Preparation And Characterization Of Monoclonal Antibodies Against Human Herpesvirus 7(HHV-7)

Human Herpesvirus 7(HHV-7) was isolated from activated CD4+ peripheral blood T cells of a healthy individual in 1990. The second independent isolation from a patient with chronic fatigue syndrome was reported in 1992. The HHV-7 genome of about 145 kb shows homologies to human cytomegalovirus (CMV) and human herpesvirus 6, which places it in the ?-herpesvirus subfamily. Human herpesvirus 7, like HHV-6, is ubiquitous (probably>85% of the population is infected) with transmission occurring early in childhood, but the primary infection may appear later in life than that of HHV-6.HHV-7, like HHV-6, grows well in CD4.+ lymphocytes but unlike HHV-6 it appears to utilize the CD4 molecule for its receptor. HHV-7 also down-modulates expression of CD4. Thus, this use of its envelope in anti-HIV therapy has been proposed.No disease has been reported that is clearly linked to HHV-7. The virus has been suggested to be a cause of Exanthema Subitum (ES) , childhood recurrent fever, Chronic Fatigue Syndrome (CFS) and Pityriasis Rosea (PR).The HHV-7 Nanjing local strain YY5 was isolated from a child with nephritis disease and grew in CBMCs or SupTl cells in our lab in 1998. In this study, we purified the virus by two-step sucrose gradient centrifugation. Then the purified virus was immunized to Balb/c mouse, and the spleen cells of the immunized mouse were fused with SP2/0 myeloma cells. The positive clones which produced McAbs against HHV-7 were screened by ELISA. As a result, clones named as 6H9, 6C11, 4D5 secreting specific McAbs against HHV-7 were obtained. Among these, 6H9 was of the IgGl, 6C11 and 4D5 were of the IgM. Ascitic litres of the antibodies were 1:6.4 X 104, 1:1.28X 105, 1:1 X 103, when tested by ELISA respectively. Western-blot showed that 6C11 was bound to 70KDa protein of HHV-7. Indirect immunofluorescence showed that 6 of 31 saliva samples from 4-6-year-old children gave bright diffuse immunofluorescence after the samples had been incubated with SupTl cells. The McAbs against HHV-7 may be useful tool for studying biological properties of HHV-7 and clinic laboratory detection.