The IsTaR 1 serodeme of Trypanosoma brucei: development of a new serodeme

An extensive serodeme of sequentially-isolated antigenic variants of African trypanosomes has been produced from both syringe-passaged and cyclically-transmitted Trypanosoma brucei of the IsTaR 1 clone derived from EATRO 164. The majority of the antigenic variants were isolated from chronically-infected deer mice (Peromyscus leucopus). The pattern of parasitemias during the course of infections initiated with syringe-passaged trypanosomes differed from those initiated with cyclically-transmitted trypanosomes. Trypanosome populations from syringe-passaged (192) and cyclically-transmitted (31) clones were each amplified by growth in lethally-irradiated mice and cryopreserved for retrospective analysis. Five clones derived from a single deer mouse during the first 44 days of infection, and 2 clones derived from an acutely-infected rat were established from these amplified populations. Homogeneous populations were grown in lethally-irradiated rats and mice for antigenic analysis purification of variant-specific glycoprotein. Six of the 7 clones were distinct variants by immunological criteria using antisera derived from whole cells or purified surface glycoproteins. Two clones, one derived from the acutely-infected rat, and the other from the first parasitemia in a chronic infection that was initiated with the former clone, were immunologically identical. Production of these clones established a well-defined serodeme that will allow detailed analysis of antigenic variation.

Cerebral trypanosomiasis in cattle with mixed Trypanosoma congolense and T. brucei brucei infections

Six Boran steers were infected simultaneously with Trypanosoma congolense and T. brucei brucei while another group of 3 was inoculated with T. b. brucei one year after infection with T. congolense. Three further steers were infected with T. b. brucei alone. Whereas, the six animals which received simultaneous infections developed clinical signs of cerebral trypanosomiasis as evidenced by depression, ataxia and occasional circling, those infected with T. b. brucei alone did not. At necropsy, 4 out of the 6 simultaneously infected animals had a mild to severe disseminated non-suppurative meningoencephalitis. Trypanosoma b. brucei was isolated from the cerebrospinal fluid (CSF) of three out of the four animals with histological lesions. Two of the cattle superinfected with T. b. brucei one year after infection with T. congolense also developed both clinical and histological evidence of cerebral trypanosomiasis. Trypanosoma congolense was isolated from the CSF of one of these 2 animals. Specific antibodies to the variable surface glycoproteins (VSGs) of the infecting T. b. brucei and T. congolense clones were found in the CSF of the 8 animals that developed cerebral trypanosomiasis. In these animals however, there was neither temporal nor quantitative correlation between VSG-specific antibodies in serum and in CSF, implying a de novo synthesis of antibodies to the infecting trypanosomes in the CSF.

Histopathological findings in mini-pigs infected with different strains of Trypanosoma brucei

Two pigs infected with Trypanosoma brucei gambiense developed low parasitemia which became undetectable after 6 months; on autopsy 13 months after infection they showed no histopathological alterations. --Five of six pigs infected with a Trypanosoma brucei brucei strain from the Ivory Coast developed low parasitemia (up to about antilog 6.5 per ml of blood) which became progressively lower but was detectable up to one year after infection. On autopsy they showed interstitial myocarditis and meningo-encephalitis; during the course of the infection, the first became milder, the second more intense; no trypanosomes were seen in the tissues. One of these pigs developed a parasitemia of up to antilog 8 and died 172 days after infection from bacterial pneumonia, histologically it had severe myocarditis with many trypanosomes in the tissue and mild meningo-encephalitis. --Three pigs infected with a Trypanosoma brucei brucei strain from the Serengeti died 47, 68, 130 days after infection. The first dying pig had a high terminal parasitemia, in the others, the parasitemia was low until the end, being only detectable by the hematocrit centrifugation technique or by mouse passage. At autopsy, all showed massive myocarditis and interstitial nephritis with masses of extravascular trypanosomes, moderate meningo-encephalitis with very few trypanosomes, and widespread colonization of other organs and tissues by trypanosomes, still without marked cellular infiltrations.

