The Relationships of Viral Content of Living and Dead Whole Eggs Inoculated With Various Concentrations of Psittacosis Virus

Evidence of the Existence of “Incomplete” Newcastle Disease Virus

“…It was first observed by Henle and Chambers (1941) that virus yields obtained in chick embryos inoculated with concentrated influenza virus were lower than those obtained by injection of diluted virus suspensions. Nadel and Fellowes (1953) obtained similar results when they employed infected psittacosis yolk sac material in mouse brains. A hypothesis which has been proposed to explain such results is that each virus initiates a multiplication cycle resulting in the accumulation of viral "building blocks".…”

Growth and Lethal Effects of the Psittacosis Agent in Chicken Embryos of Different Ages

“…Rake and Jones (1942) and Dougherty et al (1960), using staining techniques, noted the presence of elementary bodies in yolk-sac preparations from eggs which had survived well beyond the time of death of most of the embryos similarly inoculated, indicating a degree of enhanced resistance in the surviving embryos. Nadel and Fellowes (1953), by measuring the psittacosis agent content of living and dead embryos which had been inoculated with psittacosis organisms via the yolk sac, found high concentrations of the agent in a significant percentage of embryos surviving 7 days after the inoculation of 50 LD5o. This again indicates a higher resistance of these embryos to the lethal effects of the agent.…”