BackgroundProteus mirabilis poses a critical burden on the breeding industry, but no efficient vaccine is available for animals.MethodA recombinant Lactococcus lactis expressing the ompA of P. mirabilis was used to develop a vaccine. The mucosal and systemic immune responses of the recombinant vaccine were evaluated in mice after oral immunisation. The inhibition on P. mirabilis colonisation of vaccines was also determined. Moreover, Taishan Pinus massoniana pollen polysaccharides (TPPPS) were used as adjuvants to examine the immunomodulatory effects.ResultsThe pure recombinant L. lactis vaccine significantly induced the production of specific IgA and IgG, IL-2, IL-4, IFN-γ, and T lymphocyte proliferation, and the immunised mice exhibited significant resistance to P. mirabilis colonisation. Notably, the TPPPS adjuvant vaccines induced higher levels of immune responses than the pure L. lactis.ConclusionsThe L. lactis as a vaccine vehicle combined with TPPPS adjuvant provides a feasible method for preventing P. mirabilis infection.

•The composition and content of monosaccharide in TPPPS were firstly analyzed.•TPPPS can significantly eliminate immunosuppression and can serve as immunoregulator.•The pathogenicity of B. avium in chicks which co-infected with ALV-B was exacerbated.•TPPPS can enhance the immunity and resist to diseases in chicks.Chicks’ co-infection with immunosuppressive virus and bacteria seriously threaten the development of the poultry industry. In this study, a model was established in which chicks were injected with either subgroup B ALV (ALV-B) + Bordetella avium (B. avium), or ALV-B + B. avium + Taishan Pinus massoniana pollen polysaccharide (TPPPS), or B. avium only, or B. avium + TPPPS. The data showed that the group injected with ALV-B and B. avium exhibited significant inhibition of the immune function and therefore increased pathogenicity compared with the group injected with B. avium-only. Application of TPPPS effectively alleviated immunosuppression, and body weights increased sharply in the TPPPS groups compared with non-TPPPS groups. To some extent, TPPPS may reduce the proliferation of ALV-B. These results suggest that Pinus pollen polysaccharides are beneficial treating co-infections with immunosuppressive virus and bacteria and therefore have potential for development into safe and effective immunoregulator.

This study was conducted to evaluate the effect of aloe polysaccharide on immune responses of chickens immunized with Bordetella avium (B. avium) vaccine. SPF chickens were randomly divided into 6 groups and vaccinated against B. avium vaccine which respectively contained aloe polysaccharide of three different dosages, propolis and pine pollen polysaccharide. The data showed that aloe polysaccharide significantly enhanced serum and bile antibody level, blood lymphocyte ratio and splenic T lymphocyte proliferation rate in groups I, IV and V. 40 mg/ml of aloe polysaccharide made the vaccine most effective and 20 mg/ml of propolis or 20 mg/ml of pine pollen polysaccharide achieved the same effect. These results suggested that aloe polysaccharide could significantly enhance immune effect of B. avium inactivated vaccine and had important implications for the further use of aloe polysaccharide as a new type of plant-derived immunopotentiator.Highlights► We examine effect of aloe polysaccharide on chicken immunity indexes. ► 40 mg/ml of aloe polysaccharide has excellent effect of immunity enhancement. ► Aloe polysaccharide can serve as efficient immunologic potentiator and adjuvant.

