ZP-binding peptides identified via phage display stimulate production of sperm antibodies in dogs

The detection of canine anti-sperm antibody following parenteral immunization of bitches against homogenized whole sperm

Backgrounds

The development of a canine-specific method of immunocontraception is one of the non-invasive controlling strategies for humanely decreasing the dog population. This study was aimed to investigate the potential of whole sperm in stimulating the immune system and producing specific anti-sperm antibodies (ASAs) in female dogs. Mature, mixed-breed bitches were subcutaneously immunized with high (200 × 10⁶ cells/mL) and low (100 × 10⁶ cells/mL) doses of sperm vaccine, emulsified with Freund’s adjuvants. Booster immunizations were given at weeks 1, 2, 4, and 6, and serum samples were collected at days 0, 14, 28, 42, 63, and 84 prior to each immunization. Reproductive tract samples, including vaginal and uterine lavages, were also collected by flushing each section with sterile PBS at the end of the experiment. Canine anti-sperm antibody titer and specificity in sera and genital secretions were measured using an enzyme-linked immunosorbent assay technique.

Results

Specific anti-sperm antibodies were detected in the serum of both high and low dose groups and were significantly higher than those observed in the controls. A high dose of sperm induced elevated immune responses over the low dose antigen. Immunization with a high dose of sperm increased the level of ASAs in the uterine secretions and vaginal secretions significantly. Higher ASAs were observed to have transduced to the uterine lumen compared to the vagina.

Conclusions

Based on the results obtained in this study, parenteral immunization with whole sperm can induce a high level of specific antibodies in the serum and genital secretions of female dogs and the response would be dose-dependent.

A single nucleotide polymorphism in the zona pellucida 3 gene is associated with the first parity litter size in Hu sheep

Zona pellucida 3 (ZP3) is a primary sperm receptor and acrosome reaction inducer. As a candidate gene, the ZP3 gene has been widely studied since it has great influence on reproductive traits in farm animals. However, little is known about the association between polymorphisms of the coding region of the ZP3 gene and the first parity litter size in Hu sheep. Therefore, the objective of this study was to identify single nucleotide polymorphisms (SNPs) of the ZP3 gene associated with the first parity litter size in Hu sheep. A total of 462 female Hu sheep were sampled to detect SNPs in the coding region of the ZP3 gene. Six SNPs were identified and the reliability of all estimated allele frequencies reached 0.9545 except for one locus (g.2293C > T). SNP (rs401271989) was identified as that involved in amino acid change (Ile → Leu). This amino acid was located at the beginning of a β-strand and outside of the ZP3 protein membrane, and it was most likely to be a ligand-binding site (the possibility was 0.917). At this locus, individuals with AC genotype had a larger litter size than those with CC genotype in the first parity (2.050 vs 1.727, p < 0.05). In conclusion, SNP (rs401271989) in the coding region of the ZP3 gene influences the first parity litter size in Hu sheep, and it may affect the function of ZP3 protein by impacting the secondary and tertiary protein structures. The present study demonstrates that SNP (rs401271989) could be used in marker-assisted selection of the first parity litter size in Hu sheep.

Immunocontraception: Filamentous Bacteriophage as a Platform for Vaccine Development

BACKGROUND

Population control of domestic, wild, invasive, and captive animal species is a global issue of importance to public health, animal welfare and the economy. There is pressing need for effective, safe, and inexpensive contraceptive technologies to address this problem. Contraceptive vaccines, designed to stimulate the immune system in order to block critical reproductive events and suppress fertility, may provide a solution. Filamentous bacteriophages can be used as platforms for development of such vaccines.

OBJECTIVE

In this review authors highlight structural and immunogenic properties of filamentous phages, and discuss applications of phage-peptide vaccines for advancement of immunocontraception technology in animals.

RESULTS

Phages can be engineered to display fusion (non-phage) peptides as coat proteins. Such modifications can be accomplished via genetic manipulation of phage DNA, or by chemical conjugation of synthetic peptides to phage surface proteins. Phage fusions with antigenic determinants induce humoral as well as cell-mediated immune responses in animals, making them attractive as vaccines. Additional advantages of the phage platform include environmental stability, low cost, and safety for immunized animals and those administering the vaccines.

CONCLUSION

Filamentous phages are viable platforms for vaccine development that can be engineered with molecular and organismal specificity. Phage-based vaccines can be produced in abundance at low cost, are environmentally stable, and are immunogenic when administered via multiple routes. These features are essential for a contraceptive vaccine to be operationally practical in animal applications. Adaptability of the phage platform also makes it attractive for design of human immunocontraceptive agents.

Non-surgical sterilisation methods may offer a sustainable solution to feral horse (Equus caballus) overpopulation

Feral horses are a significant pest species in many parts of the world, contributing to land erosion, weed dispersal and the loss of native flora and fauna. There is an urgent need to modify feral horse management strategies to achieve public acceptance and long-term population control. One way to achieve this is by using non-surgical methods of sterilisation, which are suitable in the context of this mobile and long-lived species. In this review we consider the benefits of implementing novel mechanisms designed to elicit a state of permanent sterility (including redox cycling to generate oxidative stress in the gonad, random peptide phage display to target non-renewable germ cells and the generation of autoantibodies against proteins essential for conception via covalent modification) compared with that of traditional immunocontraceptive approaches. The need for a better understanding of mare folliculogenesis and conception factors, including maternal recognition of pregnancy, is also reviewed because they hold considerable potential in providing a non-surgical mechanism for sterilisation. In conclusion, the authors contend that non-surgical measures that are single shot and irreversible may provide a sustainable and effective strategy for feral horse control.

Phage display--a powerful technique for immunotherapy: 2. Vaccine delivery

Phage display is a powerful technique in medical and health biotechnology. This technology has led to formation of antibody libraries and has provided techniques for fast and efficient search of these libraries. The phage display technique has been used in studying the protein-protein or protein-ligand interactions, constructing of the antibody and antibody fragments and improving the affinity of proteins to receptors. Recently phage display has been widely used to study immunization process, develop novel vaccines and investigate allergen-antibody interactions. This technology can provide new tools for protection against viral, fungal and bacterial infections. It may become a valuable tool in cancer therapies, abuse and allergies treatment. This review presents the recent advancements in diagnostic and therapeutic applications of phage display. In particular the applicability of this technology to study the immunization process, construction of new vaccines and development of safer and more efficient delivery strategies has been described.