BioVector? Helicobacter pylori G27 Strain / G27 幽門螺桿菌標(biāo)準(zhǔn)模式菌株

一 產(chǎn)品基本信息與遺傳學(xué)背景

• 菌株名稱：G27 幽門螺桿菌（Helicobacter pylori G27）。

• 物種分類：細(xì)菌界（Bacteria），變形菌門（Pseudomonadota），Epsilon-變形菌綱（Epsilonproteobacteria），彎曲菌目（Campylobacterales），螺桿菌科（Helicobacteraceae），螺桿菌屬（Helicobacter）。

• 菌株背景與來源：G27 是全球幽門螺桿菌研究領(lǐng)域最經(jīng)典、應(yīng)用最廣泛的標(biāo)準(zhǔn)模式參考株（Type Strain）之一。最初于 20 世紀(jì) 80 年代末至 90 年代初，由意大利科學(xué)家從一名患有嚴(yán)重胃潰瘍（Gastric Ulcer）的意大利內(nèi)鏡患者的胃黏膜活檢標(biāo)本中分離獲得。

• 基因組與關(guān)鍵毒力因子特征（核心背景）：

  • CagA 陽性（CagA+）：G27 菌株擁有一條完整的、功能活躍的 cag 致病島（cag Pathogenicity Island, cagPAI），能夠高效表達(dá)細(xì)胞毒素相關(guān)基因 A（CagA）蛋白。CagA 被稱為 細(xì)菌癌蛋白，是引發(fā)宿主胃上皮細(xì)胞惡性轉(zhuǎn)化的核心因子。

  • VacA 活性（VacA-s1/m1 型）：攜帶高毒力的空泡毒素 A（VacA）基因型（通常為 s1/m1 型）。該毒素可在宿主細(xì)胞內(nèi)誘導(dǎo)大量的細(xì)胞質(zhì)空泡化，破壞線粒體膜電位并誘導(dǎo)上皮細(xì)胞凋亡。

  • IV 型分泌系統(tǒng)（T4SS）：G27 具備完全組裝的 T4SS 分泌針狀結(jié)構(gòu)。當(dāng)細(xì)菌與胃上皮細(xì)胞接觸時，T4SS 像微型注射器一樣穿透宿主細(xì)胞膜，將 CagA 蛋白以及肽聚糖等物理注入宿主胞質(zhì)內(nèi)。

• 電生理與操作優(yōu)勢：相比于另一株經(jīng)典高毒力株位點(diǎn)（如 26695 株），G27 最大的核心遺傳學(xué)優(yōu)勢在于其具備極高且穩(wěn)定的自然轉(zhuǎn)化能力（Highly Naturally Transformable）。這使得實(shí)驗(yàn)室對其進(jìn)行基因敲除、等位基因更換（Allelism Exchange）、插入突變以及熒光標(biāo)記質(zhì)粒導(dǎo)入的操作極為簡便且成功率極高。

• 生物安全級別：2級（BSL-2）。幽門螺桿菌是 I 類人類致癌物，活菌操作必須在二級生物安全柜內(nèi)進(jìn)行。

二 核心科研價值與轉(zhuǎn)化醫(yī)學(xué)應(yīng)用

G27 菌株將高毒力因子的病理特征與極佳的基因工程可塑性完美結(jié)合，是解析胃壁發(fā)病機(jī)制的黃金模型：

1. 宿主-病原體相互作用與細(xì)胞骨架重塑（Hummingbird Phenotype）：在體外侵染人胃癌上皮細(xì)胞（如 AGS、MKN45）時，G27 通過 T4SS 將 CagA 注入細(xì)胞。CagA 隨后被宿主激酶（如 Src、Abl）磷酸化，與 SHP-2 磷酸酶結(jié)合，引發(fā)細(xì)胞出現(xiàn)特征性的 蜂鳥表型（Hummingbird Phenotype） 也就是細(xì)胞拉長、偽足伸展、運(yùn)動性劇增。這一過程是研究胃癌細(xì)胞上皮-間充質(zhì)轉(zhuǎn)化（EMT）和癌變初始機(jī)制的標(biāo)準(zhǔn)通路。

2. IV 型分泌系統(tǒng)（T4SS）動力學(xué)與超微結(jié)構(gòu)研究：G27 常被用作解構(gòu) T4SS 針狀復(fù)合體組裝、CagL 蛋白與宿主細(xì)胞表面整合素（alpha v beta 1 integrin）識別受體結(jié)合機(jī)制的分子底盤。通過冷凍電鏡（Cryo-EM）或超分辨熒光顯微鏡，可以實(shí)時追蹤 G27 毒力因子在菌體與胃黏膜接觸面上的定向極化轉(zhuǎn)運(yùn)。

