The present invention relates to the production of antibodies in transgenic plants and screening of said antibodies for binding to antigens. The invention provides a method by which a large number of antibodies with variations in the multivariable regions are produced and screened for binding to antigens. The invention is particularly useful for the production of antibodies to antigens which may be present in different variants such as for example HIV-1 and A- or B-influenza viruses.