Sequence and immunogenicity of the Taenia saginata homologue of the major surface antigen of Echinococcus spp.

A clone (R-Tso18) was isolated from a Taenia saginata oncosphere cDNA library by screening with sera from rabbits immunised with oncosphere extract. It contained a full-length cDNA sequence of 1893 bp with an open reading frame of 1680 bp, corresponding to 559 amino acids with a deduced molecular mass of 65.173 kDa and an isoelectric point of 6.08. The R-Tso18 protein showed 80–84% nucleotide identity with the major protoscolex surface antigens of Echinococcus multilocularis (EM10) and E. granulosus (EG10). Preliminary immunogenicity studies employing the radio-labeled R-Tso18 protein in immune co-precipitation assays indicated sero-positivity for T. saginata-infected calf sera (6/13), T. solium cysticercosis human (7/22) and pig (2/2) sera and E. multilocularis (6/10)- and E. granulosus (1/12)-infected human sera, whereas other helminth-infection sera were negative. As immuno-precipitation is a relatively insensitive assay, it was concluded that further studies on the diagnostic potential of the purified recombinant R-Tso18 antigen, or its peptides, are merited. Received: 9 July 1997 / Accepted: 3 November 1997     

Isolation of fraction No. 10 fromTaenia saginata and evaluation of its specificity for the diagnosis of bovine cysticercosis

In an attempt to improve the specificity of the crudeTaenia saginata antigen for the immunodiagnosis of bovine cysticercosis, a major and highly immunogenic fraction (F10), responsible for the formation of the typical long band reaction in immunoelectrophoresis, has been isolated fromT. saginata proglottides by immunoaffinity chromatography. The immunoadsorbant was prepared by coupling a specifically raised hyperimmune serum (HIS) anti-F10 to Sepharose 4B.The purity of the isolated F10 was demonstrated by immunoprecipitation reactions. The HIS anti-F10, however, cross-reacted with several larval and adultTaenia spp. Consequently, F10 showed cross-reactions with the sera of animals infected with hydatid cysts or larvalT. hydatigena. F10 also reacted with HIS anti-F5 (Echinococcus granulosus) but was shown to be non-identical with the well known F5 ofE. granulosus. These data prove that F10 ofT. saginata was not species-specific but showed a group specificity for the taeniid family — a situation analogous to F5 ofE. granulosus.     

Immunological responses of the mammalian host against tapeworm infections. IV. Species specificity of hexacanth embryos in protecting sheep against Echinococcus granulosus

Eighty lambs were divided into four groups, each comprising twenty animals. Half the lambs in each group were vaccinated with viable eggs and half with the activated embryos of Echinococcus granulosus, Taenia hydatigena, T. ovis or T. pisiformis. These lambs together with ten control animals were subsequently challenged with eggs of E. granulosus.

Only a few hydatid cysts were established from the challenge infection in the lambs immunized with the homologous eggs or embryos. Only one acephalocyst in one animal survived. The metabolism of this cyst was of a low order compared with that of most of those in the controls.

Hydatid cysts were established from the challenge infection almost as frequently in the animals vaccinated with eggs or embryos of the sheep metacestodes T. hydatigena and T. ovis, as in the controls. Fluid accumulated in only a few hydatid cysts from the challenge infection in those sheep vaccinated with the activated embryos of these heterologous species.

The injection of viable eggs or activated embryos of the rabbit metacestode T. pisiformis induced no resistance to the establishment or to the survival of the challenge infection of E. granulosus.

     

Production and immunoanalytical application of 32 monoclonal antibodies against metacestode somatic antigens of Echinococcus multilocularis

