Transgenic Mice Secreting Coronavirus Neutralizing Antibodies into the Milk

Abstract

Ten lines of transgenic mice secreting transmissible gastroenteritis coronavirus (TGEV) neutralizing recombinant monoclonal antibodies (rMAbs) into the milk were generated. The rMAb light- and heavy-chain genes were assembled by fusing the genes encoding the variable modules of the murine MAb 6A.C3, which binds an interspecies conserved coronavirus epitope essential for virus infectivity, and a constant module from a porcine myeloma with the immunoglobulin A (IgA) isotype. The chimeric antibody led to dimer formation in the presence of J chain. The neutralization specific activity of the recombinant antibody produced in transiently or stably transformed cells was 50-fold higher than that of a monomeric rMAb with the IgG1 isotype and an identical binding site. This rMAb had titers of up to 104 by radioimmunoassay (RIA) and neutralized virus infectivity up to 104-fold. Of 23 transgenic mice, 17 integrated both light and heavy chains, and at least 10 of them transmitted both genes to the progeny, leading to 100% of animals secreting functional TGEV neutralizing antibody during lactation. Selected mice produced milk with TGEV-specific antibody titers higher than 106 as determined by RIA, neutralized virus infectivity by 106-fold, and produced up to 6 mg of antibody per ml. Antibody expression levels were transgene copy number independent and integration site dependent. Comicroinjection of the genomic β-lactoglobulin gene with rMAb light- and heavy-chain genes led to the generation of transgenic mice carrying the three transgenes. The highest antibody titers were produced by transgenic mice that had integrated the antibody and β-lactoglobulin genes, although the number of transgenic animals generated does not allow a definitive conclusion on the enhancing effect of β-lactoglobulin cointegration. This approach may lead to the generation of transgenic animals providing lactogenic immunity to their progeny against enteric pathogens.

Immune response induced by spike protein from transmissible gastroenteritis coronavirus expressed in mouse mammary cells

“…Sola et al (1998) demonstrated that the mouse mammary gland tissue performs the adequate posttranslational processing required for the correct assembly of antibody molecules. The secretion of neutralizing MAbs in the milk of transgenic animals could be applied to improve disease resistance in livestock and to prevent neonatal infections by a number of pathogens for which specific MAbs are available (Sola et al, 1998;Kolb et al, 2001). This approach may lead to the generation of transgenic animals providing lactogenic immunity to their progeny against pathogens.…”

“…Transmissible gastroenteritis coronavirus (TGEV) infects enteric and respiratory tissues of newborn pigs and causes mortality close to 100% (Cavanagh, 1997;Sola et al, 1998). The rapid spread of the transmissible gastroenteritis (TGE) can be prevented only by vaccination.…”

Therapeutic Applications of Monoclonal Antibodies

“…25 For instance, transgenic mice that express MAbs to coronavirus in their milk have been developed. 26,27 Because ruminant animals, such as cows, goats, and sheep, produce relatively large amounts of milk, genetically-modified members of these species could also be used to produce large quantities of therapeutic proteins, including MAbs. 28 Plants may be a potential source of recombinant proteins, including MAbs.…”

Antibody manufacture in transgenic animals and comparisons with other systems

“…The production of a few monoclonal antibodies in milk has been documented [30 •• ]. Mouse monoclonal antibodies, both humanized and non-humanized, that are capable of neutralizing coronavirus have been produced in mouse milk at a concentration of up to several grams per litre [40,41].…”