Bivalent nucleic acid vaccine against bronchitis and preparation method and application thereof

Abstract

The invention provides a bivalent nucleic acid vaccine against bronchitis and a preparation method and application thereof. According to the invention, the core expression region of the bivalent nucleic acid vaccine is only 1491 bp; a secretory signal peptide is introduced before an expression sequence; a Kozak sequence is introduced into the expression sequence; plasmids containing avian promotersequences are selected; hydrophobic regions which are not easy to become antigens are removed; M41 and H120 characteristic proteins are spliced, and a linker sequence is arranged between and connected with the M41 and H120 characteristic proteins, so generation of neutralizing antibodies aiming at the two toxic strains can be stimulated, and the defect of poor crossover of immunity to infectiousbronchitis viruses is overcome; Salmonella typhimurium is selected as a vector, and Salmonella typhimurium has no hidden infection dangers to a host, but can support long-term expression of nucleic acid vaccines to achieve a long-term immune effect; and an oral immunization mode is adopted for the vaccine, and the vaccine can be added into a feed, and is convenient to use and superior to a nasal dripping or injection immunization mode. During preparation of the vaccine, a culture collected after fermentation is directly used as a vaccine, so the steps of protein purification, endotoxin removaland the like are reduced, cost is saved, and large-scale production is facilitated.

Description

technical field [0001] The invention belongs to the technical field of animal vaccine antigen preparation, and relates to a preparation method of a bivalent poultry infectious bronchitis nucleic acid vaccine and its immunization application. Background technique [0002] Infectious bronchitis (IB) is an acute, highly contagious respiratory infectious disease of chickens caused by Avian infectious bronchitis virus (IBV) infection. The virus belongs to the family Coronaviridae, a single-stranded positive-sense RNA virus of the genus Coronaviridae. The virion has a capsule and a fiber, containing a fiber (S), a membrane (M) glycoprotein and an internal nucleocapsid (N) protein. After infection, coughing, sneezing and tracheal rales are the main clinical manifestations, and egg production decline, renal pathological enlargement, urate deposition, etc. may occur. Among them, the mortality rate of chicks can reach 10% to 30%. At present, there is no effective clinical treatment m...

AI Technical Summary

Problems solved by technology

Among them, the mortality rate of chicks can reach 10% to 30%. At present, there is no effective clinical treatment method, mainly based on vaccine prevention. Most of the domestically marketed attenuated vaccines are prepared from H120 and H52 chicken embryo-adapted strains, while many foreign countries have isolated Most of the strains of the virus are similar to the Massachusetts strain (M41 strain), and the inactivated vaccine of the M41 strain has been marketed, but it is subject to many and complex epidemic strains, and the influence of factors such as poor cross-immunity of each serotype, and its clinical protective effect is very limited. At present, the means of preparing vaccines also includes subunit vaccines or nucleic acid vaccines, but subunit vaccines need to be expressed and purified, and then immunized, which has complicated steps and is difficult to remove the endotoxin produced in the fermentation and expression process. Existing nucleic acid vaccines It also has the disadvantages of intranasal immunization after purification and low antigen expression and poor specificity, and the present invention comes from this

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