Oral administration of Lactic acid bacteria inhibits PEDV infection in young piglets

Since the emergence of the highly pathogenic porcine epidemic diarrhea virus (PEDV) strain in 2010, the prevention of porcine epidemic diarrhea (PED) in pig farms remains problematic. To find the reasons behind the high mortality in young piglets, the relative mRNA expression of inflammation-related factors in infected pigs of different ages as well as uninfected pigs were detected by RT-qPCR. The results showed that the mRNA expression of these factors including IL-6 and TNF-α was more increased in infected younger piglets than infected older pigs. To clarify the relationship between these inflammation related factors, the pairwise linear correlation between the relative expression of these factors were analyzed and showed as network mapping with different correlation coefficients. A strong positive correlation was observed between the expression of various factors in 1-week-old piglets. Combined with the difference in mortality of PEDV infection in pigs of different ages, we hypothesized that lactic acid bacteria (LAB) could inhibit PEDV infection in newborn piglets, and an in vivo experiment was carried out. The results of survival rate and wet/dry ratio showed that LAB alleviated PEDV indued mortality and diarrhea. The detection of viral copies and tissue section staining showed less observed viruses in LAB treated pig. RT-qPCR results of gene expression in intestines showed that LAB modulated the gene expression of various host barrier genes, indicating that LAB is potential to inhibit PEDV infection by regulating the host intestinal barrier. However, to use LAB as therapy, how to improve the efficiency on inhibiting PEDV infection needs further studies. •The mRNA level of the inflammation-related factors was significantly increased in PEDV-infected younger piglets than older pigs.•A strong positive correlation was observed between the level of inflammation-related factors in 1-week-old piglets.•PEDV-induced severe pathogenic changes were improved in the pig treated with LAB prior to viral infection.