#$%^&*AU2020101512A420200903.pdf#####ABSTRACT The present invention relates to the microbiomes of humans and other animals as biomarkers and therapeutic targets for regulation or altering of a microbiome profile associated with states of disease or disease risk, using additive and subtractive therapies aimed at restoring a microbiome profile associated with health, with reduced manifestations of disease, or with reduced disease risk. In particular, the invention provides methods of subtractive therapy using microorganism-specific avian egg yolk-derived immunoglobulins (IgY) in a fashion that titrates, without necessarily eliminating, populations of microorganisms known to be associated with human gut and extraintestinal diseases.