Development of recombinant ovalbumin-luteinizing hormone releasing hormone as a potential sterilization vaccine

摘要

Hybrid ovalbumin-LHRH (ova-LHRH) genes with 4 or 7 LHRH inserts were constructed by cassette mutagenesis and oligonucleotide mismatch mutagenesis. Recombinant ova-LHRH proteins were over-expressed in E. coli strain BL21 (DE3) using a pET expressionsystem. The antigenicity and biological effects of these recombinant proteins were tested in mice. In the 1st experiment, 17 female BALB/c mice, 7 weeks of age, were divided into 3 groups and were injected with 50μg of the recombinant ovalbumin protein(control), 50μg of the recombinant protein with 4 LHRH inserts (ova-LHRH-7) or 50μg of the recombinant protein with 7 LHRH inserts (ova-LHRH-7). One primary immunization using Freund's complete adjuvant was followed by one booster using incomplete adjuvant. Mice were killed 2 weeks after the booster, the blood was collected and the reproductive tract removed and weighed. Mice treated with ova-LHRH-7 had lower (P<0.01) uterine-ovarian weights (89±11 mg) than control (138±6 mg) and ova-LHRH-4-treated mice (126±16 mg). Ova-LHRH-7 induced LHRH antibody titres which were significantly correlated (r = -0.79) with biological response. In the 2nd experiment, 70 female BALB/c mice, 6-8 weeks of age, were divided into 7 groups and were injected with 10 or 30μg ova-LHRH in Zmax or Immumax, 30μg ovalbumin in Zmax or Immumax, or were not immunized (control). Three injections were given at 4-week intervals. Anti-LHRH titres were detected in all of the ova-LHRH-7-immunized mice. Significant decreases were shownin uterine-ovarian weight of the mice immunized with 30μg of ova-LHRH-7 with Zmax (P<0.005) and 10μg of ova-LHRH-7 with Immumax (P<0.025) compared with controls. It is concluded that the recombinant ova-LHRH-7 protein could have potential as a sterilization vaccine.