Species-Specific Chromosome Engineering Greatly Improves Fully Human Polyclonal Antibody Production Profile in Cattle

PLoS One. 2015 Jun 24;10(6):e0130699. doi: 10.1371/journal.pone.0130699. eCollection 2015.

Abstract

Large-scale production of fully human IgG (hIgG) or human polyclonal antibodies (hpAbs) by transgenic animals could be useful for human therapy. However, production level of hpAbs in transgenic animals is generally very low, probably due to the fact that evolutionarily unique interspecies-incompatible genomic sequences between human and non-human host species may impede high production of fully hIgG in the non-human environment. To address this issue, we performed species-specific human artificial chromosome (HAC) engineering and tested these engineered HAC in cattle. Our previous study has demonstrated that site-specific genomic chimerization of pre-B cell receptor/B cell receptor (pre-BCR/BCR) components on HAC vectors significantly improves human IgG expression in cattle where the endogenous bovine immunoglobulin genes were knocked out. In this report, hIgG1 class switch regulatory elements were subjected to site-specific genomic chimerization on HAC vectors to further enhance hIgG expression and improve hIgG subclass distribution in cattle. These species-specific modifications in a chromosome scale resulted in much higher production levels of fully hIgG of up to 15 g/L in sera or plasma, the highest ever reported for a transgenic animal system. Transchromosomic (Tc) cattle containing engineered HAC vectors generated hpAbs with high titers against human-origin antigens following immunization. This study clearly demonstrates that species-specific sequence differences in pre-BCR/BCR components and IgG1 class switch regulatory elements between human and bovine are indeed functionally distinct across the two species, and therefore, are responsible for low production of fully hIgG in our early versions of Tc cattle. The high production levels of fully hIgG with hIgG1 subclass dominancy in a large farm animal species achieved here is an important milestone towards broad therapeutic applications of hpAbs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Antibodies, Monoclonal / biosynthesis*
  • Antibodies, Monoclonal / genetics
  • Antibodies, Monoclonal / immunology
  • Antibodies, Monoclonal, Humanized / biosynthesis*
  • Antibodies, Monoclonal, Humanized / genetics
  • Antibodies, Monoclonal, Humanized / immunology
  • Antigens / chemistry
  • Antigens / immunology
  • Cattle
  • Cell Line, Tumor
  • Chickens
  • Chromosome Mapping
  • Chromosomes, Artificial, Human / chemistry
  • Chromosomes, Artificial, Human / immunology*
  • Gene Knockout Techniques
  • Genetic Engineering
  • Genetic Vectors / chemistry
  • Genetic Vectors / metabolism*
  • Humans
  • Immunization
  • Immunoglobulin G / biosynthesis*
  • Immunoglobulin G / genetics
  • Immunoglobulin G / immunology
  • Lymphocytes / cytology
  • Lymphocytes / immunology
  • Pre-B Cell Receptors / genetics
  • Pre-B Cell Receptors / immunology*
  • Species Specificity

Substances

  • Antibodies, Monoclonal
  • Antibodies, Monoclonal, Humanized
  • Antigens
  • Immunoglobulin G
  • Pre-B Cell Receptors

Grant support

This work was financed by internal funding of Hematech, Inc., which no longer exists and no longer has financial interest in the work. There was no external funding sources for this study. Financial interest in this work is currently owned by SAB Biotherapeutics, Inc, who did have a role in the decision to publish as well as the preparation of the manuscript. While it is considered beneficial to the interests of SAB Biotherapeutics, Inc to publish this work, this consideration played no role in the study design, data collection and analysis and preparation of the manuscript. This is evidenced by the inclusion of now independent authors with no affiliation to SAB Biotherapeutics, Inc.