Behaviour of a Trypanosoma brucei brucei stock (STIB 348C) in mice. 4. Different course of primary parasitemia in trypanosome variants of different virulence

In three types of trypanosomes with low virulence, trypanosome numbers increased by a factor of 18-21 per day on average during prepatency and by a factor of 70-219 on average from the first to second day of patency. By contrast, a very virulent trypanosome variant showed an average increase of trypanosome numbers per day by 32 and 28 during prepatency and early patency, respectively. --In detailed studies, trypanosomes of low virulence exhibited a rapidly rising parasitemia in early patency which lasted for 20-30 hours and was followed by a plateau of slowly rising and falling parasitemia. Trypanosomes of high virulence showed a constant logarithmic increase of their numbers, slowing down at concentrations above antilog 5.5 per microliters of blood. In mild trypanosomes with peak parasitemias of antilog 5-5.7 per microliters of blood, after low dose infections the primary parasitemia was abruptly terminated after 70-100 hours of patency, obviously by the action of antibody. After massive infections, the parasitemia was terminated at 109-122 hours after infection. --In trypanosomes with higher peak parasitemias, primary parasitemias were seen to last longer, in some cases for 7 to 12 days. --Mice infected with low doses of highly virulent trypanosomes died with high parasitemias after some 60-90 hours of patency, before antibodies could normally become effective. After massive infections they died at 40-60 hours after infection. There is clearly no need to invoke non-immunogenicity of these trypanosomes or immunosuppression by these trypanosomes to explain this course of the infection.

[Behavior of a Trypanosoma brucei strain (STIB 348C) in mice. 3. Histopathological findings in the terminal stage of infection]

Histopathological findings in the terminal stage of the infection of mice and rats with different variants of the Trypanosoma brucei brucei stock are described. Mice infected with mild variants showed after 12-149 days intense trypanosome colonization of the interstitial connective tissue, especially of the heart muscle, pancreas and choroid plexus, with severe tissue destructions, especially in the pancreas. With longer duration of the infection, round cell infiltrations of the leptomeninx and around intracerebral vessels developed. The alterations were the same in animals dying with high and low parasitemias. Some animals died with continuous bleeding from the tip of the tail, with serious effusions and massive edema or with generalized bacterial infection. The lymphatic organs showed intense reactive alterations, trypanosomes were only rarely found in lymph nodes. In the liver large fields of lymphatic and myeloid cells were seen, sometimes necroses developed. The kidneys showed marked deposition of eosinophilic material in the glomeruli and precipitation of proteinaceous material in dilated tubules. - Rats infected with mild trypanosomes exhibited intense colonization of the heart by trypanosomes, in some places many trypanosomes in lymph nodes, few trypanosomes in the pancreas. They died after a long phase of high parasitemia.--After infection with virulent parasites which killed the animals with high parasitemia in a few days, mice and rats had single small foci of trypanosome colonization of the interstitial connective tissue of heart, pancreas and choroid plexus as well as of the loose connective tissue in the hilum of the kidney and around lymph nodes.(ABSTRACT TRUNCATED AT 250 WORDS)

Bromoacetyl-L-carnitine: biochemical and antitrypanosomal actions against Trypanosoma brucei brucei

One of the causative agents of the African Trypanosamiases, Trypanosoma brucei brucei is able to use high intracellular carnitine concentrations and a high carnitine acetyl transferase (CAT) activity to stimulate ATP production. This paper reports that a carnitine analogue, bromoacetyl-L-carnitine, is an irreversible inhibitor of CAT from T.brucei, non-competitively inhibits carnitine uptake by T.brucei and has a potent in vitro effect against T.brucei motility and infectivity. An in vivo action in T.brucei infected mice is also reported. These results represent a new area of investigation in the important search for new antitrypanosomal agents.

The use of 75-seleno-methionine labelled Trypanosoma brucei to measure parasite replication in vivo

The suitability of 75-Se-labelled trypanosomes for the measurement of trypanosome replication rates in vivo was investigated. The principle used to estimate the doubling time of the circulating parasites was the decrease in specific activity of 10(-7) parasites and this was determined both for parasites contained in a whole blood sample and for parasites separated from the blood sample by DEAE-cellulose chromatography. When two stocks of T. brucei (TrEU 226, TrEU 667) were compared it was found that the parasitemic profiles of radio-labelled trypanosomes transfered into naive mice were essentially the same as those of unlabelled parasites of each stock. Furthermore it was found that in an acute infection (TrEU 226) there was a rapid and continuous fall in the specific activity implying a constant doubling time. However, in the more chronic relapsing infection (TrEU 667) a biphasic decrease in the specific activity occurred which although initially similar to that of the acute infection changed to a much slower rate of replication at the time of peak parasitemia. The results indicate that radiolabelled trypanosomes can be used to measure parasite replication rates in vivo, and may therefore be a valuable method for investigating the factors governing parasite growth in the circulation.

