Detection of bifidobacterial lipoproteins with anti-viral potential in donor human milk

Background: Group B coxsackieviruses (CVBs) are involved in triggering type 1 diabetes. Free bifidobacterial lipoproteins (BLps) prevent CVBs cell infection. Our objective is to isolate free BLps potentially released by bifidobacteria in breastmilk and document their bioavailability. Methods: Bifidobacterium breve and B. longum were quantified by qPCR in samples donated to the hospitals biobank (DHM) within two weeks following delivery. BLps were captured onto CV B4, analyzed by SDS-PAGE and competitive ELISA. BLps transport through Caco-2 monolayers was monitored after DHM contact. Titration of anti-CV B IgA was carried out by ELISA. Results: Among the 90 enrolled donors, seven were excluded, 68 donated a unique sample and 15 donated multiple specimens (2 to 12). B. breve and B.longum were detected in 93.0 % and 32.8% unique DHM samples, respectively. The two species showed unstable counts in the multiple donation group. Although at highly variable amounts, BLps were readily detected. Free B.longum Lps were found in absence of B.longum itself. The BLps crossed the cell layer within 4h still binding CV B4. Conclusion: DHM contained BLps able to cross a cell layer mimicking the intestine still retaining their capacity to bind CV B. It suggested a possible newborns systemic protection against CV B4 infection that needs further investigation.