Virology Laboratory

Projects

• Pilot Project (Submitted in the MBRS-SCORE 2004-2008 program to NIH)
  
  After more than 20 years of intensive research an effective vaccine against HIV is not yet available. This can be attributed to several problems including but not limited to incomplete characterization of immune correlates of protection against HIV infection and pathogenesis. Another critical factor important in the development of a successful vaccine against sexually transmitted HIV is the induction of appropriate mucosal immune responses which provide the first barrier of protection against invading viruses. These responses are expected to reduce the amount of virus crossing the mucosa and accessing lymph nodes. The recognition of the limitations of traditional vaccination modalities for preventing HIV infection has led to the development of a number of novel vaccination strategies, including recombinant live vectors and plasmid DNAs. The long-term objective of this application is to develop a strategy for the development of an effective vaccine against HIV/AIDS using influenza virus as a vector. For this purpose, previously non-tested genetic modifications of influenza virus expressing SIV epitopes will be presented to the immune system in different modalities. Based on our previous experience, we will use different influenza virus recombinants in an immunization protocol which includes SIV/VLP administration to rhesus macaques,which are the model of choice for SIV/HIV vaccine studies.
  
  
  
• EVALUATION STUDIES of a DNA VACCINE EXPRESSING SIVsmVLP
  Principal Investigator - Edmundo Kraiselburd, Ph.D.
  Collaborator - Idalí Martínez, Ph.D.
  
  The objective is to develop a vaccine capable of inducing protective immune responses in rhesus macaques against pathogenic simian immunodeficiency virus (SIV). For this purpose, we plan to evaluate the immune responses generated in macaques by an SIV DNA vaccine (Vec B7). The 1.6Kb deletion (Dpol, vif, vpr, and vpx) of SIVsmB7 provirus DNA was introduced into the SIVsmH4 DNA to construct the Vec B7 expression vector. Vec B7 expressed SIVsm gag, env and nef proteins, produced virus-like particles (VLP) in vitro, and was immunogenic in mice. The first aim is to examine cell-mediated and humoral immune responses generated in macaques by Vec B7 alone or by its codelivery with the genetic cytokine adjuvants granulocyte-macrophage colony stimulating factor (GM-CSF), and Interleukin-12 (IL-12). Our hypothesis is that immune responses will be induced by Vec B7 DNA vaccination, enhanced by genetic cytokine adjuvants, and further boosted by administration of SIVsmB7 VLP in adjuvant. Groups consisting of 5 rhesus macaques each will be inoculated with either Vec B7 alone or in combination with rhesus IL-12 and GM-CSF expression vectors. Induction of humoral and cellular responses to SIVsm antigens will be monitored by SIV-ELISA, neutralizing antibody, CTL assays, and cytokine profile determinations. In addition, we will determine if immune responses elicited by these vaccination regimens can be boosted by SIVsmB7 VLP ± rIL-12 administered in alum. The second aim is to determine if any of these four Vec B7 DNA-priming and SIVsmB7 particle boost vaccine strategies could protect macaques against challenge with pathogenic SIVsmE660. Results of this challenge will be ascertained by comparing virus loads, antibody production, and CMI responses obtained in the experimental and in control groups. Data obtained from these experiments will give important information for the development of an effective vaccine against SIV and potentially against HIV.
  
  
  
• GENETIC IMMUNIZATION OF MICE WITH A TETRAVALENT DENGUE DNA VACCINE
  Principal Investigator- Idalí Martínez, Ph.D.
  Collaborator - Edmundo Kraiselburd, Ph.D.
  
  Dengue and dengue hemorrhagic fever result from the infection with any of the four serotypes of dengue viruses. Dengue is endemic in Puerto Rico and has become a global public health problem. Research is needed to develop an effective and safe vaccine that will prevent infection and disease caused by any of these viruses. Thus, the objective of these studies is to develop an effective dengue-2 DNA vaccine. Our long-term objective is to develop a tetravalent dengue DNA-based vaccine. Our vaccine strategy is focused on the dengue envelope because this protein mediates the early binding and entry steps in infection. Neutralizing antibodies (NAb) against this protein were shown to be protective against pathogenic virus infection and disease. Dengue envelope expression vectors will be constructed and tested for immunogenicity in Balb/c mice. These DNA vectors will be evaluated alone or in combination with genetic adjuvants for their respective abilities to induce immune responses (NAb and CTL) that will protect vaccinated mice against intracranial dengue-2 virus infection. The genetic adjuvants that will be used (CD40L and GMCSF) have been shown by others to increase the immunogenicity of DNA vaccines. Standard molecular biology techniques (such as PCR and cloning) will be used to construct the individual DNA expression cassettes. Immune responses will be monitored by ELISA, virus neutralization assays and CTL assays. Efficacy studies (i.e. challenge) will also be performed. Results obtained from these studies will give important information for the design and development of DNA vaccines expressing the envelope protein of dengue-1, dengue-3 and dengue-4.