The worldwide AIDS epidemic is most devastating in developing countries, where mOfe than 40 million people are Infected. Development of an HIV-1 vaccine for POPulations In southern Africa and other developing countries is the highest priority. Currentiy HIV-1 vaccines designed to drive Th1-type and cytotoxic CD8+ T cell fesponses afe the candidate vaccines in development or in clinical trials. In addition, inhabitants in developing countries aTe also infected with helminth parasites which suppress immune responses to ThHype vaccines and expansion of viral antigenspecific C04+ and CDS+ T cell responses. Therefore, how helminth Infection impacts the induction of neutrali;!:;ing antibodies or robust T cell responses to candidate HIV-1 vaccines is an Important question to investigate prior to testing of candidate vaGCill6s in helminth infected populations. In this application we propose to examine immune responses to a gut-deUvered Listeria vector HIV-1 vaccine in naIVe and schIStosome infected mice. We chose Listeria vectors do to the fact that the gut is the ear1y site of HIV-1 replication. In addition to the impact of helminth infection, we will also examine how prior infection and then re -Infectlon with helminth parasites impacts the ability of Listeria vector HIV-1 vaccines to induce neutralizing antibody and vaccine specific T cell responses in mice . . We will also determine if reinfection with schistosomes impacts T cell memory. We also propose 10 examine both of these questions in Th1-type and Th2-type mice. The specifiC aims of this proposal are: 1) Will eradication of schistosome infection In mice allow their immune systems to mount strong C04+ and CD8+ T celi and neutralizing ab responses follOWing vaccination with Listeria vector HIV[unreadable]1 candidate vaccines? 2) Will re[unreadable] lnfection with schistosomes alter Llst~ria vector HIV-1 vaccine induced neutralizing antibody orT cell memory responses?