Establishment and characterization of a tumor cell line derived from a mouse infected with murine gammaherpesvirus 78

A tumor cell line, NB-78, was derived from a lymphoma from a BALB/c mouse infected with Murine gammaherpesvirus 78 (MHV-78). Cultures of the cells of this line underwent till now more than 100 passages, displaying an epitheloid transformed morphology and a diploid complement of 40 chromosomes. Viral antigen was detected in 12% of cells by immunofluorescence (IF) test. Reactivation of latent MHV-78 was proved by detecting infectious virus in culture medium only at passages 4345. The presence of viral M1, M2, M3, and M4 gene sequences in the genome of the cells was demonstrated by PCR. NB-78 is the first continuous cell line, which originates from a tumor of a MHV-78-infected host, harbors viral genome or at least its several genes, and produces infectious virus only rarely upon reactivation. It can be assumed that this cell line is primarily associated with MHV-78 and will serve as an invaluable tool for studying the MHV-78 latency.