阅读说明：本技术 一种对副溶血弧菌o9血清型o抗原分子分型的lamp检测方法 (LAMP detection method for molecular typing of serotype O antigen of vibrio parahaemolyticus O9 ) 是由 王磊 宁可馨 王晓晨 曹勃阳 于 2019-10-30 设计创作，主要内容包括：本发明涉及一种对副溶血弧菌O9血清型O抗原分子分型的LAMP检测方法。本发明以副溶血弧菌O9的O抗原基因簇内的特异基因,即wvdH为靶基因,建立了对副溶血弧菌O9的O抗原分型的四条引物,为肠道及水环境中副溶血弧菌的O抗原分型提供一条可信的途径。利用本发明的LAMP引物检测肠道及水环境中的副溶血弧菌,并且对其进行O抗原分型,具有操作简单、快速高效、高灵敏度等诸多优点。(The invention relates to an LAMP detection method for typing O9 serotype O antigen molecules of vibrio parahaemolyticus. According to the invention, four primers for O antigen typing of vibrio parahaemolyticus O9 are established by taking a specific gene in an O antigen gene cluster of vibrio parahaemolyticus O9, namely wvdH as a target gene, so that a reliable way is provided for O antigen typing of vibrio parahaemolyticus in intestinal tracts and water environments. The LAMP primer provided by the invention is used for detecting vibrio parahaemolyticus in intestinal tracts and water environments and performing O antigen typing on the vibrio parahaemolyticus, and has the advantages of simplicity in operation, rapidness, high efficiency, high sensitivity and the like.)

1. An LAMP detection method for serotype O antigen molecular typing of Vibrio parahaemolyticus O9 is mainly characterized by having a DNA sequence from the DNA sequences shown in SEQ ID NO. 1-SEQ ID NO. 4; the classification of the vibrio parahaemolyticus O antigen refers to that: the specific gene sequence of the O antigen gene cluster of the vibrio parahaemolyticus O9.

2. The use of the LAMP detection method for typing O antigen molecules of serotype O9 of Vibrio parahaemolyticus according to claim 1 for typing detection of O antigen in serotype O9 of Vibrio parahaemolyticus.

3. The application of the LAMP primer as claimed in claim 2, characterized in that the LAMP primer is used for O antigen typing detection in Vibrio parahaemolyticus O9 serotype.

4. The use as claimed in claim 3, wherein said Vibrio parahaemolyticus refers to a crude extract of a pure culture of a sample isolated from any environment suitable for Vibrio parahaemolyticus life.

Technical Field

The invention relates to a LAMP technology for typing O antigen of a vibrio parahaemolyticus O9 serotype strain in a sample and a preparation method thereof. The invention also designs a method for detecting by using the LAMP primer.

Background

Vibrio parahaemolyticus is a gram-negative bacterium, and is in various shapes such as arc, rod and filiform, and has no spore. Is a halophilic bacterium. Belonging to genus Vibrio of family Vibrionaceae. Vibrio parahaemolyticus is found in water, fish, pickled food with high salt content and human intestinal tracts, can cause abdominal pain, vomiting and diarrhea of people, and is an important intestinal pathogenic bacterium. The typing and identification of the vibrio parahaemolyticus are mainly based on the following: the morphological characteristics of bacteria, the physiological and biochemical characteristics of bacteria, serological reactions and other methods, and the O antigen classification of the vibrio parahaemolyticus belongs to one of the serological reactions. Due to the diversity of the environment and the antibody, the diversity of the O antigen is formed, and different strains of the vibrio parahaemolyticus can be classified and identified according to the diversity of the O antigen.

The Loop-mediated Isothermal Amplification (Loop-mediated Isothermal Amplification) can amplify nucleic acid in a short time (usually within one hour) under the Isothermal condition (60-65 ℃), and is a simple, convenient, rapid, accurate and low-price gene Amplification method. Compared with the conventional PCR, the method does not need the processes of thermal denaturation, temperature cycling, electrophoresis, ultraviolet observation and the like of the template. The loop-mediated isothermal amplification method is a brand-new nucleic acid amplification method and has the characteristics of simplicity, rapidness and strong specificity. The technology can be comparable to or even superior to the PCR technology in the indexes such as sensitivity, specificity, detection range and the like, does not depend on any special instrument and equipment to realize on-site high-flux rapid detection, and has detection cost far lower than that of fluorescent quantitative PCR.

