The present invention relates to the microbiomes of humansand other animals as biomarkers and therapeutic targets for regulation oraltering of a microbiome profile associated with states of disease or diseaserisk,using additive and subtractive therapies aimed at restoring a microbiomeprofile associated with health, with reduced manifestations of disease, orwithreduced disease risk. In particular, the invention provides methods ofsubtractivetherapy using microorganism-specific avian egg yolk-derivedimmunoglobulins (IgY) in a fashion that titrates, without necessarilyeliminating, populationsof microorganisms known to be associated with human gut and extraintestinaldiseases.
