Taenia saginata derived synthetic peptides with potential for the diagnosis of bovine cysticercosis

Immunity in Taeniids is predominantly antibody mediated and thus many serological immuno-determinants will have potential in both protection and diagnosis. The antigenicity of six peptides derived from four potentially protective molecules cloned from a Taenia saginata oncospheres cDNA library have been evaluated as targets for the specific diagnosis of bovine cysticercosis. The six peptides consist of: two peptides (HP6-2 and HP6-3) derived from the sequence of the 18 kDa surface/secreted oncospheral adhesion antigen identified by McAb-HP6, two peptides (Ts45W-1 and Ts45W-5) derived from the sequence of the T. saginata homologue of the T. ovis 45W protective gene family, one peptide (TS45S-10) derived from a T. saginata sequence with significant similarity to the T. ovis 45S protective antigen, and one peptide (TEG-1) derived from the sequence of the T. saginata homologue of Echinococcus spp. main surface protein. Longitudinal studies indicate that T. saginata infected cattle respond to all six peptides by 3-4 weeks post-infection and that the antibody levels remain high for at least 12 weeks post-infection. As protection against Taeniid parasites is predominantly antibody mediated, some of these six peptides may be of value as immuno-prophylactic tools and hence also in assays to determine resistance to infection with the parasite. For diagnosis, on the other hand, only three peptides (HP6-2, TEG-1 and Ts45S-10) performed with the necessary sensitivity and specificity to determine exposure to infection with T. saginata, and now merit an exhaustive evaluation prior to employment as routine diagnostic tools.     

Monoclonal antibodies putatively identifying porcine B cells

Comparison was made of the binding of 38 test and three standard monoclonal antibodies (mAbs) to B cells from various pig lymphoid tissues by flow cytometry (FCM) and immunohistochemistry. Some mAbs were also tested on B cells from foetal pig tissues. Twenty of the new mAbs bound, though to variable degrees, to porcine B cells but only three were given cluster assignations: C35 (#147) and BB6-11C9 (#167) were assigned to wCD21 and 2F6/8 (#057) was assigned to SWC7.     

Analyses of monoclonal antibodies reacting with porcine CD3: results from the Second International Swine CD Workshop

Among the 57 monoclonal antibodies (mAb) analyzed within the T-cell group from the Second Swine CD Workshop, six mAb fell within clusters T10 and T11 (No. 088, STH164; No. 148, FY1A3; No. 149, FY2C1; No. 150, FY1H2; No. 151, FY2A11; No. 169, BB23-8E6). The mAb within these two groups gave a similar appearance on flow cytometry and stained all peripheral blood T-cells as defined by CD4 and wCD8 staining. All six mAb precipitated a 24 kDa protein. On the basis of inhibition analyses performed as part of the workshop and from published data, the mAb define at least three epitopes. There is only minimal stimulation of resting peripheral lymphocytes, but four of the mAb produce strong stimulation in the presence of PMA. With the exception of STH164, all have been shown to react with CD3-transfected COS cells. The new mAb, therefore, react with three epitopes on porcine CD3 designated CD3a (BB23-8E6, FY2A11), CD3b (FY1A3, FY2C1), and CD3c (FY1H2). mAb STH164 appears to be reactive with another epitope, however, since its reactivity with CD3 has not been confirmed it is designated as wCD3.     

Molecular identification of Echinococcus granulosus genotypes (G1 and G7) isolated from pigs in Mexico

With the aim of genotyping Echinococcus granulosus cysts found in Mexican livestock, we collected hydatid cysts from the livers and lungs of pigs in slaughterhouses in the state of Morelos, Central Region of Mexico. DNA was extracted from the parasites and examined by polymerase chain reaction (PCR) of rDNA internal transcribed spacer 1 (ITS1-PCR), Eg9-PCR, Eg16-PCR, and PCR-restriction fragment length polymorphism (PCR-RFLP). In addition, fragments of the genes coding for mitochondrial cytochrome c oxidase subunit 1 (CO1) and NADH dehydrogenase 1 (ND1) were sequenced. Two different genotypes of E. granulosus were unequivocally identified, the common sheep genotype, G1, and the common pig genotype, G7. The G1 genotype of E. granulosus has not been previously demonstrated in Mexico. Because of its recognized infectivity in humans, G1 genotype is a direct threat to human health and its presence in Mexico is consequently of immediate public health importance and epidemiological relevance.     

Evidence that active transmission of porcine cysticercosis occurs in Venezuela

There is a paucity of quantitative data on the status of porcine cysticercosis in Venezuela, information which is essential for understanding the level of disease transmission. This study was, therefore, conducted in a typical small rural community in Yaracuy State, Venezuela, where previous cases of human Taenia solium taeniasis/cysticercosis had been reported and where the free-ranging pig management practices and the lack of rudimentary sanitary facilities indicated an obvious risk for transmission of the disease. Serum samples from 52 village pigs were screened by enzyme-linked immunosorbent assays for anti-cysticercal antibodies (Ab-ELISA), using T. solium cyst fluid as the antigen and the HP10, monoclonal antibody-based, antigen trapping ELISA for parasite antigen (HP10 Ag-ELISA). Significantly, a high proportion of the animals (65.4% for the Ab-ELISA and 42.3% for the HP10 Ag-ELISA) were sero-positive. Five of the pigs, which were selected on that basis of positive tongue palpation, were killed for autopsy, and large numbers of viable cysticerci were found in the carcases. This unequivocal documentation of porcine cysticercosis in Venezuelan pigs presents clear evidence that T. solium is actively transmitted in Venezuela. Further detailed studies and implementation of appropriate control measures are therefore indicated.     