3. 新型根除藥物與新型疫苗靶點(diǎn)高通量篩選：鑒于全球臨床幽門螺桿菌對克拉霉素、甲硝唑的耐藥性劇增，G27 作為敏感/耐藥演變的標(biāo)準(zhǔn)對照株，被廣泛用于篩選新型天然抗菌小分子、特異性尿素酶（Urease）抑制劑，以及開發(fā)針對其外膜蛋白（如 BabA、SabA）的靶向黏附阻斷劑。

三 實(shí)驗(yàn)室菌株復(fù)蘇、固體/液體微需氧培養(yǎng)與保存標(biāo)準(zhǔn)步驟

幽門螺桿菌是嚴(yán)格的微需氧菌（Microaerophilic），對氧氣濃度、濕度和培養(yǎng)基質(zhì)的營養(yǎng)及新鮮度有著極其嚴(yán)苛的要求。普通有氧或嚴(yán)格厭氧環(huán)境均會導(dǎo)致其迅速死亡或轉(zhuǎn)化為無法轉(zhuǎn)化的球形菌（Coccoid form，不具備感染力的代謝休眠態(tài)）。

1. 培養(yǎng)基與微需氧環(huán)境配置

• 固體培養(yǎng)基（最常用）：哥倫比亞瓊脂（Columbia Agar base） 或 腦心浸液瓊脂（BHI Agar）。

  • 必須添加劑：培養(yǎng)基滅菌冷卻至 50 攝氏度時，必須添加 5% 到 7% 的脫纖維裂解綿羊血（Defibrinated Sheep Blood） 或 馬血，或添加 10% 胎牛血清（FBS）。血清能有效清除培養(yǎng)基中對幽門螺桿菌致命的自由基氧化物。

  • 選擇性雙抗/多抗（針對復(fù)蘇活檢或防污染）：通常添加 幽門螺桿菌專屬選擇性添加劑（如含有萬古霉素 Vancomycin、多粘菌素 Polymyxin B、Trimethoprim、兩性霉素 B 的添加劑包），以抑制雜菌生長。

• 液體培養(yǎng)基（需特定搖擺條件）：含 10% FBS 的 BHI 肉湯。

• 微需氧物理環(huán)境（核心關(guān)鍵）：

  • 氣體標(biāo)準(zhǔn)成分：5% 氧氣、10% 二氧化碳、85% 氮?dú)狻?/p>

  • 實(shí)驗(yàn)室常規(guī)實(shí)現(xiàn)方式：使用專業(yè)的微需氧培養(yǎng)箱、或者將平板置于密封專用的抽氣罐/產(chǎn)氣袋（如 CampyGen 產(chǎn)氣包）中。

  • 培養(yǎng)溫度：37 攝氏度（絕對禁止 30 度或 42 度培養(yǎng)）。

  • 相對濕度：大于 95% 高濕環(huán)境（常在抽氣罐底部放一塊無菌濕透的紗布）。

2. 凍存菌種復(fù)蘇與接種步驟

1. 將配置好的優(yōu)質(zhì)血平板提前放入微需氧環(huán)境內(nèi)平衡預(yù)熱（保證平板表面沒有冷凝水水滴）。

2. 從液氮罐或 零下 80 攝氏度超低溫冰箱中取出 G27 凍存管，由于幽門螺桿菌對溫度劇烈波動極度敏感，必須立刻投入 37 攝氏度水浴中快速搖晃融化（1分鐘內(nèi)）。

3. 融化后迅速移入生物安全柜，用無菌移液槍吸取全量菌液（通常含有甘油保護(hù)劑），直接傾倒或滴加到血平板濃集區(qū)。

4. 輕柔操作：使用無菌涂布棒或無菌接種環(huán)，極其輕柔地在平板上進(jìn)行三區(qū)或四區(qū)劃線（切勿用力過猛劃破培養(yǎng)基表面）。

5. 迅速將平板倒置放入微需氧產(chǎn)氣罐中，投入新鮮的微需氧產(chǎn)氣袋，密封。置于 37 攝氏度恒溫培養(yǎng)箱中。

6. 耐心孵育：幽門螺桿菌生長緩慢。復(fù)蘇第一代通常需要 3 至 5 天（72 到 120 小時）。在滿 72 小時前，盡量不要頻繁打開密封罐查看，否則大量空氣逸入會導(dǎo)致脆弱的對數(shù)初期復(fù)蘇菌株直接氧化死亡。次日或第三天起，可見平板上出現(xiàn)細(xì)小的、針尖大（0.5 到 1 毫米）、半透明、水滴狀、不溶血的健康微小菌落。

