(D) MHCII-gp120 induced antibodies that neutralized HIV-1

(D) MHCII-gp120 induced antibodies that neutralized HIV-1. from pathogens have several EDM1 advantages over other vaccine strategies. DNA vaccines can easily be altered, they show good safety profiles, are stable and inexpensive to produce, and the immune response can be focused to the antigen of interest. However, the immunogenicity of DNA vaccines which is generally quite low needs to be improved. Electroporation and co-delivery of genetically encoded immune adjuvants are two strategies aiming at increasing the efficacy of DNA vaccines. Here, we have examined whether targeting to antigen-presenting cells (APC) could increase the immune response to surface envelope glycoprotein (Env) gp120 from Human Immunodeficiency Computer virus type 1 (HIV-1). To target APC, we utilized a homodimeric vaccine format denoted vaccibody, which enables covalent fusion of gp120 to molecules that can target APC. Two molecules were tested for their efficiency as targeting units: the antibody-derived single chain Fragment variable (scFv) specific for the major histocompatilibility complex RS 127445 (MHC) class II I-E molecules, and the CC chemokine ligand 3 (CCL3). The vaccines were delivered as DNA into muscle of mice with or without electroporation. Targeting of gp120 to MHC class II molecules induced antibodies that neutralized HIV-1 and that persisted for more than a year after one single immunization with electroporation. Targeting by CCL3 significantly increased the number of HIV-1 gp120-reactive CD8+ T cells compared to non-targeted vaccines and gp120 delivered alone in the absence of electroporation. The data suggest that chemokines are promising molecular adjuvants because small amounts can attract immune cells and promote immune responses without advanced equipment such as electroporation. Introduction Vaccines based on live attenuated pathogen often elicit strong, lifelong immune responses and protection against disease. However, safety and efficacy in immunocompromised individuals is a concern. In addition, live attenuated pathogens have the very rare potential to revert to a pathogenic form [1]. Therefore, RS 127445 alternative vaccine strategies are desired. Killed or inactivated pathogens may be used, but side effects may still be a problem as well as lower efficacy. A promising alternative utilizes pathogen-derived subunits delivered as protein or DNA. Subunit-based vaccines show good safety, and in particular DNA vaccines are easy and fast to produce and are stable in terms of storage and temperature changes [2], [3]. Three successful DNA vaccines have been licensed for animal use [4], [5], [6], and several clinical trials with DNA vaccines have been conducted in humans [2] (clinicaltrials.gov). Whereas pathogens harbour potent immunostimulatory molecules, these are often lost in the subunit-based vaccines. Thus, in recent years, several attempts have been made aiming at increasing the immunogenicity of such vaccines [3], [7], [8]. For subunit-based DNA vaccines, two improvements include electroporation and delivery of genetically encoded immune adjuvants. Electroporation can enhance cellular uptake of DNA, increase DNA distribution throughout the tissue, and cause a local inflammatory reaction. All these events contribute to a stronger immune response [7],[9]. The two most widely tested immune adjuvants are the cytokines granulocyte macrophage RS 127445 colony-stimulating factor (GM-CSF) and interleukin (IL)-12, which both can improve immune response [7], [10], [11], [12]. To further improve the response, electroporation may be combined RS 127445 with delivery of adjuvants [7], [8]. Targeting of antigen to endocytic molecules present on antigen-presenting cells (APCs) is another strategy that is utilized to increase immunogenicity of pathogen-derived subunits delivered as protein or as DNA. This can improve effectiveness of vaccines, reduce the amount of antigen needed, and it may also promote cross-presentation of antigens [13], [14], [15], [16]. Several targeting approaches utilize the ligand-binding properties of the variable regions of antibodies, and already in the 80s, targeting by an antibody specific for immunoglobulin or major histocompatibility complex (MHC) class II was utilized to increase immune responses [17], [18]. A widely tested targeting approach for HIV-1-derived subunits is their fusion to the C-terminus of an antibody specific for the type I C-type lectin DEC205 (CD205). Upon co-delivery with a toll-like receptor (TLR) 3-agonist, this approach results in increased antigen-specific CD4+ and CD8+ T cell responses [19], [20], [21]. Finally, chemokines may be utilized [22], [23], [24], [25], [26], [27], [28], [29], [30]. Chemokines can recruit APCs expressing the corresponding chemokine receptors to the injection site of the vaccine, and promote cellular uptake.