Isolation of human serum resistant Trypanozoon from cattle in Nigeria

Four trypanosome stocks of the subgenus Trypanozoon were isolated from a herd of cattle in the Jos Plateau of Nigerian during a study on the epizootiology of trypanosomiasis. One of the stocks was repeatedly highly resistant to normal human serum (Blood Incubation Infectivity Test), indicating potential human infectivity. These observations suggest that the domestic cattle might act as reservoir hosts for the causative agent of human trypanosomiasis.

Host-parasite interactions which influence the virulence of Trypanosoma (Trypanozoon) brucei brucei organisms

Subclones were prepared in mice from T. b. brucei ILTat 1.4 parasites. Subclones which did not differentiate to stumpy forms in mice were highly virulent and did not stimulate detectable antibody responses. A subclone which did give rise to stumpy forms in mice, was less virulent and did stimulate an antibody response specific for the trypanosome surface glycoprotein. Clones and subclones of T.b. brucei parasites which did not give rise to stumpy forms in mice, did give rise to stumpy forms in Bovidae. Plasma from cattle infected with those parasites did not stimulate differentiation of T.b. brucei parasites in mice. Murine pleomorphic and monomorphic T.b. brucei parasites retained their respective phenotypes in co-infected mice. Both types of parasites were equally pleomorphic in Bovidae. We conclude that some clones of T.b. brucei remain monomorphic in mice as a result of a high avidity interaction between slender forms and host molecules which inhibit differentiation of T.b. brucei parasites.

Repression of glycoprotein synthesis and release of surface coat during transformation of Trypanosoma brucei

The biosynthesis of the variant surface glycoprotein (VSG) and its release from the surface of Trypanosoma brucei 427 variant clone MITat 1.4 (117) during in vitro transformation of bloodstream trypomastigotes to procyclic trypomastigotes was investigated. After transfer to the transformation medium at 27 degrees C, VSG synthesis is repressed with a half-time, t1/2 = 30 min. Concomitantly VSG-specific mRNA is lost suggesting that repression operates at the transcriptional level. The expression-linked extra gene copy, which codes for VSG, is retained during and after completion of transformation. After repression of VSG synthesis, surface VSG is shed from the cells into the culture medium. During release part of VSG (apparent mol. wt. 61 000) is proteolytically cleaved to a product (apparent mol. wt. 51 000) which represents the N-terminal domain of the protein as judged by the absence of the carbohydrate moiety normally linked to the C terminus.

The course of Trypanosoma brucei ssp. infection in domestic chickens

Three unrelated stocks of Trypanosoma (Trypanozoon) brucei were tested for their ability to infect domestic chickens. One of them, Lugala/55/EATRO/459, regularly produced a chronic infection. This was characterized by a low parasitemia (3-100 mouse infective organisms per ml of blood) that lasted for nine months in pullets and over one year in cockerels. Advances and remissions of the parasitemia were detected during the course of the infection. There was no obvious impairment of the health of the birds and their growth rate was indistinguishable from that of uninfected chickens. A second stock of T. brucei produced a transient infection that lasted for a few days only and a third failed to infect. These observations, of persistent symptomless infections, raise the possibility that domestic chickens and other birds may act as reservoirs in the cycle of infection in nature, as do many game animals.

Cyclical transmission of in vitro cultivated bloodstream forms and procyclic trypomastigotes of trypanosoma brucei brucei by Glossina morsitans morsitans

In vitro cultivated bloodstream and procyclic forms of Trypanosoma b. brucei STIB 247 were cyclically transmitted by Glossina m. morsitans. The tsetse flies were infected artificially on a silicon membrane. Metacyclic trypanosomes from mature salivary gland infections were used to initiate bloodstream form cultures. They transformed into slender bloodstream forms and gave rise to established cultures that proved to be infective for the vector. The metacyclic forms retained the strain-specific basic set of variable antigen types.