Alveolar echinococcosis is a rare but potentially fatal disease. Immunodiagnosis based on antibodies or antigens plays an important role in its diagnosis. In this study, metacestode somatic antigens of Echinococcus multilocularis were used to immunize BALB/c mice, and hybridomas were formed by cell fusion. Making use of the inherent effect of monoclonal antibody techniques to isolate different epitopes, we obtained a repertoire of 32 monoclonal antibodies against the metacestode somatic antigens. These monoclonal antibodies were used to investigate the specificity and localization of the metacestode antigens by enzyme-linked immunosorbent assay and immunohistochemistry, respectively. Nine antibodies specifically reacted with E. multilocularis, while 14 and ten cross-reacted with Echinococcus granulosus and Taenia saginata, respectively. Twenty-five antibodies stained the laminated layer. Eight reacted with the tegument of the protoscolex. Fourteen antibodies recognized the germinal layer. Most of the monoclonal antibodies can react with the antigen Em2. One antibody can react with antigen Em2 and Em10. One antibody that cross-reacted with T. saginata stained the germinal layer and protoscolex, especially its hooklets and suckers, but could not react with Em2 and Em10 antigens. It detected protein bands at 26 and 52 kDa. Two E. multilocularis-specific monoclonal antibodies stained both the germinal and laminated layers and could be used not only to purify specific antigens but also for immunohistochemical studies of E. multilocularis. In summary, these 32 monoclonal antibodies could have potential applications as useful tools in further studies of E. multilocularis antigen profiles.     

Analysis of taeniid antigens using monoclonal antibodies toEchinococcus granulosus antigen 5 and antigen B

Antigens derived fromEchinococcus granulosus, Taenia hydatigena andT. pisiformis cyst fluids,T. solium cysticerci,E. multilocularis protoscoleces andE. vogeli cyst membranes were examined by enzyme-linked immunosorbent assay (ELISA) and immunoelectrophoresis (IEP) using four monoclonal antibodies (mAb) toE. granulosus antigen 5 (Ag5) and antigen B (AgB). Anti-Ag5 mAbs 24.14 and 61A12 reacted strongly withT. hydatigena andT. pisiformis cyst fluids and, to a lesser degree, anti-AgB MAbs 31.15 and 39B3 also displayed some reaction with these antigens in ELISA. The formation of a modified arc 5 band between Anti-Ag5 mAbs andT. hydatigena cyst fluid (THCF) in IEP further confirms the existence of Ag5 inT. hydatigena cyst fluid. However, the inability of THCF andT. pisiformis cyst fluid (TPCF) to form an AgB band as well as that of TPCF to form an arc 5 band with mAbs in IEP does not exclusively prove the lack of AgB in THCF and TPCF or the lack of Ag5 in TPCF. The absence of a reaction of mAbs withT. solium, E. multilocularis andE. vogeli antigen preparations in ELISA or IEP would suggest that these mAbs may recognise epitopes different from those ofT. solium, E. multilocularis andE. vogeli parasites; this might be exploited for specific differentiation ofE. granulosus.     

Effect of mebendazole againstEchinococcus granulosus andTaenia hydatigena cysts in naturally infected sheep and relevance to larval tapeworm infections in man

The ability of three treatment schedules of mebendazole to kill well-established hydatid cysts was studied. Pregnant sheep, naturally infected withEchinococcus granulosus and/orTaenia hydatigena, were treated daily with mebendazole at a dose rate of 50 mg/kg body weight for either five days, one month, or three months.At autopsy, seven months after the commencement of treatment, no evidence was found that the 5-day treatment schedule had any damaging effect onE. granulosus cysts. The effects of the one month treatment were equivocal. There was evidence of a damaging effect from the 3-month treatment schedule and protoscoleces were not infective to dogs. NoT. hydatigena cysts survived the 1- and 3-month treatments, but organisms from the 5-day treatment were infective to dogs.These results forE. granulosus in sheep suggest that long-term treatment with mebendazole may be required in hydatid disease in man. The results obtained forT. hydatigena in sheep are discussed in relation to the treatment of cysticercosis fromT. solium in man. Mebendazole showed no untoward effect on the sheep or their lambs.     

Application of antigens fromTaenia hydatigena cyst fluid for the immunodiagnosis of human hydatidosis

Fluid was collected from cysts ofTaenia hydatigena in 60 adult sheep and fluid from each animal pooled separately. By double diffusion antigen 5 was demonstrated in all pools but one. The criteria are described for selection and standardization of these preparations for use as antigens for the immunodiagnosis of human hydatid disease. Sera from 50 persons harbouring hydatid cysts and from 50 patients with other disease conditions were examined by the arc-5 double-diffusion test, using two antigens prepared fromEchinococcus granulosus andT. hydatigena cyst fluids, respectively. The results showed that a higher diagnostic sensitivity was obtained with the hydatid antigen. The significance of the findings is discussed in terms of their application to human immunodiagnosis in areas where hydatidosis, but not cysticercosis, is rare in livestock.     

