CONTAMINATION OF TRANSPLANTABLE TUMORS, CELL-LINES, AND MONOCLONAL-ANTIBODIES WITH RODENT VIRUSES

Different biological materials were tested for murine viral contaminat ion by using the mouse/rat antibody production test. Of 297 tumors exa mined, 75 (25.3%) were contaminated. Considerable differences in the c ontamination rate became evident when transplantable tumors from in vi tro and from in vivo passages were compared. Of 186 tumors that had be en propagated in animals, 36.6% were positive, whereas only 7 of III ( 6.3%) tumors propagated in vitro were contaminated. The highest rate o f contamination was detected in mouse tumors. Testing of 135 specimens of mouse origin revealed 46.7% were contaminated, and 57 (70.4%) of 8 1 samples propagated in mice were positive for murine viruses. Moreove r, 6.7% of 90 human tumors that had been passaged in athymic nude mice and 3.5% of 57 rat tumors were positive. Lymphocytic choriomeningitis virus was detected in 4 of 14 hamster tumors. The most frequent conta minant was lactic dehydrogenase elevating virus followed by reovirus 3 , lymphocytic choriomeningitis virus, minute virus of mice, mouse hepa titis virus, rat coronaviruses, Kilham rat virus, and Mycoplasma pulmo nis. Contamination with reovirus 3 and minute virus of mice was found in 4 (3.7%) of 109 cell lines tested, and 2 of 60 monoclonal antibody preparations or hybridoma cells contained lactic dehydrogenase virus. Contamination with two pathogens was detected in four mouse tumors and in one cell line.