Anti-fertility vaccines

Identification of sperm antigens as a first step towards the generation of a contraceptive vaccine to decrease fossorial water vole Arvicola terrestris Scherman proliferations

Immunocontraceptive strategies have proved to be efficient in controlling fertility of various mammalian species. In the present study we have made the first steps towards the identification of Arvicola terrestris sperm antigens that could be used as targets in the development of a contraceptive vaccine to limit the proliferations of this pest rodent. Rabbit-raised polyclonal antisera directed against complete A. terrestris spermatozoa were used to identify and characterize on 2D-gels coupled with a MALDI-TOF mass spectrometry analysis A. terrestris sperm proteins. Amongst the proteins pinpointed by this approach some were further investigated based on their tissue- and/or sperm-specific expression, and their relevance to fertility or sperm/egg interaction. In parallel, three proteins that have been already reported in the literature to be appropriate targets for the development of contraceptive vaccines in other mammalian species have also been looked for in A. terrestris. With the selected protein targets, a reverse-PCR approach using degenerate primers was employed to amplify corresponding A. terrestris cDNAs. After conceptual translation and sequence alignment, different proteins were studied to determine zones with sufficient sequence divergence and of antigenic/immunogenic nature that could be used in future assays to immunize animals.

Hormonal male contraception: progress and prospects for the 21st century

During the second half of the 20th century, progress in developing novel, practical contraceptive methods for men has lagged significantly behind developments for women. Despite the lack of reliable, reversible methods, men throughout the world continue to be strongly involved in family planning but a greater involvement will require more attractive and reliable contraceptive options for men. The closest to fruition are hormonal methods the features of which are reviewed. Landmark WHO contraceptive efficacy studies have established that hormonally-induced azoospermia provides highly effective and reversible contraception for at least 12 months with minimal short-term side effects. Even among the small subgroup of men who remain oligozoospermic during hormonal suppression, good contraceptive efficacy is achieved. The present goals are to develop improved second generation hormonal regimens which provide more uniform azoospermia to obviate the need for monitoring of sperm output and to develop long-acting depot testosterone formulations used alone or with additional gonadotrophin suppressive agents such as progestins or GnRH antagonists. Significant obstacles to progress are the flight of industry from contraceptive R&D dur to the financial deterrent posed by the product liability crisis as well as the low priority accorded male reproductive health. Together those will determine whether the range of contraceptive options available to our children in the 21st century will improve, or whether the historically recent unbalanced increase in reliance on women for family planning will continue.

Vaccinations in the Third World: a consideration of community demand

Impressive increases in immunization rates have been reported in several less developed countries (LDCs) as a result of intensive EPI programs. An issue arises as to whether existing rates of immunization coverage can be sustained/increased given projected cutbacks in funding. This issue calls into question the assumption that as immunizable disease rates fall, local populations will need less encouragement to secure immunization services. This article considers how immunizations are perceived by lay populations and how perceptions of utility and need effect demand which in turn effects the sustainability of EPI programs. Among issues addressed is the observation that when specific diseases are not linked to specific immunizations, misimpressions related to the number of immunizations needed for "good health" abound. Also considered are metamedical reasons immunizations (and immunization programs) are both resisted and demanded in particular political contexts.

Immunization to regulate fertility: biological and cultural frameworks

Deliberate immunization to control fertility differs from that to control disease. Those differences can be discussed within various frameworks, e.g., intent, recipient population, biological bases, and immunological targets. Others include differing perspectives of developers, providers and users, and rights of the state to impose programs of control. Almost all of the differences are grounded in the social, economic, and gendered aspects of societies. The intent of providing a fertility-regulating vaccine is to prevent pregnancy. In theory, men as well as women could receive such vaccines; in reality, most are designed for women. Traditional vaccines are intended to prevent disease and are generally given to susceptible individuals whether male or female, child or adult. The biological bases of contraceptive vaccines are molecules specific to reproduction. The immune response generated by most anti-fertility vaccines is directed toward 'self', one's own cells and molecules. In contrast, the bases of traditional vaccines are materials derived from non-self, disease-causing microorganisms; the immunological targets are those microorganisms or their toxic products. From a developer perspective vaccines that regulate fertility differ little from those that control disease; both prevent a particular condition. Developers cite these advantages to contraceptive vaccines: non-invasive, no serious side-effects, easy to use, reduced patient failure, and long-lasting but naturally reversible. Because anti-fertility vaccines have been tested only in small-scale clinical trials, information on user reactions and experiences is limited. Not surprisingly, the perspectives of women's health advocates and of potential users (mostly women) often differ markedly from those of developers. Women cite as disadvantages the cryptic nature of immunity which leaves one without an obvious signal for the beginning of protection (against pregnancy) and its decline, and the inability to 'turn-off' an immune response. Further, long-acting contraception can complicate alleviation and side-effects, and it leaves women always vulnerable to sexual demands. Most women object to the lack of user control and are especially concerned about the enormous potential for misuse and coercion by population control programs should fertility-regulating vaccines become widely available. Many scholars and government officials subscribe to the following logic: the global environmental crisis is due to over-population which necessitates population control programs; thus pregnancy can be considered a disease subject to state control. But pregnancy is not a disease nor is over-population the single major cause of environmental degradation. However, as governments grapple with the economic, social, and ecological consequences of population growth, draconian measures to control fertility will be ever more tempting.(ABSTRACT TRUNCATED AT 400 WORDS)

Synthetic gonadotrophin-releasing hormone (GnRH) vaccines incorporating GnRH and synthetic T-helper epitopes

A vaccine against the gonadotrophin-releasing hormone (GnRH) is being developed as an immunological method for treatment of prostatic hypertrophy, based on the observation that active immunization against GnRH leads to the production of anti-GnRH antibodies which results in the shrinkage of the prostate gland. We have been investigating the regulation of anti-GnRH antibody responses by carrier molecules. In previous studies we showed that the use of large protein molecules as carriers limits the use of such a vaccine owing to potential problems of carrier-induced anti-haptenic suppression. In this report we show that synthetic T-helper epitopes can be used as carriers for the generation of anti-GnRH antibody responses.