•REV and ALV-J co-infected chickens were established as immunosuppression models.•TPPPS, PP and TPPPS-PP improved the immunity of the immunosuppressed chickens.•TPPPS and PP elevated the antibody levels of ND vaccine in immunosuppressed chickens.•The joint use of TPPPS and PP had synergistic effects in immunomodulatory process.Co-infection of reticuloendotheliosis virus (REV) and avian leukosis virus subgroup J (ALV-J), which can cause suppressed immunity and vaccination failure, frequently occurs in chicken flocks in China. Taishan Pinus massoniana pollen polysaccharide (TPPPS) and propolis (PP) have been proven to possess immune modulatory effects and improve the immune effects of vaccines. This study aimed to investigate the immune modulatory ability of TPPPS and PP on chickens co-infected with immunosuppressive viruses. Prior to the study, chickens were artificially established as REV and ALV-J co-infection models. Four randomly assigned groups of these immunosuppressed chickens were successively administered with TPPPS, PP, mixture of TPPPS and PP (TPPPS-PP), or phosphate-buffered saline (PBS) for three days. At nine days old, the four immunosuppressed groups, as well as one normal group, were inoculated with the attenuated Newcastle disease (ND) vaccine. During the monitoring period, the indices of immune organ weight, lymphocyte transformation rates, CD4+ and CD8+ T-lymphocyte counts in peripheral blood, IL-2 and IFN-γ secretions, serum antibody titers of ND vaccine, and viral loads in spleens were determined. The results showed that chickens administered with TPPPS, PP, or TPPPS-PP could significantly enhance the levels of the above immune parameters compared to chickens in the PBS group. We observed the strongest immunity in the TPPPS-PP group, which indicates that the combination of TPPPS and PP versus TPPPS or PP alone, could generate better effects on improving the immune system effectiveness of immunosuppressed chickens.

•Taishan Pinus massoniana pollen polysaccharide exhibits potentiation on immune response and protection against PRRSV.•The medium-dose is optimal for the immunopotentiation and adjuvant saving.•Recombinant GP5 subunit is competent evaluate potentiation of adjuvants on immune response and protection.Porcine reproductive and respiratory syndrome virus (PRRSV) heavily affects the global pork industry. Current available vaccine strategies have inherent drawbacks. In this work, the immune enhancement from Taishan Pinus massoniana pollen polysaccharide (TPPPS) and Freund's adjuvant on the efficacy of a PRRSV subunit vaccine were examined. Titers of specific anti-highly pathogenic PRRSV (HP-PRRSV) ELISA antibody and neutralizing antibody were significantly higher in pigs from the groups inoculated with medium- and high-dose TPPPS (mTPPPS, hTPPPS) adjuvant co-administered with a recombinant HP-PRRSV glycoprotein 5 subunit (GP5) than those from other groups (P < 0.05). Pigs inoculated with GP5 + Freund's adjuvant developed severely delayed humoral immune responses specific to GP5 within 28 days post-inoculation (dpi). The groups treated with mTPPPS and hTPPPS adjuvant exhibited the most potent immune enhancement effects on GP5 inoculation with cellular immunity developing, as shown by the level of T lymphocyte proliferation and the percentage of the CD3+ T lymphocyte subpopulation. Although complete Freund's adjuvant elicited cell-mediated immune responses, the level of T lymphocyte proliferation in this group decreased quickly and no significant differences were observed compared with other adjuvant-alone groups at 56 dpi (P > 0.05). The ratio between CD3+CD4+ and CD3+CD8+ T lymphocyte subpopulations indicated the inoculums of GP5 + mTPPPS and GP5 + hTPPPS induced consistently higher CD3+CD4+ T lymphocyte subpopulations than other inoculums (P < 0.05). The immune responses caused by complete Freund's adjuvant were mainly mediated by CD3+CD8+ T lymphocyte subpopulation (cytotoxic T lymphocytes) in the early stage of inoculation and had no significant difference compared with other adjuvant-alone groups after 28 dpi (P > 0.05). The low-dose TPPPS (lTPPPS) adjuvant also exhibited enhancement effects on humoral immune and T lymphocyte proliferation responses but these were significantly lower than the mTPPPS and hTPPPS doses (P < 0.05). Pigs challenged with HP-PRRSV from the GP5 + mTPPPS, GP5 + hTPPPS, and GP5 + Freund's adjuvant groups showed lower viremia, fewer clinical signs, and fewer pathological lung lesions compared with the groups of GP5-alone and GP5 + lTPPPS (P < 0.05). There were significant differences between the GP5-alone and GP5 + lTPPPS groups in detection indexes after viral challenge (P < 0.05). In conclusion, moderate doses of TPPPS as an adjuvant with GP5 show promise as a candidate for a HP-PRRSV subunit vaccine to efficiently prevent and control HP-PRRSV.