Multivariate analysis of the immune response to different rabies vaccines.

In a previous study, we proposed as an alternative to the use of animals in infectious challenge studies, a new approach describing the vaccine-induced immune response through the multivariate analysis of a defined set of immune parameters characterizing the B and T immune responses. This multivariate analysis, i.e. immune fingerprint, was evaluated first to assess the impact of minor changes in well characterized vaccines. The approach showed promising results in the assessment of the compatibility between two licensed vaccines. In the present study, the immune fingerprint was used to compare adjuvants with the various immunological parameters of the immune fingerprint as well as to assess the ability of this approach to discriminate different Rabies vaccine formulations in dogs. RABISIN® was the reference vaccine, adjuvanted with aluminum hydroxide. An exploratory factor analysis was used to analyse the covariance structure of the immunological data. Significant differences were observed between groups. RABISIN and a linear polyacrylate (SPA09) adjuvanted vaccine performed better than chitosan adjuvanted ones, both for humoral and cell immune responses. This study showed that the immune fingerprint approach can be used to screen vaccine formulations. It provides additional information compared to classical vaccination and infectious challenge efficacy study.

Development of a simple, rapid and accurate in vitro whole blood technique for the detection and semi-quantification of FIV cellular viremia.

A new, simple, rapid and accurate culture technique is described for a semi-quantitative analysis of cellular viremia in FIV-infected cats. This assay can be carried out with small amounts of whole blood, and is based on the detection of FIV core gag antigen, which is released in culture supernatants. The amount of core antigen produced is measured with an enzyme-linked immunoassay using specific monoclonal antibodies. This whole blood technique (WB method) was compared with a culture method using isolated peripheral blood mononuclear cells (PBMC method). FIV could be detected in whole blood of all experimentally infected cats, but not from uninfected cats. This assay offers a number of advantages (small blood samples required, no leukocyte separation and lymphocyte purification procedures) and its reproducibility is very good. It provides a convenient in vitro cellular assay for viral semi-quantitation, well adapted for monitoring efficacy of prototype FIV vaccines or experimental antiviral drugs. Also, it could facilitate the study of the pathogenesis of FIV-related progressive immunodepression. Finally, it offers an alternative to serological techniques for diagnostic purposes in several circumstances: early viremia, maternal antibodies.