Evaluation of PLGA nanoparticles containing outer membrane proteins of Acinetobacter baumannii bacterium in stimulating the immune system in mice

Afshin Gholizadeh , Reza Shapoury , Parviz Pakzad, Mehdi Mahdavi, Hossein Danafar


Background and purpose: Acinetobacter baumannii (A. baumannii) is known as a pathogen with antibiotic resistance, causing respiratory infections. PLGA has been approved for use in vaccines as well as drug delivery. This study was performed to evaluate PLGA nanoparticles containing the outer membrane proteins (OMPs) of A. baumannii in stimulating the mice's immune system and improving pneumonia.

Experimental approach: Double emulsion solvent evaporation technique was used. The properties of the obtained nanospheres were determined using a zetasizer, FTIR, and AFM devices. Nanoparticles were administered to mice BALB/c by applying the intramuscular route. ELISA was used to measure the amounts of immunoglobulins produced; also, an opsonophagocytic killing assay was used to measure the effectiveness of immunoglobulins. Immunized mice were then challenged with live A. baumannii through the lungs; their internal organs were also removed for bacteriological studies. 

Findings/Results: The prepared particles were 550 nm in diameter with a negative surface charge. The production of the OMPs specific IgG was much higher in the group receiving nanoparticles containing antigen as compared to those getting pure antigen. The immunoglobulins produced against nanoparticles were superior to those developed against pure antigens. Mice that received the new nanovaccine were more resistant to pneumonia caused by this bacterium than those that received pure antigen.

Conclusion and implication: Overall, it can be said that PLGA nanoparticles could deliver their internal antigens (OMPs) well to the immune system of mice and stimulate humoral immunity in these animals, thus protecting them against pneumonia caused by A. baumannii.


Keywords: Acinetobacter baumannii; Encapsulation; Nanoparticles; OMPs; PLGA.

Full Text:



Durante-Mangoni E, Zarrill R. Global spread of drug-resistant Acinetobacter baumannii: molecular epidemiology and management of antimicrobial resistance. Future Microbiol. 2011;6(4):407-422.DOI: 10.2217/fmb.11.23.

Higgins PG, Dammhayn C, Hackel M, Seifert H. Global spread of carbapenem-resistant Acinetobacter baumannii. J. Antimicrob Chemother. 2010;65(2):233-238. DOI: 10.1093/jac/dkp428.

Rice LB. Federal funding for the study of antimicrobial resistance in nosocomial pathogens: no ESKAPE. J Infect Dis. 2008;197(8):1079-1081. DOI: 10.1086/533452.

Montefour K, Frieden J, Hurst S, Helmich C, Headley D, Martin M, et al. Acinetobacter baumannii: an emerging multidrug-resistant pathogen in critical care. Crit Care Nurse. 2008;28(1):15-25.PMID: 18238934

Bayuga S, Zeana C, Sahni J, Della-Latta P, el-Sadr W, Larson E. Prevalence and antimicrobial patterns of Acinetobacter baumannii on hands and nares of hospital personnel and patients: the iceberg phenomenon again. Heart Lung. 2002;31(5);382-390. DOI: 10.1067/mhl.2002.126103.

Gusten WM, Hansen EA, Cunha BA. Acinetobacter baumannii pseudomeningitis. Heart Lung. 2002;31(1):76-78. DOI: 10.1067/mhl.2002.120258.

Chen N, Zhou M, Dong X, Qu J, Gong F, Han Y, et al. Epidemiological and clinical characteristics of 99 cases of 2019 novel coronavirus pneumonia in Wuhan, China: a descriptive study. Lancet. 2020;395(10223):507-513. DOI: 10.1016/S0140-6736(20)30211-7.

Lorente C, Del Castillo Y, Rello J. Prevention of infection in the intensive care unit: current advances and opportunities for the future. Curr Opin Crit Care. 2002;8(5):461-464.DOI: 10.1097/00075198-200210000-00015.

Zheng Y, Chen H, Yao M, Li X. Bacterial pathogens were detected from human exhaled breath using a novel protocol. J Aerosol Sci. 2018;117:224-234. DOI: 10.1016/j.jaerosci.2017.12.009.

Peek LJ, Middaugh CR, Berkland C. Nanotechnology in vaccine delivery. Adv Drug Deliv Rev. 2008;60(8):915-928. DOI: 10.1016/j.addr.2007.05.017.

Treuel L, Jiang X, Nienhaus GU. New views on cellular uptake and trafficking of manufactured nanoparticles. J R Soc Interface. 2013;10(82):1-14. DOI: 10.1098/rsif.2012.0939.

Jain S, O’Hagan DT, Singh M. The long-term potential of biodegradable poly(lactide-co-glycolide) microparticles as the next-generation vaccine adjuvant. Expert Rev Vaccines. 2011;10(12):1731-1742. DOI: 10.1586/erv.11.126.

Allahyari M, Mohit E. Peptide/protein vaccine delivery system based on PLGA particles. Hum Vaccin Immunother. 2016;12(3):806-828. DOI: 10.1080/21645515.2015.1102804.

Makadia HK, Siegel SJ. Poly lactic-co-glycolic acid (PLGA) as biodegradable controlled drug delivery carrier. Polymers (Basel). 2011;3(3):1377-1397. DOI: 10.3390/polym3031377.

Zhang X, Yang T, Cao J, Sun J, Dai W, Zhang L. Mucosal immunization with purified OmpA elicited protective immunity against infections caused by multidrug-resistant Acinetobacter baumannii. Microb Pathog. 2016;96:20-25. DOI: 10.1016/j.micpath.2016.04.019.

