Intramuscular (IM) immunization is generally considered incapable of generating a protective mucosal immune response. In the swine industry, attempts to develop a safe and protective vaccine for controlling porcine epidemic diarrhea (PED) via an IM route of administration have been unsuccessful. In the present study, porcine chemokine ligand proteins CCL25, 27, and 28 were constructed and stably expressed in the mammalian expression system. IM co-administration of inactivated PEDV (iPEDV) particles with different CC chemokines and Freund's adjuvants resulted in recruiting CCR9+ and/or CCR10+ inflammatory cells to the injection site, thereby inducing superior systemic PEDV specific IgG, fecal IgA, and viral neutralizing antibodies in pigs. Moreover, pigs immunized with iPEDV in combination with CCL25 and CCL28 elicited substantial protection against a virulent PEDV challenge. We show that the porcine CC chemokines could be novel adjuvants for developing IM vaccines for modulating mucosal immune responses against mucosal transmissible pathogens in pigs.Vaccines 2020, 8, 102 2 of 16 immunization region to mucosal sites [25][26][27][28][29][30]. On the other hand, the CCL25/TECK expressed by mucosal epithelial cells can chemo-attract CCR9+ cells and support CCR9 expression leukocytes to migrate to the small intestine [30,31]. The application of CCL27 and CCL25 as an adjuvant in DNA vaccines was proven to enhance systemic and/or mucosal immune responses following IM injection in mice or macaques [32,33]. Therefore, the incorporation of these CC chemokines as immune trafficking signals could be a potential strategy for the development of effective parenteral PEDV vaccine regimens.In the present study, three porcine CCL proteins, namely, CCL27, CCL28, and CCL25 were constructed and stably expressed in the mammalian cell expression system. Different combinations of these chemokines were intramuscularly co-administrated with inactivated PEDV (iPEDV) viral particles and Freund's adjuvant in pigs. Immunohistochemical (IHC) staining was performed to detect the infiltration of cognate chemokine receptors, CCR9+ or CCR10+, bearing immune cells, to the sites of immunization. The immunogenicity and protective efficiency of iPEDV adjuvanted with Freund's adjuvant in different combinations of CC chemokines were evaluated in 5-week-old pigs.