Process for purifying an antibody from egg yolk, products and uses thereof

A process for purifying an IgY antibody from egg yolk with a minimum level of purity of 98-%, consisting of:

• diluting the egg yolk 7 times with water, wherein the step of diluting the yolk is carried out at a pH of 5;
• freezing and thawing the egg yolk, wherein the step of freezing the egg yolk is carried out at a temperature between −20-0° C., between 8-24 hours;
• wherein thawing the egg yolk is carried out at a temperature between 15-25° C., between 2-10 hours;
• centrifuging the egg yolk in order to obtain an aqueous soluble protein fraction (SPF);
• wherein the step of centrifuging the thawed egg yolk in order to obtain the soluble aqueous fraction is carried out at 5000 g, at a temperature of 4° C. and for 60 minutes;
• subjecting the aqueous soluble protein fraction to at least one precipitation step with a precipitating agent;
• ultrafiltrating the aqueous soluble protein fraction subjected to at least one precipitation step in order to obtain the purified antibody, and removing the precipitating agent;
• wherein the step of subjecting the aqueous soluble protein fraction to at least one precipitation step with a precipitating agent comprises a first and a second precipitation step with a precipitating agent, wherein the precipitate obtained on the first precipitation step is resuspended;
• wherein the precipitating agent is polyethylene glycol;
• wherein the polyethylene glycol has a molecular weight between is 6000 g/mol;
• wherein the first precipitation step is carried out with a concentration of 8.5% wtpolymer/VSPF polyethylene glycol, and wherein the second precipitation step is carried out with a concentration of 12% wtpolymer/VIgY resuspended after first precipitation step polyethylene glycol;
• and
• wherein the step of ultrafiltration of the aqueous soluble protein fraction is carried out with a filter with pores of 150 kDa, and
• optionally, a prior step of preserving an egg between 1-12 weeks and/or a step of separating the egg yolk from the egg white, wherein albumin is removed from the surface of the egg yolk sac membrane before said membrane is punctured.