The first injection is given in Complete Freund's adjuvant. Adjuvant is combined with the antigen to improve the immune response so that less vaccine is needed to produce more antibodies. The adjuvant allows a slow release of the antigen which allows for continual stimulation. Injections are routinely performed subcutaneously at multiple sites. A pre-immune bleed should be drawn from each host animal to produce a baseline to which the production bleeds can be compared.
Sodium azide is a broad-spectrum enzyme inhibitor and acts as an antimicrobial agent.
Sodium azide should not be added to sera when using in cell culture or in vivo studies. If a high background is observed in assays using the antisera, various purification techniques are available. It is important to first check that the background is non-specific and not due to the response against the peptide. This can be determined by performing a competitive peptide blocking study. Peptide blocking studies check that the response against the target protein is not a background artifact.