Immuno-enhancement of Taishan Pinus massoniana pollen polysaccharides on recombinant Bordetella avium ompA expressed in Pichia pastoris.

Bordetellosis, caused by Bordetella avium, continues to be an economic problem in the poultry industry of China. Vaccines with good protective ability are lacking. Thus, developing a novel vaccine against the B. avium infection is crucial. Here, we constructed a recombinant Pichia pastoris transformant capable of expressing the outer membrane protein A (ompA) of B. avium to prepare the recombinant ompA subunit vaccine and then evaluated its immune effects. To further investigate the immunomodulation effects of Taishan Pinus massoniana pollen polysaccharides (TPPPS) on this subunit vaccine, three concentrations (20, 40, and 60 mg/mL) of TPPPS were used as the adjuvants of the ompA subunit vaccine respectively. The conventional Freund's incomplete adjuvant served as the control of TPPPS. Chickens in different groups were separately vaccinated with these vaccines thrice. During the monitoring period, serum antibody titers, concentrations of serum IL-4, percentages of CD4(+) and CD8(+) T-lymphocytes in the peripheral blood, lymphocyte transformation rate, and protection rate were detected. Results showed that the pure ompA vaccine induced the production of anti-ompA antibody, the secretion of IL-4, the increase of CD4(+) T-lymphocytes counts and lymphocyte transformation rate in the peripheral blood. Moreover, the pure ompA vaccine provided a protection rate of 71.67% after the B. avium challenge. Notably, TPPPS adjuvant vaccines induced higher levels of immune responses than the pure ompA vaccine, and 60 mg/mL TPPPS adjuvant vaccine showed optimal immune effects and had a 91.67% protection rate. Our findings indicated that this recombinant B. avium ompA subunit vaccine combined with TPPPS had high immunostimulatory potential. Results provided a new perspective for B. avium subunit vaccine research.

Immunological and protective effects of Bordetella bronchiseptica subunit vaccines based on the recombinant N-terminal domain of dermonecrotic toxin.

Dermonecrotic toxin (DNT) produced by Bordetella bronchiseptica (B. bronchiseptica) can cause clinical turbinate atrophy in swine and induce dermonecrotic lesions in model mice. We know that the N-terminal of DNT molecule contains the receptor-binding domain, which facilitates binding to the target cells. However, we do not know whether this domain has sufficient immunogenicity to resist B. bronchiseptica damage and thereby to develop a subunit vaccine for the swine industry. In this study, we prokaryotically expressed the recombinant N-terminal of DNT from B. bronchiseptica (named DNT-N) and prepared it for the subunit vaccine to evaluate its immunogenicity. Taishan Pinus massoniana pollen polysaccharide (TPPPS), a known immunomodulator, was used as the adjuvant to examine its immune-conditioning effects. At 49 d after inoculation, 10 mice from each group were challenged with B. bronchiseptica, and another 10 mice were intradermally challenged with native DNT, to examine the protection imparted by the vaccines. The immune parameters (T-lymphocyte counts, cytokine secretions, serum antibody titers, and survival rates) and skin lesions were determined. The results showed that pure DNT-N vaccine significantly induced immune responses and had limited ability to resist the B. bronchiseptica and DNT challenge, whereas the mice administered with TPPPS or Freund's incomplete adjuvant vaccine could induce higher levels of the above immune parameters. Remarkably, the DNT-N vaccine combined with TPPPS adjuvant protected the mice effectively to prevent B. bronchiseptica infection. Our findings indicated that DNT-N has potential for development as an effective subunit vaccine to counteract the damage of B. bronchiseptica infection, especially when used conjointly with TPPPS.

Co-adjuvant effects of plant polysaccharide and propolis on chickens inoculated with Bordetella avium inactivated vaccine.

Taishan Pinus massoniana pollen polysaccharide (TPPPS), propolis (PP) and aloe polysaccharide (AP), used as adjuvants, have been proven to possess immunity-enhancing functions. However, their collaborative immunomodulatory effects are largely unknown. To determine which combination can induce the best effects, the three adjuvants were separately or conjointly added into Bordetella avium inactivated vaccines to investigate their co-adjuvant effects on vaccinated chickens. We found that, among all six adjuvant-treated vaccine inoculated groups (TPPPS, PP, AP, TPPPS-PP, PP-AP and TPPPS-AP), the chickens inoculated with TPPPS, PP or TPPPS-PP adjuvant vaccines showed significantly higher levels of antibody titre, cytokine, lymphocyte transformation and peripheral blood T-lymphocyte count than those of non-adjuvant vaccine inoculated groups (P < 0.05), indicating the good immune-enhancing effects of TPPPS and PP. The TPPPS-PP group showed the highest levels of antibody titres and interleukin-2 (IL-2) at 14-28 days post the first inoculation (dpi), lymphocyte transformation rates (LTRs) at 14-35 dpi, CD4(+) T-lymphocyte counts at 14-42 dpi, and CD8(+) T-lymphocyte counts at 28 dpi. The results revealed that B. avium inactivated vaccine used conjointly with TPPPS and PP induced the strongest humoral and cellular immune responses. Thus, there was a synergistic effect between TPPPS and PP on enhancing immunity, which suggests that they can be used as a novel adjuvant formulation for the development of poultry vaccines.