Contraception in mice immunized with recombinant zona pellucida subunit 3 proteins correlates with Th2 responses and the levels of interleukin 4 expressed by CD4+ cells

Oral and Subcutaneous Immunization with a Plant-Produced Mouse-Specific Zona Pellucida 3 Peptide Presented on Hepatitis B Core Antigen Virus-like Particles

A short mouse-specific peptide from zona pellucida 3 (mZP3, amino acids 328-342) has been shown to be associated with antibody-mediated contraception. In this study, we investigated the production of mZP3 in the plant, as an orally applicable host, and examined the immunogenicity of this small peptide in the BALB/c mouse model. The mZP3 peptide was inserted into the major immunodominant region of the hepatitis B core antigen and was produced in Nicotiana benthamiana plants via Agrobacterium-mediated transient expression. Soluble HBcAg-mZP3 accumulated at levels up to 2.63 mg/g leaf dry weight (LDW) containing ~172 µg/mg LDW mZP3 peptide. Sucrose gradient analysis and electron microscopy indicated the assembly of the HBcAg-mZP3 virus-like particles (VLPs) in the soluble protein fraction. Subcutaneously administered mZP3 peptide displayed on HBcAg VLPs was immunogenic in BALB/c mice at a relatively low dosage (5.5 µg mZP3 per dose) and led to the generation of mZP3-specific antibodies that bound to the native zona pellucida of wild mice. Oral delivery of dried leaves expressing HBcAg-mZP3 also elicited mZP3-specific serum IgG and mucosal IgA that cross-reacted with the zona pellucida of wild mice. According to these results, it is worthwhile to investigate the efficiency of plants producing HBcAg-mZP3 VLPs as immunogenic edible baits in reducing the fertility of wild mice through inducing antibodies that cross-react to the zona pellucida.

Optimizing the Expression and Solubilization of an E. coli-Produced Leukemia Inhibitory Factor for Anti-LIF Antibody Production and Use Thereof for Contraception in Mice

Leukemia inhibitory factor (LIF) is an essential cytokine for blastocyst implantation. This study evaluated the effect of LIF inhibition on the blockage of embryo implantation. A truncated mouse LIF (tmLIF) was designed and expressed in E. coli. The protein expression was optimized using different culture media and inducers. To block pregnancy, the mice were immunized by the purified protein via maternal injection of the protein or in utero injection of the anti-LIF serum. The expression of implantation-relevant genes was quantified in the uterine tissue. The results showed that the protein was expressed in aggregated form in E. coli. The highest yield of protein was produced in the M9 medium. The insoluble protein was completely dissociated by SDS and 2-ME combination, but not by urea. The maternal immunization reduced the number of offspring, but not significantly. Instead, in utero injection of the anti-LIF serum prevented the blastocyst implantation. Gene expression analyses showed decrease of Jam2, Msx1and HB-EGF genes and increase of Muc1 gene as the result of intrauterine administration of the anti-LIF serums. In conclusion, SDS-mediated solubilization of inclusion bodies was compatible with in vivo studies. The intrauterine administration of anti-LIF serum could prevent mouse pregnancy. This indicates that in utero application of LIF antibodies might be used as a contraceptive.

Enhanced contraception of canine zona pellucida 3 DNA vaccine via targeting DEC-205 in mice

Zona pellucida 3 (ZP3) is a potential antigen for the development of contraceptive vaccines to control animal population. In this study, we designed a canine ZP3 (CZP3) DNA vaccine through targeting DEC-205 (named as pcD-scFv-CZP3c) and investigated its contraceptive effect in mice. Female BALB/c mice were intramuscularly immunized 3 times at 2 weeks intervals. After immunization, humoral and cellular immune responses were detected by ELISA and flow cytometry. The results showed that pcD-CZP3 and pcD-scFv-CZP3c induced CZP3-specific antibody (Ab) responses both in serum and vaginal secretions compared to pcDNA3.1. Additionally, compared to pcD-CZP3, pcD-scFv-CZP3c increased the levels of CZP3-specific Abs after a third immunization. Abs induced by these two DNA vaccines could bind with mice and dogs oocytes. Moreover, pcD-scFv-CZP3c enhanced the activation of CD4⁺ T cells characterized by the increased frequencies of CD4⁺CD44⁺ T cells. Finally, the contraceptive effect was evaluated in the immunized mice. These two DNA vaccines significantly decreased a mean litter size of mice compared to pcDNA3.1, but pcD-scFv-CZP3c group showed the smallest mean litter size. The mean litter size of pcD-scFv-CZP3 were 3.2 ± 0.742 and 4.6 ± 1.118 in two mating tests, which were significantly lower than pcDNA3.1(P < 0.001 and P < 0.05). Our results suggest that the CZP3 DNA vaccine targeted with DEC-205 may be a potential strategy for developing a contraceptive DNA vaccine.

