patients with acquired immunodeficiency syndrome (AIDS) or lymphoproliferative diseases. Two variants A and B of HHV‐6 have been described, variant B being more common in children with exanthema subitum. HHV‐6 infection was studied in cases of AIDS‐associated non‐Hodgkin's lymphoma (NHL), and in three control populations in order to evaluate the possible etiologicai role of HHV‐6 in this lymphoproliferative disease. Tumor specimens from various organs were obtained from 27 patients with AIDS‐associated NHL and 20 human immunodeficiency virus (HlV)‐seronegative patients with NHL. Lymph node specimens were obtained from four HIV‐seropositive and nine HIV‐seronegative patients with lymph node follicular hyperplasia. A specific polymerase chain reaction (PCR) was used to detect HHV‐6 DNA. Subsequently HHV‐6 variant was identified by using variant‐specific PCR. Human cytomegalovirus (CMV) infection was detected in parallel by means of specific PCR. HHV‐6 DNA was detected in 12 of 27 tumor tissues (44%), including 8 of 15 lymph node specimens (53%) from patients with AIDS‐associated NHL. The corresponding values in HIV‐seronegative patients with NHL were 35% (7/20) and 36% (5/14), respectively. Lymph node specimens were positive for HHV‐6 in two of four (50%) HIV‐seropositive and five of nine (55%) HIV‐seronegative patients with follicular hyperplasia. Variant A was detected in two cases of AIDS‐associated NHL, variant B in one case, and both variants in six cases. The distribution of HHV‐6 variants exhibited a similar pattern in the three control groups. CMV was only detected in 3 of 27 tumor tissues (11%) from patients with AIDS‐associated NHL. The prevalence of HHV‐6 DNA and the distribution of its variants did not differ significantly among the four populations studied. HHV‐6 was more prevalent than CMV, a closely related herpesvirus. Most cases of HHV‐6 infection involved both HHV‐6 variants A and B. These results do not support strongly that HHV‐6 infection is closely associated with the occurrence of NHL in AIDS patients but demonstrate that mixed HHV‐6 infections are more common than previously assumed.