OBJECTIVE
To develop a trivalent genetically engineered inactivated Escherichia coli vaccine (K88ac-3STa-LTB) that neutralizes the STa toxin by targeting fimbriae and entertoxins for the treatment of enterotoxigenic E coli.
ANIMALS
18- to 22-g mice, rabbits, pregnant sows.
PROCEDURES
Using PCR, the K88ac gene and LTB gene were cloned separately from the template C83902 plasmid. At the same time, the 3 STa mutant genes were also amplified by using the gene-directed mutation technology. Immune protection experiments were performed, and the minimum immune dose was determined in mice and pregnant sows.
RESULTS
The ELISA test could be recognized by the STa, LTB, and K88ac antibodies. Intragastric administration in the suckling mouse confirmed that the protein had lost the toxicity of the natural STa enterotoxin. The results of the immune experiments showed that K88ac-3STa-LTB protein could stimulate rabbits to produce serum antibodies and neutralize the toxicity of natural STa enterotoxin. The efficacy test of the K88ac-3STa-LTB-inactivated vaccine showed that the immune protection rate of the newborn piglets could reach 85% on the first day after suckling. At the same time, it was determined that the minimum immunization doses for mice and pregnant sows were 0.2 and 2.5 mL, respectively.
CLINICAL RELEVANCE
This research indicates that the K88ac-3STa-LTB trivalent genetically engineered inactivated vaccine provides a broad immune spectrum for E coli diarrhea in newborn piglets and prepares a new genetically engineered vaccine candidate strain for prevention of E coli diarrhea in piglets.
Acrivastine is a second-generation H1-receptor antagonist, and its structure is sensitive to ultraviolet. Four unknown and one reported degradation products can be detected in the ultraviolet radiation solutions of acrivastine. To improve the quality control of acrivastine, the photodegradation impurities were isolated and structurally elucidated. There are four new impurities (1-3 and 5), and one reported compound (4). The isolation strategy was designed as preparative high-performance liquid chromatography using a reversed phase column with volatile acid addition in the mobile phase, combined with preparative thinlayer chromatography using silica gel with alkaline addition in the mobile phase. Using the developed methods, five impurities (1-5) were efficiently purified after two or three chromatography runs with purities > 95%. The structures of compounds 1-5 are elucidated based on spectroscopy analysis of MS, and nuclear magnetic resonance spectroscopy. Using the impurity standard, the highperformance liquid chromatography method was developed and validated. The method was proved to be sensitive, accurate (Recovery% 96.1-107.7%), linear (0.15-0.75 μg/mL, R 2 > 0.996), robust, and specific, and it was successfully used to determine the degradation impurities of acrivastine and its formulation.
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