Another example is the production of the bovine β-lactoglobulin (BLG) in L. lactis [30, 31] . BLG, a 162 amino acid residues globular protein, is the dominant allergen in cow's milk and was produced in L. lactis to test the immunomodulation of the allergenic response in mice when BLG is delivered by a bacterial vector [30] . Western blot and ELISA showed that BLG production was significantly higher when BLG was fused to SP Usp45 although the SE was very low, with no detectable BLG in the supernatant of pSEC:BLG strains [30] . Further studies revealed that a fusion between the LEISS propeptide and BLG could not enhance the SE of BLG above ~5%, as determined by ELISA [31] .