Research

Characterisation of immune responses and protective efficacy in mice after immunisation with Rift Valley Fever virus cDNA constructs

Nina Lagerqvist^1,2,4 , Jonas Näslund^2,3 , Åke Lundkvist^2,3 , Michèle Bouloy⁵ , Clas Ahlm² and Göran Bucht^1,6

¹  Swedish Defence Research Agency, Department of CBRN Defence and Security, SE-901 82 Umeå, Sweden

²  Department of Clinical Microbiology, Division of Infectious Diseases, Umeå University, SE-901 85 Umeå, Sweden

³  Department of Clinical Microbiology, Division of Virology, Umeå University, SE-901 85 Umeå, Sweden

⁴  Swedish Institute for Infectious Disease Control, SE-171 82 Solna, Sweden

⁵  Institut Pasteur, Unité de Génétique Moléculaire des Bunyaviridés, Paris, France

⁶  National Environment Agency, Environmental Health Institute, 11 Biopolis Way, 06-05/08, Helios Block, 138667, Singapore

author email corresponding author email

Virology Journal 2009, 6:6doi:10.1186/1743-422X-6-6

Published:	17 January 2009

Abstract

Background

Affecting both livestock and humans, Rift Valley Fever is considered as one of the most important viral zoonoses in Africa. However, no licensed vaccines or effective treatments are yet available for human use. Naked DNA vaccines are an interesting approach since the virus is highly infectious and existing attenuated Rift Valley Fever virus vaccine strains display adverse effects in animal trials. In this study, gene-gun immunisations with cDNA encoding structural proteins of the Rift Valley Fever virus were evaluated in mice. The induced immune responses were analysed for the ability to protect mice against virus challenge.

Results

Immunisation with cDNA encoding the nucleocapsid protein induced strong humoral and lymphocyte proliferative immune responses, and virus neutralising antibodies were acquired after vaccination with cDNA encoding the glycoproteins. Even though complete protection was not achieved by genetic immunisation, four out of eight, and five out of eight mice vaccinated with cDNA encoding the nucleocapsid protein or the glycoproteins, respectively, displayed no clinical signs of infection after challenge. In contrast, all fourteen control animals displayed clinical manifestations of Rift Valley Fever after challenge.

Conclusion

The appearance of Rift Valley Fever associated clinical signs were significantly decreased among the DNA vaccinated mice and further adjustment of this strategy may result in full protection against Rift Valley Fever.