Tzipe Govezensky

Shift from an early protective Th1-type immune response to a late permissive Th2-type response in murine cysticercosis (Taenia crassiceps).

In early stages of experimental murine cysticercosis caused by Taenia crassiceps, there is a clear but transient Th1-type immune response (characterized by high levels of interleukin [IL]-2, interferon-gamma, concanavalin A, and antigen specific response, delayed-type hypersensitivity, and immunoglobulin [Ig]G2a antibodies) that associates with a low rate of parasite reproduction. As time of infection progresses an energic and more permanent Th2-type response follows (characterized by high levels of IL-4, IL-6, IL-10, IgG2b, and IgG1 antibodies) that in turn associates with an increment in the rate of parasite reproduction. The sequential activation of Th1-type and Th2-type responses in murine cysticercosis would appear to favor progressively parasite reproduction, explaining the long time residence and the massive parasite intensity reached in chronic infections.

Cysticercosis vaccine : cross protecting immunity with T. Solium antigens against experimental murine T. Crassiceps cysticercosis

Summary Vaccination of mice with an antigen extract from Taenia solium cysticerci induced protection against challenge with T. crassiceps cysticerci as successfully as did antigen extracts from T. crassiceps. Vaccination was more effective in male than in female mice and in the resistant strain (BALB/B) more so than in the susceptible strain (BALB/c). While only the resistant strain was completely protected by vaccination, the parasite load of the susceptible strain was significantly reduced by vaccination. Cross immunity between the human and murine parasites establishes murine T. crassiceps cysticercosis as a convenient laboratory model in which to test promising T. solium antigens aimed at vaccine development against T. solium cysticercosis. Further, results point to strong interactions of the immune system with sexual and histocompatibility factors in the hosts dealing with cysticercosis.

MurineTaenia crassiceps cysticercosis: H-2 complex and sex influence on susceptibility

Several inbred strains of mice were infected by intraperitoneal injection of tenTaenia crassiceps cysticerci per mouse. Genes linked with the major histocompatibility complex (H-2) were found to influence parasite growth greatly, as demonstrated by the different parasite loads of H-2 congenic mice with BALB background: BALB/c (H-2d) mice were the most susceptible, whereas BALB/k (H-2k) and BALB/b (H-2b) animals were comparatively resistant. Non-H-2 genes had no significant effect on susceptibility in H-2d strains, as reflected by the similar parasite loads in BALB/c, DBA/2, and (BALB/cxDBA/2)F1 mice. Using the H-2b (BALB/b, C57BL/6J) and H-2k (C3H/HeJ, BALB/k, and C3HeB/FeJ) strains, we found that non-H-2 background genes caused a small but significant influence on parasite load. A recombinant mouse strain alleles (Kk, Ik, Sd, Dd) was also susceptible, indicating that S and/or D regions of the H-2d complex are probably involved in the control of resistance to murine cysticercosis. Females of all mouse strains were more susceptible than males. The same effects were observed for H-2 genes and sex, with two strains ofT. crassiceps differing in their rate of growth.

A role for 17-beta-estradiol in immunoendocrine regulation of murine cysticercosis (Taenia crassiceps).

In experimental murine cysticercosis caused by Taenia crassiceps, parasite reproduction is favored by thymectomy or by orchidectomy, and restricted by ovariectomy. Hormonal reconstitution experiments showed that 17-beta-estradiol increases parasite numbers whereas 5-alpha-dihydrotestosterone was ineffective. Parasite numbers decreased with increments in cellular immunity but were insensitive to antibody levels. A possible immunoendocrinological interaction involving estrogen as a depressor of cellular immunity is envisaged in the control of cysticercosis.

Thymus-related cellular immune mechanisms in sex-associated resistance to experimental murine cysticercosis (Taenia crassiceps)

The role of sex, thymus, and cellular immune mechanisms in mouse resistance to experimental cysticercosis with Taenia crassiceps was studied in male and female susceptible mice treated with cyclophosphamide, as well as in mice neonatally thymectomized and passively transferred with T-enriched lymphoid cells. High doses of cyclophosphamide increased delayed hypersensitivity and resistance of mice of both sexes without affecting antibody production. Neonatal thymectomy diminished resistance in both sexes but depressed delayed hypersensitivity in females only, without significantly affecting antibody response in either sex. Passive transfer of T-enriched lymphoid cells to thymectomized mice restored resistance to control levels without greatly affecting delayed hypersensitivity. Thus, our results indicate that cell-associated immune mechanisms are implicated in resistance to murine cysticercosis with T. crassiceps. Because neonatal thymectomy nearly equalized the intensity of infection of female and male mice, it is argued that the thymus is importantly involved in the interaction between gonads and the immune system in the control of this cysticercosis.

Immunization of pigs against Taenia solium cysticercosis: factors related to effective protection

Fifty-six (56) pigs were immunized against Taenia solium cysticercosis with antigens from Taenia crassiceps metacestodes, in a variety of protocols, and then challenged orally with Taenia solium proglottids or eggs. Results of immunization (expressed as individual parasite loads) ranged from significant reduction of parasite loads (host protection) to clear increase (parasite facilitation) in apparent relation to the immunogen dose, adjuvant employed and genetic background of the pigs. In all trials, however, immunized pigs harboured more damaged cysticerci than controls, indicating that immunization does induce some restrictions to parasite these are eventually overwhelmed by other parasite-promoting factors. Western blots in immunized-protected pigs indicated antigens of 242, 234, 118, 77, 55 and 45 kDa as possibly being involved in immunological protection.