The technical principle is as follows: the temperature of 60-65 ℃ is the intermediate temperature of renaturation and extension of double-stranded DNA, and the DNA is in a dynamic equilibrium state at about 65 ℃. Thus, DNA synthesis at this temperature is possible. The use of 4 specific primers relies on a highly active strand-displacing DNA polymerase. So that strand displacement DNA synthesis is continuously self-circulating.

Amplification is in two stages: stage 1 is the initial stage, in which either primer undergoes base-pairing extension to the complementary portion of the double-stranded DNA, the other strand dissociates and becomes single-stranded. The F2 sequence of the upstream inner primer FIP is firstly combined with the template F2c, and is extended forward under the action of strand displacement type DNA polymerase to start strand displacement synthesis. The outer primer F3 binds to and extends from template F3c, displacing the entire FIP-ligated complementary single strand. F1c on FIP and F1 on this single strand are complementary structures. Self base pairing forms a ring structure. Using the strand as a template, the downstream primers BIP and B3 sequentially initiate synthesis similar to FIP and F3 to form a single strand with a dumbbell-shaped structure. Starting immediately with the F1 segment at the 3' end. DNA synthesis and extension are carried out by taking the self as a template to form a stem-loop structure. This structure is the initial structure of the LAMP gene amplification cycle.

Stage 2 is the amplification cycle stage. FIP binds to the F2c region of the stem-loop using the stem-loop structure as a template. Strand displacement synthesis is started, and a loop structure is also formed in the dissociated single-stranded nucleic acid. The B1 segment at the 3' end is taken as a starting point, the self is taken as a template, DNA synthesis extension and strand displacement are formed, 2 pieces of DNA with different lengths and new stem loop structures are formed, B2 on the BIP primer is hybridized with the DNA, a new round of amplification is started, and the length of the product DNA is doubled. 2 circular primers LF and LB are added into the reaction system, and are respectively combined with the stem-loop structure to start strand displacement synthesis. In cycles, the final product of amplification is a mixture of DNAs with different stem-loop structures and different lengths, and the product DNA is an alternating inverted repeat sequence of the amplified target sequence.

The inventor has applied for: specific nucleotides for vibrio parahaemolyticus K36, K37 and K68 and application thereof; specific nucleotides for vibrio parahaemolyticus K36, K37 and K68 and application thereof. The differences between this application and the already published patent applications are: the detection means does not use a gene chip (the amplification and hybridization are carried out separately, the time is long), but uses LAMP technology to detect (one-step reaction amplification detection, is simple and quick, does not depend on any special instrument and equipment to realize on-site high-flux quick detection, and has low detection cost).

Disclosure of Invention

In order to achieve the aim, the invention discloses an LAMP primer for typing serotype O antigen of Vibrio parahaemolyticus O9 in a sample, which comprises an FIP primer, an F3 primer, a BIP primer and a B3 primer.

4 primers are designed at 6 different sites such as Bl, B2 and B3 regions at the 5' end. 3 the F3c, F2c and Flc regions at the 3' end and LAMP primer were designed mainly for six different regions of the target gene based on the target gene

The Flc region at the 5' end has the same sequence. FIP (Forward: upstream Inner Primer consisting of F2 region and F1C region, F2 region is complementary to F2c region at 3' end of target gene, F1C region is Primer of Inner target gene)

(Forward, consisting of the F3 region and complementary to the F3c region of the target gene Outer F3 Primer: upstream Outer Primer)

The Blc region at the 5 'end has the same sequence, the B2c region at the 3' end of 3 is complementary, the B1C region is complementary with the target gene (Backward, consisting of B1C and B2 regions, the B2 region is complementary with the target gene Inner BIP Primer: downstream Inner Primer)

(Backward, consisting of the B3 region, complementary to the B3c region of the target Gene Outer B3 Primer: downstream Outer Primer)

The method is mainly characterized in that the O9 serotype O antigen typing of the vibrio parahaemolyticus refers to the following steps: the O antigen gene cluster specific gene sequence of vibrio parahaemolyticus O9 serotype has one DNA sequence of the DNA sequences shown in SEQ ID NO. 1-SEQ ID NO. 4.

