STUDIES ON THE PSITTACOSIS-LYMPHOGRANULOMA GROUP H. A NON-INFECTIOUS PHASE IN VIRUS DEVELOPmeNT FOLLOWING ADSORPTION TO HOST

The pattern of development of meningopneumonitis virus in the allantois of the chick embryo was described in a recently published report from this laboratory (1). The growth cycle of this virus was determined by titrating allantoic fluids and membrane suspensions, obtained at various intervals after the inoculation of virus, for infectivity in mice and chick embryos. The development of virus in allantoic membranes was characterized by the following pattern: (a) an increase in infectivity during the first few hours following inoculation; (b) a decrease in infectivity which was rather marked during the next 6 hours, and which then continued at a reduced rate until about the 22nd hour of incubation; (c) an increase in infectivity due to the new generation of virus. A typical growth curve in membranes is included in Fig. 4 of this report (lower curve). The present report concerns the first two phases of virus development and the data presented suggest that: (a) the initial increment of virus infectivity was due to the adsorption of virus from the allantoic fluid to the allantoie membrane and not to immediate virus reproduction; (b) the decrease of virus infectivity, following this initial increase, was due to a change in the virus from an infectious to a non-infectious state. Since in vitro methods were employed as a tool in this study, it was necessary to show that the same type of growth pattern occurred when infected allantoic membranes were placed in tissue culture. The accuracy of such methods of culture was also studied and will be discussed.