Molecular adjuvant interleukin-33 enhances the antifertility effect of Lagurus lagurus zona pellucida 3 DNA vaccine administered by the mucosal route

It has been shown that cytokines can act as molecular adjuvant to enhance the immune response induced by DNA vaccines, but it is unknown whether interleukin 33 (IL-33) can enhance the immunocontraceptive effect induced by DNA vaccines. In the present study, we explored the effects of murine IL-33 on infertility induced by Lagurus lagurus zona pellucida 3 (Lzp3) contraceptive DNA vaccine administered by the mucosal route. Plasmid pcD-Lzp3 and plasmid pcD-mIL-33 were encapsulated with chitosan to generate the nanoparticle chi-(pcD-Lzp3+pcD-mIL-33) as the DNA vaccine. Sixty female ICR mice, divided into 5 groups (n=12/group), were intranasally immunized on days 0, 14, 28, and 42. After intranasal immunization, the anti-LZP3-specific IgG in serum and IgA in vaginal secretions and feces were determined by ELISA. The results showed that chi-(pcD-Lzp3+pcD-mIL-33) co-immunization induced the highest levels of serum IgG, secreted mucosal IgA, and T cell proliferation. Importantly, mice co-immunized with chi-(pcD-Lzp3+pcD-mIL-33) had the lowest birth rate and mean litter size, which correlated with high levels of antibodies. Ovaries from infertile female mice co-immunized with chi-(pcD-Lzp3+pcD-mIL-33) showed abnormal development of ovarian follicles, indicated by atretic follicles and loss of oocytes. Our results demonstrated that intranasal delivery of the molecular adjuvant mIL-33 with chi-pcD-Lzp3 significantly increased infertility by enhancing both systemic and mucosal immune responses. Therefore, chi-(pcD-Lzp3+pcD-mIL-33) co-immunization could be a strategy for controlling the population of wild animal pests.

Granulocyte-macrophage colony-stimulating factor enhances the humoral immune responses of mouse zona pellucida 3 vaccine strategy based on DNA and protein coadministration in BALB/c mice

We recently demonstrated that co-administration of mouse zona pellucida 3 (mZP3) DNA and protein vaccine enhanced the contraception of mice by increasing humoral immune responses. In this study, we try to use granulocyte-macrophage colony-stimulating factor (GM-CSF) to further improve the humoral immune responses induced by mZP3 DNA and protein co-administration. BALB/c mice were intranasally pre-injected with GM-CSF 4 days before co-administration. Compared to DNA and protein coadministration without GM-CSF, the combination of GM-CSF and coadministration significantly enhances humoral immune responses, especially the level of secretory immunoglobulin A (sIgA) in vaginal washes. The enhanced antibody responses are correlated with the upregulated level of interleukin 4 (IL-4) and enhanced maturation of dendritic cells (DCs). Thus, GM-CSF is a potential candidate adjuvant to be used for the development of a safe and effective contraceptive vaccine.

The effects of GM-CSF and IL-5 as molecular adjuvants on immune responses and contraception induced by mZP3 DNA vaccination

PROBLEM

Various approaches have been developed to improve the antibody response of zona pellucida glycoprotein-3 (ZP3) vaccination. In this study, we investigated whether GM-CSF and IL-5 can be used as cytokine adjuvants to increase the humoral immune response generated by mouse ZP3 (mZP3) DNA vaccine.

METHOD OF STUDY

Mice in experimental group were injected by GM-CSF 4 days before the co-immunization of IL-5 and mZP3 DNA vaccine. The contraception and the correlation with humoral and cellular immune responses were analyzed after immunization and mating. The effect of cytokine adjuvant on the maturation of DCs was evaluated.

