Hypertrans Protein Expression System – What is it, and what are its benefits?

Protein expression systems have been developed for many host platforms with the aim of producing large amounts of protein. These can then be used in a number of applications, such as research, diagnostic and therapeutic medicines.

Eukaryotic expression systems typically contain: a strong promoter to drive transcription (the process of producing mRNA); a terminator, that contains the signals to end the mRNA strand and attach a polyadenylation sequence that aids mRNA stability; and sequences which allow for efficient translation (protein production by ribosomes from mRNA) from the mRNA.


The Hypertrans® system is a plant-based expression method developed by George Lomonossoff and Frank Sainsbury at the John Innes Centre and delivers high levels of protein expression in plants. This system was developed through the discovery that mutation, particular sequences in the promoter of the Cowpea mosaic virus (CPMV, a plant virus), resulted in the high-level expression of protein when the gene of interest replaced the native CPMV protein. The CPMV terminator sequences also appear to result in enhanced mRNA stability.

While the Hypertrans® system is based on viral sequences, it does not require viral replication for the transmission or expression. This means that the size of the gene that can be expressed in the system is not limited by the size restrictions of viral systems. In addition, since no viral replication occurs it cannot spread to other plants, meaning there are not the requirements of containment associated with viral replicating systems.

In the Hypertrans® system, the features from CPMV are combined with a gene silencing suppressor. Plants have evolved many ways to control the levels of mRNA present in a cell, thereby making it difficult to generate enough mRNA to produce large amounts of protein. This process is known as post-transcriptional gene silencing, as it effectively silences the expression of the gene. However, nature has provided mechanisms to overcome this suppression, with many plant viruses containing proteins that can prevent this silencing. In the Hypertrans® system, P19 from the tomato bushy stunt virus (David Baulcombe) is co-expressed allowing for enhanced transient expression in plants.

All of the features of the Hypertrans® system have been combined in an easy to use plasmid series (pEAQ), which allow the simple one-step cloning of your gene of interest into a vector which can be introduced into Agrobacterium and expressed in a plant.


What are the benefits of the Hypertrans® system and how does it compare to other systems?

The flexible nature of the system enables production to be scaled from small scale research quantities to pilot-scale production very quickly. The speed of the system means that it can rapidly produce large amounts of protein and so it is well suited to rapidly responding to emergencies like pandemics. And…..less time in production equates to significant patent extension, perhaps as much as 12 months.

The technology is disruptive, and to date, there are no licensed products on the market that have been produced in plant systems. To a customer that can be seen as a considerable gamble, but what is true about the system is that a feasibility study to confirm whether the protein of interest will express can be done very quickly and at a fraction of the price compared to more conventional systems. Moreover, accurate likely costs of goods can also be established very quickly because the system is directly scalable, it’s just a case of adding more plants.

There’s also the question around regulatory approval. Conventional systems often face regulatory concerns over product purity and potential adventitious agents from the use of animal-derived raw materials and infection of patients. With plants, these concerns are avoided altogether as no animal-derived products are used in any part of the manufacturing process, either upstream or downstream.

These advantages all culminate in plant expression generally being much more cost-effective and facilitating greater R&D throughput, so surely it’s worth a try?

National Apprenticeship Week 2019

National Apprenticeship Week 2019

To mark National Apprenticeship Week, we asked our talented Apprentice Laboratory Technicians, Joe and Karen, to share their experiences of the programme.


Joe Ball

I joined Leaf Expression Systems in August 2017 after finishing my A-levels in Maths, Further Maths and Physics. I chose this route instead of accepting my offer to study a degree in physics because I wanted to gain a recognised qualification and work experience at the same time. I also believe that learning about a topic and then putting that knowledge straight into practice is a great way to learn.

