We suggested that the moderate immersion depth of MPER in membranes, which made MPER more exposed, but antigenically preserved, was another reason underlying the ability of NCM to elicit higher titers of MPER-specific antibodies. Interestingly, the induced MPERspecific Paclitaxel antibodies mainly targeted an extended 4E10 epitope as we had expected. Thus, physicochemical property and structure changes, together with decreased immersion depth, may correlate with the increased immunogenicity of MPER in NCM. Although NCM could elicit relatively higher titers of MPER-specific antibodies than non-mutated NCM or other gp41- derived recombinant proteins described previously, it lacks the ability to induce highly potent and broad neutralizing antibodies against primary HIV-1 isolates. Therefore, more efforts should be taken to make NCM a rational candidate for an HIV vaccine to elicit higher titer and more potent and broader neutralizing antibodies. Fortunately, many studies have provided some useful suggestions, such as implementing a new immunization strategy, using strong adjuvants to break B-cell tolerance, or introducing mutations which could favor the formation of prehairpin intermediate conformation or prolong exposure of MPER. In conclusion, our study presented a rationally designed immunogen consisting of the gp41 6HB core and the exposed MPER tail with a double mutation. This immunogen could elicit high titers of MPER-specific antibodies with broad neutralizing activity. Although the precise underlying molecular mechanism remained unclear, we confirmed that that double T569A/I675V mutations in gp41 are ASP1517 critical for significantly enhancing the immunogenicity of neutralizing epitopes in the gp41 MPER. Therefore, this study might provide important implications for designing novel MPER-based HIV-1 vaccines with increased immunogenicity for eliciting potent and broad neutralizing antibodies. Therapeutic monoclonal antibodies with more than 20 products in clinical use and over 200 candidates in clinical investigation constitute a promising avenue for the treatment of several major diseases including autoimmune, cardiovascular, infectious diseases, cancer and inflammation. Furthermore, development of novel antibody targets for the treatment of several neurological diseases such as Alzheimer��s disease is being currently investigated. However, major drawbacks that presently limit the use of therapeutic antibodies following systemic delivery is related to the poor distribution at the targeted tissues, inadequate pharmacokinetics, and elevated costs of manufacture. The development of new methods for the continuous delivery of antibodies and/or its fragments that would allow reduction of interventions, prolonged retention at the targeted site, slow clearance and low cost of goods is therefore highly desirable.