Molecular phylogenetic analysis of Cysticercus ovis from Egypt based on MT-CO1 gene sequences.

Cysticercus ovis or sheep measles is the larval stage of Taenia ovis, which is the intestinal tapeworm of dogs. It is found in the cardiac and skeletal muscles of sheep and can be the cause of partial or total condemnation of carcasses at abattoirs. The aim of the current work was to determine the prevalence of C. ovis among sheep in Upper Egypt and to present the molecular and phylogenetic analysis of this using the amplified Mitochondrial Cytochrome Oxidase subunit 1 (MT-CO1) gene. A total of 1885 sheep slaughtered at local abattoirs of 4 different governorates of Upper Egypt (Asuit, Sohag, Qena and Aswan) were carefully examined for C. ovis. The overall prevalence of infection was 2.02%. The highest rate of infection was observed in adult animals over 4 years of age (44.73%). There was no significant effect of animal sex on infection rates. The phylogenic analysis of C. ovis Egyptian isolates showed very close similarity to the New Zealand isolate (AB731675). This is the first report showing the genetic analysis of C. ovis in Egypt, which provides a very powerful tool for taxonomy and definitive diagnosis of C. ovis, which could be helpful for preventive and control programs.

Cloning, expression, purification, and kinetic characterization of mitochondrial thioredoxin (TsTrx2), cytosolic thioredoxin (TsTrx1), and glutaredoxin (TsGrx1) from Taenia solium.

We report the complete coding sequences of mitochondrial thioredoxin (TsTrx2) and glutaredoxin (TsGrx1) from the cysticerci of T. solium. The full-length DNA of the TsTrx2 gene shows two introns of 88 and 77 bp and three exons. The TsTrx2 gene contains a single ORF of 423 bp, encoding 140 amino acid residues with an estimated molecular weight of 15,560 Da. A conserved C64NPC67 active site and a 30-amino acid extension at its N-terminus were identified. An insulin reduction reaction was used to determine whether it was a functional recombinant protein. The full-length DNA of the TsGrx1 gene shows one intron of 39 bp and a single ORF of 315 bp, encoding 105 amino acid residues with an estimated molecular weight of 12,582 Da. Sequence analysis revealed a conserved dithiol C34PYC37 active site, GSH-binding motifs (CXXC, Lys and Gln/Arg, TVP, and CXD), and a conserved Gly-Gly motif. The r-TsGrx1 kinetic constants for glutathione (GSH) and 2-hydroxyethyl disulfide (HED) were determined. In addition, cytosolic thioredoxin (TsTrx1), as reported by (Jiménez et al., Biomed Res Int 2015:453469, 2015), was cloned and expressed, and its catalytic constants were obtained along with those of the other two reductases. Rabbit-specific antibodies showed immune cross-reactions between TsTrx1 and TsTrx2 but not with TsGrx1. Both TsTGRs as reported by (Plancarte and Nava, Exp Parasitol 149:65-73, 2015) were biochemically purified to obtain and compare the catalytic constants for their natural substrates, r-TsTrx1, and r-TsTrx2, compared to those for Trx-S2E. coli. In addition, we determined the catalytic differences between the glutaredoxin activity of the TsTGRs compared with r-TsGrx1. These data increase the knowledge of the thioredoxin and GSH systems in T. solium, which is relevant for detoxification and immune evasion.

Molecular phylogenetic analysis of Cysticercus ovis from Egypt based on MT-CO1 gene sequences / Análise filogenética molecular de Cysticercus ovis do Egito com base nas sequências do gene MT-CO1

Abstract Cysticercus ovis or sheep measles is the larval stage of Taenia ovis, which is the intestinal tapeworm of dogs. It is found in the cardiac and skeletal muscles of sheep and can be the cause of partial or total condemnation of carcasses at abattoirs. The aim of the current work was to determine the prevalence of C. ovis among sheep in Upper Egypt and to present the molecular and phylogenetic analysis of this using the amplified Mitochondrial Cytochrome Oxidase subunit 1 (MT-CO1) gene. A total of 1885 sheep slaughtered at local abattoirs of 4 different governorates of Upper Egypt (Asuit, Sohag, Qena and Aswan) were carefully examined for C. ovis. The overall prevalence of infection was 2.02%. The highest rate of infection was observed in adult animals over 4 years of age (44.73%). There was no significant effect of animal sex on infection rates. The phylogenic analysis of C. ovis Egyptian isolates showed very close similarity to the New Zealand isolate (AB731675). This is the first report showing the genetic analysis of C. ovis in Egypt, which provides a very powerful tool for taxonomy and definitive diagnosis of C. ovis, which could be helpful for preventive and control programs.

