Genetic Vaccines and Therapy

Several studies have shown that cell-mediated immune responses play a crucial role in controlling viral replication. As such, a candidate SARS vaccine should elicit broad CD8+ T-cell immune responses. Several groups of mice were immunized alone or in combination with SARSnucleocapsid immunogen. A high level of specific SARS-CD8+ T-cell response was demonstrated in mice that received DNA encoding the SARS-nucleocapsid, protein and XIAP as an adjuvant. We also observed that co-administration of a plasmid expressing nucleocapsid, recombinant protein and montanide/CpG induces high antibody titers in immunized mice. Moreover, this vaccine approach merits further investigation as a potential candidate vaccine against SARS. Introduction The SARS epidemic had a high mortality rate as well as a huge economic impact worldwide. Treatment with antiviral drugs or an effective vaccine is not available for protection against this disease [1,2]. The SARS-CoV is a singlestranded RNA virus that has been identified as a new type of coronavirus. The genome is approximately 30 kb long and contains four structural proteins: spike, envelope, matrix and nucleocapsid in the same order as other coronaviruses [3,4]. However, the sequence analysis of SARSCoV with other members of the coronavirus family did not show more than 20% nucleotide homology [5]. The SARS-NC gene encodes a 46 kDa protein that participates in the replication and transcription of the virus and interferes with the cell cycle of host cells [6]. Previous studies in other coronavirus members suggest that this protein is highly immunogenic and could be a good target for the design of an effective vaccine [7-10]. The expression of NC in CHO cells led to the observation that this protein folds spontaneously into viral-like particles (VLPs). These particles are effectively incorporated at several stages of the virus life cycle, including assembly, budding from cells, and receptor-binding leading to membrane fusion. The viral particles also present antigens Published: 22 August 2005 Genetic Vaccines and Therapy 2005, 3:7 doi:10.1186/1479-0556-3-7 Received: 09 May 2005 Accepted: 22 August 2005 This article is available from: http://www.gvt-journal.com/content/3/1/7 © 2005 Azizi et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.