A human tumor xenograft contaminated with mouse hepatitis virus (MHV) was implanted in a nude rat in order to decontaminate the tumor line. The decontamination failed in the first trial, but succeeded in the second trial. The difference between the two trials was the duration of implantation of the tumor in the nude rat, i.e., 12 days in the first and 24 days in the second trial. Duration of implantation might be a factor in the decontamination of transplantable tumors infected with MHV by passaging in the nude rat.

Examination of serum specimens from a patient with chronic active hepatitis proved negative to the Australia-SH antigen by immunodiffusion and by complement fixation. Because the sera were anticomplementary they were examined with the electron microscope, and virus-like structures similar to members of the coronavirus group were identified. The possible significance of this finding in human serum and its relation to mouse hepatitis virus are discussed.A sample of the serum pool containing the MS-1 agent was found negative when examined by immunodiffusion, complement fixation, and electron microscopy. The possible lack of immunological identity between infectious and serum hepatitis is discussed.