Growth-Curve Studies of Chick Embryo-Propagated Infectious Bronchitis Virus

ALTHOUGH there are reports in the literature on the concentration of infectious bronchitis virus (IBV) in chicken embryos at various intervals after inoculation, no growth-curve studies have been published. Cunningham and El Dardiry (1948), in making a study of the distribution of IBV in embryonating chicken eggs inoculated via the allantoic sac, made titer determinations on harvests of embryo fluids and tissues at 12, 24, 32, 36 and 48 hours postinoculation. Their results indicated that the chorioallantoic membrane and allantoic fluid harvested from living embryos 24 to 38 hours postinoculation were the materials of choice for obtaining the highest concentration of virus. Fabricant (1951) titrated fluids harvested at 24, 36–40, and 48 hours postinoculation and corroborated the findings of Cunningham and El Dardiry (1948) that IBV titers reached the maximum 24 hours postinoculation. The influence of concentration of inoculum upon virus titer in chicken embryos was reported by Cunningham…