Recombinant C. crescentus displaying elafin, BmKn2, α-1-antitrypsin, indolicidin and an indolicidin multimer individually within the S-layer were incubated with HIV-189.6 for 1 hour before adding TZM-bl cells or PBMCs and HIV-1 infection was measured 48 hours later. This evidence concerns the gene PI3 and HIV-1 infection.