Serological studies on pigs experimentally infected with Taenia solium or Taenia hydatigena

Pigs were infected with either Taenia solium or T. hydatigena eggs and the course of infection was followed using double diffusion tests for precipitating antibodies, the passive haemagglutination test for agglutinating antibodies and the immediate intradermal and passive cutaneous anaphylaxis (PCA) reactions. No precipitins were detected.The passive haemagglutination test comprised a homologous system with pig red blood cells and serum from the same animals as stabilizer. It proved highly sensitive but not specific, the antigen of T. hydatigena cyst reacting with antiserum of T. solium infested pigs, but not vice versa. The titres bore some relationship to the level of infection given, but not with the number of cysts found at necropsy. Animals reinfected with T. solium had fewer cysts when killed than once-infected animals and no anamnestic response was seen.The results of the immediate intradermal reaction were equivocal. Using the sera of pigs infected with either organism positive PCA reactions were obtained at 4, but not at 72, hours after challenge with antigen. The specificity and low order of reactions are discussed.Antibody produced in rabbits immunized against T. solium or T. hydatigena became passively fixed to pig skin and was detectable in the 4 hour PCA reaction.     

Molecular characterization of Echinococcus granulosus in a hyperendemic European focus,the Republic of Moldova

Cystic echinococcosis is a zoonosis caused by the tapeworm Echinococcus granulosus sensu lato. The lifecycle of the parasite is mainly domestic, requiring dogs as definitive hosts and livestock species as intermediate hosts. Although human cystic echinococcosis is a high public health priority in the Republic of Moldova, the rare animal data available concerns only infection in cattle. A preliminary slaughterhouse survey was conducted to assess prevalence and perform the first molecular characterization of E. granulosus sensu lato in sheep and cattle. For the survey, 40 sheep and 19 cattle were inspected. Very high prevalence in sheep (82.5 %) and in cattle (78.9 %) was found. Molecular analyses identified genotypes G1 and G3 of E. granulosus sensu stricto in all the liver and lung samples. Based on the concatenated sequences of cox1?+?nad3 (701 bp), 23 different haplotypes were obtained. Mixed infections by different haplotypes/genotypes were frequently identified in both sheep and cattle. The relatively high (20.0 %) cyst fertility observed in cattle argues for the potential contribution of cattle to the lifecycle of E. granulosus sensu stricto, unlike previous observations in Europe. The hyperendemic situation of Moldova can be explained by a high majority of animals slaughtered at home usually without veterinary inspection. Further extensive slaughterhouse surveys with molecular identification also involving pigs and goats are needed to obtain a better overview of the epidemiological situation of E. granulosus sensu lato in this hyperendemic focus in the Republic of Moldova.     

Prevalence and diversity of cystic echinococcosis in livestock in Maasailand, Kenya

Cystic echinococcosis (CE) is a zoonotic disease caused by several members of the Echinococcus granulosus species complex. In East Africa, several species/strains are known to occur in livestock and humans, but host preferences, relative frequencies and spatial distribution of these taxa are poorly known. Here, we contribute livestock data for Maasailand of southern Kenya. Total CE prevalence was 25.8?% in cattle (151/587), 16.5?% in sheep (71/430) and 10.8?% in goats (21/194), which is a significant increase compared to surveys done about three decades ago. The majority of cysts occurred in the liver (56?% in cattle, 70?% in sheep and 65?% in goats). Molecular characterization by PCR?CRFLP and sequencing of parts of the mitochondrial nad-1 gene was done for a subsample of 285 cysts. E. granulosus G1 was dominant in all host species (200 of 201 cysts from cattle, 68 of 69 from sheep and 11 of 15 from goats); the remaining taxa were Echinococcus canadensis G6 (one cyst from sheep, four from goats) and Echinococcus ortleppi (one cyst from cattle). Considering cyst fertility, sheep appear to be the most important hosts for E. granulosus G1, while goats were found to be suitable hosts for E. canadensis G6 (three of four cysts were fertile). For the first time, E. ortleppi was found in cattle from southern Kenya. Our data show an intense and possibly increasing level of CE transmission in southern Kenya, and the predominance of E. granulosus G1, which appears to be particularly pathogenic to humans, calls for urgent control measures.     

