other <strong>Background:</strong> Among the enterococci strains,<em> Enterococcus faecalis</em> is considered as one of the important nosocomial pathogens affecting immunocompromised patients. In this study, the immunogenicity of PpiC, GelE, and VS87_01105 proteins against enterococcal infection was investigated in a mice model. <strong>Methods:</strong> The genes encoding these proteins were cloned into pET21a expression vector, and the recombinant proteins were produced. Mice and rabbits were immunized with the purified recombinant proteins, and subsequently, mice were challenged with <em>E. faecalis </em>for the evaluation of their survival and bacterial clearances. The antibody responses to recombinant proteins were determined by ELISA assay, and <em>opsonophagocytic </em>activities of the antibodies were also measured. Passive immunization was performed using purified antibodies. Mice were challenged, and their survival and bacterial clearance were determined. <strong>Results:</strong> Immunized mice with PpiC, GelE, and VS87_01105 recombinant proteins showed 80%, 70%, and 40% survival rate, respectively. The survival rates among passively immunized mice that received 500 &micro;g of IgG fraction in 100 &micro;l PBS buffer of each of anti-PpiC, anti-GelE, and anti-VS87_01105 were 60%, 50%, and 20%, respectively. The rates of opsonization with anti-PpiC, anti-GelE, and anti-VS87_01105 antibodies at 1/10 dilution were 77%, 64%, and 23%, respectively. <strong>Conclusion:</strong> Based on our findings, PpiC, and GelE proteins can protect the mice against <em>E. faecalis</em> ATCC 29212 and effectively induce a protective antibody response. Thus, these proteins could be used as an additional therapeutic tool against enterococcal infections. Further studies to determine the role of PpiC in ligand binding and demonstration of epitope mapping may establish a credible target for vaccination. Enterococcus, Immunogenicity, Molecular cloning 344 353 http://ibj.pasteur.ac.ir/browse.php?a_code=A-10-1-790&slc_lang=other&sid=1 Hamid Kazemian 0000-0002-6593-9540 No Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Mohammad Reza Pourmand 0000-0003-1280-5765 Yes Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Seyed Davar Siadat 0000-0002-6892-5603 No Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran Mehdi Mahdavi No Recombinant Vaccine Research Center, Tehran University of Medical Sciences, Tehran, Iran Mohammad Hossein Yazdi 0000-0001-8567-8555 No Department of Pharmaceutical Biotechnology and Biotechnology Research Center, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran Peyman Avakh Majelan 0000-0002-5838-6116 No Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Davoud Afshar 0000-0002-3259-3790 No Department of Microbiology and Virology, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran Mehdi Yaseri 0000-0002-4066-873X No Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Mehdi Davari 0000-0002-6107-7373 No Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran Muhammad Ibrahim Getso 0000-0002-0752-702X No Department of Medical Mycology, School of Public Health, Tehran University of Medical Sciences, International College, Tehran, Iran