Pellagra, which is caused by a deficiency in vitamin B3 (niacin), showing up in hamsters because of large-scale monoculture.

Mice, rats, or hamsters are immunized by giving biweekly injections of a purified antigen, cultured cells, or cDNA. For mice, if a pure, soluble protein antigen is being used and is abundant, a dose of 50–100 µg in adjuvant at each immunization is a sensible general recommendation; for rats and hamsters, a dose of 100–200 µg is sufficient. Lower doses can be used for antigens with higher immunogenicity. Adjuvants (Freund's, Ribi, Hunter's TiterMax, ImmunEasy, or Alum) should be mixed with the immunizing antigen for the first two immunizations only; Complete Freund's adjuvant is only used with the first immunization. Subsequent immunizations are performed in phosphate-buffered saline (PBS) or normal saline, with or without Incomplete Freund's adjuvant. The choice of adjuvant is dependent on the subclass of immunoglobulin required. Over the course of the 6-wk immunization schedule, each animal usually receives a total of six injections (three subcutaneous and three intraperitoneal). Once a good titer has developed against the antigen of interest, regular boosts and bleeds are performed to collect the maximum amount of serum. For rats and hamsters, boosts should be spaced every 2–3 wk, and serum samples of 400–500 µL should be collected 10–12 d after each boost. For mice, boosts should be spaced every 2–3 wk, and serum samples of 200–300 µL should be collected 10–12 d after each boost.

Subtractive immunization is useful for directing the immune response away from dominant epitopes to allow antibodies against less immunogenic antigens to be developed. It is also useful when there is a need to downplay the response to carriers added to peptides and recombinant proteins, such as Gst and Ig, to aid in production and purification. Subtractive immunization protocols also can be helpful if the target protein is part of a mixture (such as a cell lysate) or present on the surface of transfected cells.

The repetitive immunization at multiple sites (RIMMS) protocol capitalizes on the animal's innate immune system, which is genetically preprogrammed to recognize many antigens. By repetitively immunizing the animal, B cells that recognize the antigen are kept continuously expanding until the lymph nodes are harvested for hybridoma generation. This is a good method for making a more diverse repertoire of antibodies or antibodies directed against conformational epitopes.

Desperate times call for desperate measures.

Two Russian hamsters prove their incredible speed going head-to-head in a race around a wheel, shoving each other aside as their competitive streak shows. BBC Earth filmed the hilarious hamster race.