An NZB virus or NZB mice with viral infections?

Evidence for and against the possibility that the autoimmune disease of NZB mice has a viral aetiology is presented. It is considered that the case for a viral aetiology is unproven, although the possibility exists that virus may be present in incomplete form. Widely varying experimental results can be expected in experiments involving NZB mice until acceptable standards of mouse strain definition are laid down. Thus the comparison of results obtained from studies of NZB mice of diverse origin may invite misleading conclusions.