Contamination of transplantable murine tumors with lymphocytic choriomeningitis virus

Lymphocytic choriomeningitis virus (LCMV) was isolated from a transplantable tumor after mice bearing the tumor began to die prematurely. Tumor lines, mice and laboratory personnel that had an association with the index laboratory were tested for LCMV infection. Testing of tumor lines from the index laboratory and four other laboratories revealed that 16 of 55 tumor samples used in vivo and one of eight tumor samples maintained in vitro were contaminated with LCMV. Laboratory personnel and uninoculated mice that were exposed to infected tumors had no LCMV antibody. The use of carefully monitored seed stocks is recommended to protect transplantable tumors that may be inadvertently contaminated by viruses.