Immunoconglutinin and antibody against fibrinogen products in hemolytic anemia and nephritis resulting from infection with a Haemobartonella-like agent.

An agent morphologically similar to Haemobartonella muris was isolated from the blood of rats infected with a strain of Trypanosoma lewisi kept at this Department. It caused acute hemolytic anemia, splenomegaly, glomerulonephritis, and death within 5 to 8 days in mature Sprague-Dawley rats. The disease was less severe in weanling rats which usually recovered within 3 to 4 wk. The anemia was accompanied by phagocytosis of erythrocytes by monocytes of the spleen and bone marrow, by high titers of cold-active hemagglutinin, high titers of antibody to the third component of fixed complement (immunoconglutinin), and antibody to fibrinogen/fibrin related products. Filtrates of blood from anemic rats passing a 0.20-micron filter did not produce disease or signs of infections, but filtrate from a 0.45-micron filter was infective. Attempts to grow the agent on rat embryo fibroblast cultures and in embryonated chicken eggs were successful. Tests for bacteria, mycoplasma, and spirochetes gave negative results. Blood of infected rats did not produce signs of infections when inoculated into laboratory mice, and normal rats housed in cages with acutely infected rats did not develop signs of infection or disease. Morphological similarity did not allow differentiation of the agent from H. muris. However, its virulence for mature rats differs markedly from that usually seen in H. muris infection.