The phospholipases of pathogenic and non-pathogenic Trypanosoma species

Four species of trypanosome were examined for phospholipase activities using 1-[3H]palmitoyl-2-acyl-sn-glycero-3-phosphocholine and 1-acyl-2[14C]linoleoyl-sn-glycero-3-phosphocholine as substrates. The major activity in each species is a phospholipase A1 (EC 3.1.1.32) which does not require calcium. The most effective of the detergents tested for activation of the enzyme from each species, and the Ph optima, are as follows: Trypanosoma brucei, 0.125% Triton X-100 at pH 6.0-8.5; T. congolense, 0.5 mM linoleate at pH 6.0; T. theileri, 0.1% Triton X-100 at pH 6.75; T. lewisi, 0.2 mM sodium dodecyl sulfate at pH 5.2. The specific activity of the enzyme from a pathogenic species, T. brucei, is very high (145 nmol/min/mg/protein) and could contribute to the tissue damage characteristically caused by this parasite. The level in T. lewisi, a non-pathogenic species, is relatively low (1 nmol/min/mg). The levels in T. theileri (31 nmol/min/mg) and T. congolense (10 nmol/min/mg are intermediate. These results are compatible with the hypothesis that phospholipases contribute to the pathogenicity of trypanosomes.

The susceptibility of chickens to Trypanosoma brucei subspecies

Chickens were susceptible to infection with three different stocks of the subgenus Trypanozoon: two of presumptive Trypanosoma b. brucei and one of T. b. rhodesiense. Two groups of chickens were used: the first hatched following inoculation with either T. b. brucei or T. b. rhodesiense during embryonic development, and the second were infected as adult birds. In both experimental groups, parasitaemia persisted for prolonged periods, but was mostly subpatent and detectable only by subinoculation of blood into mice. In chickens infected as embryos, parasitaemias were patent for five weeks after hatching, but subpatent thereafter (to weeks 13 to 17). Quantitative estimations of the parasitaemias of seven of the birds hatched from embryos inoculated with T. b. brucei revealed fluctuations in the number of circulating trypanosomes, with an initial peak between days 2 to 9 after hatching. Between weeks 13 to 17 after hatching the chickens appeared to have recovered spontaneously from the trypanosome infections. Homologous challenge at week 20 failed to produce a recrudescence of parasitaemia, indicative of a possible acquired immunity. The infections of ten chickens inoculated with either T. b. brucei or T. b. rhodesiense as adult birds were microscopically subpatent throughout the observation period of six weeks, but subinoculation of blood into mice showed the chickens were parasitaemic from week one and thereafter. Different aspects of infection of avian hosts by the Trypanozoon subspecies are discussed.

The separation and structure of infective trypanosomes from cultures of Trypanosomas brucei grown in association with tsetse fly salivary glands

Infective trypanosomes developed when Trypanosoma brucei was cultivated at 28 C in a liquid medium containing tsetse fly head-salivary gland explants. They were separated from the noninfective culture forms using DEAE-cellulose column chromatography. It was demonstrated by light and electron microscopy that the separated organisms were morphologically similar to metacyclic stages found in a tsetse fly and that they had a characteristic surface coat. Single metacyclic trypanosomes isolated from the cultures gave rise to infections in mice.

In vitro cloning of animal-infective bloodstream forms of Trypanosoma brucei

Clones of animal-infective bloodstream forms of Trypanosoma brucei (stocks S.427 and LUMP 227) were made by transferring a single organism from bloodstream-form cultures into each well of Microtest II Tissue Culture Plates containing bovine fibroblast-like feeder cells. When the number of trypanosomes increased to 10(2)--10(3)/well on days 4--16, they were transferred into plastic T-25 culture flasks also containing feeder cells and fresh medium. Cultures were thereafter maintained by partially replacing the trypanosome suspension with the same volume of fresh medium (diluting the density to 2--5 x 15(5) trypanosomes/ml) every 24 h. Sub-cultivations could be made by transferring 1--2 ml of the trypanosome suspension to a new culture flask at 4--5 day intervals. A total of 42 clones in the 3 series TC221, TC52 and TC227, carrying variable antigen types (VATs) 221, 052 and ILTat 1.4, respectively, have been established. Average population doubling times for clones of TC221, TC52 and TC227 were 8.7, 14.5 and 15.5 h respectively. Of 35 populations examined, 34 clones retained the original specificity of their VATs for at least 8--32 days from cloning. One cloned population of TC52 consisted of 99.8% VAT 052 and 0.2% VAT 221 at the time when the first VAT test was made on day 18.

