Vaccine 26 (2008) 5888–5895 Contents lists available at ScienceDirect Vaccine journal homepage: www.elsevier.com/locate/vaccine Protective immunity against challenge with Leishmania (Leishmania) chagasi in beagle dogs vaccinated with recombinant A2 protein Ana Paula Fernandes a,∗ , Míriam Maria Silva Costa b , Eduardo Antônio Ferraz Coelho b , Marilene Suzan Marques Michalick c , Eloísa de Freitas c , Maria Norma Melo c , Wagner Luiz Tafuri d , Daniela de Melo Resende b , Vinícius Hermont e , Christiane de Freitas Abrantes e , Ricardo Tostes Gazzinelli b,f,g a Department of Clinical and Toxicological Analysis, School of Pharmacy, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil b Department of Biochemistry and Immunology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil c Department of Parasitology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil d Department of Pathology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil e Hertape-Calier Saúde Animal, Juatuba, MG, Brazil f René Rachou Institute, Oswaldo Cruz Foundation, Belo Horizonte, MG, Brazil g Department of Medicine, University of Massachusetts Medical School, Worcester, MA, USA article info Article history: Received 18 March 2008 Received in revised form 22 May 2008 Accepted 26 May 2008 Available online 9 September 2008 Keywords: Canine visceral leishmaniasis Recombinant vaccine A2 antigen abstract In this study, we investigated in dogs the immunogenicity and protective immunity against Leishmania (Leishmania) chagasi infection induced by vaccination with a formulation containing the recombinant A2 protein, an amastigote specific antigen, and saponin. Vaccinated animals produced significantly increased levels of total IgG and IgG2, but not IgG1 anti-A2 antibodies, and remained negative in conventional leishmaniasis serodiagnostic methods. Significantly increased IFN- and low IL-10 levels were detected in vaccinated animals before and after challenge, as compared to control animals. Importantly, while the symptoms onset appeared as early as three months after infection in most control dogs, 14 months after challenge, 5 out of 7 vaccinated dogs remained asymptomatic. Therefore, immunization with rA2 antigen was immunogenic and induced partial protection in dogs, and allowed the serological differentiation between vaccinated and infected animals, an important requirement for a canine visceral leishmaniasis (CVL) vaccine. © 2008 Elsevier Ltd. All rights reserved. 1. Introduction Leishmaniasis is an infectious disease with an overall prevalence of 12 million cases and 350 million people at risk of infec- tion [1]. Leishmania parasites are transmitted through the bite of an infected sand fly to vertebrate hosts, leading to a spec- trum of clinical manifestations, including visceral leishmaniasis [1]. Leishmania (Leishmania) infantum and Leishmania (Leishmania) chagasi, which are now considered synonymous species [2], and Leishmania (Leishmania) donovani are the major etiologic agents of visceral leishmaniasis (VL), a fatal infection if diagnosis and ∗ Corresponding author at: Faculdade de Farmácia, Universidade Federal de Minas Gerais, Avenida Antônio Carlos, 6627, Belo Horizonte CEP 30 270 901, Minas Gerais, Brazil. Tel.: +55 31 34096884. E-mail addresses: anav@uai.com.br, anapaula.fernandes@pq.cnpq.br (A.P. Fernandes). treatment are not promptly established. Dogs are highly sus- ceptible to infection and considered the major reservoir for L. (L.) infantum and L. (L.) chagasi, in different geographical regions of the globe [3]. Canine visceral leishmaniasis (CVL) is assum- ing increasing importance in countries around the Mediterranean Basin and in the Americas. Research has recently revealed much new information, but advances in treatment and control have been disappointing. Treatment of infected dogs is of limited effec- tiveness and not recommended in endemic regions, since dogs that respond to treatment may still be a source of parasites [3,4]. The epidemiological control of VL depends of actions against the vectors (sand flies) and reservoirs, mainly the domestic dogs. Therefore, the development of a protective vaccine against CVL is an alternative approach for interrupting the VL domestic cycle [3,5]. Ideally, this vaccine should reduce symptoms, tissue parasitism as well as vector transmission rates. In addition, it is recommended that it allows for the serological differentiation of vaccinated and infected dogs, by means of serological tests using promatigote 0264-410X/$ – see front matter © 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.vaccine.2008.05.095