Antiviral Effect And Immune Regulation Mechanism Of Intestinal Probiotics To Enterovirus Infection

The application of probiotics has lasted for decades, though the live action mechanism is not yet clear, but their significant curative effection on the digestive tract diseases have been fully confirmed in clinic.People paid more and more attention for the immune regulating function of probiotics. It is commonly believed that the molecular and cellular mechanisms of probiotics' protect effection of infectious diarrhea mainly involves three aspects:(1) the probiotic bacteria can produce antibacterial material and competitive and pathogenic microorganism adhesion in the intestinal epithelium to prevent adhesion and engraftment of pathogens in the intestinal tract;(2) the probiotics can improve the survival rate of intestinal epithelial cells and protect the intestinal normal physiological structure when virus infection.Meanwhile,probiotics can stimulate protective immune responses to regulate the body's immune;(3) probiotics can protect and defend against pathogenic microorganisms By adjuste the intestinal microecological balance.This research mainly from the molecular level, cellular level and animal test three aspects in this paper, test the antiviral effect of the pig source probiotics to TGEV and PEDV in vitro and in vivo. Obtained the following results:(1) Separating out 3 antiviral strains of porcine intestinal probiotics Y091231, Y091221 and Y224031, by 16 s rDNA identification of saliva respectively Lactobacillus(Lactobacillus saliarius), Johnston's Lactobacillus(Lactobacillus johnsonii) and dung Enterococcus(Enterococcus faecalis).(2) Selected probiotics play a protective role of TGEV infection on ST cells. Three access probiotic bacteria and their metabolites in a different order, inhibition of virus is different also, Y091231 bacteria suspension in the case of access in advance can achieve maximum inhibition rate(65%), while Y091221 and Y224031 when access together with virus showed higher inhibition rate. By semi-quantitative rt-pcr test results, the three probiotic bacteria and their metabolites can reduce TGEV in ST cell proliferation, Y091231 bacteria suspension in the treatment group, has the stable high virus inhibition.In addition, the probiotic bacteria in vitro TGEV resistant, can increase IL- 8 and IL- 12, while lowering IL- 4 and INF- a four kinds of cytokines in the amount of expression in the cell culture supernatant, thus stimulating cellular immunity, resist virus invasion.(3) Identification of PEDV- WN strain isolated, animal model was constructed. Isolated from clinical disease material PEDV and RT- PCR identification of the strains and M, S gene sequence analysis, and CV777 plant comparative analysis of PEDV- WN strains of M gene is highly conservative, to test for the target genes of PEDV; S genetic polym, S the core of the protein in neutralization epitope(499-638- aa) CEO, a total of nine amino acids locus mutation happened. Finally will PEDV- WN regression experimental animals, successfully build a typical PEDV infection animal model.(4) Saliva Lactobacillus has inhibition effect of PEDV- WN strains, and plays a protective role for infected piglets. The strain of the preventive and therapeutic interventions can improve piglet survival rate, improve piglet growth performance, reduce the virus on the intestinal tissue pathological damage, and can reduce the virus proliferation in the body.Probiotic intervention, moreover, can adjust the body serum IL- 4, IL- 8, IL- 12, INF-a and MHCII five kind of the expression of cytokines, thus stimulating the body's immune, reach the role of antiviral.(5) PEDV infection, serious damage to the structure of normal intestinal flora and bacterial species abundance, saliva Lactobacillus intervention can protect a healthy intestinal microecological balance, and can quickly repair intestinal microecological imbalance. This study with a 16 s rDNA of fecal flora of high-throughput sequencing method, from the world, door, classes, orders, and families, genera and species of seven classification level of PEDV infection and probiotic intervention of the intestinal flora of different experimental analysis of the change rule and differences are compared.