Name: Micro-Colony Forming Unit Assay to Quantify Mycobacteria
Uploaded: 2023-07-28T13:10:00
Description: Watch this Scientific Journal Video about Micro-Colony Forming Unit Assay to Quantify Mycobacteria at JoVE.com

micro-colony forming unit assay to quantify mycobacteria

Micro-CFU 방법을 사용한 결핵 판정 가속화

Tuberculosis (TB) is the leading cause of death worldwide by a single infectious agent, bacterium Mycobacterium tuberculosis (M.tb), killing more people than any other pathogen. In 2021, TB was responsible for 1.6 million deaths and was surpassed by COVID-19 during the 2019-2021 pandemic1. Moreover, according to the World Health Organization&#180;s global TB report of 2022, the COVID-19 pandemic was responsible for an increase in new TB cases. The WHO also reports large drops in the number of people diagnosed with TB during this period, which could increase further the number of TB cases1.
The Bacillus Calmette-Gu&#233;rin (BCG) is a live-attenuated strain of the pathogenic Mycobacterium bovis, used for the first time as a vaccine more than 100 years ago. This is the only vaccine against TB and is the oldest licensed vaccine in the world still in use2,3. Currently, there are 12 vaccines in different phases of clinical trials4, and dozens of vaccines are under pre-clinical development5,6. Pre-clinical assessment of vaccines against TB includes the evaluation of the safety and immunogenicity7, which can be obtained in diverse animal models such as zebrafish, mice, guinea pigs, rabbits, cattle, and non-human primates8,9,10. Additionally, assessing the capacity of a vaccine to induce protection against M.tb infection and/or transmission, i.e., the vaccine efficacy, requires an M.tb challenge in vivo5,11. Interestingly, BCG vaccination induces non-specific effects that affect the survival of other bacterial and viral pathogens12,13&#160;through the mechanism of trained immunity14. To quantify the viable bacterial burden in an infected animal, the method of choice is the enumeration of bacterial colonies through the colony-forming units (CFU) assay5,15. CFU is a unit that estimates the number of microorganisms (bacteria or fungi) that form colonies under specific growth conditions. CFUs originate from viable and replicative microorganisms, and the absolute number of living microorganisms within each colony is difficult to estimate. It is uncertain whether a colony has originated from one or more microorganisms. The CFU unit reflects this uncertainty, hence a great variability can be observed in replicates of the same sample. This time-consuming assay requires specialized technicians trained to work in a biosafety level 3 (BSL3) facility, substantial laboratory and incubator space, takes from 4 to 6 weeks to conclude, and is prone to contamination.
In this study, we describe an optimized method for colony enumeration, the micro-CFU (mCFU), and offer a simple and rapid solution to analyze the results15,16,17,18,19,20. The mCFU assay requires tenfold fewer reagents, reduces the incubation period threefold, taking 1 to 2 weeks to conclude, reduces lab space and reagent cost, and minimizes the health and safety risks associated with working with large numbers of M.tb. We propose that this method should be universally adopted for pre-clinical studies of vaccine efficacy determination, ultimately leading to time reduction in the development of vaccines against TB. Finally, this optimized method of CFU enumeration has been used to quantify not only Mycobacteria but also other bacteria, such as Escherichia coli and Ralstonia solanacearum21.

저자 스포트라이트: 결핵 백신 효능 및 항원 제시 분석의 효율적인 평가를 위한 CFU 결정 최적화 

결핵에 대한 백신의 효능 평가를 위한 Micro-colony Forming Unit Assay

CFU determination is necessary to measure the efficacy of the immune response against bacteria. However, it is very low throughput and becomes cumbersome and expensive when applied to pathogenic bacteria such as Mycobacterium tuberculosis. This is a significant limitation when we need to test large panels of treatments.The research focuses on tuberculosis and on the assessments of TB vaccines. It explores safety, immunogenicity, and efficacy of vaccines against Mycobacterium tuberculosis. The study presents an optimized method to micro-CFU for enumerating bacterial colonies to assess vaccine efficacy in preclinical studies.This protocol aims to optimize CFU determination by generating results from a small droplet similar to those from a regular Petri dish. Quantifying bacteria viability from such a small sample allows us to analyze thousands of data points using a fraction of the materials and time necessary for the classical method. Our research aims to dissect the antigen presentation machinery and to identify the most relevant antigens to optimize antigen presentation.This will inform us to design and develop better vaccines to improve or replace the current TB vaccine, which is BCG.

Watch this Scientific Journal Video about Micro-Colony Forming Unit Assay to Quantify Mycobacteria at JoVE.com

Micro-Colony Forming Unit Assay to Quantify Mycobacteria  

마이코박테리아를 정량화하기 위한 Micro-colony Forming Unit Assay

웰 플레이트를 사용하여 연속 희석을 수행하려면 먼저 96웰 플레이트의 A열과 E열에 Mycobacterium 현탁액을 놓습니다. 연속 희석 공정을 위해 180마이크로리터의 탈이온수를 나머지 웰에 추가합니다. 12채널 피펫을 사용하여 A열의 현탁액을 재현탁하고 20마이크로리터를 B열로 옮깁니다.D열의 마지막 희석에 도달할 때까지 B열과 C열에 대해 현탁액 이동을 반복합니다.마이크로 액적 도금의 경우, 팁이 얇은 0.5-10마이크로리터 멀티채널 피펫을 사용하여 96웰 플레이트의 각 행에서 단단한 중간 사각형 플레이트로 5마이크로리터를 옮깁니다.물방울이 한천에 약간 닿도록 하여 적절한 전달을 보장하고 팁 내부의 액체 잔류를 최소화합니다. 물방울을 말리고 한천 접시를 닫습니다. 섭씨 37도에서 배양하면서 박테리아 성장을 모니터링합니다.선택적으로 건조를 방지하기 위해 한천 플레이트를 밀봉된 비닐 봉지에 넣습니다. 6-10일 동안 잠복한 후 육안으로 볼 수 있는 개별 군체를 확인합니다. 가장 낮은 배율의 대물렌즈를 사용하여 도립 현미경 아래에 플레이트를 놓습니다.또는 카메라를 사용하여 물방울의 사진을 찍고 자동 집락 계수를 위해 ImageJ를 사용하여 컴퓨터에서 수동으로 집락을 계산합니다. 마이크로 콜로니 형성 단위 또는 마이크로 CFU 분석은 소량의 한천 플레이트에서 많은 양의 데이터를 생성하는 데 사용되었습니다. 사퀴나비르 전달을 위해 리포좀을 사용하면 약물 내성이 다른 마이크로박테리아 균주에 대한 치료 효능이 증가합니다.

Research

JoVE Journal

Medicine

Micro-Colony Forming Unit Assay to Quantify Mycobacteria

Micro-Colony Forming Unit Assay for Efficacy Evaluation of Vaccines Against Tuberculosis

Tuberculosis (TB), the leading cause of death worldwide by an infectious agent, killed 1.6 million people in 2022, only being surpassed by COVID-19 during ...

연구

의학

Bacillus Calmette-Gu&#233;rin (BCG) Vaccine Production

BCG(Bacillus Calmette-Guérin) 백신 생산

Micro-Colony Forming Unit Counting of Mycobacteria Using Fiji &#40;Image J&#41;

Micro-Colony Forming Unit Counting of Mycobacteria Using Fiji (Image J)  

피지를 사용한 마이코박테리아 의 미세 콜로니 형성 단위 계수(이미지 J)