Vaccine 32 (2014) 918–923 Contents lists available at ScienceDirect Vaccine j our nal homep ag e: www.elsevier.com/locate/vaccine Immunotherapeutics to prevent the replication of Brucella in a treatment failure mouse model N. Jain-Gupta a , A. Contreras-Rodriguez b , G.P. Smith a , V.K. Garg c , S.G. Witonsky d , S. Isloor e , R. Vemulapalli c , S.M. Boyle a , N. Sriranganathan a,∗ a Department of Biomedical Sciences and Pathobiology, Center for Molecular Medicine and Infectious Diseases, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA 24061-0342, United States b Departmento de Microbiologia, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico c Department of Comparative Pathobiology, School of Veterinary Medicine, Purdue University, West Lafayette, IN 47907, United States d Department of Large Animal Clinical Sciences, Center for Molecular Medicine and Infectious Diseases, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA 24061-0342, United States e Department of Veterinary Microbiology, Veterinary College, Karnataka Veterinary, Animal Sciences and Fisheries University, Hebbal, Bangalore 560024, India a r t i c l e i n f o Article history: Received 9 October 2013 Received in revised form 12 December 2013 Accepted 18 December 2013 Available online 4 January 2014 Keywords: Brucellosis Treatment failure Immunotherapy Therapeutic vaccine Outer membrane vesicles Cell mediated immunity and humoral immunity a b s t r a c t Outer membrane vesicles (OMVs) from Brucella melitensis and irradiated Brucella neotomae have been shown to be effective vaccines against a B. melitensis challenge in a mouse model. The present study evaluates the efficacy of these two vaccines as immuno-therapeutics in combination with conventional antibiotics against a B. melitensis infection. BALB/c mice chronically infected with B. melitensis were treated for 4 weeks with doxycycline and gentamicin and vaccinated twice during the course of therapy. Antibiotics in sub-therapeutic concentrations were chosen in such a way that the treatment would result in a therapeutic failure in mice. Although no additive effect of vaccines and antibiotics was seen on the clearance of B. melitensis, mice receiving vaccines along with antibiotics exhibited no Brucella replication post-treatment compared to mice treated only with antibiotics. Administration of irradiated B. neotomae along with antibiotics led to higher production of IFN- ex vivo by splenocytes upon stimulation with heat inactivated B. melitensis while no such effect was seen by splenocytes from mice vaccinated with OMVs. OMV vaccinated mice developed significantly higher anti-Brucella IgG antibody titers at the end of the treatment compared to the mice that received only antibiotics. The mice that received only vac- cines did not show any significant clearance of Brucella from spleens and livers compared to non-treated control mice. This study suggests that incorporating OMVs or irradiated B. neotomae along with conven- tional antibiotics might be able to improve therapeutic efficacy and control the progression of disease in treatment failure cases. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction Brucellosis is the most common bacterial zoonotic disease worldwide [1]. Treatment of animal brucellosis is economically not feasible and infected animals and their products remain the source of infection for humans [2]. The World Health Organization’s recommendation for treatment in humans involves combination antibiotic therapy for 6–8 weeks [3]. Even after prolonged treat- ment, the rate of treatment failure is 1–5% and the relapse rate ∗ Corresponding author at: Department of Biomedical Sciences and Pathobiology, Center for Molecular Medicine and Infectious Disease (CMMID), Virginia Polytechnic Institute and State University, 1410 Prices Fork Road, CMMID, Blacksburg, VA 24061- 0342, United States. Tel.: +1 540 231 7171; fax: +1 540 231 3426. E-mail address: nathans@vt.edu (N. Sriranganathan). remains as high as 5–10% in humans [2]. In the case of humans, treatment failure is defined by the persistence of signs and symp- toms at the end of scheduled therapy [4]. Relapse is defined as the reappearance of signs and symptoms or positive blood cultures within one year of treatment. In the case of experimental murine brucellosis, treatment failure is characterized by the presence of Brucella in targeted organs like spleen, liver and lung at the end of the therapy. There is no relapse model following treatment of Bru- cella infection in mice. The reasons for such high treatment failure in humans are not completely understood. Patient non-compliance due to the long duration of therapy can be the major cause for treatment failure; thus, shorter therapy duration is desirable. In the case of relapses, isolated Brucella usually are sensitive to the same antibiotic treatment, indicating lack of development of drug resistance [5]. Thus, there is a need for an alternative therapeu- tic option other than conventional antibiotics. This should help to 0264-410X/$ – see front matter © 2014 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.vaccine.2013.12.058