DYNAMICS OF MULTIPLICATION OF INFLUENZA VIRUS (FM_1 STRAIN) IN THE MOUSE LUNG

In this report the multiplication of a strain of mouse lung adapted in-fluenza virus (FM_1) was studied.The amount of virus increase in the mouselung at different intervals during the course of reproduction was determinedby titrating the infectious titre and the haemagglutinating titre of the infectedlung suspensions.It was found that the rate of multiplication of the virusdepended on the size of inoculum,and once the infectious titre had reached thehighest level,it began to decrease. As a whole,the curve of increase and decline of the infectious titre showeddirect correlation with the haemagglutinating titre.However,the latter wasnot detectable even when the former reached to 4.5—5.5 log units.The sig-nificance of this phenomenon is discussed in the paper. It was also pointed out that the selection of proper inoculum and time in-terval during serial passage of the virus in the mouse lung,may shorten thecourse of adaptation and increase the infectious titre of the virus in the lungof the infected host.