Immunologic Research

, Volume 56, Issue 1, pp 61–72 | Cite as

Immunisation with foamy virus Bet fusion proteins as novel strategy for HIV-1 epitope delivery

  • Michael Mühle
  • Kerstin Hoffmann
  • Martin Löchelt
  • Joachim Denner


The induction of 2F5- and 4E10-like antibodies broadly neutralising HIV-1 and targeting the membrane external proximal region (MPER) of the transmembrane envelope protein gp41 would be a major advancement for the development of a preventive HIV-1 vaccine, but successful attempts remain rare. Recent studies demonstrated that broadly reactive antibodies develop relatively late during infection and after intensive affinity maturation. Therefore, a prolonged antigen delivery might be beneficial to induce them. Replicating foamy viruses which are characterised by apathogenic but persistent infection could represent suitable carrier viruses for this purpose. In order to develop such a system, we modified the accessory foamy virus Bet protein to contain the MPER of gp41, or the MPER linked to the stabilising fusion peptide proximal region of gp41 and analysed here the antigenic and immunogenic properties of such hybrid proteins. The antigens, expressed and purified to homogeneity, were recognised by the monoclonal antibodies 2F5 and 4E10 with nanomolar affinities and induced high levels of antibodies specific to gp41 after immunisation of rats. The antisera also bound to virus particles attached to infected cells, and peptide-based epitope mapping showed that they recognised the 2F5 epitope. Although no HIV-1 neutralising activity was observed, the presented data demonstrate that using the foamy virus Bet for HIV-1 epitope delivery is successfully applicable. Together with the attractive potential for sustained antigen expression after transfer to replicating virus, these results should therefore provide a first basis for the development of chimeric foamy viruses as novel HIV-1 vaccine vectors.


HIV-1 Vaccine MPER Foamy virus Bet protein 



This work was supported by the Volkswagenstiftung. We thank C.M. Schmidt, M. Keller and D. Wirths for excellent technical support and A. Bleiholder for critical reading of the manuscript. All authors have approved the final article and declare that there is no conflict of interest.

Supplementary material

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Copyright information

© Springer Science+Business Media New York 2013

Authors and Affiliations

  • Michael Mühle
    • 1
  • Kerstin Hoffmann
    • 1
  • Martin Löchelt
    • 2
  • Joachim Denner
    • 1
  1. 1.Center for HIV and RetrovirologyRobert Koch InstituteBerlinGermany
  2. 2.Division Genome Modifications and Carcinogenesis, Research Topic Infection and CancerGerman Cancer Research Center (DKFZ)HeidelbergGermany

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