Study On Effects Of Anti-infection And The Immunizing Synergism Of Lactobacillus Casei Zhang

In vitro antimicrobial test was carried out with the fermentation broth,thallus and metabolite of L. casei.Zhang.After being fed with suspl,the mice were attacked by Escherichia coil O157 and K88. Escherichia coil and lactobacilli were isolated from intestinal contents of mice with selective medium at the 4th day, and its DNA was extracted and amplified by ERIC-PCR.Further, adhesion test to chick intestinal cell was carried out.the lactobacillus The results showed that both the oral suspl and metabolizes had stronger antimicrobial activity, but the thallus had no antimicrobial activity. The metabolite of lactobacillus was more heat-stable, and it can be tolerant to high temperature (115℃). But the pH value highly influenced the antimicrobial ability of metabolite, and it's antimicrobial ability would rise while the pH value decreased. The antimicrobial ability of metabolite would have been lost in neutral condition, and it was not largely influenced by trypsin and pepsin. L.casei Zhang could protect the mice from infection, and could attach to the gut of mice. Because L.casei Zhang was isolated from the mice at the fourth day after stop feeding it. E. coil O157 and K88 could not be isolated from the feeding lactobacilli groups, so L.casei Zhang had the antagonism effect on E. coil. L.casei Zhang could adhere to the intestinal cells of chicks.In this research, the mice were fed with the milk suspension (2.0³.0×10¹⁰ cfu/ml) and fermented milk (2.0³.0×106 cfu/ml) which were made of L.casei Zhang by different dosages. IgG content in the blood and SIgA content in the gut were determined at 5th, 10th, 15th, 20th, 25th, 30thday respectively using ELISA.The T cell CD3+, CD4+,CD8+ ,as well as the CD4+/CD8+ ratio in the blood were determined at the10th,20th,30th day respectively using FCM. The results showed that the contents of IgG in the blood and SIgA in the gut of the mice which were fed with L.casei Zhang were significantly increased compared with the control group(p<0.05, p<0.01), and there were also significant differences among milk suspension groups, fermented milk groups and the different dosages (p<0.05, p<0.01). SIgA and IgG content have the tendency that was increased with time. the proportions of T cell CD3+, CD4+,CD8+ in the blood were increased after the mice were fed with the milk suspension and fermented milk which were made of L.casei Zhang , the CD4+/CD8+ ratio was optimized. Cellular immunity and humoral immunity of mice were improved by L.casei Zhang.One day old chick were divided into two groups fed with living and inactivated milk suspension which was made of L.casei Zhang by differe dosages. One group was vaccinated with ND, the other group was vaccinated with avian influenza vaccine. The valence of HI antibody was determined at 7th, 14th day after second vaccination. The result showed that compare with the control group, the antibody level of each experimental group was all significant and extremely significant (p<0.05, p<0.01), it indicated that L.casei Zhang has a good synergism effect with ND and Avian influenza inactivated vaccine.it can improve the immunological function in chicks.Chicks were vaccinated with ND or avian influenza inactivated vaccine in which peptidoglycan or DNA of L.casei Zhang was added as a adjuvant.. the valence of HI antibody was determined at 7th, 14th day after second vaccination.The experiment groups were significantly higher than control group(p<0.05 or p<0.01), so, PG and DNA of L.casei Zhang had good immunological enhancement effects, and they were effective adjuvants.