3. 日常傳代與活化維持

• 傳代時機(jī)：當(dāng)菌落長成清晰可見的水滴狀、且尚未融合成大片干枯菌斑時（通常在接種后 48 到 72 小時內(nèi)），必須進(jìn)行傳代。如果任由菌落老化超過 96 小時，細(xì)菌會大量由健康的螺旋狀（Spiral/Rod form）自發(fā)轉(zhuǎn)變?yōu)榍驙睿–occoid form）。球狀菌在鏡下呈細(xì)碎的小圓點(diǎn)，失去定殖和促使宿主細(xì)胞病變的能力，且無法再次傳代復(fù)蘇。

• 傳代操作：

  1. 用無菌無抗 PBS 或液體 BHI 肉湯溫潤血平板。

  2. 使用無菌刮鏟或接種環(huán)輕輕將平板上的菌落刮下，收集至無菌管內(nèi)。

  3. 按照 1 比 3 至 1 比 5 的稀釋比例，重新接種涂布到新鮮配置的血平板上。

  4. 重新密封放入微需氧環(huán)境，后續(xù)常規(guī)傳代通常僅需 48 小時即可長滿。

4. 菌株長期冷凍保存

• 凍存液配方：腦心浸液（BHI）肉湯加 20% 到 25% 優(yōu)質(zhì)無菌甘油加 10% 胎牛血清（FBS）。

• 冷凍操作：

  1. 收集培養(yǎng)了 48 小時左右、正處于對數(shù)生長最旺盛期、鏡下觀察 95% 以上均為標(biāo)準(zhǔn)短桿狀/螺旋狀的健康 G27 菌體。

  2. 用無菌刮鏟將菌體洗脫并高密度懸浮于上述配置好的專屬凍存液中（菌液需要達(dá)到極高密度，呈現(xiàn)明顯的乳白色渾濁濁度）。

  3. 分裝至冷凍管中，禁止梯度降溫。為了防止液體中慢速結(jié)冰產(chǎn)生的晶體刺破細(xì)菌脆弱的雙層膜，應(yīng)將凍存管直接投入 零下 80 攝氏度超低溫冰箱中急速深凍，或者直接沒入液氮（零下 196 攝氏度）中長期保存。在此溫度下，活菌的毒力因子及活性可穩(wěn)定維持?jǐn)?shù)年以上。

Part 2 English Section

I General Information and Genetic Architecture

• Organism Name: Helicobacter pylori G27 Standard Paradigm Reference Strain.

• Taxonomic Classification: Domain Bacteria, Phylum Pseudomonadota, Class Epsilonproteobacteria, Order Campylobacterales, Family Helicobacteraceae, Genus Helicobacter, Species Helicobacter pylori.

• Strain Background and Origin:G27 is recognized globally as one of the most vital paradigm standard type strains within the Helicobacter pylori clinical research ecosystem. It was originally recovered in the late 1980s to early 1990s by Italian investigators from a gastric mucosal antral biopsy obtained from an endoscopy patient presenting with severe Gastric Ulcer pathology in Italy.

• Genomic Architecture and Virulence Profiles (Critical Background):

  • CagA Positive Matrix (CagA positive): The G27 genome harbors a completely intact, functionally hyper-active cag Pathogenicity Island (cagPAI) matrix. It drives robust transcription of the Cytotoxin-Associated Gene A (CagA) effector protein. CagA functions as a designated bacterial oncoprotein, acting as the primary catalyst driving host gastric epithelial cell oncogenic transformation.

  • VacA Activity (VacA-s1/m1 Allelic Mosaic): Expresses the high-toxicity Vacuolating Cytotoxin A (VacA) genotype (classically mapped to the s1/m1 mosaic structural permutation). This secreted toxin creates vast intracellular vacuoles inside target gastric epithelial sheets, down-regulates mitochondrial membrane potential, and induces host cellular apoptosis cascades.

  • Type IV Secretion System (T4SS): G27 features a fully assembled, rigid T4SS macromolecular syringe structure. Upon physical alignment with host target membranes, the T4SS system penetrates epithelial boundaries to physically translocate CagA, alongside specific cell wall peptidoglycans, directly into the host cell cytoplasm.