During my time at Leaf I have been taught a lot of theoretical and practical knowledge and techniques like: agroinfiltration, plate streaking, culture growing, protein purification, media/buffer/solution creation, and more. I have also learned a great deal about the safety precautions and training involved and how important safe operating procedures along with risk assessments are in this industry, especially when using expensive and potentially hazardous equipment (if untrained) such as: autoclaves, orbital shakers/incubators, heat stirrers, infiltrators. This is alongside the use of a vast range of chemicals, buffers, solutions and more.

This role has surpassed my expectations and I have learned so much more than I thought I would. It has also developed my skills in areas like team working, communication, planning and research, and self-management to name a few. Overall it has been massively positive experience and I would recommend this route.


Karen Annison

I left school with science GCSEs & A-Levels, I wanted to pursue a career in science, but I wasn’t interested in going to university, so I started looking for apprenticeships within the science field.  I spotted the advert for this apprenticeship which seemed like an opportunity to get a qualification through working as I prefer to learn through hands-on experience instead of working in a classroom.

In the 18 months that I’ve been an apprentice, I’ve learned more than I thought I would, and I’ve been able to put practical techniques that I learned at school into use working within this company. The key things that I have learned include writing SOPs and EHS documentation, as well as key transferable skills such as pipetting and microbiological techniques. I also sit on the EHS committee and I am a first aider within the company. I would like to carry on working in the science sector and progress up the career ladder and work through the different fields within                                                          the industry.




CEO Update from Simon Saxby

Having been CEO of Leaf Expression Systems for 3 months, the following thoughts have struck me about the company and our Hypertrans® transient plant expression technology, and about our industry.

Firstly, Leaf Expression Systems Ltd has been operational for about two years, but not enough people know about us. We must and will change that – quickly!

Leaf is based on the Norwich Research Park, but very few people that I have spoken to in the UK seem to know anything about NRP, even though the John Innes Centre, Plant Biosciences Ltd, and the Earlham and Quadram Institutes are all on the campus, with Norwich Hospital right next door. I would be willing to bet that even fewer people working in the (non-agricultural) life sciences industry outside the UK know anything about NRP, despite the fact that if Nobel Prizes were awarded for plant research, JIC would rival LMB in Cambridge for the number of winners!!

I have also learned that using plants like Nicotiana benthamiana to produce monoclonal antibodies, enzymes, virus like particles (VLPs) for vaccines, and complex natural products in their leaves is incredibly simple and quick. Having spent over 30 years in the business of making and producing MAbs in mammalian or bacterial expression systems, I was expecting the process of infiltrating plant leaves to be equally complicated and time consuming. During my first week at Leaf, watching our scientists “dunk” the plants in a suspension of Agrobacterium which contained the protein sequence of interest, expose the plants to a vacuum for about 10 minutes and then watch as the leaves regain some of their rigidity when the vacuum is released and the suspension is sucked back into the leaves, – and “job done”, – was nothing short of a revelation. The fact that the leaves from our living “bioreactors” are harvested 7 – 10 days later, and that within just 12 weeks of receiving the sequence of interest to having gram quantities of purified product available for our clients, was equally astonishing.

Our industry is under increasing pressure to deliver new, better and cheaper diagnostics, vaccines and therapies so that Third World – and not just First World patients, can have improved health and quality of life. The flip side to those demands is that we work in a highly regulated and therefore very conservative and risk averse industry where the knee-jerk reaction to change is almost always the perception that the regulators will be resistant, and that change will increase risk and cost of gaining market approval for their products. In my experience, the regulators are far more receptive to change than the perception, and the earlier you engage with them the more helpful they are able to be. In addition, innovative thinking consistently delivers higher quality and efficiencies that far outweigh the costs of implementing the changes in the first place, and I believe that plant-based expression systems will have an increasingly significant role to play in the changing dynamics of our industry.

We at Leaf gladly accept the challenge of convincing the industry to take another look at the innovation we bring with Hypertrans® and we look forward to helping our clients accelerate their product R&D programmes, reduce their drug development costs, and meet the challenges we all face in delivering better patient outcomes for the future.