lymphoproliferative disease. Four were of an ambiguous phenotype and were MHV-68
negative. One, S11, was a B lymphocyte that contained MHV-68 genomes in both linear and
episomal forms and released virus. The line was clonable and grew into tumors in nude
mice. This is the first naturally occurring MHV-68-positive B-cell line to be generated, and it
will be an invaluable tool for the study of MHV-68 latency.