• Electrophysiological and Genetic Engineering Advantages:When benchmarked against alternative clinical reference isolates (such as strain 26695), G27 premier evolutionary advantage is its highly robust, stable endogenous capacity for natural transformation (Highly Naturally Transformable). This biological baseline streamlines laboratory gene targeting protocols, including allelic exchange, insertional mutagenesis, targeted locus knockouts, and the introduction of custom fluorescent reporting replicons.

• Biosafety Matrix: Classified under Biosafety Level 2 (BSL-2) containment parameters. Helicobacter pylori is indexed as a Class I Definitive Human Carcinogen; consequently, all continuous vegetative workflows must be handled inside validated Class II Biosafety Cabinets.

II Strategic Research Value and Translational Fields

The G27 line cleanly unifies an aggressive native pathogenic profile with superb genetic tractability, serving as a golden tool to decipher the mechanical baseline of gastric barrier degradation:

1. Host-Pathogen Mechanical Cross-Talk and Morphological Cytoskeletal Remodeling (Hummingbird Phenotype):During in vitro infection screens targeting human gastric carcinoma lines (such as AGS, MKN45), G27 utilizes its T4SS apparatus to micro-inject CagA into the cell cytoplasm. Intracellular CagA is subsequently phosphorylated by host-derived oncogenic tyrosine kinases (such as Src and Abl family elements), setting off physical binding with SHP-2 tyrosine phosphatase. This triggers a dramatic, diagnostic cytoskeletal collapse known as the Hummingbird Phenotype, which is characterized by extreme cellular elongation, continuous filopodia extension, and hyper-activated cell motility. This framework models the genesis of Epithelial-Mesenchymal Transition (EMT) and early carcinogenetic pathways in real time.

2. Type IV Secretion System (T4SS) Structural Assembly and Transport Kinetics:G27 serves as a standard molecular chassis to resolve the fine-scale macromolecular building loops of the T4SS needle core, and to track how specialized loop proteins (such as CagL) align with host cell surface integrin receptors (alpha v beta 1 integrin). Leveraging Cryo-Electron Microscopy (Cryo-EM) or super-resolution fluorescence microscopy captures the structural polarization and transport kinetics of active virulence payloads along the bacteria-host cell junction plane.

3. High-Throughput Screening of Eradication Chemotypes and Target Vaccines:Driven by the steep global escalation in multi-drug resistant (MDR) clinical H. pylori isolates resistant to Clarithromycin and Metronidazole, G27 is integrated worldwide as a sensitive baseline control to discover novel small-molecule bactericidal compounds, identify potent Urease inhibitors, and validate blocking molecules engineered to interrupt essential outer membrane protein (OMP) attachment bridges (such as BabA, SabA adhesins).

III Microaerophilic Cultivation, Thawing, Passaging, and Cryopreservation Routines

Helicobacter pylori is a strict microaerophile. It maintains an exceptionally low tolerance for ambient oxygen tensions, moisture fluctuations, and stale nutrient conditions. Permitting exposure to standard atmospheric oxygen scales or absolute anaerobic conditions causes rapid cell death or forces cell sheets into an irreversible Coccoid Transformation (an encapsulated, morphologically spherical metabolic dormancy state completely stripped of infectious or proliferative capacities).

1. Formulating Growth Matrices and Microaerophilic Structural Calibration

• Solid Agar Matrices (Highly Standardized): Columbia Blood Agar Base or Brain Heart Infusion (BHI) Agar.

  • Mandatory Supplements: Once the post-autoclave basal agar drops to 50 degrees Celsius, investigators must supplement the matrix with 5% to 7% sterile, whole Defibrinated Sheep Blood (or Horse Blood equivalents), or incorporate 10% high-grade Fetal Bovine Serum (FBS). Blood/serum proteins act as critical metabolic scavengers, purging cytotoxic free-radical oxides from the media layout.

  • Selective Multi-Antibiotic Cocktails (Contamination Prevention): Supplement plates with specific H. pylori selective matrices (comprising calibrated volumes of Vancomycin, Polymyxin B, Trimethoprim, and Amphotericin B) to prevent overgrowth by secondary bacterial contaminants.

• Liquid Growth Matrix: Brain Heart Infusion (BHI) broth supplemented with 10% premium FBS (requires continuous orbital micro-agitation).

• Microaerophilic Gas Chemistry (Critical Operational Baseline):

  • Standard Certified Gas Formulation: 5% Oxygen, 10% Carbon Dioxide, and 85% Nitrogen.

  • Laboratory Implementation Routes: Deployed inside dedicated, gas-controlled Microaerophilic Incubators, or by sealing plates within custom gas-tight GasPak Jars/Canisters integrated with microaerophilic gas-generator sachets (such as CampyGen systems).

