Development of a Contraceptive Vaccine for Use by the Human Male: Results of a Feasibility Study Carried Out in Adult Male Bonnet Monkeys (Macaca radiata)

Abstract

Among the various methods being evaluated for contraceptive use in the human male, the development of an effective contraceptive vaccine appears attractive. Currently three possible immunogens are considered: two are polypeptide hormones [lutenizing hormone-releasing hormone (LHRH) and follicle-stimulating hormone (FSH)] and the third is a sperm-specific protein [lactic dehydrogenase χ (LDH-X)]. The merits/demerits of using these as a vaccine are provided in Table 23.1. The use of LHRH as a vaccine is in keeping with the clinical observation that both gonadotropins (2), FSH and LH, are required for maintenance of spermatogenesis (2). However, since blockade of LH secretion leads to cessation of testosterone production and consequently loss of libido, immunization with LHRH would require continuous supplementation with exogenous testosterone. The long-term effects of continuous testosterone supplementation remain to be investigated. Although sperm-specific antigens have been shown to be effective immunogens (3), their contraceptive efficacy has been demonstrated by imunizing only the females of the species, and, as such, this does not qualify as a vaccine for the male.