A first object of the invention is CGRP or an agonist of the CGRP receptor for use in the prevention of an HIV infection in a human subject. A second object of the invention is a method for selecting an active compound for the prevention of an HIV infection in a human subject, comprising the steps of: a) contacting Langerhans cells with a candidate compound b) in vitro infecting of Langerhans cells from step a) by at least one HIV variant, c) measuring of at least one of the following parameters: HIV content, adhesive potential of Langerhans cells, in particular to TCs, secretion of anti-HIV chemokines by Langerhans cells. A third object of the invention is therefore a composition comprising CGRP or agonist of the CGRP receptor for use in the prevention of an HIV infection in a human subject. A fourth object of the invention is a method for the in vitro diagnosis of an HIV infection in a human subject, characterized in that it comprises determining the level of CGRP from a biological sample from said subject. A fifth object of the invention is a method for assaying the efficiency of HAART in the treatment of HIV infection in a subject, characterized in that it comprises determining the level of CGRP from a biological sample from said subject.