  • Thermal Window: Set strictly to 37 degrees Celsius (never cultivate at 30 degrees Celsius or 42 degrees Celsius).

  • Relative Environmental Humidity: Maintain greater than 95% continuous saturation (typically secured by placing a sterile, water-saturated gauze pad at the floor of the sealed jar).

2. Cryovial Thawing and Initial Inoculation Protocol

1. Pre-equilibrate premium blood agar plates inside the microaerophilic incubation workspace to ensure the agar matrix reaches 37 degrees Celsius and surface condensation fully desorbs.

2. Extract the G27 cryovial from ultra-low freezers or liquid nitrogen containment. Because H. pylori cells disintegrate under extended thermal transition pathways, submerge the vial instantly inside a 37 degrees Celsius water bath and shake rapidly to complete thawing within 60 seconds.

3. Spray the exterior with 75% ethanol and transfer into the Class II Biosafety Cabinet. Extract the entire slurry via a sterile pipette tip and drop it directly onto the central concentrated zone of the pre-warmed blood agar.

4. Gentle Mechanical Handling: Utilizing a sterile single-use cell spreader or wire loop, smoothly transition the fluid into a classical three- or four-quadrant streak orientation. Do not apply heavy mechanical friction, as tearing the delicate agar surface or shear-stressing the vegetative bacteria disrupts recovery.

5. Instantly invert the inoculated plates, drop them into the target airtight canister, activate a fresh microaerophilic sachet, and secure the sealing mechanisms. Transfer the assembly into the 37 degrees Celsius incubator.

6. Incubation Patience Window: G27 vegetative kinetics develop slowly. The initial post-thaw recovery generation (P1) requires a baseline of 3 to 5 days (72 to 120 hours). Avoid opening the canister to inspect plates prior to the 72-hour threshold, as influxes of atmospheric oxygen will oxidize and kill recovering cells. Tiny, pinpoint-sized (0.5 to 1.0 mm), translucent, water-drop-like non-hemolytic colonies will begin breaking through the agar matrix by day 3 or 4.

3. Subculturing and Continuous Line Passaging

• Confluency and Timing Mandate: Passaging must occur precisely when colonies show distinct dewdrop structures but prior to fusing into dry, flattened macro-crusts (typically within 48 to 72 hours post-inoculation). If allowed to age beyond 96 hours, the culture triggers a massive, autogenous shift from healthy, flagellated Spiral/Rod morphologies into aberrant, metabolic Coccoid spheres. Coccoid forms look like granular point-debris under oil-immersion microscopy, lose cell-adhesion and pathogenicity parameters, and cannot be subcultured or revived.

• Passaging Execution Steps:

  1. Moistened the donor agar plate surface by dripping 1 to 2 mL of sterile, antibiotic-free PBS or plain BHI broth over the colonies.

  2. Utilizing a sterile cell scraper or smooth loop, gently harvest the cell mass from the agar surface, pooling the slurry into a sterile microfuge tube.

  3. Dilute the slurry and inoculate fresh blood agar setups utilizing standard empirical split ratios ranging from 1 to 3 to 1 to 5.

  4. Seal the newly seeded plates back inside the microaerophilic workspace. Established continuous passages expand rapidly, routinely hitting full density within a crisp 48-hour window.

4. Cryopreservation Protocol

• Cryoprotectant Freezing Matrix: High-nutrient Brain Heart Infusion (BHI) broth supplemented with 20% to 25% analytical-grade sterile glycerol and 10% premium Fetal Bovine Serum (FBS).

• Cryovial Preservation Guide:

  1. Exclusively harvest active cultures incubated for approximately 48 hours (late-logarithmic phase), verifying via light microscopy that greater than 95% of the cell sheet retains standard, highly motile helical/short-rod phenotypes.

  2. Wash the vegetative mass from the plates using a sterile scraper and adjust the cell density inside the preservation matrix to a high density (the fluid must present a heavy, milky-white opaque turbidity profile).

  3. Aliquot the dense bacterial suspension into sterile cryovials. Do not implement slow controlled-rate gradient freezing box pathways. To prevent slow ice crystallization from tearing through the delicate dual-membrane actin envelope of the spiral bacteria, plunge the cryovials instantly into a minus 80 degrees Celsius ultra-low freezer or submerge directly within the vapor phase of a liquid nitrogen tank (minus 196 degrees Celsius). Under these deep cryogenic baselines, the viability, genomic integrity, and virulence cascades of G27 remain uncompromised for years.

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