Sperm vaccine

Immunity as a contraceptive

Specialists are aware of cases when women develop immune and allergic reactions to partner's sperm. This phenomenon is the cause of discomfort in intimate relationships and infertility, however, it may be able to serve a good service as a means of contraception.

The idea of using the immune system to prevent unwanted conception is not new. In 1899, Karl Landsteiner and Ilya Mechnikov independently demonstrated that sperm injection can cause the formation of antibodies specific to it in animals. However, they received the Nobel Prizes not for this, but for the discovery of blood groups and immunity research. Later, other scientists showed that the described phenomenon can lead to infertility. The first human study was conducted in 1929, and a patent for a "spermotoxic" vaccine was filed in 1937.

Since then, some progress has been made in the development of methods for using the immune system for the deliberate induction of infertility. Many may have a question: why do this if hormonal contraceptives are already safe enough and provide reliable protection? However, in addition to undesirable side effects, taking hormonal drugs is associated with a number of problems that can be solved by switching to contraceptive vaccines.

Firstly, according to existing data, 80 million women develop unplanned pregnancies every year in the world, 45 million of which end in abortions. In the United States, about half of all pregnancies are unplanned and about a million of them are also disposed of through abortions. At the same time, about half of these unplanned pregnancies develop against the background of the use of any of the generally accepted methods of contraception.

Another serious problem is the lack of availability of contraceptives. In developing countries, where family planning, at first glance, is an extremely important task, people are not always able to receive qualified medical care and afford contraceptives.

All this points to the need to find a method of contraception that would be acceptable, effective and affordable for the population of both developed and developing countries. It should be non-steroidal, non-barrier, non-chirurgical, independent of sexual intercourse and reversible. Contraceptive vaccines have been proposed as an alternative that meets most, if not all, of the requirements for an ideal contraceptive. High specificity, long-term action, low cost and the absence of any side effects would make such vaccines a landmark achievement in the field of contraception. Given that both developed and developing countries have the infrastructure for mass immunization, the creation of contraceptive vaccines seems to be a very attractive prospect.

There are several approaches to the creation of contraceptive vaccines, implying the use of different targets. Some of them are directed against certain hormones, the neutralization of which prevents the formation and development of sperm or eggs. However, given that many of these hormones are involved in processes unrelated to reproduction, such vaccines may have undesirable side effects. For example, the GnRH protein, known as gonadoliberin (gonadotropin-releasing factor, gonadotropin-releasing hormone), triggers the release of other hormones necessary for the formation of sperm and eggs, which makes it a potential target for the vaccine. Neutralization of this hormone can lead to impotence, which excludes the possibility of its use for humans, however, this method is currently used for non-surgical sterilization of domestic and stray animals.

Another potential target for the vaccine is chorionic gonadotropin (hCG) expressed by fertilized embryos. Exposure to this hormone, associated exclusively with the state of pregnancy, minimizes the likelihood of side effects. However, researchers have not yet been able to launch an effective immune response against it. In addition, such a vaccine would be effective only for women.

The appearance of a sperm vaccine would solve these problems. Such a vaccine could be used for both women and men (blocking sperm production in men and preventing fertilization in women). At the same time, the immunogenicity inherent in sperm should significantly facilitate the development of a method for triggering an effective immune response. Currently, several groups of specialists are working on turning this idea into reality.

The main disadvantage of this approach is the inability to eliminate the contraceptive effect "at will". Since 1929 and up to the present time, during clinical trials, vaccination has had a temporary effect and, over time, the ability to conceive has been restored. However, the "shutdown" of the immune response in the case of a patient's desire to have a child is beyond control. Theoretically, this can be done by selectively destroying B-lymphocytes that produce antibodies to sperm components, but until the effectiveness of this approach is proven, the use of a sperm vaccine is unacceptable if there is a possibility that the patient will want to have a child in the future.

Apparently, in the foreseeable future we will have to make do with hormonal and barrier methods of contraception, however, in any case, the idea of creating a vaccine against sperm is a very vivid example of the possibility of using the immune system in the literal sense of the word "for other purposes".

Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of ScienceBlogs:
Vaccinating Against Semen - Immunity as Contraceptive.

20.01.2012