Resumo Cysticercus ovis "sheep measles" é o estágio larval da Taenia ovis, encontrada nos músculos de carneiros, causado pela ingestão de ovos de Taenia ovis, parasita de cães. O objetivo do presente trabalho foi determinar a prevalência de C. ovis entre ovinos no Alto Egito e apresentar as análises moleculares e filogenéticas, utilizando o gene da subunidade mitocondrial citocromo-oxidase amplificada 1 (MT-CO1). Um total de 1885 ovinos abatidos em matadouros locais de 4 províncias diferentes do Alto Egito (Asuit, Sohag, Qena e Aswan) foram cuidadosamente examinados para C. ovis. A prevalência geral de infecção foi de 2,02%. A maior taxa de infecção foi observada em animais adultos com mais de 4 anos de idade (44,73%). Não houve efeito significativo do sexo nas taxas de infecção. A análise filogenética de isolados egípcios de C. ovis mostrou uma similaridade muito próxima ao isolado da Nova Zelândia (AB731675). Este é o primeiro relato mostrando a análise genética de C. ovis no Egito, fornecendo uma ferramenta para taxonomia e diagnóstico definitivo de C. ovis, podendo ser útil para programas preventivo e de controle.

Molecular phylogenetic analysis of Cysticercus ovis from Egypt based on MT-CO1 gene sequences / Análise filogenética molecular de Cysticercus ovis do Egito com base nas sequências do gene MT-CO1

Cysticercus ovis or sheep measles is the larval stage of Taenia ovis, which is the intestinal tapeworm of dogs. It is found in the cardiac and skeletal muscles of sheep and can be the cause of partial or total condemnation of carcasses at abattoirs. The aim of the current work was to determine the prevalence of C. ovis among sheep in Upper Egypt and to present the molecular and phylogenetic analysis of this using the amplified Mitochondrial Cytochrome Oxidase subunit 1 (MT-CO1) gene. A total of 1885 sheep slaughtered at local abattoirs of 4 different governorates of Upper Egypt (Asuit, Sohag, Qena and Aswan) were carefully examined for C. ovis. The overall prevalence of infection was 2.02%. The highest rate of infection was observed in adult animals over 4 years of age (44.73%). There was no significant effect of animal sex on infection rates. The phylogenic analysis of C. ovis Egyptian isolates showed very close similarity to the New Zealand isolate (AB731675). This is the first report showing the genetic analysis of C. ovis in Egypt, which provides a very powerful tool for taxonomy and definitive diagnosis of C. ovis, which could be helpful for preventive and control programs.(AU)

Cysticercus ovis sheep measles é o estágio larval da Taenia ovis, encontrada nos músculos de carneiros, causado pela ingestão de ovos de Taenia ovis, parasita de cães. O objetivo do presente trabalho foi determinar a prevalência de C. ovis entre ovinos no Alto Egito e apresentar as análises moleculares e filogenéticas, utilizando o gene da subunidade mitocondrial citocromo-oxidase amplificada 1 (MT-CO1). Um total de 1885 ovinos abatidos em matadouros locais de 4 províncias diferentes do Alto Egito (Asuit, Sohag, Qena e Aswan) foram cuidadosamente examinados para C. ovis. A prevalência geral de infecção foi de 2,02%. A maior taxa de infecção foi observada em animais adultos com mais de 4 anos de idade (44,73%). Não houve efeito significativo do sexo nas taxas de infecção. A análise filogenética de isolados egípcios de C. ovis mostrou uma similaridade muito próxima ao isolado da Nova Zelândia (AB731675). Este é o primeiro relato mostrando a análise genética de C. ovis no Egito, fornecendo uma ferramenta para taxonomia e diagnóstico definitivo de C. ovis, podendo ser útil para programas preventivo e de controle.(AU)

A gel-free proteomic analysis of Taenia solium and Taenia crassiceps cysticerci vesicular extracts.

