Development of Transgenic Mice Expressing Calcitonin as a Beta-lactoglobulin Fusion Protein in Mammary Gland

Genetically modified animals for use in biopharmacology: from research to production

Introduction: In this review, the analysis of technologies for obtaining biologically active proteins from various sources is carried out, and the comparative analysis of technologies for creating producers of biologically active proteins is presented. Special attention is paid to genetically modified animals as bioreactors for the pharmaceutical industry of a new type. The necessity of improving the technology of development transgenic rabbit producers and creating a platform solution for the production of biological products is substantiated.

The advantages of using TrB for the production of recombinant proteins: The main advantages of using TrB are the low cost of obtaining valuable complex therapeutic human proteins in readily accessible fluids, their greater safety relative to proteins isolated directly from human blood, and the greater safety of the activity of the native protein.

The advantages of the mammary gland as a system for the expression of recombinant proteins: The mammary gland is the organ of choice for the expression of valuable recombinant proteins because milk is easy to collect in large volumes.

Methods for obtaining transgenic animals: The modern understanding of the regulation of gene expression and the discovery of new tools for gene editing can increase the efficiency of creating bioreactors for animals and help to obtain high concentrations of the target protein.

The advantages of using rabbits as bioreactors producing recombinant proteins in milk: The rabbit is a relatively small animal with a short duration of gestation, puberty and optimal size, capable of producing up to 5 liters of milk per year per female, receiving up to 300 grams of the target protein.

Recombinant porcine lactoferrin expressed in the milk of transgenic mice enhances offspring growth performance

The European Commission has proposed a permanent ban on the use of antibiotics as an ingredient in animal feed to promote growth. Lactoferrin is a globular multifunctional protein that has been shown to play a role in iron absorption and to have antimicrobial and anti-inflammatory activities. Therefore, lactoferrin may serve as a nontherapeutic alternative to antibiotics in livestock husbandry. As a pilot study toward this goal, transgenic mice have been generated harboring a porcine lactoferrin (pLF) gene driven by the mammary gland-specific promoter of the bovine alpha-lactalbumin (alphaLA) gene. The alphaLA-pLF hybrid gene was confirmed to have been successfully integrated and transmitted stably through the germ-line in 9 (5 females and 4 males) of 14 transgenic founders. In the female progenies of six lines analyzed, the transgene copy numbers ranged from 1 to 20 with 1-4 integration sites. Significant levels of pLF protein in milk ranging from 40 to 106 microg/mL with physical characteristics similar to those of native pLF in sow's milk were achieved in three of the transgenic lines obtained. Tissue- and stage-specific pLF expressions were restricted to the mammary gland of the transgenic female mice during lactation. It was further demonstrated that the growth performance of animal pups is enhanced by directly feeding the genetically engineered milk containing enriched pLF protein in transgenic mice. Furthermore, this enhanced growth performance in suckling mice was proportional to the concentration of pLF present in milk.