Protection against murine cysticercosis using cDNA expression library immunization.

Genetic or DNA-based immunization, including genomic immunization, has shown to be a viable alternative approach to induce protective immunity against a number of pathogens in several disease models. Here we describe a new method, cDNA expression library immunization (cDELI), based on the use of a large number of cDNA clones. This immunization strategy was tested in experimental murine Taenia crassiceps cysticercosis model. A partial cDNA expression library of 2 x 10(4) members was constructed in eukaryotic expression vector pcDNA3 and used to immunize BALB/c female mice subcutaneously (s.c.) and intramuscularly (i.m.). In both cases significant reduction of parasite load (up to 65%) was obtained. We were unable to directly measure T. crassiceps-specific humoral immune response in any of the immunized mice, although the expression of pathogen proteins in vitro in macrophages transfected with cDNA expressing plasmids was demonstrated. Also, in three out of five randomly selected immunized mice detectable levels of interferon-gamma (IFN-gamma) were obtained. cDELI has additional advantages compared with recently developed single gene or genomic immunization approaches because a cDNA population represents only those genes that are being expressed in the pathogen cells and the selection of stage-specific antigens is possible. The use of cDELI could be particularly attractive for the pathogens with complicated life cycles and large genomes.

Immunization against Taenia crassiceps cysticercosis: identification of the most promising antigens in the induction of protective immunity.

Cross immunity between Taenia solium and Taenia crassiceps parasites points to T. crassiceps cysticercosis as a convenient model to test promising antigens aimed at the development of a vaccine against T. solium cysticercosis. Since total antigens from T. crassiceps metacestodes induce significant levels of protection in pigs against T. solium cysticercosis, we initiated this work to identify the most interesting antigens involved in protection. Twelve different antigen fractions isolated from T. crassiceps cysticerci were evaluated with respect to their capacity to induce resistance against a challenge with 10 T. crassiceps cysticerci in male BALB/cAnN mice. Mice were intraperitoneally immunized with 2 doses of each antigen, 5 or 15 micrograms per mouse. The 12 antigen fractions were classified as protecting (200, 123, 74, 66, 56, 40-50, 27 and 8-14 kDa), facilitating (220-205 kDa), or irrelevant (150-160, 93, 108 kDa), according to their effect on the parasite load. The 3 most promising antigen fractions were reevaluated via subcutaneous immunization with Freunds complete adjuvant. A high level of protection was obtained when antigen fractions of 56, 66, and 74 kDa were used together. Interestingly, antigens with similar molecular weights were also detected in early steps of differentiation in T. solium cysticercosis. These observations may be helpful in the development of a synthetic or a recombinant vaccine against cysticercosis.

Neurocysticercosis: HP10 Antigen Detection Is Useful for the Follow-up of the Severe Patients

Background The most severe clinical form of neurocysticercosis (NC) occurs when cysticerci are located in the subarachnoid space at the base of the brain (SaB). The diagnosis, monitoring and treatment of NC-SaB, constitutes a severe clinical challenge. Herein we evaluate the potential of the HP10 antigen detection enzyme-linked immunosorbent assay (HP10 Ag-ELISA) in the long term follow-up of NC-SaB cases. Assay performance was compared with that of Magnetic Resonance Imaging (MRI). In addition, the robustness of the HP10 Ag-ELISA was evaluated independently at two different institutions. Methodology/Principal Findings A double-blind prospective cohort trial was conducted involving 38 NC-SaB cases and a total of 108 paired serum and cerebrospinal fluid (CSF) samples taken at intervals of 4 to 8 months for up to 43 months. At each medical visit, results of sera and CSF HP10 Ag-ELISA and MRI obtained at last visit were compared and their accuracy was evaluated retrospectively, considering radiological evolution between appointments. In the long-term follow-up study, HP10 Ag-ELISA had a better agreement than MRI with retrospective radiological evaluation. High reproducibility of HP10 Ag-ELISA between laboratories was also demonstrated. Conclusions Results reported in this study establish for the first time the usefulness of the comparatively low cost HP10 Ag-ELISA for long term follow-up of NC-SaB patients.

IMMUNODOMINANT EPITOPE AND PROPERTIES OF PYROGLUTAMATE-MODIFIED Aβ-SPECIFIC ANTIBODIES PRODUCED IN RABBITS

N-truncated and N-modified forms of amyloid beta (Abeta) peptide are found in diffused and dense core plaques in Alzheimers disease (AD) and Downs syndrome patients as well as transgenic mouse models of AD. Although the pathological significance of these shortened forms Abeta is not completely understood, previous studies have demonstrated that these peptides are significantly more resistant to degradation, aggregate more rapidly in vitro and exhibit similar or, in some cases, increased toxicity in hippocampal neuronal cultures compared to the full length peptides. In the present study we further investigated the mechanisms of toxicity of one of the most abundant N-truncated/modified Abeta peptide bearing amino-terminal pyroglutamate at position 3 (AbetaN3(pE)). We demonstrated that AbetaN3(pE) oligomers induce phosphatidyl serine externalization and membrane damage in SH-SY5Y cells. Also, we produced AbetaN3(pE)-specific polyclonal antibodies in rabbit and identified an immunodominant epitope recognized by anti-AbetaN3(pE) antibodies. Our results are important for developing new immunotherapeutic compounds specifically targeting AbetaN3(pE) aggregates since the most commonly used immunogens in the majority of vaccines for AD have been shown to induce antibodies that recognize the N-terminal immunodominant epitope (EFRH) of the full length Abeta, which is absent in N-amino truncated peptides.