不同非洲猪瘟病毒株j5R基因及其编码蛋白的比较

根据非洲猪瘟病毒ＭａｌａｗｉＬＩＬ２０／１株ｊ５Ｒ阅读框Ｃ端抗原决定簇序列制备的合成肽能被不同毒株感染康复猪的免疫血清识别。多聚酶链反应研究表明,９个不同毒株的ｊ５Ｒ基因长度略有差异;蛋白转印杂交试验证明,这种基因长度的差异导致相应蛋白多肽的长度多样性。这些结果进一步证明,长度多样性是非洲猪瘟病毒基因及其编码蛋白较为普遍的特点。     

Differential molecular identification of Taeniid spp. and Sarcocystis spp. cysts isolated from infected pigs and cattle

In the present work, the species-specific identification of Taeniid spp. cysticerci and sarcocystis cysts isolated from infected pigs and cattle was achieved by PCR. In particular: (i) multiplex-PCR derived from HDP2 DNA fragment, specific for Taenia saginata/Taenia solium; (ii) PCRs and PCR-RFLPs of the rDNA internal transcribed spacers 1 and 2 (ITS1 and ITS2) for the differential diagnosis of taeniids; (iii) PCR derived from the 18S rRNA gene and sequencing, specific for Sarcoystis spp. The combined application of these three PCR protocols provided an unequivocally specific diagnosis of T. saginata, T. solium, T. hydatigena, Sarcocystis hominis and Sarcocystis suihominis, and may have practical application in the identification of calcified degenerating or morphologically dubious cysts, for example in the slaughter house situation or in human biopsy samples.     

Ag-ELISA and PCR for Monitoring the Vaccination of Cattle against Taenia saginata Cysticercosis Using an Oncospheral Adhesion Protein (HP6) with Surface and Secreted Localization

A Taenia saginata oncosphere-derived adhesion protein (HP6) with surface and secreted localization was used to successfully vaccinate calves against oral challenge with T. saginata eggs. In contrast, vaccination using a combination of T. saginata oncosphere-derived peptides, selected on the basis of their antigenic index, and including three derived from the HP6 molecule (HP6-1, HP6-2 and HP6-3), was unsuccessful. This either indicated that the wrong peptides were selected or, in the case of the HP6 protein, that the protective epitope is conformational in nature. The protection experiments were monitored using a parasite antigen detection ELISA (HP10 Ag-ELISA), which allowed the early determination of the success of the vaccination protocol, subsequently confirmed at autopsy. PCR assays were used for the first time to confirm the presence of T. saginata DNA in lesions recovered at autopsy and thus verify the parasite origin of the lesions.     

Nematode antigens in protection, diagnosis and pathology

A thorough study of parasite antigens is a prerequisite for control programmes based on protection by vaccination, accurate serodiagnosis and perhaps immune modulation to diminish pathological sequelae. Stage specific surface secreted and somatic antigens may be of particular value in proceeding towards these goals. The design of vaccines is most appropriately focused on surface antigens. With respect to pathology, certain antigens must stimulate humoral and, or cellular immune responses which are responsible for the undesirable immunopathologic consequences of the disease. The ultimate objective, therefore, is identification of those particular antigens followed by appropriate down regulation of the immune system in order to delete such potentially harmful immunological reactions. The relevant illustration presented in this context is an interesting correlation between one particular clinical condition of onchocerciasis ("sowda") and the serological response, defined both in terms of the parasite antigen and an immunoglobulin class restricted antibody response. Current parasitological methods of diagnosis consistently underestimate parasite prevalence. Failure to detect low level patent infections incurs the risk of having a reservoir capable of perpetuating infections. There is, then, an urgent requirement for accurate serodiagnosis, to be used in association with, and for the evaluation of, drug treatment and vector elimination in parasite control programmes. Given the high sensitivity of current immunoassay technology, the only bar to establishing the necessary immunological tests is the choice of suitably specific antibody-antigen systems. Once these are identified, a combination of recombinant nucleic acid biochemistry and hybridoma technology should provide the necessary reagents for inexpensive, robust and specific diagnostic tests. In addition, it may not be many years before the ubiquitous RIA and ELISA technology gives way to the newly developing biosensor systems. Finally, given the sensitivity and specificity of today's nucleic acid hybridization techniques, we may soon expect to see specific identification of infective larvae in their vectors of this, a cloned DNA probe specific for Onchocerca volvulus, and with potential for the detection of infective larvae in blackflies is described.