Bonin RF, Chapeaurouge A, Perales J, da Silva JG, do Nascimento HJ, Assef APDC, et al. Identification of immunogenic proteins of the bacterium Acinetobacter baumannii using a proteomic approach. Proteomics Clin Appl. 2014;8(11):916-923. DOI: 10.1002/prca.201300133.

Hassan A, Naz A, Obaid A, Paracha RZ, Naz K, Awan FM, et al. Pangenome and immuno-proteomics analysis of Acinetobacter baumannii strains revealed the core peptide vaccine targets. BMC Genomics. 2016;17:732-756. DOI: 10.1186/s12864-016-2951-4.

Smani Y, Dominguez-Herrera J, Pachon J. Association of the outer membrane protein Omp33 with fitness and virulence of Acinetobacter baumannii. J Infect Dis. 2013;208(10): 1561-1570.DOI: 10.1093/infdis/jit386.

Huang W, Yao Y, Wang S, Xia Y, Yang X, Long Q, et al. Immunization with a 22-kDa outer membrane protein elicits protective immunity to multidrug-resistant Acinetobacter baumannii. Sci Rep. 2016;6:20724,1-12. DOI: 10.1038/srep20724.

Cuensa FF, Pascual A, Martinez LM, Conejo MC, Perea EJ. Evaluation of SDS-polyacrylamide gel systems for the study of outer membrane protein profiles of clinical strains of Acinetobacter baumannii. J Basic Microbiol. 2003;43(3):194-201. DOI: 10.1002/jobm.200390022.

Shafiqul Islam AHM, Singh KKB, Ismail A. Demonstration of an outer membrane protein that is antigenically specific for Acinetobacter baumannii. Diagn Microbiol Infect Dis. 2011;69(1):38-44. DOI: 10.1016/j.diagmicrobio.2010.09.008.

Zhang Y, Chan HF, Leong KW. Advanced materials and processing for drug delivery: the past and the future. Adv Drug Deliv Rev. 2013;65(1):104-120. DOI: 10.1016/j.addr.2012.10.003.

Amini Y, Jamehdar SA, Sadri K, Zare S, Musavi D, Tafaghodi M. Different methods to determine the encapsulation efficiency of protein in PLGA nanoparticles. Bioned Mater Eng. 2017;28(6):613-620. DOI: 10.3233/BME-171705.

Yasin H, Al-Taani B, Sheikh Salem M. Preparation and characterization of ethylcellulose microspheres forsustained-release of pregabalin. Res Pharm Sci. 2021;16(1):1-15. DOI: 10.4103/1735-5362.305184.

Paschall AV, Middleton DR, Avci FY. Opsonophagocytic killing assay to assess immunological responses against bacterial pathogens. J Vis Exp. 2019;146:e59400,1-7.DOI: 10.3791/59400.

Huang W, Yao Y, Long Q, Yang X, Sun W, Liu C, et al. Immunization against multidrug-resistant Acinetobacter baumannii effectively protects mice in both pneumonia and sepsis models. PLoS One. 2014;9(6): e100727. DOI; 10.1371/journal.pone.0100727.

Ahmad TA, Tawfik DM, Sheweita SA, Haroun M, El-Sayed LH. Development of immunization trials against Acinetobacter baumannii. Trials Vaccinol. 2016;5:53-60. DOI: 10.1016/j.trivac.2016.03.001.

Mundargi RC, Babu RV, Rangaswamy V, Patel P, Aminabhavi TM. Nano/micro technologies for delivering macromolecular therapeutics using poly (D, L-lactide-co-glycolide) and its derivatives. J Control Release. 2008;125(3):193-209. DOI: 10.1016/j.jconrel.2007.09.013.

Thomas C, Gupta V, Ahsan F. Influence of surface charge of PLGA particles of recombinant hepatitis B surface antigen in enhancing systemic and mucosal immune responses. Int J Pharm. 2009;379(1):41-50. DOI: 10.1016/j.ijpharm.2009.06.006.

Fairley S.J, Singh Sh. R, Yilma A.N, Waffo A.B, Subbarayan P, Dixit S, Taha M.A, Cambridge C.D, Dennis V.A. Chlamydia trachomatis recombinant MOMP encapsulated in PLGA nanoparticles triggers primarily T helper 1 cellular and antibody immune responses in mice: a desirable candidate nanovaccine. Int J Nanomedicine. 2013;8:2085-2099. DOI: 10.2147/IJN.S44155.

Du X, Xue J, Jiang M, Lin S, Huang Y, Deng K, et al. A multiepitope peptide, rOmp22, encapsulated in chitosan-PLGA nanoparticles as a candidate vaccine against Acinetobacter baumannii infection. Int J Nanomedicine. 2021;16:1819-1836. DOI: 10.2147/IJN.S296527.

Hamdy S, Haddadi A, Hung RW, Lavasanifar A. Targeting dendritic cells with nano-particulate PLGA cancer vaccine formulations. Adv Drug Deliv Rev. 2011;63(10-11):943-955. DOI: 10.1016/j.addr.2011.05.021.

Raghuvanshi RS, KatareYK, Lalwani K, Ali MM, Singh O, Panda AK. Improved immune response from biodegradable polymer particles entrapping tetanus toxoid by use of different immunization protocols and adjuvants. Int J Pharm. 2002; 245(1-2):109-121.DOI: 10.1016/S0378-5173(02)00342-3.


  • There are currently no refbacks.

Creative Commons LicenseThis work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License which allows users to read, copy, distribute and make derivative works for non-commercial purposes from the material, as long as the author of the original work is cited properly.