Anti-LHRH and anti-pituitary gonadotropin vaccines: their development and clinical applications

Male contraception: Past, present and future

Male contraception research has yielded a number of promising leads over the past 50 years. Yet, little is known by the public due to lack of institutional support and funding. This is unfortunate since, apart from condom and vasectomy, there are many male methods which may be safer, more effective and easier to use. This paper explores male contraception which has been used in the past and the present and discusses some of its potential developments.

Long-lasting specific antibodies against P277 induced by mucosal administration of P277 repeat sequences carried by Hsp65 in the absence of adjuvants

To improve the weak immunogenicity of peptide P277, the recombinant expression plasmid pET28-Hsp65-6 x P277 was constructed by inserting 5 x P277 which was amplified by PCR into the vector pET28-Hsp65-P277. It was transformed into Escherichia coli BL21 (DE3) and the fusion protein (Hsp65-6 x P277) was expressed effectively as soluble protein after inducing by lactose. The fusion protein was purified by means of cell disruption, ammonium sulfate precipitation, double-distilled H2O dialysis, DEAE52-cellulose column chromatography, and then used to immunize female NOD mice with three i.n. inoculations in the absence of adjuvants. Serum samples from the immunized mice were collected at 3 weeks interval. Antibodies against P277 and HSP65 were detected in immunized mice sera by enzyme-linked immunosorbent assay (ELISA) and Western blot. Specific antibodies were successfully induced and lasted for more than 20 weeks in animals immunized with the fusion protein via intranasal route even in the absence of adjuvants.

Fertility control in wildlife: humans as a model

In a time of accelerated extinction rates and biodiversity loss, it may seem illogical to be concerned with methods limiting the reproduction of wild populations; however, there is an urgent need to inhibit the proliferation of a wide variety of species. The range of animals for which fertility control is desired makes the development of a single method impossible. The various reproductive strategies used by individual species, the desired outcome of contraceptive programs (reversible or irreversible; male or female directed) and our ignorance of the reproductive biology of many endangered species necessitate thorough species-specific investigations. As fertility control in humans is a reality and research into methods of fertility control is more advanced, humans serve as a model for developing contraceptive approaches for wild species. Population control by traditional methods (indirect or direct intervention by culling, poisoning, translocation, etc.) is increasingly unacceptable to the public, making human studies even more valuable for finding solutions to overabundant wild populations. This review compares and contrasts the range of contraceptive methods used in both wildlife and humans.

Antibody against cholesteryl ester transfer protein (CETP) elicited by a recombinant chimeric enzyme vaccine attenuated atherosclerosis in a rabbit model

The recombinant chimeric enzyme of AnsB-TTP-CETPC, which comprised asparagianse, tetanus toxin helper T-cell epitope and CETP B-cell epitope, was used to vaccinate New Zealand white rabbits in alum adjuvant. After anti-CETP antibodies were successfully produced, rabbits were fed with a high cholesterol diet for fifteen weeks until atherosclerotic lesions formed in arteries. The results showed that after CETP was inhibited by anti-CETP antibodies the fraction of plasma cholesterol in HDL increased and the fraction of plasma cholesterol in LDL decreased in rAnsB-TTP-CETPC immunized rabbits. The average size of aorta atherosclerotic plaques in rabbits treated with rAnsB-TTP-CETPC was 42.3% less than in rabbits treated with OVA (neutral control), or 47.6% less than in rabbits treated with rHSP 65 (negative control). The average thickness of hyperplastic coronary artery in rAnsB-TTP-CETPC immunized rabbits was 159+/-12 microm, which was significantly lower than in rHSP 65 immunized rabbits (187+/-15 microm) or OVA immunized rabbits (248+/-18 microm). The data reported here demonstrated that rAnsB-TTP-CETPC could significantly attenuate the development of atherosclerosis in rabbits fed with high cholesterol diet, and might be developed to an anti-atherosclerosis vaccine in the future.

Long-lasting specific antibodies against CETP induced by subcutaneous and mucosal administration of a 26-amino acid CETP epitope carried by heat shock protein 65 kDa in the absence of adjuvants

The heat shock protein 65 kDa (Hsp65) of Mycobacterium tuberculosis var. bovis was fused with the linear polypeptide epitope of cholesteryl ester transfer protein C-terminal fragment (CETPC) and expressed as soluble protein in Escherichia coli. The fusion protein Hsp65-CETPC was purified by anion exchange column and eluted at 100-130 mM NaCl in 10mM phosphate buffer (pH 8.0), and then used to immunize mice via subcutaneous injection or intranasal delivery in the absence of adjuvants. Antibodies against CETPC were detected in immunized mice sera by enzyme-linked immunosorbent assay (ELISA) and verified by Western blot analysis. Specific antibodies were successfully induced and lasted for more than 12 weeks in animals immunized with the fusion protein via both subcutaneous and intranasal routes even in the absence of adjuvants. Results showed that Hsp65 could be used as a convenient carrier molecule for presenting foreign polypeptide epitopes, such as CETPC, to the immune system in vivo. Antibodies induced by Hsp65-CETPC could partially inhibit the excessive activity of CETP to normal level. Therefore, Hsp65-CETPC might be further developed to a vaccine against atherosclerosis.

