Team:Hong Kong HKUST/FutureApplication

HKUST iGEM Team 2017

Possible Future Applications

1. Probiotics - A Platform For Drug Delivery

Nowadays, drug are not necessarily produced by chemical combination purified from plants or other substances. One example is the probiotics that treat Clostridium Difficiles, replacing traditional antibiotics or fecal transplantation which may cause negative effects.

There is an increasing support on the effect of microbiomes on human health. Microbiome species present inside human body can tell whether a person gets sick and what kinds of illness that could be. Thus, microbiome therapeutics is a new hope and breakthrough technology.

The genetically modified bacteria used in the therapeutics can be programmed to detect signals when some dangerous or pathogenic bacteria invade the environment. This signal transduction allows bacteria to produce desired proteins that help combat with the disease bacteria. Nevertheless, while engineered probiotics offer several advantages to human health, it is still deemed as GMOs. Thus, safe implementation is necessary to remove engineered gene in this application.

In the light of growing microbiome therapeutics market size, we proposed that microbes can be functioned to deliver suitable amount of drugs under a concentration which can optimally cure human diseases. The engineered bacteria can be delivered simply in a form of pills like bacterial spore inside an oral capsule. Our construct simulating sensing, time delay and knockout condition will be suitable for tourists or soldiers who need to take these pills before traveling to a place with high risk of transmissible disease, but this drug will not need to express immediately unless diseases are detected. This would be cost saving and safer than taking drugs frequently especially when it involves antibiotics.

In addition, the environment will be kept safe by reverting microbes to their original state that can balance human flora and continue to serve beneficial purpose to human bodies.

2. Sensor for horizontal gene transfer

GFP is a well-known reporter used by many iGEM teams and researchers. Such visual reporters have limited use in some context such as soils, because it can only work in the presence of oxygen and the color output can be hardly detected under layers of soils.

Recently, Rice University researchers have developed gas biosensors that can track the presence of horizontal gene transfer without disturbing the soil matrices. This discovery can further aid the study of soil environment and horizontal gene transfer i.e., how hydration affects horizontal gene transfer.

Using our construct as a proof of concept, we can use gas biosensors to detect the release of constitutively expressed recombinant products and, at the same time, use our method of recombination to knockout the recombinant genes. Moreover, this may also provide additional knowledge about the fitness of genetically modified organism comparative to the wild-type bacterium.

When horizontal gene transfer is detected, recombinase can knockout the gene of interest and later knock out the reporter gene after enough concentration of reporter is established.

This allows scientists to study bacterial interactions in a selected sample environment, and investigate the prevention of gene transfer between engineered and wild-type bacteria.

As extracting products from organisms require many purification steps and it is costly, it may be more favorable to be able to use engineered organisms equipped with safeguard system in the field.

3. Reduced allergenic response by immune system for transgenic expression in mammalian cells

Hiroshi Ochiai (2010) reported that positive feedback system provides efficient transgenic expression in Hela cells both in vitro and in vivo.

Additional papers regarding gene therapy suggested that using a plasmid that lacks bacterial backbone due to deletion by site-specific recombination will improve the efficiency of transgenic expression, because the host immune system will most likely reject foreign vectors such as bacterial plasmids. The example of such plasmid is the ‘minicircles’.

The recombination of origin of replication and marker gene or antibiotic resistance gene can reduce allergic responses in an individual should the application be used in eukaryotic cells such as gene therapy.

4. Reduced GM pollens dissemination

The propagation of GM pollen by GM crops has been a major concern, especially in its effect on undesired gene flow. Removal of transgene in pollen prior to its dissemination is, thus, a crucial step to prevent gene flow happens.

Our sensing module can be adjusted to detect specific stimuli and temporally produce proteins of interest, necessary for plants for a controlled period. Recombinase can later knockout the gene of interest safely.

References

  1. Sarah Smith (2016) Microbiome Therapeutics Market, 2015 - 2030. Retrieved from: http://www.prnewswire.com/news-releases/microbiome-therapeutics-market-2015---2030-300364091.html
  2. Mark Mimee (2016) Microbiome Therapeutics - Advances and Challenges. Elsevier, 105, 44-54. Retrieved from: http://www.sciencedirect.com/science/article/pii/S0169409X16301429
  3. J. Clin. Med (2016) Advances in the Microbiome: Applications to Clostridium difficile Infection, 5(9), 83, doi: 10.3390/jcm5090083
  4. Baylor College of Medicine (2017) Reducing risk of gut bacterial infections with next-generation probiotic? Retrieved from: https://www.sciencedaily.com/releases/2017/08/170809140202.htm
  5. Mike Williams. (2017). Gas sensors ‘see’ through soil to analyze microbial interactions. Retrieved from http://news.rice.edu/2016/07/19/gas-sensors-see-through-soil-to-analyze-microbial-interactions/
  6. Positive Feedback System Provides Efficient and Persistent Transgene Expression Hiroshi Ochiai, Hideyoshi Harashima, and Hiroyuki Kamiya Molecular Pharmaceutics 2010 7 (4), 1125-1132 DOI: 10.1021/mp1000108
  7. Hou, X., Jiao, R., Guo, X., Wang, T., Chen, P., & Wang, D. et al. (2016). Construction of minicircle DNA vectors capable of correcting familial hypercholesterolemia phenotype in a LDLR-deficient mouse model. Gene Therapy, 23(8 & 9), 657-663. http://dx.doi.org/10.1038/gt.2016.37
  8. Mlynarova, L., Conner, A., & Nap, J. (2006). Directed microspore-specific recombination of transgenic alleles to prevent pollen-mediated transmission of transgenes. Plant Biotechnology Journal, 4(4), 445-452. http://dx.doi.org/10.1111/j.1467-7652.2006.00194.x