The taeniasis/cysticercosis complex is a zoonosis caused by the presence of the parasite Taenia solium in humans. It is considered a neglected disease that causes serious public health and economic problems in developing countries. In humans, the most common locations for the larval form are the skeletal muscles, ocular system, and the central nervous system, which is the most clinically important. Several glycoproteins of T. solium and Taenia crassiceps cysticerci have been characterized and studied for their use in the immunodiagnosis of neurocysticercosis and/or the development of synthetic or recombinant vaccines against cysticercosis. The aim of this study was to perform a gel-free shotgun proteomic analysis to identify saline vesicular extract (SVE) proteins of T. solium and T. crassiceps cysticerci. After solubilization of the SVE with and without surfactant reagent and in-solution digestion, the proteins were analyzed by LC-MS/MS. Use of a surfactant resulted in a significantly higher number of proteins that were able to be identified by LC-MS/MS. Novel proteins were identified in T. solium and T. crassiceps SVE. The qualitative analysis revealed a total of 79 proteins in the Taenia species: 29 in T. solium alone, 11 in T. crassiceps alone, and 39 in both. These results are an important contribution to support future investigations and for establishing a Taenia proteomic profile to study candidate biomarkers involved in the diagnosis or pathogenesis of neurocysticercosis.

Genetic variability of Taenia solium cysticerci recovered from experimentally infected pigs and from naturally infected pigs using microsatellite markers.

The adult Taenia solium, the pork tapeworm, usually lives as a single worm in the small intestine of humans, its only known definitive host. Mechanisms of genetic variation in T. solium are poorly understood. Using three microsatellite markers previously reported [1], this study explored the genetic variability of T. solium from cysts recovered from experimentally infected pigs. It then explored the genetic epidemiology and transmission in naturally infected pigs and adult tapeworms recovered from human carriers from an endemic rural community in Peru. In an initial study on experimental infection, two groups of three piglets were each infected with proglottids from one of two genetically different tapeworms for each of the microsatellites. After 7 weeks, pigs were slaughtered and necropsy performed. Thirty-six (92.3%) out of 39 cysts originated from one tapeworm, and 27 (100%) out of 27 cysts from the other had exactly the same genotype as the parental tapeworm. This suggests that the microsatellite markers may be a useful tool for studying the transmission of T. solium. In the second study, we analyzed the genetic variation of T. solium in cysts recovered from eight naturally infected pigs, and from adult tapeworms recovered from four human carriers; they showed genetic variability. Four pigs had cysts with only one genotype, and four pigs had cysts with two different genotypes, suggesting that multiple infections of genetically distinct parental tapeworms are possible. Six pigs harbored cysts with a genotype corresponding to one of the identified tapeworms from the human carriers. In the dendrogram, cysts appeared to cluster within the corresponding pigs as well as with the geographical origin, but this association was not statistically significant. We conclude that genotyping of microsatellite size polymorphisms is a potentially important tool to trace the spread of infection and pinpoint sources of infection as pigs spread cysts with a shared parental genotype.

Effect of Transforming Growth Factor-ß upon Taenia solium and Taenia crassiceps Cysticerci.

Taeniids exhibit a great adaptive plasticity, which facilitates their establishment, growth, and reproduction in a hostile inflammatory microenvironment. Transforming Growth Factor-ß (TGFß), a highly pleiotropic cytokine, plays a critical role in vertebrate morphogenesis, cell differentiation, reproduction, and immune suppression. TGFß is secreted by host cells in sites lodging parasites. The role of TGFß in the outcome of T. solium and T. crassiceps cysticercosis is herein explored. Homologues of the TGFß family receptors (TsRI and TsRII) and several members of the TGFß downstream signal transduction pathway were found in T. solium genome, and the expression of Type-I and -II TGFß receptors was confirmed by RT-PCR. Antibodies against TGFß family receptors recognized cysticercal proteins of the expected molecular weight as determined by Western blot, and different structures in the parasite external tegument. In vitro, TGFß promoted the growth and reproduction of T. crassiceps cysticerci and the survival of T. solium cysticerci. High TGFß levels were found in cerebrospinal fluid from untreated neurocysticercotic patients who eventually failed to respond to the treatment (P = 0.03) pointing to the involvement of TGFß in parasite survival. These results indicate the relevance of TGFß in the infection outcome by promoting cysticercus growth and treatment resistance.

