We have previously demonstrated that recombinant C. crescentus displaying MIP1α, CD4, anti-viral lectins and HIV-1 fusion inhibitors are able to provide 22–85% protection from HIV-1 infection in vitro, likely through direct interaction with either the viral envelope (CD4, anti-viral lectins, fusion inhibitors) or co-receptor blocking on the target cell (MIP1α)20,22. The gene discussed is CD4; the disease is HIV-1 infection.