Cloning and characterization of Taenia saginata paramyosin cDNA

A ZAP-express cDNA library of Taenia saginata metacestodes was constructed. Antibody screening yielded a clone with an insert of 3,408 bp, an open reading frame of 2,589 bp, a deduced sequence of 863 amino acid and a molecular mass of 98.89 kDa. Alignments of the predicted amino acid sequence showed identity with paramyosins from several species: 98.8% with Taenia solium, 96.3% with Echinococcus.granulosus and about 70% with Schistosoma spp. The insert was expressed and purified. A collagen binding assay was performed which showed that T. saginata GST-paramyosin retained this property in a dose-dependent manner. Problems were encountered due to high backgrounds in serological assays in the homologous T. saginata system. However, the recombinant paramyosin was recognized by antibodies present in 31.6% of sera from T. solium seropositive cysticercosis patients and 100% of the sera from acute cysticercosis patients. The immunodominant epitope was the carboxyl-terminal fragment of the molecule.Nucleotide sequence data reported in this paper has been submitted to the GenBank, EMBL and DDBJ databases under the accession number AJ439882     

Antibody responses of experimentally infected lambs to antigens collected during in vitro maintenance of the adult,metacestode or oncosphere stages ofTaenia hydatigena andTaenia ovis with further observations on anti-oncospheral antibodies

The antigenicity and specificity of crude antigens collected during the in vitro maintenance ofTaenia hydatigena andT. ovis, excretory/secretory (ES) antigens, were assessed in a peroxidase microenzyme-linked immunosorbent assay (ELISA), using sera from lambs given experimental monospecific infections withT. hydatigena, T. ovis, Echinococcus granulosus orFasciola hepatica.ES antigens of larval cysts ofT. ovis andT. hydatigena were less reactive than those of adult or oncosphere stages. Strong interspecific cross-reactions occurred between all antigen preparations, and these antigens offered no better specificity than crude somatic extracts. IgG₁ was the major immunoglobulin detected in sera from lambs experimentally infected withT. ovis orT. hydatigena using antigens prepared from sonicated oncospheres. Discrete peaks of anti-oncospheral antibodies were detected following initial and challenge infections with eggs (whether the homologous or heterologous species), when sera were assayed with a PBS sonicate or an ES antigen from oncospheres. However, when oncospheres solubilised with sodium deoxycholate were used, the antibody response was prolonged and resembled that reported previously when somatic extracts of adult and metacestode stages were used as antigen. The results showed that oncospheres share antigens in common with other life-cycle stages, but also support the notion that they may possess some unique stage-specific antigenic determinants.     

Echinococcus spp. in central Kenya: a different story

Research on cystic echinococcosis (CE) has a long history in Kenya, but has mainly concentrated on two discrete areas, Turkana and Maasailand, which are known to be foci of human CE in Africa. Here, we report on a survey for CE in livestock from central to northeastern Kenya, from where no previous data are available. A total of 7,831 livestock carcasses were surveyed. CE prevalence was 1.92 % in cattle (n?=?4,595), 6.94 % in camels (n?=?216), 0.37 % in goats (n?=?2,955) and 4.62 % in sheep (n?=?65). Identification of the parasite was done using an RFLP-PCR of the mitochondrial nad1 gene, which had been validated before against the various Echinococcus taxa currently recognized as distinct species. From a total of 284 recovered cysts, 258 could be identified as Echinococcus granulosus sensu stricto (n?=?160), E. ortleppi (n?=?51) and E. canadensis (n?=?47) by RFLP-PCR of nad1. In cattle, fertile cysts occurred mostly in the lungs and belonged to E. ortleppi (31 of 54), while the vast majority were sterile or calcified cysts of E. granulosus s.s.. Most fertile cysts in camels belonged to E. canadensis (33 of 37); sterile or calcified cysts were rare. Goats harboured fertile cysts of E. ortleppi (n?=?3)—which is the first record in that host species—and E. canadensis (n?=?1), while all cysts of E. granulosus were sterile. Only sterile cysts were found in the three examined sheep. Typically, all cysts in animals with multiple infections belonged to the same species, while mixed infections were rare. Our data indicate that the epidemiological situation in central to northeastern Kenya is clearly different from the well-studied pastoral regions of Turkana and Maasailand, and the apparently low number of human CE cases correlates with the infrequent occurrence of E. granulosus s.s.     

