Dr. Murai Éva szerk.: Parasitologia Hungarica 19. (Budapest, 1986)
ism. The negative protection achieved with the convalescent sera means that the trypanosomes were not present and did not persist in the resistant rodents (voles and rabbits). Nevertheless, we have to keep in mind that the strong parasitaemia that existed during the examination could have temporarily exhausted the antibody content of the serum. Rats (Rattus_rattus_) are as susceptible to T. equiperdum as mice are. However, they develop a fatal septicaemia only after a longer time, usually by days 8-12 PI, obviously because of their greater body mass. Therefore, for trypanosome antigen production it is advisable to perform group infections with high doses, subcutaneously, since in that case the rats will die already on PI days 4-6, in a somewhat protracted manner. Table 3 Deaths in the simultaneously infected groups, each consisting of 6 mice Method of inoculation Number of deaths on PI day Method of inoculation 1 2 3 4 5 6 7 8 9 10 11 12 Concentrated hyperimmune rabbit serum 0 and trypanosome 2 1 3 1:10 diluted rabbit immune serum 0 and trypanosome + 1 1 3 1 Egyptian spiny mouse serum" and trypanosome + A 11 6 mi c e í stay e d iliv e ! 1:10 diluted serum of Egyptian spiny mouse x and trypanosome"*" 1 3 1 1 Concentrated normal rabbit serum and trypanosome"*" 1 4 1 Trypanosome without serum (controls) 1 3 2 + = 0.2 ml blood suspension, containing about 5xlO á trypanosomes, was inoculated ip. , simultaneously with the antibody-containing sera of 0.5 ml volume each o = hyperimmune serum was raised in rabbits using twice-washed trypanosomes obtained from rat blood by centrifugation X = Serum of Egyptian spiny mouse, taken 1 1/2 months after infection with T. equiperdum. After the serum had separated, we kept it at 4°C for 2 days to kill the trypanosomes present in it. In general, a group should be killed by bleeding when 1/4 of the animals have already died, or are agonizing, since by that time trypanosomes will have multiplied considerably in other animals of the group. Intraperitoneal inoculation of groups of rats is not advisable since in that case fatal septicaemia can develop abruptly and consistently. In such a case, all the inoculated rats may die during one night. In the dead rats the only pathological sign of septicaemia is the 2- to 4-fold enlargement of the spleen. Protection experiments were carried out in infected rats with immune sera (antibodies), and we obtained precisely the same result as for mice. The performance of more experiments of this kind was hindered by the small amount of blood serum obtainable from resistant and survived rodents. No satisfactory protection (resistance) could be induced in the highly susceptible mouse or rat even by simultaneous infection. Therefore, further on we examined a simpler way of maintaining the T. equiperdum strain, i.e. the infection of resistant rodents. Fig. 4: A lot of Trypanosoma equiperdum are seen among red and white blood cells in blood of mice killed in agony (Magnification 1:1000)
