Available online at www.sciencedirect.com Vaccine 25 (2007) 7885–7892 New chemical method of viral inactivation for vaccine development based on membrane fusion inhibition Fausto Stauffer a , Joari De Miranda a , Marcos C. Schechter a , Fernando A. Queiroz a , Nathalia O. Santos a , Ada M.B. Alves b , Andrea T. Da Poian a,∗ a Instituto de Bioqu´ ımica M´ edica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-590, Brazil b Laborat´ orio de Imunopatologia, Instituto Oswaldo Cruz, Funda¸ c˜ ao Oswaldo Cruz, Rio de Janeiro, RJ 21040-900, Brazil Received 10 July 2007; received in revised form 30 August 2007; accepted 3 September 2007 Available online 29 September 2007 Abstract Membrane fusion is an essential step in the entry of enveloped viruses into their host cells. This process is triggered by conformational changes in viral surface glycoproteins. We have demonstrated previously that modification of vesicular stomatitis virus (VSV) with diethylpyrocarbonate (DEPC) abolished the conformational changes on VSV glycoprotein and the fusion reaction induced by the virus. Moreover, we observed that viral treatment with DEPC inactivates the virus, preserving the conformational integrity of its surface proteins. In the present work, we evaluated the potential use of DEPC as a viral inactivating chemical agent for the development of useful vaccines. Pathogenicity and viral replication in Balb/c mice were abolished by viral treatment with 0.5 mM DEPC. In addition, antibodies elicited in mice after intraperitoneal immunization with DEPC-inactivated VSV mixed with adjuvants were able to recognize and neutralize the native virus and efficiently protected animals against the challenge with lethal doses of VSV. These results together suggest that viral inactivation with DEPC seems to be a suitable method for the development of safe vaccines. © 2007 Elsevier Ltd. All rights reserved. Keywords: Viral inactivation; Diethylpyrocarbonate; Vesicular stomatitis virus 1. Introduction Vaccination is a valuable public health tool, being a safe and cost-effective strategy for controlling infectious diseases [1]. The progress in development and use of vaccines resulted in the decline and, in some cases, eradication of impor- tant infectious diseases, as smallpox [2]. Traditionally, the vaccines developed against viruses consist of attenuated or inactivated pathogens or subunits vaccines. Live attenuated vaccines are based on the attenuation of the pathogen until its virulence is greatly decreased but its immunogenicity is retained. Alternatively, inactivated vaccines consist of whole killed virus, while subunit vaccines are based on only one or few virus proteins. In the case of whole virus inactivated vac- ∗ Corresponding author. Tel.: +55 21 22706264; fax: +55 21 22708647. E-mail address: dapoian@bioqmed.ufrj.br (A.T. Da Poian). cines, the inactivation treatment through different processes (for review, see [3,4]) must assure that all virus particles are inactivated in order for the vaccine to be safe. Despite the advances in the field of immunology, molecular biology and genetics, viral inactivation remains an important procedure in basic research, since it is an easy and relatively cheap approach to produce new and safe vaccines. The entry of enveloped viruses into a target cell always requires virus-mediated membrane fusion catalyzed by viral surface glycoproteins [5–7]. Virus-induced fusion may occur through two different general mechanisms: (i) fusion between viral envelope and host cell plasma membrane after virus interaction with its cellular receptor, or (ii) fusion with the endosomal membrane, after virus internalization by receptor- mediated endocytosis. In the latter case, the decrease in the pH of the endosomal medium triggers conformational changes in viral glycoproteins. This mechanism seems to be conserved 0264-410X/$ – see front matter © 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.vaccine.2007.09.025