The action of terramycin on the growth of strains of influenza, herpes simplex, and rabies viruses in chick embryos and mice.

‘The value of terramycin as an antibacterial agent has been shown in previous publi~ationsl-~ and in other reports presented in this monograph. It is the purpose of this paper to describe some experiences with terramycin salts and how they influenced the course of a few experimental virus infections. The bulk of our attention has been focused on the action of this drug in influenza virus infections. Mention will also be made, however, of some work done on two strains of herpes simplex virus and a strain of rabies virus. Malerial and Melhods. The sodium terramycin salt was highly soluble in phosphate saline buffer (pH 7.4). Consequently, this diluent was used in all chick embryo experiments. The final pH of the solutions used was between 8.3 and 8.6. The material inoculated subcutaneously in mice was dissolved in distilled water and had approximately the same pH. All solutions were made up fresh for each inoculation. The viruses used and their passage history are as follows: PR8 strain of type A influenzaFerrets 198, Mouse 285, Egg 64, for egg inoculation and F 198, M 846 for mouse inoculation; Lee strain of Type B influenza virus, M 137E141; Armstrong strain of herpes simplex virus, M 49E31, M5E6; HF strain of herpes simplex virus, M?M5; rabies virus, passed in mice with passage once a month in rabbits, number of passages not known. The volume of drug solution injected in all instances was 0.2 ml. and contained the desired dosage of terramycin. The interval between injection of terramycin and virus was varied and is discussed under results. Most injections of both virus and terramycin were made into the allantoic cavity of 10 to 12 day-old embryos. A few tests utilizing the yolk sac as the route of injection were done and resulted in more deaths than by the allantoic method. In all tests, simultaneous controls of drug alone and virus alone were also carried out. Furthermore, preliminary tests for the toxic effect of drug alone were carried out in groups of 8 to 20 eggs. Influenza virus was diluted 10-fold in nutrient broth, and herpes simplex in 10 per cent horse serum in saline. The volume of inoculum was 0.2 ml., and 4 to 6 eggs were used for each dilution of virus. The eggs were incubated for 40 hours a t 35°C. for influenza and 72 hours at 37°C. for herpes. The eggs were chilled for 2 hours at 4°C. in those instances where allantoic fluids were to be removed. Such fluids were tested by diluting 1 to 4 with Experimenls with Chick Embryos.