Association of human herpesvirus 6 with lymphoid malignancies in Iraqi patients


Background: Human herpesvirus type 6 (HHV-6) is associated with roseola infantumduring childhood followed by life-long latency that periodically reactivated inimmunocompromised individuals. In spite of several studies to establish the pathogenicrole of HHV-6 in lymphoid malignancies, the issue is still controversial.Objectives: This study was arranged to explore the association of HHV-6 infection inlymphoid malignancies using different serological and molecular techniques and toquantify the plasma viral load.Patients and methods: This cross-sectional case control study was conducted inNational Center for Hematological Diseases (NCHD) at Al-Mustansiriyah Universityand Baghdad Teaching Hospital (BTH) in Baghdad-Iraq from September 2013 tillApril 2015. The patient group consists of 11 patients with Hodgkin lymphoma and39 Non-Hodgkin's lymphoma of both sexes. The age range was between 15-80 years.The diagnosis of lymphomas was based on hematological and histopathologicalcriteria. 59 apparently healthy individuals were enrolled as control group. They werechosen from unpaid blood donors. The age range was between 18-59 years. Humanprivacy was respected by taken participant's oral consensus. The seropositivity rate ofanti-HHV-6 IgG and IgM antibodies were detected by enzyme linked immunosorbentassay (ELISA) and indirect immunofluorescent test (IFAT). The molecular detectionand determination of plasma viral DNA load was achieved by quantitative polymerasechain reaction (qPCR). All data were statistically analyzed, and P values < 0.05 wereconsidered significant.Results: The anti-HHV-6 IgG positivity rate by IFAT was insignificantly higher in HL(81.8% vs 61.0% p=0.186) and NHL (64.1% vs 61.0%, p =0.758) compared to controlgroup. The anti-HHV-6 IgG positivity rate by ELISA was 81.8% in HL, 84.6% inNHL versus 72.9 % in controls which were insignificant in both groups (p=0.534 andp=0.173) respectively. The anti-HHV-6 IgM positivity rate by ELISA techniqueamong patients with HL was significantly higher compared to controls (27.2% vs 6.8%,p= 0.038), but not significant in NHL (17.9% vs 6.8%, p= 0.086). HHV-6 DNA wasdetected in (27.3%) patients with HL by PCR technique, but none of the controls orNHL patients was positive. The plasma viral DNA load of the patient with HL was1.4± 0.3 x105 copies/milliliter.Conclusion: Although a higher anti-HHV-6 antibodies positivity rate among patientswith HL and NHL, the pathogenic role of the virus in the development of thesemalignancies was difficult to be ascertain.