Recombinant Protein Expression in Milk of Livestock Species

Abstract

Producing complex recombinant proteins in the milk of transgenic animals offers several advantages: large amounts of proteins can be obtained, and in most cases, these proteins are properly folded, assembled, cleaved, and glycosylated. The level of expression of foreign genes in the mammalian gland cannot be predicted in all cases, and appropriate vectors must be used. The main elements of these vectors are as follows: a well-characterized specific promoter, the coding region of the gene of interest, preferably with a homologous or heterologous intron, to improve transcription efficiency, and an insulator or boundary element to counteract the chromosomal position effects at the integration site. Once high expression levels are achieved, and the recombinant protein is purified, an essential step in the analysis of the final product is determining its degree of glycosylation. This is an important readout because it can affect among other parameters the stability and immunogenicity of the recombinant protein.

Characterization of the Rabbit Neonatal Fc Receptor (FcRn) and Analyzing the Immunophenotype of the Transgenic Rabbits That Overexpresses FcRn

“…Subsequently, the linearized DNA was run on a pulsed-field gel and recovered from the gel by GElase digestion (Epicentre Biotechnologies, Madison, WI, USA) [72]. The linearized BAC DNA was injected into pronuclei of New Zealand White rabbit zygotes.…”

Hybrid expression cassettes consisting of a milk protein promoter and a cytomegalovirus enhancer significantly increase mammary‐specific expression of human lactoferrin in transgenic mice

“…Although many long regulatory elements have been useful for driving targeted transgene expression in milk, low efficiency and uncertain expression are seen in most transgenic individuals (Bosze and Hiripi, 2012). This has caused researchers to spend considerable time and effort producing animals over‐expressing these transgenes.…”

“…Constructing vectors and transferring large foreign DNA fragments is demanding and difficult. Due to the relatively complex relationship between the host genome and the introduced transgene, the actual and final protein expression level in milk is unpredictable (Bosze and Hiripi, 2012).…”

Current Research, Challenges, and Perspectives of Biotechnology: An Overview

“…Many genes for growth hormones have been constructed with engineered promoters to produce human pharmaceutical peptides and proteins in the milk of mice, rabbits, sheep, goats, swine, and cattle. It is likely that this approach is feasible to produce human pharmaceutical products rather than conventional industrial procedures (Bosze and Hiripi, 2012). Although many attempts have been carried out, the first two therapeutic agents to be isolated from the milk of transgenic animals, C1 inhibitor and antithrombin, are now commercialized.…”