African Swine Fever Virus is a highly contagious and fatal emerging pathogen that threatens the swine industry worldwide. Currently, no ASF vaccine is available and the complexity of the virus and our limited understanding of the viral proteins that confer protective immunity in pigs have significantly hindered progress on vaccine development. The overall goals of the study proposed here are to identify ASFV proteins that contribute to host immune responses and to define effector immune functions that are important for protection. Notably, a recent study on ASFV demonstrated induction of sterile immunity against ASFV following immunization with an attenuated vaccine candidate, suggesting that host immune responses against viral proteins may play an important role in protection. Based on these findings, we hypothesize that ASFV virion proteins are important inducers of effector host immune responses to ASFV. To address this hypothesis, we propose the following specific aims: 1) To determine the role of ASFV virion proteins on induction of effector antibody responses; and 2) To determine the role of ASFV virion proteins on induction of effector T cell responses. To achieve these objectives, we will use a poxvirus-ASFV expression library encoding all 20 ASFV virion proteins localized to the outer envelope, capsid, inner envelope and core shell which form the basic architecture of the virus particle to immunize pigs and assess host antibody and T cell responses elicited against the individual proteins. On Aim 1, antibody responses to each of the ASFV virion proteins will be assessed by indirect immunofluorescence (IFA) and/or ELISA assays. Effector antibody responses will be evaluated by virus neutralization assays and by hemadsorption inhibition (HAI) assays. Additionally, the ability of each individual virion protein to induce antibody-dependent cellular cytotoxicity (ADCC) will also be evaluated following immunization. Aim 2 will focus on dissecting ASFV-specific T cell responses elicited by immunization with each virion protein in our library. Initially, the ability of each protein to induce T cell responses will be assessed by lymphocyte proliferation and IFNγ secretion assays. Proteins that induce T cell responses, as assessed by proliferation and IFNγ secretion assays, will also be evaluated for their ability to elicit cytotoxic T cell responses. We expect to identify important ASFV virion proteins that contribute to host specific immunity and define immune effector functions elicited against individual ASFV proteins. An improved understanding of the viral and host determinants of immunity may lead to the rational development of effective first-generation vectored ASFV vaccines.