Influence of carrier protein conjugation site and terminal modification of a GnRH-I peptide sequence in the development of a highly specific anti-fertility vaccine. Part I

PROBLEM

We previously immunoneutralized gonadotrophin releasing hormone (GnRH), using an analogue of GnRH (des-1 GnRH-I), conjugated to tetanus toxoid via a carbodiimide reaction. The castration effect on the reproductive system was not consistent in all the treated animals. Therefore, we examined the possibility that conjugation to the carrier protein via the N- or C-terminal could have an effect on efficacy.

METHOD OF STUDY

GnRH analogue sequences were synthesized consisting of an additional cysteine at either terminal and specific conjugation was carried out using a bifunctional linker agent.

RESULTS

Conjugation of the monomer through the N-terminal proved to be a highly effective means of causing immunocastration in terms of decreased gonadotrophin and testosterone concentrations and testicular size, whereas conjugation through the C-terminal proved to be ineffective. This was reflected in the ability of the antibodies to bind native GnRH, but not the levels of the anti-GnRH antibodies.

CONCLUSION

Immunoneutralization efficacy was attributed to the importance of preserving the GnRH C-terminal.

Life-style vaccines

Multiple immunotherapy approaches are under development to treat various chronic diseases or conditions. Thanks to dramatic technological improvements, the field of vaccinology can now extend from prophylaxis to therapy, and from infectious diseases to dysimmune disorders like cancer or autoimmunity, or even to non-immune related conditions, including neurological or cardiovascular disorders. Life-style vaccines defined as vaccines to manage chronic conditions in healthy individuals can, therefore, also be envisaged. Three examples will be reviewed and discussed here, from both technical and ethical aspects: contraceptive vaccines, vaccines to treat addictions, and anti-dental caries vaccines.

Immunoneutralisation of GnRH-I, without cross-reactivity to GnRH-II, in the development of a highly specific anti-fertility vaccine for clinical and veterinary use

In recent years, several forms of gonadotrophin releasing hormone (GnRH) molecules have been isolated from primate brain. These molecules are very similar in sequence and this raises the question of whether previously developed neutralisation vaccines based on GnRH (now termed GnRH-I) would remove other forms of GnRH (namely GnRH-II) as well. As the function of these other molecules has not yet been clearly defined, potential health risks could exist by their ablation. In view of the high sequence homology between the molecules, this paper describes the production of highly specific polyclonal antibodies against GnRH-I and GnRH-II, with negligible cross-reactivity. The ultimate aim of this is to develop an anti-fertility vaccine which does not present any inappropriate side-effects, caused by neutralisation of a GnRH molecule which may or may not be directly involved in reproduction. Several formulations were investigated, based on analogues of the following molecules, conjugated to tetanus toxoid: 1. GnRH-I pGlu-His-Trp-Ser-Try-Gly-Leu-Arg-Pro-Gly-NH2 and 2. GnRH-II pGlu-His-Trp-Ser-His-Gly-Trp-Tyr-Pro-Gly-NH2. The specificity of the antibodies produced was examined, together with effects on fertility and any inappropriate side-effects. Immunostaining of hypothalamic sections was carried out, using the generated antisera, to determine the regional distribution of GnRH-I and GnRH-II neurones, as well as to further evaluate the specificity of the antibodies.

Basic aspects of immunomodulation through active immunization

This paper reviews how immunomodulation through active vaccination has evolved in the past 25 years. Although initially it progressed isolated from the main stream of immunological research and vaccine development, lately it merged with this main stream and is taking full advantage of the newest developments in vaccinology. The first immunomodulation vaccine is already on the market, while various others are close to it. Not in the least because one of the major stumbling blocks of immunomodulation through active vaccination, the inherent low immunogenicity of 'self' antigens, has in a number of other cases been solved. Most progress has been made in veterinary applications and has helped to formulate practical rules, necessary to break immunotolerance. It is not unlikely that these rules will be used to design better immunomodulation vaccines to be used in humans; notably to control fertility or combat tumours.

Immunoregulation of mammalian fertility

Fertility management is a global issue of agricultural, medical, economic, and social consequence. Although many methods have been devised to both inhibit and assist reproduction, more acceptable alternatives are needed. Regulation by immune intervention is a promising technology as applied to livestock, pets, wildlife, and human beings. Outcome is dictated by site within the reproductive axis that is targeted. Fertility is suppressed by immunization against gonadotropin-releasing hormone, gonadotropins, prostaglandin F2 alpha, oxytocin, gonadotropin receptors, and gamete/embryonic antigens. It also is possible to lyse gonadal cells with ligand-antibody hybrid molecules. Ovulation rates are enhanced by vaccination with inhibin. Antibodies to sex steroid hormones have yielded mixed results. Perhaps recombinant viral vectors can be used to deliver reproductive immunogens. A new and simple technique to generate sustained autoimmune reactions to hormones and cellular antigens entails direct gene transfer into somatic cells. Evolving advances in reproductive immunology and biotechnology should furnish us with novel nonsurgical contraceptives and profertility agents that can be efficiently and safely implemented.