Preparation Of Clove Oil Oral Liquid And Its Therapeutic Effect On Artificial Infection Of Chicken Salmonella

Salmonella is a common zoonotic pathogen,which seriously endangers human public health and animal health.Pullorum disease caused by Salmonella infection continues to endanger the development of chicken industry,resulting in an annual economic loss of about 10 billions dollars.Antibiotics are the first choice for the treatment of Salmonella infection,while the emergence,spread and prevalence of antibiotic resistance have resulted in a significant decline or even loss of the therapeutic efficacy of the existing antibiotics.Therefore,there is an urgent need to develop new drugs or anti-infection strategies to prevent and control Salmonella infcetion,.The genome of Salmonella carries two distinct sets of pathogenicity islands(SPI),type Ⅲ secretion system(T3SS)encoded by SPI-1 mainly play a role in invading host cells,T3 SS encoded by SPI-2 is mainly involved in the intracellular survival,replication and proliferation.Therefore,taking the Salmonella T3 SS as the target for drugs screening and development is an ideal strategy to anti-infection of Salmonella.In this study,Salmonella T3 SS was used as the target for inhibitors screening.The results showed that eugenol could effectively inhibit the function of T3 SS without antibacterial activity,and significantly reduce the pathogenicity of Salmonella in vivo and in vitro.In this study,clove oil oral liquid was developed with clove oil as raw material.Firstly,the prescription composition was determined through the screening of excipients and the investigation of prescription process: clove oil was the main component,PEG 400 was the main solvent(solvent),polysorbate 80 was the co-solvent,citric acid was the p H regulator,BHT was the antioxidant and ethanol was the cosolvent.Through the study of preparation and stability after dilution,it was found that the preparation process of clove oil oral liquid was good.Through the study on the accelerated stability and long-term stability of three batches of different pilot products,the results shown that except for the decrease of the content of active ingredients to a certain extent,the other indexes meet the requirements.Through the effector-β-lactamase fusion report system,RT-PCR and Western blotting were used to explore the action mechanism of clove oil oral liquid inhibiting the function of Salmonella T3 SS,the results showed that clove oil oral liquid inhibited the function of Salmonella T3 SS by inhibiting the transcription of Salmonella effector protein and regulatory protein gene,down regulating effector protein(Sip A and Sip B)and regulatory protein(Hil A).Through the treatment experiment of clove oil oral liquid on artificially infected Salmonella of chicken,the results showed that clove oil oral liquid had good therapeutic effect.In order to investigate the safety of clove oil oral liquid on chickens,it was administered according to the recommended dose,three times and five times of the recommended dose for 15 days,the safety of clove oil oral liquid was evaluated by clinical symptoms,blood routine examination,blood biochemistry,ocular lesions and histopathological indexes,the results showed that clove oil oral liquid was safe for chickens.In conclusion,this study successfully prepared clove oil oral liquid with eugenol as the main component with definite curative effect,clear action mechanism and good safety,which provides a new strategy for prevention and treatment of Salmonella infection and lays foundation for the clinical application of new veterinary medicines.