Antigenic variation in clones of animal-infective Trypanosoma brucei derived and maintained in vitro

Eighteen clones of variable antigen type 052 of Trypanosoma brucei stock S.427 were derived and maintained as animal-infective bloodstream forms in vitro for up to 60 days of cultivation. The antigenic composition of such clones was monitored weekly by immunofluorescent analysis of viable trypanosomes, using antisera raised to isolated variant-specific surface glycoproteins of both 052 and variable antigen type (221) which consistently appeared in the first relapse population of type 052 in vitro. The appearance of new variants was detected in 9 of the 18 clones 18--46 days following initiation of the clone and variable antigen type 221 was found in all 9 clones. On one or more occasions in 8 of such clones, viable trypanosomes were found which did not react with either antiserum but were mouse-infective on the 4 occasions tested and probably represent other variable antigen types. The process of antigen variation in vitro appears to resemble the process in vivo except that new variant types are detected earlier in vivo. This possibly results from different growth rates of the trypanosomes in vivo and in vitro, together with the fact that elimination of the initial variant population by the host's immune response facilitates the detection of newly arising variable antigen types in vivo.

Identification by the blood incubation infectivity test of Trypanosoma brucei subspecies isolated from game animals in the Luangwa Valley, Zambia

A total of 7 stocks of Trypanosoma brucei subspecies, isolated from naturally infected game animals in the Luangwa Valley, Eastern Province, Zambia were examined using a modified version of the Blood Incubation Infectivity Test (BIIT). One stock giving consistent BIIT responses typical of T.b. rhodesiense, was obtained from warthog (Phacochoerus aethiopicus). Four other stocks, 2 from hyaena (Crocuta crocuta), 1 from a waterbuck (Kobus ellipsiprymnus) and 1 from a lion (Panthera leo) responded like T.b. brucei. One stock from a waterbuck and 1 from a giraffe (Giraffa camelopardalis) failed to infect mice after incubation in human serum for 30 min at 37 degrees C when first tested, but after 5 or 6 further serial passages in mice and even with serum incubation time increased to 5 h, they retained infectivity.

Trypanosoma brucei: in vitro propagation of metacyclic forms derived from the salivary glands of Glossina morsitans

1 Metacyclic forms of Trypanosoma brucei obtained from the salivary glands of the tsetse fly, Glossina morsitans have been cultured for the first time in their infective forms for more than 200 days in continuous culture. The parasites were grown at 25 C and 30 C on a bovine embryonic spleen (BESP) feeder layer in buffered RPMI 1640 medium supplemented with 20% heat-inactivated bovine fetal serum (BFS) and 5% lactalbumin hydrolysate. Initial growth rate was enhanced when normal, noninfected, salivary glands were added to the cultures. The parasites thus cultured appeared like slender or intermediate blood stream forms which were infective to rats and mice. Addition of rat anti-T. brucei specific antiserum to the cultures caused agglutination of the parasites and rendered them noninfective. This study opens up new areas of investigating sleeping sickness. The cultured metacyclic parasites have the potential of being applied as antigens for controlling African trypanosomiasis.

Infectivity of Trypanosoma brucei cultivated at 28 C with tsetse fly salivary glands

When transformed procyclic noninfective trypanosomes of several unrelated stocks of Trypanosoma brucei were cultivated in T-30 Falcon flasks at 28 C in a liquid medium containing head-salivary gland explants of Glossina morsitans morsitans some of the organisms developed into forms infective for mice. Infective trypanosomes were detected 7 to 14 days after the cultures were prepared and they persisted for varying periods of up to 88 days when the cultures were terminated. A few of the salivary glands became invaded with parasites about the time infective organisms appeared in the cultures. Using T. brucei TREU 929, it was shown that trypanosomes grown with between 2m and 50 explants were capable of producing infections consistently for prolonged periods. On the other hand, trypanosomes cultivated with 25 or fewer explants rarely infected mice. Infectivity titrations on trypanosome suspensions from cultures of stocks TREU 1275 and TREU 929 revealed that the maximum number of infective organisms was present 26 to 50 days after initiation of the cultures. Control cultures of trypanosomes grown in medium alone were generally not infective but 2 of the 6 stocks gave rise to a few sporadic infections. A few epimastigote-like and metacyclic-like trypanosomes were seen in stained preparations of infective inocula.

