Abstract: Described herein are expression signatures of genes and coordinately expressed gene networks associated with skin aging, methods used to determine the physiological age of skin, and methods used to screen for compounds used to reduce the visible signs of aging of the skin.

Abstract: The present invention relates, generally, to the production of one or more OspA proteins in plant cells. Heterologous DNA comprising genes encoding one or more desired OspA protein(s) are introduced into plant cells. The one or more OspA protein(s) can be recombinantly-produced in the plant cells, optionally purified from the plant cells, and used as an oral vaccine to prevent the transmission of Lyme disease, particularly by animal vectors. The recombinantly-produced OspA protein(s) can be provided in oral and parenteral formulations. The present invention also relates to oral administration of OspA protein(s) to vaccinate against Lyme disease. The OspA protein(s) may be provided in a dosage form that is suitable for oral administration as a vaccine to prevent an animal from developing Lyme disease after exposure to a source of Borrelia burgdorferi.