A New Living Vaccine against Fowl Plague Disease

Abstract

IN a previous investigation¹ three attenuated substrains from a pea fowl strain were obtained by serial passages mainly in pigeon embryos. One of these substrains (PEC₂ P₁₁ C₃₀)—that is, pea fowl strain subjected to 2 passages in chick-embryos, 11 in pigeon-embryos and 30 in chick-embryos successively—was subjected for further attenuation to more than 400 passages in pigeon embryos using either the intra-allantoic or the intra-yolk route of inoculation. During these passages 33 desiccated batches were prepared from the pigeon embryos. These batches were titrated in chick-embryos, fowls, and afterwards tested for safety and potency in laboratory and field experiments.