Anaphylaxis in Guinea Pigs following Sensitization with Chick-Embryo Yellow Fever Vaccine and Normal Chick Embryos

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Abstract
As anaphylacto-genic agents, chick-embryo aqueous base yellow fever vaccine and normal chick-embryo extracts prepd. from 13- or 14-day embryos were found to be more effective than those employing 10- or 11-day embryo material for their prepn. In 5 expts., 81.5% of young guinea pigs sensitized with single, subcut. injns. of 14-day embryo extracts and challenged by the intracardial route showed anaphylactic reac-tions; 44.4% underwent fatal shocks. When 10-day embryos were employed, > 15% of the guinea-pigs demonstrated anaphylaxis; no fatal reactions were encountered. In a 6th expt., antigens prepd. from normal chick-embryos incubated for 6, 9, 10, 11, 12, 13 and 14 days, respectively, were employed. All sensitizing and challenging doses were comparable on a basis of N content. No reactions were observed with the youngest embryo material tested. Both number and severity of anaphylactic reactions increased with increasing embryo age, being most pronounced with 14-day embryo extracts. The significance of these results is that in preparing biologicals utilizing chicken embryos, the younger embryos should be employed.