Fax +41 61 306 12 34 E-Mail karger@karger.ch www.karger.com Original Paper Intervirology 2006;49:253–260 DOI: 10.1159/000093454 Truncated Recombinant Dobrava Hantavirus Nucleocapsid Proteins Induce Strong, Long-Lasting Immune Responses in Mice Piet Maes a Els Keyaerts a Véronique Bonnet b Jan Clement a Tatjana Avsic-Zupanc c Alain Robert b Marc Van Ranst a a Laboratory of Clinical and Epidemiological Virology, Rega Institute for Medical Research, University of Leuven, Leuven, Belgium; b Centre d’Immunologie Pierre Fabre, Saint-Julien en Genevois, France, and c Institute of Microbiology and Immunology, Medical Faculty of Ljubljana, Ljubljana, Slovenia be protected against DOBV challenge. Our results indi- cate that the rNp constructs coupled to rP40, represent promising vaccine candidates. Copyright © 2006 S. Karger AG, Basel Introduction Hantaviruses are trisegmented, negative-stranded RNA viruses, belonging to the Bunyaviridae family [1]. The genome encodes four structural proteins, the L-seg- ment encoding the RNA polymerase, the M-segment en- coding two envelope glycoproteins (G1 and G2), and the S-segment encoding the nucleocapsid protein (Np) [2]. Hantaviruses give rise to severe human clinical diseases like hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome, but produce persistent, non-pathogenic infections in rodents [3–5]. In Europe, Dobrava hantavirus (DOBV) seems to be the most viru- lent hantavirus. DOBV can bear a fatality rate up to 12%, mainly due to severe hemorrhagic manifestations [6] . Two closely related DOBV subspecies are carried by two rodent species, the yellow-necked mouse (Apodemus fla- vicollis) and the striped field mouse (Apodemus agrarius) Key Words Recombinant vaccine  Recombinant antigen  Nucleocapsid protein  Dobrava hantavirus  P40 Abstract We describe the cloning and expression of Dobrava han- tavirus (DOBV) nucleocapsid proteins and a truncated form consisting of the first 118 N-terminal amino acids, and the capacity of these E. coli ICONE 200-expressed recombinant proteins (rNp) to induce a protective im- mune response against DOBV in mice. As an alternative carrier protein, the outer membrane protein A derived from Klebsiella pneumoniae (rP40) has been coupled to different rNp constructs. All recombinant proteins were found to be highly immunogenic after three immuniza- tions of rNp. The immunizations resulted in the induction of a strong Np-specific IgG response with a predomi- nance of IgG1 over IgG2b and IgG2a, suggesting a mixed Th1/Th2 cell involvement. A specific IgG3 response could not be detected. Mice immunized with recombinant DOBV rNp without rP40 showed lower nucleocapsid- specific antibody responses in comparison with the rP40-conjugated constructs, but all mice were found to Received: January 6, 2005 Accepted after revision: July 20, 2005 Published online: May 22, 2006 Prof. Dr. Marc Van Ranst Laboratory of Clinical and Epidemiological Virology Department of Microbiology & Immunology, Rega Institute for Medical Research Minderbroedersstraat 10, B–3000 Leuven (Belgium) Tel. +32 16 347908, Fax +32 16 347900, E-Mail marc.vanRammt@umcutrecht.nl © 2006 S. Karger AG, Basel 0300–5526/06/0495–0253$23.50/0 Accessible online at: www.karger.com/int