RESULTS

Co-immunization of GM-CSF and IL-5 with mZP3 DNA vaccine induced the highest level of serum IgG and IL-4 expression in CD4(+) T cells. Importantly, this strategy reduced mice fertility without disrupting normal ovarian morphology. GM-CSF enhanced the maturation of DCs evidenced by up-regulating the expression of MHC-II and CD86.

CONCLUSION

GM-CSF and IL-5 co-administration enhanced humoral immune responses to mZP3, and this may be a potential strategy for development of immunocontraceptive vaccine.

Intranasal co-delivery with the mouse zona pellucida 3 and GM-CSF expressing constructs enhances humoral immune responses and contraception in mice

Granulocyte-monocyte colony-stimulating factor (GM-CSF) regulates the function of antigen-presenting cells (APCs) and has been broadly used as the adjuvant. Here, we tested whether intranasal delivery of GM-CSF can improve the contraception of mouse zona pellucida 3 (mZP3) DNA vaccine. Our results showed that co-administration of GM-CSF and mZP3 DNA vaccine increased the levels of secretory IgA (sIgA) and IgG antibodies in vaginal washes and serum, respectively. Co-administration enhanced Th2 responses through improving the maturation of dendritic cells. Importantly, GM-CSF significantly reduced the fertility rate and mean litter size induced by mZP3 DNA vaccine alone without interfering the normal follicular development. These data suggest that GM-CSF could be used as adjuvant to develop immunocontraceptive vaccine.

Tolerogenic DNA vaccine for prevention of autoimmune ovarian disease

DNA vaccines have been widely used to induce immune responses against molecular targets. In this study, we explored the possibility of using DNA vaccine combined with the immunosuppressant FK506 (tacrolimus) to antigen-specifically suppress unwanted immune responses and prevent autoimmune ovarian disease. To that end, we immunized C57BL/6 mice with a DNA vaccine encoding mouse zona pellucida 3 (ZP3) together with FK506. The immunization induced ZP3-specific CD4(+)CD25(+)Foxp3(+) regulatory T cells (Treg), which suppressed the induction of ZP3-specific delayed-type hypersensitivity in the animals. Significantly, the immunization also protected the animals from experimentally induced autoimmune ovarian disease. These results suggest that DNA vaccination in the presence of FK506 may be used to induce Treg cells and prevent AOD.

Intranasal co-administration with the mouse zona pellucida 3 expressing construct and its coding protein induces contraception in mice

The zona pellucida 3 (ZP3), an autoantigen, once used to develop contraceptive vaccine has been faced a safety issue. Avoiding its pathogenic T cell activation, we intranasally co-delivered the mZP3 DNA- and protein-based vaccines in mice and observed that a higher level of sIgA and IgG antibodies in vaginal washes, bronchoalveolar lavages and serum and yielded a lower level of fertility and mean litter size. Importantly, histological analysis showed that normal follicular developments of the infertile mice were not disrupted in the co-delivered group. Thus, the intranasal co-delivery may present a safe strategy for the development of contraceptive vaccine.

Enhanced contraceptive response by co-immunization of DNA and protein vaccines encoding the mouse zona pellucida 3 with minimal oophoritis in mouse ovary

Zona pellucida 3 (ZP3) acts as the primary sperm receptor, induces autoantibody that can prevent oocyte fertilization and has been proposed as a vaccine candidate for contraception in humans. Due to the elicited autoreactive T cell inflammation that causes ovarian destruction, ZP3-based vaccine with removed T epitopes from the ZP3 is considered as a preferred approach. We present here a new strategy to eliminate the T cell inflammation while retaining a high level of antibody by co-immunization of mZP3 DNA and protein vaccines, which resulted in a higher reduction rate of fertility in this group. Histological analysis showed that there were normal follicular developments of infertile mice in the co-immunized group; while other vaccine groups of the most infertile mice lacked mature follicles. There was a significant correlation between normal follicular development and the inhibition of T cell response in co-immunized mice. At the same time, co-immunization reduced the production of inflammatory cytokine, IFN-gamma, and increased the productions of IL-10 and FoxP3 in CD4 T cells, suggesting the anti-inflammation may be via a T regulatory function. The results indicate that co-immunization of mZP3 DNA- and protein-based vaccines can reduce fertility without interfering with the normal follicular development and present a novel strategy to develop a contraceptive vaccine in humans.

