Preliminary Results of LTE Testing

Studies have been begun using the Tetanus toxoid vaccine in anticipation of initiating MIMIC™ validation studies. In a preliminary study, we examined pre- and post-immunization responses in a volunteer subject. Results were recorded five weeks following vaccination (summarized below). Serum antibody titers for Tetanus were is 40 ug/mL and 300 ug/mL pre and postimmunization, respectively.

TT-specific antibody responses in the LTE.

Flow cytometric analysis showed a robust increase in antigen-specific proliferation of B lymphocytes. Proliferative data were accompanied by an approximate 14-fold increase in Tetanus-specific spot forming cells following Tetanus boosting. These results are encouraging in our capacity of the LTE to clearly differentiate between pre- and post-boost response profiles. We anticipate a large number of donors in Tetanus toxoid studies in the near future as an initial arm in MIMIC™ vaccine validation studies. We have observed correlations between vaccine history and in vitro LTE results and anticipate broadening our database in the near future via vaccine validation studies.

An MIMIC™ vaccine immunogenicity test is being validated using commercially available vaccines for tetanus toxoid (Tripedia®), influenza (trivalent inactivated – Fluzone®), and Hepatitis B vaccine (Recombivax®). VaxDesign will continue to validate the vaccine test with commercially available vaccines, with government agencies, and with commercial validation partners. We also plan to conduct retrospective studies comparing the vaccine test predictions with actual human clinical trial results and, ultimately, to participate in prospective clinical trials. Future plans for MIMIC™ vaccine test will also increase the number of vaccines tested, the types of vaccines tested (e.g., DNA vaccines, live attenuated virus, killed inactivated virus), and the mucosal route of administration.

Number of antigen-specific B cells produced in the LTE for influenza vaccines and antigens. Click the thumbnail to view a larger, more detailed version of the chart.

We are developing assay systems for the production of fully human antibody secreting cells against naive and recall antigens. We have extensive data that MIMIC™ technology can be used to generate humoral responses specific for primary antigens. The MIMIC™ assay system can routinely be used for the generation of rapid, sensitive and robust culture method for the induction of naive antigen-specific B cell response against a variety of protein antigens. The figure below shows the ability of MIMIC to generate Abs to both recall (Hepatitis B from Recombivax and influenza from Fluzone) and naive Ags(gp120 from HIV and rPA from bacillus anthracis).

Antibody responses to naive and recall antigens

To obtain physiologic immune responses, we have optimized the following experimental conditions:

• cell types
• kinetics
• culture media
• Number of cells for recall and naive responses
• DC:T cell ratio
• CD4⁺ T cell help
• Microenvironment
• FDCs

A dataset for gp120-specific Ab responses taking the aforementioned conditions into accounts is shown below.