Inactivation or elimination of potentially trypanolytic, complement-activating immune complexes by pathogenic trypanosomes

Trypanosoma brucei subsp. brucei and T. congolense incubated in homologous antibody at 0 degrees C for 30 min were lysed by subsequent addition of guinea pig complement. Trypanosomes incubated in antibody at 37 degrees C before complement treatment remained intact. Parasites bearing adsorbed antibody also remained intact when incubated at 37 degrees C before complement treatment. The proportion of cells which survived complement treatment decreased with increasing antibody concentration. Parasites which survived complement treatment continued to express antigens which could bind complement-activating antibody, but did not bear complement-activating immune complexes. Virtually all cells in T. brucei populations exposed to antibody at 37 degrees C, but only 10(-3) to 10(-5) of the cells in populations exposed to antibody at 0 degrees C before complement treatment, remained infective for X-irradiated mice. Only 10(-6) to 10(-7) of T. brucei populations exposed to antibody at 0 or 37 degrees C before complement treatment infected mice immunized with homologous antigens. Serotype analysis of substrains and of T. brucei populations isolated from mice infected with antibody and complement-treated parasites suggested that variant-specific antigens participated in trypanolysis and that T. brucei which survived complement treatment could undergo antigenic variation. Mechanisms by which trypanosomes may inactivate or eliminate surface immune complexes and the possible significance of this phenomenon in trypanosomiasis are discussed.

Antigenic analysis by agglutination of Trypanosoma brucei brucei parasitemias initiated in mice with in vitro-produced metacyclics

Trypanosomes from 14 first-peak parasitemias initiated in mice by injection of in vitro-produced metacyclics were stabilated. Strains derived from these stabilates were analyzed for their antigenic composition by cross-agglutination with immune sera produced in rabbits against 12 of the stabilates. The antigenic composition of the 14 stabilates was compared also with two first-peak parasitemias from mice inoculated with fly-derived metacyclics, the variant-specific antigen of the strain used to initiate the cultures that ultimately became infective, and the antigenic variant that was used to infect the flies. One variant-specific, presumably basic, antigen was found, either as the predominant (nine parasitemias) or as a minor (seven parasitemias) antigen, in all first peak-parasitemia strain initiated with culture- or fly-derived metacyclics; it was absent, however, from the strains (not first-peak parasitemias) used to start the cultures or to infect the flies. Only one of the first-peak parasitemias appeared to have the basic antigen alone. The remaining parasitemia populations seemed to have from about two to six antigens, some of which were common to culture- and fly-derived infections. There was very little, if any, antigenic relationship between the foregoing populations and the strains employed for initiation of cultures or for infection of flies. It is evident from the results that much antigenic similarity exists between the culture- and tsetse fly-derived first-peak parasitemias.

Sleeping sickness: in vitro cultivation of Trypanosoma brucei from the salivary glands of Glossina morsitans

Two strains of Trypanosoma brucei were propagated from the salivary glands of 5 Glossina morsitans for more than 200 days on a bovine embryonic spleen feeder layer using buffered RPMI 1640 medium supplemented with 20% bovine fetal serum. In the first 2 to 3 weeks of cultivation the density of parasites in the salivary glands and culture medium remained constant probably because of defective binary fission. The parasites were infective to rodents only on days 17 and 25. Electron microscopic examination of the parasites on 6 different occasions revealed that they were similar to the immature metatrypomastigotes of T. brucei described in the salivary glands of infected tsetse flies.

Growth of infective forms of Trypanosoma (T.) brucei on buffalo lung and Chinese hamster lung tissue culture cells

Infective cultures of Trypanosoma (T.) brucei (strain 427) have been initiated and maintained on Chinese hamster lung tissue culture cells and buffalo lung tissue culture cells. By changing daily one-third of the RPMI-1640 plus 20% fetal bovine serum medium, the cell numbers can be maintained at 2--4 X 10(6) cells/ml. The cultured trypanosomes on these two tissue culture cell types were infective to mice and morphologically similar to bloodstream slender trypomastigotes in having a subterminal kinetoplast and a surface coat. In addition, they possessed the L-alpha-glycerophosphate oxidase, the predominant steady state terminal oxidase identified in bloodstream trypomastigotes.

