THE TRANSFER OF RAT ANEMIA TO NORMAL ANIMALS

Fifty-eight white and hooded rats have been splenectomized and all of them have shown a more or less severe anemia and an infection of the red blood cells with Bartonella muris. Another strain of white rats obtained from Littlestown showed no anemia and no bartonellas in the blood after splenectomy, until exposed to infected rats. Others of these Littlestown rats, kept in the laboratory for some time before operation and exposed to infected rats, came down with bartonella anemia within 6 days after splenectomy. Whole blood or the washed red blood corpuscles from splenectomized rats which show bartonellas and anemia will produce a similar condition in young rats when injected intraperitoneally. Adult rats of strains which harbor the virus (as demonstrated by splenectomy) cannot be infected by injection. Intravenous inoculation of young normal rabbits with blood from an infected rat will sometimes produce a similar infection and anemia in the rabbit, and the virus can then be transferred back to young rats. The virus of rat anemia may be transferred from young normal rat to young normal rat with the appearance of Bartonella muris and the production of anemia. In the early transfers the disease may be fatal, but it usually becomes milder in successive passages. Although we have not yet been able to cultivate Bartonella muris and prove its etiological relationship to rat anemia by inoculation of cultures, we have added to the evidence that Bartonella muris is the cause of the anemia. Washed red blood corpuscles, containing bartonellas, will produce the anemia in the usual way while plasma from the same cells will either fail to produce it altogether or only after a prolonged incubation period. Blood heated to 57°C. for ½ hour fails to produce anemia or the appearance of bartonellas in the blood of inoculated animals. From these observations the following conclusions may be drawn: 1. All rats which harbor Bartonella muris ratti come down with a more or less severe anemia after splenectomy. 2. Young rats which have not yet developed an immunity undergo the typical anemia after intraperitoneal injection of blood from a splenectomized animal in the early stages of the anemia. 3. Young rabbits may show bartonellas and develop anemia following intravenous inoculation of infected blood. 4. The virus of rat anemia and Bartonella muris ratti may be transferred from normal animal to normal animal for successive generations. Such strains have now been transferred for five, nine and thirty generations. 5. The resistance of rats to bartonella anemia is almost wholly dependent on the spleen. Other organs do not take over this function of protection as shown by the relapse of splenectomized rats many months after recovery. Young rats which have recovered from an attack of anemia are not protected by this previous infection from the invasion of the virus following splenectomy. Adult splenic tissue mixed with infected blood before injection does not inhibit or neutralize the virus. 6. The virus of rat anemia is highly contagious and rats exposed to infection acquire it in some unknown way. 7. Bartonella muris ratti represents the virus of rat anemia or at least cannot be separated from the virus because: (a) The anemia in splenectomized and injected animals is always preceded by the appearance of bartonellas and the grade of anemia is proportional to the degree of infection with bartonellas. (b) Washed corpuscles containing bartonellas always produce anemia. Plasma either fails to do so, or produces a mild anemia after a long incubation period with a few bartonellas in the blood. (c) The thermal death point of virus and bartonella is the same.