Expression of Human Milk Proteins in Plants

Abstract

Human milk proteins are believed to have a multitude of biological activities benefiting the newborn infant. Such functions include antibacterial and antiviral activities, enhancement of the immune system and increased nutrient absorption. To date, only breast-fed infants have been exposed to these proteins. However, by using genetic engineering it is now possible to express these proteins in plants, such as rice, at very high levels. Recombinant human milk proteins can subsequently be added to infant formula and baby foods. Prior to such addition, safety tests and efficacy trials need to be conducted. The safety tests will initially be done in rats and then in humans. The efficacy trials should also evaluate stability against heat treatment (processing), pH (stomach conditions) and proteolytic enzymes (digestion). To date, we have expressed recombinant human lactoferrin, lysozyme and α₁-antitrypsin in rice at very high expression levels. These recombinant proteins showed a stability and activities similar to those of the native milk proteins, suggesting that they may be able to exert biological activities in infants when added to formula or baby foods.

• human milk proteins
• recombinant milk proteins
• plant expression

Key teaching points:

• Recombinant human milk proteins can be expressed in plants at high levels.

• Recombinant human milk proteins appear to have biological activities similar to those of the native proteins.

• Recombinant human milk proteins appear to have stability against heat, low pH and proteolytic degradation that is similar to that of the native proteins.

• Extensive safety and efficacy trials will be needed prior to the potential addition of these proteins to infant formula or baby foods.

Key teaching points:

• Recombinant human milk proteins can be expressed in plants at high levels.

• Recombinant human milk proteins appear to have biological activities similar to those of the native proteins.

• Recombinant human milk proteins appear to have stability against heat, low pH and proteolytic degradation that is similar to that of the native proteins.

• Extensive safety and efficacy trials will be needed prior to the potential addition of these proteins to infant formula or baby foods.