LASTING BIOLOGICAL EFFECTS OF EARLY ENVIRONMENTAL INFLUENCES* IV. NoTEs ON THE PHYSICOCHEMICAL AND IMMDNOLOGICAL CHARACTERISTICS OF AN ENTEROVIRUS THAT DEPRESSES

A lasting depression of body weight can be achieved consistently by contaminating newborn mice, specific pathogen-free (SPF), with a filterable agent derived from the intestine of mice raised under ordinary conditions of husbandry (1, 2). Adult SPF mice, contaminated with this agent after birth, exhibit a variety of metabolic abnormalities, such as reduced ability to incorporate amino acids and to utilize dietary nitrogen (2). Although the active filterable agent has been cultivated in tissue culture (1), there is as yet no convincing evidence that it has been completely separated from other agents. For the sake of convenience, it will be tentatively designated here as enterovirus, using as single criterion of its pathogenicity its ability to cause a lasting depression of body weight of SPF mice. The present report describes the effect of certain physical, chemical, and immunological procedures on the biological activities of preparations of this agent administered by the oral route into newborn mice.