The Screening Of Anti-Ndv Chicken Probiotics Strains And Its Changes In Gastrointestinal Simulated Conditions

Newcastle disease (ND) is birds of a highly contagious, deadly infectious diseases, and serious economic losses to the poultry industry in many countries. The pathogen of ND is Newcastle disease, a member of the paramyxovirus Division mumps virus, and is an enveloped RNA virus, seriously harm the development of the chicken industry. The infection of NDV absolutly depends on the host’s cell. As is known to all, The pathogenicity of the virus to the host first amplified by infecting host cells and their number, and then with the host circulatory system spread to the other organizations. Thus, to prevent the virus infection on host cells is critical.However, probiotics on the host cell’s protective effect is precisely reflected in its interfering with the process of virus infection on host cell, has played a spread of the virus proliferation inhibition. With the gradually deepening, understanding of probiotic studies have found that the cell model to study the relationship between probiotic bacteria and viruses, the results of probiotics can protect cell integrity. However, studies on probiotics are mostly limited to research on the human virus, and the source of strain is mostly isolated from food. The purpose of this study is to filter the contents from the intestines of healthy chickens against NDV activity of probiotics and analysis of its possible anti-viral mechanism.In the experiment, we preliminarily filtered out the61strains by the use of Gramstain and Hydrogen peroxide experiment;11in61strains can reduce the NDV hemagglutination prices; we determined the cell viability after treated by probiotics using MTT and use susceptibility testing to filter out highly sensitive antibiotics to these probiotics. Finally, we filter out6strains with strongly antiviral effect through the method of cells co-cultured with probiotics and cells co-cultured with the supernatant of probiotics incubation with virus.Based on the above, we simulated gastrointestinal environment to further detect the effect of antiviral.Definite experiments grouped as follows:The experiment was divided into two parts:The acidic environment pretreatment section, using pU2、pH3、pH4、pH6.4; Bile salts pretreatment section, the concentration of0.1%、0.2%、0.3%. These two parts accorded to the following method of grouping determination.Groupl:Adding to virus after pre-treatment of CEF cells with probiotics; Group2: Simultaneously adding to probiotics and virus; Group3:Probiotics control;Group4:The virus control; Group5:CEF cells controls.The results:in the experiment of probiotics on the NDV titer in vitro,11probiotics fitered out significantly reduced NDV hemagglutination price, however differences exist amony strains; The remaining50strains of hemagglutination price is a slight decrease or no change,the results showed there are kind of case of difference between the probiotic strains; In the experiment two kinds of pathogens on NDV HI price had no impact in contrast with the probiotics, the contrast between HI price of the bacteria showed that probiotics may have the function of directly impact on the virus or its hemagglutinin,and differences exist amony probiotics.We determined the cell activity after probiotics and NDV treated by MTT method, and alculated the viral inhibition rate by formula,and the results showed that11probiotics all have a certain anti-NDV role in the CEF, but there are some differences between the probiotic in effect.Therefore,we selected6strains whose antiviral effect is very significant to make species identification. Through biochemical tests and16SrRNA identification, we named these probiotics as MCl、MC19、 T4-Lactobacillus salivarius、T6-Lactobacillus pensus、T12-Lactobacillus intestinal、T14-Lactobacillus plantarum.Taking into account the environmental changes of the chicken gastrointestinal tract, The experiments were respectively simulated to study the antiviral effect of probiotic live bacteria and culture supernatant under different pH and different bile salts. The results showed as the pH lower suppression of anti-virus also reduced.This is possible because the strains of viable cells in the low pH decreases, the concentration and dilution have declined.This shows that probiotics play a role on NDV is highly significant dose-effect relationship. Probiotics change slightly as the bile salt concentration increased, but also the performance is that as the bile salt concentration increased viral suppression rate decreases. Showing that the intestinal salt concentration has a little effect on probiotic itself and does not affect the role of anti-virus; Or salts may stimulate cell growth and proliferation. The results of Group1and Group2both showed inhibitng NDV infection. Revealing that probiotics may have a direct role in destruction of the virus or an ability of adsorbing NDV and interfering with NDV infection.This article filter out the MC1, MC19, T4, T6, T12, T14strain, In the experiment of probiotics on the NDV titer in vitro, probiotics were significantly reduced the titer of NDV and protect cells against virus invasion. The study simulated the intestinal environment to research the antiviral activity of probiotics and analyze the possible mechanism, Lay the foundation for the development of probiotic anti-NDV viral agents.