Prospects for virally vectored immunocontraception in the control of wild house mice (Mus domesticus)

The wild house mouse (Mus domesticus) is not native to Australia and was introduced from Europe with early settlement. It undergoes periodic population explosions or plagues, which place significant economic and social burdens on agricultural communities. Present control mechanisms rely on improvements to farm hygiene and the use of rodenticides. This review covers over a decade of work on the use of virally vectored immunocontraception (VVIC) as an adjunct method of controlling mouse populations. Two viral vectors, ectromelia virus (ECTV) and murine cytomegalovirus (MCMV) have been tested as potential VVIC vectors: MCMV has been the most widely studied vector because it is endemic to Australia; ECTV less so because its use would have required the introduction of a new pathogen into the Australian environment. Issues such as efficacy, antigen choice, resistance, transmission, species specificity and safety of VVIC are discussed. In broad terms, both vectors when expressing murine zona pellucida 3 (mZP3) induced long-term infertility in most directly inoculated female mice. Whereas innate and acquired resistance to MCMV may be a barrier to VVIC, the most significant barrier appears to be the attenuation seen in MCMV-based vectors. This attenuation is likely to prevent sufficient transmission for broad-scale use. Should this issue be overcome, VVIC has the potential to contribute to the control of house mouse populations in Australia.

Immunocontraception in mice using repeated, multi-antigen peptides: immunization with purified recombinant antigens

Two immunocontraceptive antigens (AgE and AgF) were constructed that included different combinations of highly species-specific peptides from the mouse reproductive antigens SP56, ZP3, ZP2, and ZP1 in the form of multi-antigen peptides (MAPs). Both AgE and AgF contained three tandem repeats each of ZP2 and ZP3 peptide epitopes and a single copy of a ZP1 peptide sequence all of which had previously been demonstrated to individually have immunodominant or contraceptive effects. In addition, AgF contained a single contraceptive peptide derived from SP56, the putative ZP3 receptor protein on sperm. The antigens were expressed and affinity purified as recombinant repeated multi-antigen (polyepitope) peptides using an Escherichia coli maltose binding protein (MBP) expression system. Female BALB/c mice actively immunized with these antigens in Freund's adjuvants produced variable serum antibody responses to the component peptides. Fertility rates for animals immunized with AgE (40%) and AgF (20%) were significantly reduced compared to MBP immunized mice (90%), but the reduction in fertility did not correlate with peptide-specific serum antibody levels. Ovaries from all immunized mice appeared histologically normal with no evidence of oophoritis. These results demonstrate that high levels of immunocontraception can be achieved in mice, without apparent side-effects, using species-specific immunogens that include repeated peptides from proteins involved in fertilization.

Immunogenicity and contraceptive potential of three infertility-relevant zona pellucida 2 epitopes in the marsupial brushtail possum (Trichosurus vulpecula)

In a previous study, three infertility-relevant epitopes of possum ZP2 (Pep12 (amino acids 111–125), Pep31 (amino acids 301–315), and Pep44 (amino acids 431–445)) were identified using sera from possums (Trichosurus vulpecula) immunized with recombinant possum zona pellucida 2 (ZP2) constructs, and a synthetic peptide library of possum ZP2 protein. In this study, the three peptides were conjugated to keyhole limpet hemocyanin and 300 μg of each conjugated peptide were administered subcutaneously to female possums (n = 20 per peptide) in complete Freund’s adjuvant. Immunogen doses were repeated 3 and 6 weeks later using incomplete Freund’s adjuvant. Control animals were immunized with either phosphate-buffered saline only (n = 10) or 300 μg keyhole limpet hemocyanin (n = 10), administered with the same adjuvants. Serum antibodies from animals immunized against these three epitopes bound to the corresponding possum ZP2 peptides, recombinant possum ZP2 protein constructs, and native zona. Possum fertility was assessed following superovulation and artificial insemination. Peptides Pep12 and Pep31 had no significant effects on fertility parameters (P > 0.05). However, animals immunized with Pep44 had lower egg fertilization rates (immunized 19.5% versus control 60.5%, P < 0.05) and produced significantly fewer embryos than control animals (immunized 0.5 embryos versus control 2.4 embryos, P < 0.05). The number of Pep44-immunized females that produced embryos was reduced by 64%. Identification and characterization of possum infertility-relevant epitopes on possum ZP2 protein will assist development of safe, humane, and possum-specific immunocontraceptive vaccines for controlling the introduced possums in New Zealand.