Evaluation of recombinant HP6-Tsag,an 18 kDa <Emphasis Type="Italic">Taenia saginata</Emphasis> oncospheral adhesion protein,for the diagnosis of cysticercosis

With the objective of providing inexpensive and reproducible assays for the detection of antibodies indicating exposure to Taenia saginata and Taenia solium, we have evaluated the diagnostic utility of the T. saginata oncosphere adhesion protein (HP6-Tsag), expressed in baculovirus (HP6-Bac) and bacteria (HP6-GST [glutathione S-transferase]), employing enzyme-linked immunosorbent assays (ELISAs) and sera from T. saginata infected cattle, T. solium infected pigs and serum and cerebrospinal fluid (CSF) samples from clinically defined T. solium neurocysticercosis (NCC) patients. The two recombinant proteins were antigenic in all three systems, with the signal to background ratio of the HP6-Bac ELISA slightly higher than that for the HP6-GST ELISA. Assay performance in cattle was similar to previously described peptide-based ELISA assays, although NCC sample sensitivity/specificity was marginally better. The sensitivity of the HP6-Bac and HP6-GST ELISAs was close for active human NCC (77.4 and 80.6% for serum and 76.9 and 73.1% for CSF samples, respectively). In inactive human NCC, however, the sensitivity of the HP6-Bac ELISA was almost twice that of the HP6-GST ELISA. Because peptides are relatively expensive and recombinant proteins are simple and economical to produce, the latter may provide useful reagents for antibody detection in countries with endemic cysticercosis/NCC.     

The nuclear 18S ribosomal RNA gene as a source of phylogenetic information in the genus Taenia

Most species of the genus Taenia are of considerable medical and veterinary significance. In this study, complete nuclear 18S rRNA gene sequences were obtained from seven members of genus Taenia [Taenia multiceps, Taenia saginata, Taenia asiatica, Taenia solium, Taenia pisiformis, Taenia hydatigena, and Taenia taeniaeformis] and a phylogeny inferred using these sequences. Most of the variable sites fall within the variable regions, V1–V5. We show that sequences from the nuclear 18S ribosomal RNA gene have considerable promise as sources of phylogenetic information within the genus Taenia. Furthermore, given that almost all the variable sites lie within defined variable portions of that gene, it will be appropriate and economical to sequence only those regions for additional species of Taenia.     

High resolution melting technique for molecular epidemiological studies of cystic echinococcosis: differentiating G1, G3, and G6 genotypes of Echinococcus granulosus sensu lato

Reliable and rapid genotyping of large number of Echinococcus granulosus sensu lato isolates is crucial for understanding the epidemiology and transmission of cystic echinococcosis. We have developed a method for distinguishing and discriminating common genotypes of E. granulosus s.l. (G1, G3, and G6) in Iran. This method is based on polymerase chain reaction coupled with high resolution melting curve (HRM), ramping from 70 to 86 °C with fluorescence data acquisition set at 0.1 °C increments and continuous fluorescence monitoring. Consistency of this technique was assessed by inter- and intra-assays. Assessment of intra- and inter-assay variability showed low and acceptable coefficient of variations ranging from 0.09 to 0.17 %. Two hundred and eighty E. granulosus s.l. isolates from sheep, cattle, and camel were used to evaluate the applicability and accuracy of the method. The isolates were categorized as G1 (93, 94, and 25 %), G3 (7, 4, and 4 %), and G6 (0, 2, and 71 %) for sheep, cattle, and camel, respectively. HRM results were completely compatible with those obtained from sequencing and rostellar hook measurement. This method proved to be a valuable screening tool for large-scale molecular epidemiological studies.     

Evaluation of “crude” antigen prepared fromTaenia saginata for the serological diagnosis ofT. saginata cysticercosis in cattle using the enzyme-linked immunosorbent assay (ELISA)

A crude antigen prepared from the strobilate stage ofTaenia saginata was tested for its suitability in the peroxidase microenzyme-linked immunosorbent assay (ELISA) for the diagnosis ofT. saginata cysticercosis in cattle. Sera were tested from laboratory and pasture-reared calves experimentally infected withT. saginata as well as from cattle naturally infected by grazing on pasture irrigated with sewage effluent. The specificity of the diagnostic antigen was assessed using sera from laboratory-reared cattle with monospecific infections ofT. saginata, T. hydatigena, Fasciola hepatica, or gastro-intestinal nematodes, and natural infections ofF. hepatica. Cross-reactions occurred in sera from all heterologous infections but the highest level occurred in cattle experimentally or naturally infected withF. hepatica. Clear diagnostic antibody levels were found in cattle experimentally infected withT. saginata but the test was not found to be reliable in individual animals with natural infections when compared with sera from cattle naturally infected withF. hepatica. On a group or herd basis ELISA using crude antigen and taking the mean absorbance values, could be useful as an indicator of a high prevalence rate ofT. saginata cysticercosis.     