Transcriptome profiling of the cysticercus stage of the laboratory model Taenia crassiceps, strain ORF.

Neurocysticercosis (NC) is a serious public health problem mainly in developing countries. NC caused by the cysticercus stage from cestode Taenia solium is considered by the WHO and ITFDE as a potentially eradicable disease. Definitive diagnosis of NC is challenging because of the unspecific clinical manifestations such as the non-definitive evidence presented by neuroimaging (in most cases) and the lack of definitive serological test. Taenia crassiceps (ORF strain) is a cestode closely related to T. solium and it has frequently been used as a source of antigens for immunodiagnostics. A murine model to study host immune response to infection has also been established by using T. crassiceps. Despite the extensive use of T. crassiceps for research, molecular information for this cestode is scarce in public databases. With the aim of providing more extensive information on T. crassiceps biology, an RNA-seq experiment and subsequent bioinformatic transcriptome processing of this cestode parasite mRNA in its cysticercus stage were carried out. A total of 227,082 read/ESTs were sequenced using the 454-GS FLX Titanium technology and assembled into 10,787 contigs. This transcriptome dataset represents new and valuable molecular information of the cestode T. crassiceps (ORF). This information will substantially improve public information and will help to achieve a better understanding of the biology of T. crassiceps and to identify target proteins for serodiagnosis and vaccination.

[Morphological and molecular identification of Cysticercus fasciolaris isolated from rodent hosts (Rattus norvegicus) in Buenos Aires province (Argentina)]. / Identificación morfológica y molecular de Cysticercus fasciolaris aislado de un roedor (Rattus norvegicus) de la provincia de Buenos Aires (Argentina).

In a rodent (Rattus norvegicus) survey in Buenos Aires province, metacestodes of tapeworms were found encysted in the liver of the host. The aim of this work was the morphological and molecular identification of this parasite. To achieve the molecular characterization of the parasite, ribosomal (28S) and mitochondrial (COI) DNA were amplified and sequenced. Based on both morphological and molecular data using bioinformatic tools, the metacestode was identified as Cysticercus fasciolaris. The adult form of this tapeworm (Taenia taeniaeformis) commonly infects felid and canid mammalian hosts. This is the first report on the molecular identification of Cysticercus fasciolaris in Buenos Aires province (Argentina).

Identificación morfológica y molecular de Cysticercus fasciolaris aislado de un roedor (Rattus norvegicus) de la provincia de Buenos Aires (Argentina) / [Morphological and molecular identification of Cysticercus fasciolaris isolated from rodent hosts (Rattus norvegicus) in Buenos Aires province (Argentina)].

In a rodent (Rattus norvegicus) survey in Buenos Aires province, metacestodes of tapeworms were found encysted in the liver of the host. The aim of this work was the morphological and molecular identification of this parasite. To achieve the molecular characterization of the parasite, ribosomal (28S) and mitochondrial (COI) DNA were amplified and sequenced. Based on both morphological and molecular data using bioinformatic tools, the metacestode was identified as Cysticercus fasciolaris. The adult form of this tapeworm (Taenia taeniaeformis) commonly infects felid and canid mammalian hosts. This is the first report on the molecular identification of Cysticercus fasciolaris in Buenos Aires province (Argentina).

Identificación morfológica y molecular de Cysticercus fasciolaris aislado de un roedor (Rattus norvegicus) de la provincia de Buenos Aires (Argentina). / [Morphological and molecular identification of Cysticercus fasciolaris isolated from rodent hosts (Rattus norvegicus) in Buenos Aires province (Argentina)].

