To investigate the biological and immunological characteristics of the Nanjing local strains of HHV7, four strains of herpesvirus were isolated from saliva specimens of one healthy individual and three children suffering from a kidney disease in Nanjing. The viruses were identified by transmission electron microscopy(EM), indirect immunofluorescence assay (IFA) with a specific monoclonal antibody; nested polymerase chain reaction, restriction mapping and DNA sequencing. The virus-infected cells showed the typical cytophathic effect (CPE) under microscopy and could be detected by IFA with the human herpesvirus-7 (HHV-7) specific antibody. Under EM, herpesvirus-like and virions capsids could be found in their cytoplasm or nucleoplasm.HHV-7 DNA fragments amplified from infected cells by nested PCR were confirmed by restriction mapping and DNA sequencing. Similarly to DC strain, an known HHV-7 strain used in the present study as the positive control, the virus could be inactivated by ultraviolet irradiation for 10 min, heated at 45℃ for 30 min, pH＜5 or＞9 at 4℃ for 2 h and ether or chloroform for 10 h. The virus induced the production of TNF-α, IL-10 and IL-12p70 while inhibited IFN-γ secretion, increased the percentage of CD2+ cells while decreased that of CD4+ or CD45RA+ cells. The results indicate that the viruses isolated in Nanjing are HHV-7, which has similar biological characteristic to the known HHV-7 strain, DC. Infection with HHV-7 in vitro could affect immune function of lymphocytes by disturbing cytokine production and CD antigen expression. Cellular & Molecular Immunology. 2004; 1(5):367-372.
