The Influence of the Indigenous Bacterial Flora upon the Interferon Response of Mice

Lobund Laboratory University of Notre Dame, Notre Dame Indiana 46556 U.S.A. The reticuloendothelial system has been implicated as a major site of interferon production (Kono & Ho, 1965; De Somer & Billiau, 1966; Fruitstone et al. 1966). Due to a general, lack of stimulation, the reticuloendothelial system of germ-free animals is relatively under-developed (Thorbecke et al. 1957; Thorbecke, 1959) and we thought it of interest to investigate the capacity of such animals for interferon production. Germ-free or conventional CFW mice of the LOBUND strain, 8 to 10 weeks old were challenged intravenously with 0.2 ml. of an optimal interferon inducing dose of Newcastle disease virus (8 x 10 8 p.f.u.). At 2 hr intervals sera from three or four animals were pooled. The interferon titres of these sera were determined as described by Wagner (1961), using plaque reduction of vesicular stomatitis virus on Earle's L cells. The response of the conventional animals reached a peak of about 6000 interferon units/ml. 6 hr after challenge (Fig. 1). * This work was done under a contract from the Office of Naval Research to the University of Notre Dame: Nonr 1623(14). It is based on a dissertation submitted by E. A. Havell in partial fulfillment of the requirements for the Ph.D. degree at the University of Notre Dame. Supported by PHS Training Grant No. GMO 1248 from National Institute of Medical Sciences (awarding unit). Present address: Department of Dermatology, Roswell Park Memorial Institute, 666 Elm Street, Buffalo, N.Y. 14203, U.S.A. Received 13 April 1970; accepted 11 June 1970.