Induction of host cell protein synthesis by human herpesvirus 6

We observed an increase in host cell protein synthesis in human cord blood lymphocytes (CBL) infected with human herpesvirus 6 relative to uninfected cultures. The magnitude of this effect could not be explained by a smaller decrease in cell number in the infected cultures. The induction of host cell protein synthesis by HHV-6 does not appear to be mediated by a stable soluble factor present in the infected cell culture supernatant. When CBL were infected with virus that had been exposed to ultraviolet irradiation (UV) for various intervals, we found that the level of increase in cell number, host protein synthesis, viral DNA and viral antigen was inversely proportional to the length of time of virus exposure to UV. No increase in cell number or host cell protein synthesis was seen in CBL infected in the presence of 50 micrograms/ml phosphonoacetic acid, an inhibitor of HHV-6 DNA replication. These results indicate that components of input virions do not induce the increased protein synthesis and that the induction is dependent on viral DNA replication.