Typhoid, paratyphoid envelope protein vaccine

Abstract

An outer membrane vaccine for preventing the infection of typhoid bacillus and paratyphoid bacillus A and B is disclosed. Its preparing process includes such steps as culturing said bacilli in culture liquid, getting their thallus, and preparing vaccine.

Description

Technical field: [0001] The invention relates to a method for preparing bacterial outer membrane protein from bacterial cells obtained from Salmonella typhi, Salmonella paratyphi A and Salmonella paratyphi B culture fluid, and a vaccine prepared by the method. Background technique: [0002] Typhoid fever and paratyphoid fever are systemic, acute, febrile infectious diseases caused by Salmonella typhi bacilli, type A paratyphi bacilli, and type B paratyphi bacilli that are pathogenic to humans. The main manifestations are persistent high fever, abdominal pain, malaise, headache, and inflammation of the small intestine and colon. Constipation is common in adults and older children, and diarrhea is common in younger children. About 50-70% of patients can isolate typhoid bacilli from feces during the illness period, and even in the convalescent period feces can continue to excrete bacteria, and about 2% of typhoid patients can become chronic carriers. During the excretion perio...

AI Technical Summary

Problems solved by technology

In the 1960s and 1970s, clinical studies of inactivated whole-cell vaccines were carried out in many countries, but the side effects were relatively large and the effect was not satisfactory, so it has been discontinued.

Streptomycin-dependent typhoid mutant live vaccines have poor reproductive ability in normal humans, and the effect after immunization is unsatisfactory, and the freeze-dried vaccine has completely lost its protective power, and research has also stopped

The typhoid Ty21a live attenuated vaccine has undergone a large number of clinical trials and has been proven to be one of the safest and most effective typhoid vaccines without serious side effects. However, some scholars have raised the following controversial issues about the Ty21a mutant strain for a long time: The genetic stability of the attenuated strain cannot be determined, and it is speculated that its virulence may return to the ancestor; the mutation of the galE gene cannot fully explain the attenuation mechanism of the vaccine; there are mutations in other unknown parts of the gene; the freeze-dried dosage form is attenuated The irregular stability of live vaccines, too many oral vaccinations, and severe gastrointestinal reactions are unacceptable, and the current use is limited

The above research results show that typhoid outer membrane protein antigens can induce the body to produce functional antibodies, and more than half of the experimental animals can resist 10-500LD 50 For the challenge of a dose of live bacteria, the dose of the immunogen used in the above-mentioned experiments is mostly 20-100 micrograms per bird, and the dose of the immunogen used in the experiment is relatively large. From the test results, it is difficult to infer the dose for human use. The selection of references has limited significance, and the current typhoid vaccine was not selected as a positive control when conducting animal experiments

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