Chimeric antigens for eliciting an immune response

Abstract

Disclosed herein are compositions and methods for eliciting immune responses against antigens. In particular embodiments, the compounds and methods elicit immune responses against antigens that are otherwise recognized by the host as “self” antigens. The immune response is enhanced by presenting the host immune system with a chimeric antigen comprising an immune response domain and a target binding domain, wherein the target binding domain comprises a xenotypic antibody fragment. By virtue of the target binding domain, antigen presenting cells take up, process, and present the chimeric antigen, eliciting both a humoral and cellular immune response.

1 - 49 . (canceled) 
     
     
         50 . A purified chimeric antigen for eliciting an immune response against Human immunodeficiency virus (HIV) in a host, said chimeric antigen comprising:
 an immune response domain, wherein the immune response domain comprises at least one antigenic portion of an HIV protein selected from the group consisting of Gag, Env, Tat, Rev, Vpr and Vpu, and a combination thereof, a target binding domain, wherein the target binding domain consists of a hinge region, at least a portion of a C H 1 region and a xenotypic Fc antibody fragment comprising at least part of a C H 2 and C H 3 domain, wherein the immune response domain and the target binding domain are linked by peptide linkage.   
     
     
         51 . The chimeric antigen of  claim 50 , wherein the chimeric antigen elicits a humoral immune response, a cellular immune response, or both a humoral immune response and a cellular immune response. 
     
     
         52 . The chimeric antigen of  claim 50 , wherein the chimeric antigen elicits a Th1 immune response, a Th2 immune response or both Th1 and Th2 immune responses. 
     
     
         53 . The chimeric antigen of  claim 50 , wherein the immune response is an in vivo immune response. 
     
     
         54 . The chimeric antigen of  claim 50 , wherein the target binding domain is capable of binding to an antigen presenting cell (APC). 
     
     
         55 . The chimeric antigen of  claim 50 , further comprising one or more of a 6×His tag, a protease cleavage site, and a linker for linking the immune response domain and the target binding domain. 
     
     
         56 . The chimeric antigen of  claim 50 , wherein the linker is selected from the group consisting of leucine zippers, biotin bound to avidin, or a covalent peptide linkage. 
     
     
         57 . The chimeric antigen of  claim 50 , wherein the chimeric antigen is glycosylated. 
     
     
         58 . The chimeric antigen of  claim 50 , wherein the chimeric antigen is mannose glycosylated. 
     
     
         59 . A method of delivering an antigen to an antigen presenting cell, the method comprising administering to the antigen presenting cell a chimeric antigen of  claim 50 . 
     
     
         60 . The method of  claim 59 , wherein the antigen presenting cell is a dendritic cell. 
     
     
         61 . A method of activating an antigen presenting cell, the method comprising contacting the antigen presenting cell with a chimeric antigen of  claim 50 . 
     
     
         62 . The method of  claim 61 , wherein the contacting takes place ex vivo. 
     
     
         63 . The method of  claim 61 , wherein the contacting takes places in vivo. 
     
     
         64 . The method of  claim 63 , wherein the contacting takes place in a human. 
     
     
         65 . The method of  claim 63 , wherein the method comprises administering to a subject a composition comprising a chimeric antigen comprising an immune response domain and a target binding domain, wherein the immune response domain comprises one or more antigenic portions of one or more HIV proteins selected from the group consisting of Gag, Env, Tat, Rev, Vpr and Vpu, and a combination thereof, and the target binding domain comprises a xenotypic Fc antibody fragment, and wherein the antigen presenting cell is in the subject. 
     
     
         66 . The method of  claim 63 , wherein the contacting results in a humoral immune response, a cellular immune response, or both a humoral immune response and a cellular immune response. 
     
     
         67 . The method of  claim 66  wherein the cellular immune response is one or more of a Th1 response, a Th2 response, and a CTL response. 
     
     
         68 . The method of  claim 65 , wherein the subject has, or is likely to have, HIV. 
     
     
         69 . The method of  claim 65 , wherein the subject is not HIV-infected. 
     
     
         70 . A pharmaceutical composition comprising a chimeric antigen of  claim 50  and a pharmaceutically acceptable excipient.