CNR - Institute of Neuroscience CNR
Institute of Neuroscience


Construction and validation of recombinant viral vectors for prevention and/or therapy of infectious diseases

Construction and evaluation of recombinant viral vectors for Prevention and/or Therapy of Infectious Diseases

The goal of our research program is the preparation and evaluation of new recombinant vectors based on the genetic background of avipoxviruses unable to replicate in mammalian cells. The virus we engineered is an attenuated fowlpox poultry vaccine strain which, being currently used to immunize fowls against smallpox, was shown to be safe in humans and to express at high levels one or more foreign genes for therapeutic and/or prophylactic use.

At present, AIDS and papillomas are the most relevant viral diseases we are currently pursuing by inserting HIV-1 gag/pol and env structural genes, and HPV-16 E6/E7 oncogenes into non-essential regions of fowlpoxvirus. The constructs have been evaluated both in vitro and in vivo for the correct expression of the transgenes as well as for their ability to elicit a complete immune response in non-human primates (Rh. monkeys), rabbits and mice.

Recently, groups of SIV-infected macaques whose viremia was pharmacologically controlled by HAART (Highly Active Antiretroviral Therapy) were therapeutically immunized following a prime/boost protocol. In this experiment our fowlpox-based vaccines demonstrated to be able to restore the cellular immunity in these chronically infected animals.

The refining of these constructs and their optimized use in macaques for a therapeutic and/or prophylactic approach of AIDS and papillomatosis are the aim of our ongoing researches.

Construction of recombinant viruses for the prophylaxis of diseases caused by agents suitable for bioterrorism

In the context of controlling the event of a voluntary diffusion of an infectious agent we intend to develop different types of recombinant constructs (based on avipox genome) coding for heterologous genes important for protection against viral agents putatively considered as bioweapons. The most important aspect of our technology is the ability to construct live recombinant viral immunogens completely safe for the humans (being unable to replicate in mammalian cells) but expressing high levels of the transgene/s. Methodologically, we will construct a series of avipox-based recombinants containing transgenes expressing immunologically relevant proteins able to elicit both neutralizing antibodies and cellular immune response. The development and continued refinement of techniques for the efficient insertion and expression of heterologous DNA and RNA sequences of infectious virus recombinants are among the most promising current approaches to effective immunoprophylaxis against a variety of human and animal pathogens. Because of its medical relevance, this field is the subject of intense research interest and has evolved rapidly during the past few years. Recombinant virus vectors carrying foreign protective genes from different pathogenic microorganisms are now being studied for the prevention of a wide variety of human and animal infectious diseases. Although safety issues have recently emerged in their utilization in vivo due to adverse side effects, vector cytotoxicity, occasional host hyper immune response and failure to elicit complete protection, viral vectors are still the more promising vaccine carriers. Currently, several replication-competent and replication-defective viruses including poxviruses, adenoviruses, herpesviruses, alphatogaviruses and picornaviruses are under investigation to determine their gene expression, immune activity and efficacy. Among the several different classes of animal viruses, only a minority has been genetically engineered to obtain live recombinant vaccines. The most important characteristics that such vectors should possess to constitute an efficient and safe vaccine are: no residual pathogenicity; thermal stability; simple and inexpensive production; ability to mimic natural infection and elicit both humoral and cellular immune responses; restricted penetration to non-immune cells.


From this last point of view, viruses are very efficient at infecting target cells where their genome is expressed to produce new viral particles. Therefore, by replacing or inactivating genes that are non-essential for their replication with foreign genes of interest, they can become vectors able to express the foreign proteins in the cells they infect. As live viruses have evolved as parasites, they all elicit a complete immune response to both the vector and the heterologous protein they express, with a preferential antigen delivery to class I MHC pathway of endogenously synthesized peptides. However, as live vector vaccines are able to drive the synthesis of new viral progeny and/or heterologous proteins by the host cells, they are expected to induce both class I and class II restricted immune responses involving both T helper and cytotoxic T cells (CTL). Being involved in specific recognition, T helper cells provide interleukins, such as IL-2, which stimulate division and terminal differentiation of the corresponding B cells to plasma cells that release antigen-specific antibodies. Based on these considerations, virus vectors appear to be particularly useful as immunoprophylactic agents since they are able to drive both the humoral and cellular arms of the immune response.


  • Souquière S, Mouinga-Ondeme A, Makuwa M, Beggio P, Radaelli A, De Giuli Morghen C, Mortreux F, Kazanji M (2009) T-cell tropism of simian T-cell leukaemia virus type 1 and cytokine profiles in relation to proviral load and immunological changes during chronic infection of naturally infected mandrills (Mandrillus sphinx). J. Med. Primatol. 38:279-89.
  • Pozzi E, Basavecchia V, Zanotto C, Pacchioni S, Morghen Cde G, Radaelli A (2009) Construction and characterization of recombinant fowlpox viruses expressing human papilloma virus E6 and E7 oncoproteins. J. Virol. Methods 158:184-9.
  • Radaelli A, Bonduelle O, Beggio P, Mahe B, Pozzi E, Elli V, Paganini M, Zanotto C, De Giuli Morghen C, Combadière B (2007) Prime-boost immunization with DNA, recombinant fowlpox virus and VLP(SHIV) elicit both neutralizing antibodies and IFNgamma-producing T cells against the HIV-envelope protein in mice that control env-bearing tumour cells. Vaccine 25:2128-38.


  • T. Cardi, CNR - IGV, Institute of Plant Genetics, Portici, Italy.
  • M. R. Capobianchi, National Institute for Infectious Diseases "L. Spallanzani", Rome, Italy.
  • G. Franchini, NIH, NCI, Bethesda, Washington DC, USA.
  • B. Combadière, H. Salpétrière, Paris, France.
  • C. Stahl-Hennig, German Primate Centre, Gttingen, Germany.
  • M. Kazanji, Département de Rétrovirologie, CIRMF, BP 769 Franceville - Gabon.
  • J. L. Heeney, University of Cambridge, UK; and Biomedical Primate Research Centre, Rijswijk, The Netherlands.


PI photo

Antonia Radaelli

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