The present invention relates to a novel antibody against HERV-K envelope that targets a conserved region not affected by glycosylation or by native conformation, and its use in diagnostics and/or in therapy.本發明係關於一種新穎抗HERV-K套膜之抗體,其以未受到醣苷化或天然構型影響的保留區為標的,及其於診斷及/或治療的用途。