In a rodent (Rattus norvegicus) survey in Buenos Aires province, metacestodes of tapeworms were found encysted in the liver of the host. The aim of this work was the morphological and molecular identification of this parasite. To achieve the molecular characterization of the parasite, ribosomal (28S) and mitochondrial (COI) DNA were amplified and sequenced. Based on both morphological and molecular data using bioinformatic tools, the metacestode was identified as Cysticercus fasciolaris. The adult form of this tapeworm (Taenia taeniaeformis) commonly infects felid and canid mammalian hosts. This is the first report on the molecular identification of Cysticercus fasciolaris in Buenos Aires province (Argentina).

Changes in cyst's nuclear chromatin resulting after experimental manipulation of Taenia crassiceps mice infections: biological implications.

During some estimations of the nuclear DNA content, based on determinations propidium iodide (PI) binding through fluorocytometry for Taenia crassiceps cysticerci, significant variation in the results were found. This initial observation led to a series of experiments designed to explain the variation. These changes could be induced by the diameter of the needles in the syringes used for the mouse to mouse transfer of the cysts. Nuclei from cysts transferred through 27-gauge needles showed 30% less PI staining than those transferred through 21 gauge needles, after 2 months infections. Reduction in PI capture induced by 27-gauge needle was reversible when the cysts were maintained in their mice hosts during 5 months. Moreover, variation in PI binding to cysticercal DNA was also found when comparing parasites grown in male versus female mice. The use of agents that homogenize the chromatin structure during PI staining, allowed demonstrating that variation were entirely due to differences in the chromatin relaxation/compaction. Additional experiments demonstrated that the higher compaction is accompanied by a reduced ability of cysts to grow in the peritoneal cavity of BALB/cAnN mice. Furthermore, proteomic analysis also showed that these changes in chromatin relaxation/compaction resulted in different levels and patterns of protein expression. Our results strongly suggest that chromatin is involved in several well characterized phenomena of the T. crassiceps murine model, and open new avenues for a detailed approach to understand such a complex host-parasite relationship.

Diagnostic epitope variability within Taenia solium 8 kDa antigen family: implications for cysticercosis immunodetection.

To study diagnostic epitopes within the Taenia solium 8 kDa antigen family, six overlapping synthetic peptides from an 8 kDa family member (Ts8B2) were synthesized and evaluated by ELISA and MABA with sera from patients with neurocysticercosis (NCC), from infected pigs and from rabbits immunized with recombinant Ts8B2 protein. The pre-immune rabbit sera and the Ts8B2 recombinant protein served as negative and positive controls, respectively. A similar analysis was done with the already described antigenic peptides from another member of the 8 kDa family, highly similar to Ts8B2, the CyDA antigen. Surprisingly, neither the Ts8B2 peptides nor the CyDA peptides were recognized by infected human and porcine sera. However, the entire Ts8B2 recombinant, as well as amino and carboxy-terminal halves were recognized by the positive serum samples. The observed lack of recognition of linear Ts8B2 peptides suggests that the principal serological response to the Ts8B2 family is focused on conformational epitopes in contrast to the previously observed antigenicity of the CyDA peptides. This differential antigenicity of 8 kDa family peptides could be related with parasite antigenic variability. The fact that rabbits experimentally immunized with Ts8B2 did make anti-peptide antibodies to peptides Ts8B2-6 and CyDA-6, located in the carboxy-terminal region demonstrated that the Ts8B2 peptides are not intrinsically non-immunogenic.

TsAg5, a Taenia solium cysticercus protein with a marginal trypsin-like activity in the diagnosis of human neurocysticercosis.

