3'-Sialyllactose consists of the monosaccharide N-acetylneuraminic acid linked to the galactosyl subunit of lactose at the 3 position. It is an abundant oligosaccharide in the milk of many mammals, including cows and humans, particularly postpartum.{27235,27232} 3'-Sialyllactose avidly binds several viral strains, including strains of influenza, HIV-1, reovirus, and polyomavirus.{27234,27230,27228,27229} In some cases, binding of 3’-sialyllactose to viral proteins alters viral infectivity.{27234,27230,27228} 3'-Sialyllactose also alters Helicobacter activity and impacts bacterial colonization of gut.{27231,27233}