Comparative study of cattle, sheep and goats on biochemical profiles of hydatid cyst fluid from the lungs and liver

Hydatid cysts are one of the most prevalent zoonotic diseases and cause major economic and health problems around the world. The aim of this study was to evaluate and compare the biochemical profiles of hydatid cyst fluid obtained from the lungs and liver of cattle, sheep and goats naturally infected with Echinococcus granulosus. In each species, 11 biochemical profiles of hydatid cyst fluid (calcium, sodium, potassium, magnesium, glucose, urea, uric acid, cholesterol, triglyceride, creatinine and total protein) were determined and compared between the lung and the liver. No significant differences in biochemical profiles were observed in cattle, sheep or goats (P?>?0.05) indicating that biochemical profiles of hydatid cyst fluids do not relate to cyst location.     

Echinococcosis

Echinococcosis is a human disease caused by the larval form of Taenia echinococcus, which lives in the gut of the dog, wild canides and other carnivorous animals which represent the definitive hosts and involves as intermediate hosts both domestic and wild animals. Humans become accidental intermediate hosts by ingesting Taenia eggs. The main species pathogenic for man are E granulosus causing cystic echinococcosis with worldwide distribution and endemic in sheep and cattle breeding countries, and E multilocularis causing alveolar echinococcosis, with preferential distribution in the northern hemisphere. After ingestion of contaminated food, hexacanth embryos migrate by the portal system to liver and later lung, brain and other tissues. Symptoms are related to both cyst location and size. E granulosus infection of the central nervous system (CNS) may be primary or secondary and has been estimated to be low (2%). Sharply demarcated, spherical and intraparenchy-mal, cysts may reach a large size causing neurological symptoms. Spilling of cyst fluid due to trauma or surgery may trigger anaphylaxis as well as disseminated infection. Host reaction is minimal in the brain but a foreign giant cell reaction may develop. E multilocularis develops within the liver as a rapid invasive pseudomalignant growth and may metastasize to the CNS, where estimated incidence reaches 5%. Hydatid antigens induce an immune reaction in the host which is helpful for the diagnosis. DNA probes and PCR may be applied to differentiate between Echinococcus spp. Although the host develops an immunological protection from reinfection, the parasite evades host immune attack. A wide range of evasion mechanisms have been advanced, including a barrier for host cells due to hydatid cyst laminated cuticle, polyclonal activation of lymphocytes by parasite soluble antigens, and depression of host cell immune responses. Chronic stimulation of the host by cyst fluid antigens leads to increased specific IgG4 production, which might act as blocking antibodies against anaphlaxis suggestive of host response immuno-modulation.     

Homologous and heterologous immunization against the metacestodes ofTaenia saginata andTaenia taeniaeformis in cattle and mice

Summary Cattle and mice were immunized against infection withTaenia saginata andTaenia taeniaeformis, respectively, using antigens obtained from both homologous and heterologous species of cestodes. Mice were protected against infection withT. taeniaeformis when they were immunized intramuscularly or orally with either a somatic antigen extracted from the metacestodes or an excretory/secretory (E/S) antigen collected during the in vitro culture of oncospheres ofT. taeniaeformis. Also, the intramuscular or oral immunization of mice with the E/S antigens from the oncospheres ofT. saginata was highly effective in inducing protection against infection withT. taeniaeformis, as was intramuscular immunization with a somatic antigen extracted from the metacestodes ofTaenia crassiceps and prior infection with viable metacestodes ofT. crassiceps. Furthermore, three-month-old calves developed a protective immunity against infection withT. saginata when they were immunized intramuscularly with the E/S products of oncospheres of the homologous parasite or a heterologous parasite,T. taeniaeformis. In addition, the E/S products of the heterologous parasite,T. taeniaeformis, as well as the homologous parasite,T. saginata, were highly effective when used to immunize pregnant heifers, either intramuscularly or via the intramammary route, resulting in a passive transfer of immunity againstT. saginata to newborn calves.