Trypanosoma brucei-cultivation in vitro of infective forms derived from the midgut of Glossina morsitans

Infective forms of Trypanosoma brucei derived from the midgut of Glossina morsitans, have been propagated in vitro for 61 days on a bovine embryonic spleen (BESP) feeder layer using RPMI 1640 medium. It was reproducibly shown that only parasites cultured from the midgut of tsetse flies 12-14 hr after feeding on infected animals could be established in vitro. Cultures thus established were infective to rats and tsetse flies. Only midgut vector types of the parasites were identified by light and electron microscopic techniques.

Trypanocidal activity of antitumor antibiotics and other metabolic inhibitors

A microtest has been devised for the rapid preliminary assay in vitro of the effect of over 100 drugs and inhibitors on African trypanosomes (Trypanosoma brucei and T. rhodesiense). Parasite motility and infectivity for mice are indexes, respectively, of respiration and glycolysis and of cell division; trypanocidal titers based on these indexes can show primary metabolic areas of drug attack. Various specific inhibitors have also been tested to detect metabolic sites which might be therapeutically vulnerable. RNA synthesis inhibitors are highly active (adenine nucleosides, daunorubicin, doxorubicin, chromomycin, actinomycin D, mitomycin C); the activity of the nucleoside cordycepin was increased in vitro and in vivo by an adenosine deaminase inhibitor. In view of the polyanionic nature of the trypanocide suramin, a series of polyanions was tested; several showed activity but only poly-d-glutamic acid was active in vivo. Among various miscellaneous inhibitors, quercetin, disulfiram, and the Ca-complexing agents arsenazo I and III showed marked activity, the latter exclusively on the arsenical-resistant T. brucei. The implications of these results for combination chemotherapy and depot prophylaxis (with polyanions) are indicated.

[Investigations on the susceptibility of Mastomys natalensis to Trypanosoma (trypanozoon) brucei gambiense (author's transl)]

Mastomys natalensis ("redeyed variant") proved to be as susceptible as suckling rats to infections with Trypanosoma (Trypanozoon) brucei gambiense (14 passages after isolation). The susceptibility of M. natalensis and rats was significantly higher than that of mice. After 21 further passages the T. (T.) b. gambiense strain was fully adapted to M. natalensis. Polymorphic trypanosome strains could be isolated from pigs and dogs in Liberia using M. natalensis as recipient rodents. Some of these strains were examined for their sensitivity to human plasma in the "blood incubation infectivity test" (BIIT) using M. natalensis as well. 6 strains were highly resistant resp. subresistant to human plasma and can be regarded as potentially infective (T. (T.) b. gambiense) for man. Referring to the investigations 1.) on the susceptibility, 2.) the isolation of trypanosome strains of the subgenus Trypanozoon from animal and 3.) the biological differentiation of these strains in the BIIT, M. natalensis can be regarded as suitable experimental animals for field and laboratory studies.

Cultivation of bloodstream Trypanosoma brucei

Animal-infective forms of Trypanosoma brucei (Strain 427) were successfully propagated in HEPES-buffered RPMI 1640 medium in the presence of bovine fibroblast-like cells for over 310 days. The organisms grown in this system were morphologically identical to the long slender bloodstream forms, retained their infectivity for mammalian hosts, and displayed variant-antigen on their surface. Technical details for establishing such bloodstream form cultures are described in the present paper.

A study of the antigenic relationships of isolates of Trypanosoma brucei from three areas in East Africa

Eleven stabilates of T. brucei, prepared from isolates collected from cattle and tsetse flies in three areas of East Africa, were compared serologically by direct agglutination tests, using (a) stabilate-specific antisera prepared in rats and (b)antisera to the predominant variant antigens of each isolate prepared in rabbits. The results indicated that groups of isolates from any one area tended to produce antigens in common, whereas isolates from different areas were generally antigenically distinct. The comparison of isolates of T. brucei on the basis of their predominant variant antigens, as a technique, was more simple to effect, and more sensitive in the detection of antigenic relationships, than comparison founded on basic strain antigens.