Neurocysticercosis is an endemic parasitic disease caused by Taenia solium larva. Although the mechanism of infection is not completely understood, it is likely driven by proteolytic activity that degrades the intestinal wall to facilitate oncosphere penetration and further infection. We analyzed the publicly available T. solium EST/DNA library and identified two contigs comprising a full-length cDNA fragment very similar to Echinococcus granulosus Ag5 protein. The T. solium cDNA sequence included a proteolytic trypsin-like-domain in the C-terminal region, and a thrombospondin type-1 adherence-domain in the N-terminal region. Both the trypsin-like and adherence domains were expressed independently as recombinant proteins in bacterial systems. TsAg5 showed marginal trypsin-like activity and high sequence similarity to Ag5. The purified antigens were tested in a Western immunoblot assay to diagnose human neurocysticercosis. The sensitivity of the trypsin-like-domain was 96.36% in patients infected with extraparenchymal cysts, 75.44% in patients infected with multiple cysts, and 39.62% in patients with a single cyst. Specificity was 76.70%. The thrombospondin type-1 adherence-domain was not specific for neurocysticercosis.

Genetic diversity of Taenia solium cysticerci from naturally infected pigs of central Mexico.

This study was designed to explore if each individual case of naturally acquired porcine cysticercosis, living in different geographic rural areas of central Mexico, is caused by one or more different specimens of Taenia solium tapeworm. The genetic variability among cysticerci from the same pig and that from different pigs was assessed by random amplified polymorphic DNA markers (RAPDs), through the percentage of polymorphic loci, the number of effective alleles, the expected heterozygosity and the Shannon index. The parasite population's reproductive structure was estimated through the association index (I(A)), and the degree of genetic differentiation and variation was determined using AMOVA. Using six different random primers, and a total of 181 cysticerci from 14 pigs, 88 different loci were amplified: 85% were polymorphic between pigs and 24% within pigs. The phenogram grouped the cysticerci into eight major clusters, with differences in the genetic distances among all cysticerci from 14 pigs ranging from 0.78 to 1. Most of the cysticerci grouped in accord with their different geographical origin and with their pig of origin. The similarity matrix produced from the phenogram (obtained by UPGMA) and the original similarity matrix yielded a good cophenetic correlation (r=0.82317, P=0.0004), which suggests that the phenogram accurately represents the original genetic similarities between isolates. The combination of I(A) (0.0-0.089) with the genetic diversity index (0.009-0.073) supports the idea that DNA diversity in T. solium cysticerci of naturally infected pigs is within the range expected from a recombination process occurring during sexual reproduction. The small genetic diversity found within the cysticerci of each pig (33.81%), when compared with that between pigs (66.19%), indicates that pigs are rarely infected by different tapeworms. It would then appear that porcine cysticercosis courses with effective concomitant immunity, as occurs in ovine cysticercosis.

Taenia crassiceps cysticercosis: variations in its parasite growth permissiveness that encounter with local immune features in BALB/c substrains.

This study describes the first days of Taenia crassiceps infection in BALB/c substrains, BALB/cAnN and BALB/cJ, using two stocks of the same strains which were kept in different animal facilities, conventional and pathogen-free conditions, respectively. This study shows that parasite growth restriction shown by conventional BALB/cJ mice changed to parasite growth permissiveness when pathogen-free BALB/cJ mice were used. In addition, the higher number of macrophages, NK cells and intraperitoneal level of IFN-gamma found in the conventional restrictive BALB/cJ substrain vanished when the permissiveness to the parasite growth increased. No differences were found in DNA sequences of parasites collected before and after the change in the permissiveness to parasite growth which favors the possibility that the observed modifications could be due to changes in the murine strains and/or their maintenance conditions.

Genetic similarity between cysticerci of Taenia solium isolated from human brain and from pigs.

Mitochondrial (mt) cox1 and ribosomal ITS1 DNA sequences from Taenia solium cysticercus isolates from pigs and cysticerci (racemose and cellulose types) from patients with neurocysticercosis were amplified by the polymerase chain reaction (PCR). The amplicons were sequenced in order to determine the genetic relationship between these types of cysticerci. Phylogenetic trees were constructed and evolutionary distances were calculated. ITS1 and mt cox1 cysticerci sequence data were compared with previously published Taenia spp. sequences. The variation in the ITS1 and cox1 sequences of samples collected from Mexico was minimal, regardless of geographical origin, size or colour of cysticerci from either pigs or human brain. These results suggest that the racemose and cellulose types represent genetically identical metacestodes of T. solium. Alignment of the mt cox1 sequences of the Mexican samples with sequences of other Taenia taxa showed that most were very similar to T. solium from Mexico and T. solium from Colombia; one T. solium Mexican isolate and Taenia hydatigena were placed in the same group close to Taenia crassiceps. The ITS1 sequences for the Mexican T. solium samples indicated the majority were in the same group as the Latin American T. solium. Two Mexican T. solium samples and T. solium from Philippines were placed together in a different group.

