Both HIV-1NL4-3 env mutant strains (V38A, X23) were as susceptible to the antiviral effect of lemon balm extract as the wildtype strain in a luciferase reporter assay on TZM-bl cells (Fig. 5A), while mutants required higher concentrations of enfuvirtide to inhibit infection compared to the wildtype strain, as reported previously [14,15]. Here, ERVW-1 is linked to infection.