Preliminary studies with recombinant chorionic gonadotropin beta-subunit produced in Escherichia coli for use as an...

Prototype human chorionic gonadotropin (hCG) vaccines based on natural sources are unsuitable for widespread applications due to their complex manufacturing procedures, cost, and carrier-mediated immune suppression.

Wistar rats were immunized with alum-adsorbed CG beta (recombinant), CG beta-TT, and nCG beta (native CG beta)-TT, whereas Bonnet monkeys were immunized with only CG beta. The anti-hCG antibody titre in the sera obtained at different time points were quantified by radioimmunoassay. The sera of Wistar rats were characterized in terms of their affinity to hCG, bioneutralization capacity (by inhibition of hCG-induced testosterone production in Leydig cells), and cross-reactivity with human luteinizing hormone, human follicle-stimulating hormone, and human thyroid-stimulating hormone (by direct binding assays).

Antigen-binding capacities of sera obtained upon immunization with CG beta were 3,080 +/- 943 ng/ml (n = 6) and 3,993 +/- 1,292 ng/ml (n = 4), respectively, in rats and monkeys. The analysis of data revealed that immunization of rats with CG beta produced antibodies comparable to that of CG beta-TT and nCG beta-TT.

The study opens up the possibility of producing pure and highly immunogenic CG beta by a recombinant DNA route, as a consistent source of antigen for birth control vaccine.