Interference in the Establishment of Superinfections with Trypanosoma congolense in Cattle

Abstract

To examine the influence of an established infection on subsequent challenge with another unrelated trypanosome serodeme, cattle were subjected to two challenges, 5 to 6 wk apart, with unrelated isolates of Trypanosoma congolense. The primary infection inhibited the establishment of the second infection despite the initial absence of detectable antibody to the trypanosomes used for the second challenge. This was true whether the second challenge consisted of bloodstream forms of the parasite or metacyclics from infected Glossina m. morsitans. Rechallenge with bloodstream forms resulted in a slight antibody response, which was only detectable by immunofluorescence and was much less than in the challenge controls. Although animals subjected to the second challenge by tsetse flies showed no appreciable increase in parasitemia and, in most instances, no chancre reaction at the site where the tsetse bit, they developed readily detectable neutralizing antibody to the metacyclic trypanosomes. That this interference effect was not the result of specific immunity and required an active infection was confirmed by the finding that when infected animals were treated with Berenil prior to rechallenge, they were fully susceptible to the infection.

Trypanosoma vivax,T. congolense“forest type” andT. simiae: prevalence in domestic animals of sleeping sickness foci of Cameroon

“…Up till now, the interaction and the evolution of different trypanosome species or subspecies in the infected hosts remain not yet well understood. Experimental studies have shown that primary infection with T. congolense prevents the establishment of a second strain of T. congolense (Morrison et al , 1982) while an animal already infected with T. congolense becomes refractory to T. brucei s.l. infections (second infection), but not T. vivax (Dwinger et al , 1989).…”

Protective immunity and specificity of antibody responses elicited in cattle by irradiated Trypanosoma brucei

“…The clone of T. brucei known as ILTat 1.3 was used throughout the study. The origin of this clone has been described elsewhere (Wells et al 1982). By using hyperimmune serum to the VSG in a neutralization assay, the population of trypanosomes was shown to be antigenically homogeneous to a level of lo4 organisms.…”

“…Trypanosomiasis is the major constraint to domestic livestock production in areas of Africa infested by the tsetse fly (reviewed by Morrison, Murray & McIntyre 1981). Susceptible cattle introduced into endemic areas develop a severe, often fatal, disease whose main manifestations are anaemia and cachexia.…”

Interference between different serodemes of Trypanosoma congolense in the establishment of superinfections in goats following transmission by tsetse

“…In rabbits superinfected 14 or 21 days after a primary infection, local skin reactions were reduced in size or completelely absent and the appearance of trypanocidal antibodies against the serodeme used for superinfection was considerably delayed. Although Morrison et al (1982) were unable to superinfect cattle at day 42 after the initial infection, Akol & Murray (1983) did so 95 days after primary infection. These contrasting results indicated the possible time dependency of the interference phenomenon in cattle.…”

“…Recently, an interference phenomenon has been reported to occur in cattle (Morrison , et al 1982) and in rabbits (Luckins & Gray 1983) infected with different serodemes of T. congolense; when attempts were made to superinfect either by tsetse flies or by intravenous inoculation, the infection was delayed or did not become established.…”