Genetic polymorphism in Taenia solium cysticerci recovered from experimental infections in pigs.

Taenia solium cysticerci recovered from naturally infected pigs from Mexico, Honduras and Tanzania show a clonal structure and local lineages with probable events of genetic recombination without genetic flow within them, as revealed by RAPD. To evaluate genetic polymorphism from cysticerci recovered from experimental infections, 4 pigs were infected with T. solium eggs obtained from tapeworms released by 3 human carriers, a 10-year-old female, a 25-year-old female, and a 44-year-old male, the 4th pig was infected with a mixture of eggs from the 3 tapeworms. Each pig was orally inoculated with 50,000 eggs. After 16 weeks pigs were humanely euthanized and cysticerci were excised. Parasites recovered from each pig were analyzed by RAPD. The proportion of polymorphic loci and the mean heterozygosity as well as a dendogram and an analysis of principal coordinate and minimum spanning tree were obtained. All four pigs developed viable cysticerci; the percent infection was obtained from the ratio of the number of eggs used for infection and the number of cysticerci counted in each pig after necropsy. Infection varied from 0.2 to 4.2%. The values obtained for the proportion of polymorphic loci (0.14-0.55) and the average of expected heterozygosity (0.06-0.22) in the present experimental infection had a broader range than those reported in the literature from natural infections. The dendogram obtained clustered cysticerci into two main groups; the minimum spanning tree allowed to corroborate the data obtained in the dendogram and gave a better discrimination because in a three-dimensional plot it was easier to see that all cysticerci from each tapeworm were clustered amongst themselves. The results obtained could be hypothetically explained because environmental factors and genetic selection agents present in nature influence natural infections but do not participate in experimental ones.

Effect of Cysticercus cellulosae on neutrophil function and death.

Neutrophils, eosinophils and macrophages interact with invading parasites and naive hosts. The initial reaction of leukocytes is the generation of reactive oxygen species (ROS). The cytotoxic effects of extracts derived from intact Cysticercus cellulosae and from the scolex or membrane fractions on neutrophils were examined. DNA fragmentation of neutrophils was observed when cells were incubated with an extract from the intact metacestode; however, the addition of antioxidant enzymes to the incubation medium had a protective effect. The scolex and membrane extracts did not affect DNA fragmentation of neutrophils. Hydrogen peroxide production of neutrophils incubated with metacestode fractions from C. cellulosae increased by 190% (total extract), 120% (scolex) or 44% (membrane). An increase in antioxidant catalase activity (28%) concomitant with the increased production of ROS was observed in neutrophils incubated with metacestode fractions, which could be an attempt at self-protection. ROS production by neutrophils in the presence of the intact cysticerci extract did not alter phagocytosis. In contrast, the scolex and membrane fractions increased the phagocytic capacity of neutrophils by 44 and 28%, respectively. The results showed that the extract from intact C. cellulosae was toxic for neutrophils via ROS production, leading to DNA fragmentation and inhibition of phagocytic capacity, but neutrophils are able to protect themselves against oxidative stress by via catalase activity.

Detection of genetic variation in Taenia solium.

Genetic variability among Taenia solium isolates was studied in 160 cysticerci from 6 pigs, 4 from Mexico, 1 from Honduras, and 1 from Tanzania. Random amplified polymorphic DNA (RAPD) analysis performed with 4 commercial primers showed 88% polymorphic loci and an average heterozygosity of 0.077; however, several alleles were fixed within each isolate. Linkage disequilibrium analysis indicated that 3 of the 6 isolates had a random association of alleles, whereas the other 3 had a clonal structure. These results suggest the existence of local lineages in T. solium, with events of genetic recombination within them.