| Aluminum adjuvants are the most commonly used adjuvants in vaccine formulations for both human and veterinary use.There are three main aluminum-containing adjuvants,aluminum hydroxide[AlO（OH）],aluminum phosphate[Al（OH）x（PO4）y]and alum adjuvant[KAl（SO4）2·12H2O].Aluminum hydroxide adjuvant is the first approved adjuvant by the United States Food and Drug Administration（FDA）for human use.It has been used for more than 90 years as adjuvants in vaccines.With the rapid development of nanotechnologies in recent years,nano-aluminum hydroxide adjuvants have shown a better targeting effect and sustained-release effects during immune stimulation due to its small size particle,large specific surface area,high surface active center and large proportion of surface atoms.However,nano-aluminum adjuvants mainly are used to antigens such as peptides,proteins and viruses,the immune response caused by nano-aluminum adjuvants is slow when combined with pathogenic microorganisms.Pseudomonas aeruginosa is a widespread pathogen of human and zoonotic diseases.With the increasing of multi-drug resistant PA strains,many clinical isolates are resistant to carbapenem antibiotics or polymyxin antibiotics.So PA infections are in urgent need of new treatment methods,then vaccines and antibodies are currently the ideal choice.In this study,we designed and fabricated aluminum oxyhydroxide nanorods adjuvant via bicontinuous reverse microemulsion（RM）technique.Using whole P.aeruginosa PAO1 as antigens,the immune response of aluminum hydroxide nanorods adjuvant to PAO1 was evaluated in vivo and in vitro.The main results and conclusions are as follows:（1）Preparation of aluminum（oxy）hydroxide nanorods（Al-NRs）The synthesis of Al-NRs was performed using the RM technique.The results showed that the aluminum（oxy）hydroxide nanorods adjuvant can be prepared when the reaction condition was constructed as follow:pH 8pH 11,reaction temperature was50°C,stirring speed was 600 rpm and reaction time was 2.5 hours.（2）Identification of Al-NRsThe products structure was characterized by XRD,EDS,SEM,AFM,and DLS.The results showed that the obtained products have a uniform rod morphology with mean diameter of 200±80 nm and length of 1.1±0.6μm.The particle charge was around 39±0.5 mV.（3）Immune effects of P.aeruginosa PAO1-adsorbed Al-NRsIn this study,inactivated whole P.aeruginosa was used as antigen.We evaluated the cellular and humoral immune response ability,proliferation ability of splenocyte,presentation capacity of APCs to PAO1,local inflammation reactions at the injection site and protection ability.The results showed that the Al-NRs group induced significantly higher levels of antigenspecific IgG than the other adjuvants control groups in the first week after the initial immunization,on day 56,the Al-NRs group still maintained a high level of antibody titer;It could induce strong and comprehensive cellular and humoral immune responses,especially in the cellular immune response;In addition,it could could be more readily internalized and presented by antigen presenting cells,reduce local pathological changes at the injection site and improve the protection rate of immunized mice.In summary,P.aeruginosa PAO1-adsorbed Al-NRs can induce immunized mice early response,high response,low inflammation and high protection rate.And,these results provided important experimental evidence and technical support for solving the needs for rapid emergency vaccination. |