Molecular cloning and assessment of the immunocontraceptive potential of the zona pellucida subunit 3 from Brandt's vole (Microtus brandti)

A full-length cDNA encoding Brandt's vole (Microtus brandti) zona pellucida glycoprotein subunit 3 (vZP3) was isolated using rapid amplification of cDNA ends-polymerase chain reaction (RACE-PCR). The cDNA contains an open reading frame of 1254 nucleotides encoding a polypeptide of 418 amino acid residues. The deduced amino acid sequence of vZP3 revealed high overall homology with hamster (82.1%), mouse (81.3%) and rat (80.6%). A synthetic vZP3 peptide corresponding to amino acid residues 328-343 was conjugated to keyhole limpet hemocyanin (KLH-vZP3(328-343)) and used to immunise female Brandt's voles in order to test the efficacy of this peptide as a contraceptive antigen. High IgG antibody levels to the vZP3(328-343) peptide were present in the sera of female voles immunised with KLH-vZP3(328-343) and these also cross-reacted to the zona pellucida in ovaries of Brandt's vole. The fertility of the KLH-vZP3(328-343) -immunised voles was reduced by 50% compared with controls without evidence of significant ovarian pathology.

Immunisation of the male tammar wallaby (Macropus eugenii) with spermatozoa elicits epididymal antigen-specific antibody secretion and compromised fertilisation rate

Immunocontraception has been proposed as an effective and humane means of controlling overabundant kangaroo populations in Australia. We have examined the feasibility of using a sperm-based vaccine for this purpose using a model macropod species, the tammar wallaby (Macropus eugenii). This study has demonstrated immunocontraception in a marsupial species following immunisation of males with homologous spermatozoa. Serum anti-sperm IgG titres were associated with a significant reduction in fertilisation rates following mating with superovulated female wallabies. Antigen-specific IgG penetrated the reproductive tract at the rete testis and bound spermatozoa in vivo. IgG was detected bound to the acrosome and midpiece regions of both epididymal and ejaculated spermatozoa. The absence of adverse testicular pathology and sperm movement effects suggests that contraception may have been achieved by antibody-mediated blocking of sperm surface antigens essential for fertilisation. This study demonstrates that a contraceptive vaccine targeting sperm antigens has potential for fertility control in male macropods.

Contraceptive responses of female hamsters immunized with recombinant sperm protein P26h

BACKGROUND

A number of antigens have been characterized and proposed as potential candidates for immunocontraception. P26h, a 26-kDa hamster sperm protein located on the acrosomal cap, is known to be involved in sperm-zona pellucida interactions. Furthermore, in vivo fertilization can be blocked by active immunization of male hamsters against P26h or maltose-binding protein recombinant P26h (MBP-P26h).

OBJECTIVE

The aim of this study was to investigate the immune response and reproductive function of female hamsters immunized against MBP-P26h.

RESULTS

Active immunization against MBP-P26h resulted in anti-P26h circulating antibodies, with enzyme-linked immunosorbent assay (ELISA) titers showing interindividual variability. The antibodies produced by the animals immunized against MBP-P26h reacted with the native P26h protein in ELISA, in Western blot analysis and in immunostaining performed on cauda epididymal spermatozoa. Mating of immunized female hamsters resulted in a significant decrease in the number of viable fetuses only in females with high titers of anti-P26h circulating antibodies.

DISCUSSION

This result is in agreement with the sperm-zona pellucida binding assay's results. Indeed, sera collected from immunized animals, and not from control animals, significantly blocked sperm-zona pellucida binding in vitro. Histological studies showed that active immunization did not cause any pathology in the reproductive tissues.

CONCLUSION

These findings suggest that P26h is a potential candidate for the development of a contraceptive vaccine in both males and females.