2586. Human Breast Milk Inhibits the Replication of Parechovirus-A3

BACKGROUND: Parechovirus-A3 (PeV-A3) is an emerging pathogen causing sepsis and meningoencephalitis in neonates and young infants. We previously reported that maternal antibodies against PeV-A3 are important to protect neonates and young infants from the infection. Recent studies showed that (1) breastfeeding had a protective effect against enterovirus, which is closely-related virus to PeV-A, and (2) human breast milk (HBM) neutralized enterovirus in vitro. Currently, no report is available related to the antiviral effect of HBM against PeV-A3. METHODS: HBM (colostrum, 3–5 days after childbirth; mature milk, 1 month after childbirth) and serum (within ± 1 week of child’s birthday) samples were obtained from mothers at obstetrics clinic in Niigata, Japan. Neutralizing antibody titers (NATs) against PeV-A3 were measured using the Vero cells. RESULTS: The anti-PeV-A3 NATs of colostrum (n = 32) ranged from 1:8 to 1:2048, those ≥1:32 was 59% (19/32). Whereas, the anti-PeV-A3 NATs of mature milk ranged from 1:8 to 1:96. and those ≥1:32 was 20% (2/20) (P < 0.001). The median NATs anti-PeV-A3 was higher in colostrum (1:32) compared with mature milk (1:8) (P < 0.001). There was a strong positive correlation between the NATs of colostrum and serum (r = 0.604, P < 0.001, Figure). CONCLUSION: This study showed that HBM had high NATs against PeV-A3, which was correlated with serum NATs. Further studies are necessary to investigate which components of HBM has antiviral effects against PeV-A3. [Image: see text] DISCLOSURES: All authors: No reported disclosures.