The LAMP primer for typing the serotype O antigen of vibrio parahaemolyticus O9 in the sample is characterized in that the primer sequence is as follows: has primers shown in SEQ ID NO. 1-SEQ ID NO. 4.

The invention further discloses an LAMP primer for typing O-antigen molecules of serotype O9 of Vibrio parahaemolyticus in a sample, and application of the LAMP primer in the aspect of O-antigen molecule typing detection of Vibrio parahaemolyticus O9. The Vibrio parahaemolyticus refers to a crude extract of a pure culture of a sample isolated from any environment suitable for the life of Vibrio parahaemolyticus. The experimental results show that: the invention can be used for typing the vibrio parahaemolyticus O antigen under lower DNA concentration.

The invention provides a LAMP system for detecting a serotype in an environment, which comprises: WarmStartColorimetric LAMP 2X Master Mix (NEB), 10. mu.M FIP, F3, BIP and B3 primers, 1. mu.L DNA and ddH₂And O. The primer designed according to the O antigen gene cluster specific gene sequence of the vibrio parahaemolyticus O9 serotype: the length of B3 and F3 primers designed by http:// primer explorer.jp/e/in specific gene sequence of O antigen gene cluster of vibrio parahaemolyticus O9 serotype is about20 nt, Tm is between 55-60 ℃; the length of the BIP primer and the FIP primer is about 50 nt; wherein "-" in the primer sequence represents "TTTT".

The invention is the practical application of LAMP loop-mediated isothermal amplification technology, and is used for the typing and identification of vibrio parahaemolyticus O9 serotype.

According to the technical scheme, the LAMP technology is introduced into the field of the O antigen typing of the vibrio parahaemolyticus for the first time, the LAMP detection method for the O9 serotype of the vibrio parahaemolyticus in the sample, which is rapid, sensitive, high in accuracy and strong in repeatability, is established, the LAMP probe can be used for achieving the purpose of identifying the common O serotype strain of the vibrio parahaemolyticus in the sample, and the LAMP probe is simple and convenient to operate, high in accuracy and strong in repeatability, and has important application value for real-time rapid detection of the O antigen typing of the vibrio parahaemolyticus in the sample by various medical departments.

Drawings

FIG. 1 detection of LAMP reaction positivity and specificity of VP O9: the LAMP system of the Vibrio parahaemolyticus genome sample O9 is added with the genomes of Vibrio parahaemolyticus O1, O2, O3, O4, O5, O6, O7, O8, O9, O10, O11, O12 and O13 respectively, and the genomes except O9 do not intersect, which shows that the LAMP primer specificity of the Vibrio parahaemolyticus O9 is good;

FIG. 2 detection of LAMP reaction exogenous strain by PS O9: the genome of the neisseria shigelloides O45 and the genome of the legionella pneumophila O5 are added into the LAMP system of the vibrio parahaemolyticus genome sample O9, so that the LAMP primer specificity of the vibrio parahaemolyticus O9 is good.

Detailed Description

The invention is described below by means of specific embodiments. Unless otherwise specified, the technical means used in the present invention are well known to those skilled in the art. In addition, the embodiments should be considered illustrative, and not restrictive, of the scope of the invention, which is defined solely by the claims. It will be apparent to those skilled in the art that various changes or modifications in the components and amounts of the materials used in these embodiments can be made without departing from the spirit and scope of the invention. The raw materials and reagents used in the present invention are commercially available.

The sources of the vibrio parahaemolyticus strains used in the present invention are shown in table 1 below:

TABLE 1 bacterial species used in this experiment

Taiwan biological resource preservation and research center

b, CDC: chinese center for disease prevention and control

c，CNCTC：Czech National Collection of Type Cultures, the Czech Republic