Studies on Experimental Influenza in Mice

III. Early Distribution of P³² Labeled Virus in Organs of Mice after Administration from Three Different Routes

Abstract

The same amount of P³² labeled influenza virus, PR8, was given to mice by intranasal instillation, intracerebral and intraperitoneal inoculations and the radioactivity of the six organs, i.e. brain, trachea, lung, liver, kidney and spleen was determined both 30 minutes and 3 hours after infection. The count detectable in lung was highest at the time of instillation, but the high distribution of the virus in the lung tissue was not the case, after intracerebral and intraperitoneal inoculations. At the time of intracerebral inoculation, radioactivity was highest in brain de-creasing from 30 minutes to 3 hrs. and next in liver. At the time of intraperitoneal inoculation, the total detectable count was low when compared to the activity obtained by other procedures. Here, highest distribution was in the liver.
The virus amount found in several organs was almost consistent when 30 minutes activity was compared to that of 3 hours, except in the case of intraperitoneal injection where the titer shift was found in liver, probably owing to the slow penetration of the virus from peritoneal cavity.
The radioactivities of liver, kidney and spleen at 3 hours were in good agreement with the infectivity found on the first day of the infection.
Sudden rise of P³² activity in the blood was noticed at 4 hrs. after intranasal instillation, and the fact was explained as the breakdown of virus particles.
The concept pneumotropism of influenza virus has been discussed from the results obtained in this study.