Frequently Asked Questions - Infectious Disease Antigens
All ABI antigens are supplied frozen on dry ice. Vial sizes of 1 mL and 25 mL are offered to enable manufacturers to move directly from evaluation/qualification to production without incurring additional freeze-thaw cycles.
ABI offers a variety of antigens, from viruses to pathogenic bacteria, in different purities to address individual assay/cost requirements. Purification methodology varies according to the individual product requirements, as do the buffers in which the antigens are frozen.
We recommend that you contact us with your assay specifications so that we may suggest the appropriate form and purity.
We recommend that all antigens be stored frozen at -70°C or below. Avoid multiple freeze-thaw cycles as this will affect antigen activity. Do not dilute and freeze — make final dilution just prior to use.
ABI infectious disease antigens are made in infected cells using cell culture. Recombinant antigens are made in various systems, generally yeast or baculovirus. All are screened for function in ELISA and Western blot prior to release.
A modified BCA protein assay is used with Bovine Serum Albumin (BSA) as the protein standard.
All ABI infectious disease antigens work in ELISA. However, it is critical to use an appropriate primary antibody and conjugate dilution. Double-block titrations should be performed to determine the optimum use dilutions in your system.
All ABI infectious disease antigens work in Western blot according to the considerations mentioned for ELISA. For reference use, ABI uses the following procedure for Western blot (to be developed with monoclonal antibodies): The antigen is electrophoresed on a 4 - 15% polyacrylamide gel then transferred to a nitrocellulose membrane. The membrane is blocked with 5% non-fat dry milk in Phosphate Buffered Saline + 0.1% Tween-20 (PBST) and allowed to dry. The membrane is then cut into strips, and incubated with monoclonal antibody, at an appropriate dilution, in blocking buffer. The strip is washed in three changes of PBST for 5 - 10 minutes each and incubated with diluted Goat anti-mouse IgG-AP in blocking buffer. The strip is washed as before and developed with BCIP/NBT as per manufacturer's instructions.
