The Effect And Influence Of Recombinant Porcine Interferon Alpha On Pseudorabies Virus Infection

Interferon?IFN?is a protein that is secreted by cells and induced by a certain interferon inducer and has various biological activities such as antiviral,antitumor and immune regulation.Interferon alpha?IFN-??is mainly produced by mononuclear phagocytic cells.It is a bridge between natural immunity and acquired immunity.It can activate the cytotoxicity of NK cells and promote their proliferation and regulate immunity.It has an antiviral effect and can be used in combination with a vaccine to enhance the immune effect.It can also be used alone to improve the animal's immune function and treat porcine viral diseases.This study was based on the successful construction of a recombinant porcine interferon-alpha yeast strain in the previous period.The recombinant porcine interferon-alpha expression culture was amplified,cultured in a 50-liter fermentor,and then5%mannitol was used as a lyoprotectant.Lyophilization was performed.Finally,lyophilized recombinant porcine interferon-alpha was subjected to a safety test and a PRV preventive test.In this experiment,we will inoculate the recombinant yeast strains with alpha interferon gene modification in a 50 L fermentor.BSM base medium and PTM1 trace elements are selected.The optimized fermentation conditions are used:the optimal incubation time of the seed fluid is 24 h.The inoculation amount was 5%,the pH of the fermentation broth before induction was 5,the temperature was 30?,the induction began to adjust the pH to 6.0,the temperature was adjusted to 28?,and the volume of the fermentation broth was generally not more than 2/3 of the fermenter volume.should.The porcine alpha interferon obtained by fermentation in a large tank was lyophilized with 5%mannitol as a lyoprotectant to solve the problems of poor thermal stability,difficulty in long-term preservation,and long-distance transportation of the product.The antiviral potency of porcine interferon alpha was measured on vero cell monolayer by cytopathic inhibition,and the results were observed with 100TCID₅₀0 PRV.The results showed that the activity of recombinant porcine interferon against porcine pseudorabies virus was 4.9×10⁷U/L.Clinical safety tests of genetically engineered porcine interferon-alpha?IFN-??were carried out in?Guangdong province?Guangdong huanong wenshi Lianzhou branch,?Fujian province?Zhangzhou wenshi agriculture and animal husbandry co.,ltd.Nanjing animal husbandry branch and?Guangxi autonomous region?Hezhou Guangdong wenshi livestock and poultry co.,ltd.Pigs were injected repeatedly with recommended dosage,overdosage and recommended dosage in suckling piglets,weaned piglets,back-up sows,sows and boars respectively.The safety of the pilot-scale products was investigated by monitoring the mental state,behavior and feeding,drinking water and growth performance of inoculated pigs,and injecting local and systemic reactions.The test results showed that all pigs were safe under laboratory conditions,recombinant porcine interferon?was used to prevent porcine pseudorabies.Twenty30-day-old weaned piglets identified as pseudorabies negative by ELISA were randomLy divided into A,B,C and D 4 experimental groups with 5 piglets in each group.Group A was blank control group,group B was interferon control group,group C was interferon prevention group,and group D was virus control group.Group B and C were injected with20,0 000 IU/head of recombinant porcine interferon-?,while group A was injected with the same amount of normal saline.Three days later,group C and group D were treated with anti-virus test at the same time and observed for one week.24 hours after challenge,the first clinical symptoms appeared in D challenge group.the body temperature of 5 pigs increased to above 40?on the second day after challenge,and then shivering,tremor,cough,diarrhea and other symptoms appeared,the incidence rate was 100%.On the 5th day after challenge,the body temperature of 3 pigs in the interferon prevention group of group C increased.There were no obvious clinical symptoms in group B and C.Lung congestion,liver surface necrosis and meningeal hemorrhage were found in group D,and no abnormality was found in group A?C,and typical lung and kidney congestion,edema and lymphocyte proliferation were found in group D.In summary,the experiment successfully expressedrecombinant porcine interferon-alpha in a 50 L fermentor and the supernatant was lyophilized and stored at 2??8?.Safety tests were conducted in four pig farms in three provinces in China.Prophylactic tests were conducted on pseudorabies in laboratory conditions to prove that the product is safe and has no side effects.It has a significant preventive effect against pseudorabies and is a recombinant pig.Alpha-interferon lays the foundation for large-scale production and use in the prevention of viral diseases on porcine.