UT researchers to create Zika vaccine candidates
Author: Katre Tatrik / ERR Novaator
The infection, which usually displays no symptoms, might cause paralysis and women infected during pregnancy might give birth to babies with underdeveloped brains. This is caused by the Zika virus, its spread can currently only be contained with campaigns that warn of mosquitoes and promote safe sex. Can virologists of the University of Tartu find a reasonable way out of the global emergency?
“We can do it!” UT Professor of Biomedical Technology Mart Ustav is confident that in two months, together with colleague Andres Merits, Professor of Applied Virology, they can start to create the synthetic Zika virus, the genetic structure of which can be altered according to need. “Two-three months and we will also have flagged this virus for better monitoring of infection,” promises Andres Merits.
By a flagged virus the professors mean a virus carrying luciferase (light-emitting) or fluorescent protein genes. Such viruses are primarily used to monitor the spread of a virus and to test potential antiviral drug candidates. Cells in which the virus “glows” after administering the medication are a sign that the preparation does not work. In cells which have “faded out”, the medication has suppressed the virus and corresponding compound can be considered as “hit”.
In addition, in cooperation with the biotechnology company Icosagen, the UT researchers have access to high-quality technology and modern methods. This enables to quickly and efficiently isolate genes encoding for antiviral antibodies. By using those genes, it is possible to produce the necessary antibodies in large quantities and, in principle, use to create an antiviral protection in humans.
“Many researchers have samples of the Zika virus but, at the moment, no one has enough antibodies that could systematically hinder the virus’ activity—inhibit it. There are also not enough antibodies to analyse virus infection cycle. Simply, so far, there has been not enough reasons to work on it,” says Merits.
“The easiest way of course is to take blood samples of an infected person and the antibodies as well as the genes of these antibodies it contains and isolate those to clear out the virus. But Mart Ustav wants to produce these antibodies using the isolated genes not only in large quantities for elimination of viral infection, but to use these also in gene therapy applications systematically.”
A flagged and genetically modifiable Zika virus and the corresponding antibodies are great tools to contribute in solving the erupted crisis but which no one in the world currently possesses. UT researchers are able to produce these tools within a couple of months and then share them with others.
Ustav and Merits used the same strategy to develop Ebola vaccine and medications.
“We are not Ebola experts. We have never even held this virus. But by applying our molecular biology, molecular virology as well as molecular immunology skills and technologies, we were able to create Ebola vaccine candidates and isolate and produce potentially curative antibodies to treat people infected with the virus. Whether they are suitable for helping people will be shown by human trials,” says Ustav.
For this, Andres Merits with the UT laboratory and Mart Ustav with the biotechnology company Icosagen will already on 16 March submit their application to the major European Union funded Ebola virus vaccine project. The project is led by French scientists and active participation of Italian, Spanish, Swedish labs gives Tartu researchers the chance to complete vaccine trials and proving the curative effect of therapeutic antibodies in actual viral infection situations. It would never have happened if Estonian researchers had not reacted quickly.
“We did preparatory work for a year to now get the opportunity to solve a major global issue and use the necessary financial resources.”
“We are also hoping to complete the tools necessary first to study and then to fight Zika before the others manage to agree on who they will give the funding for developing,” UT professors approve of Rector Volli Kalm’s very operational decision to allocate 30 000 euros for Zika research from the reserve fund. The Institute of Technology will allocate the same amount. The researchers are planning to ask funding also from the European Union.
“When the World Health Organisation declared global emergency on Monday, on Tuesday we discussed the topic with the rector and by Wednesday, decisions had been made,” Mart Ustav describes the course of events at the university.
Researchers stress that at least for now, they are not going to research the molecular biology of the Zika virus themselves. “Zika is a member of the virus family Flaviviridae and its molecular biology is not our primary research interest. We know as much or a bit more about it than about all other viruses but we have never worked with this virus or any of its close relatives.”
This does not, however, stop Merits and Ustav as specialists of synthetic biology and molecular virologists to take themselves to a level, where they are able to solve crucial problems so that partners with great resources would invite them to cooperate.
One option for this is to use novel tools needed for developing a vaccine and then, with partners who have more experience in this field, participate in researching the interactions of the Zika virus and its hosts—humans and mosquitoes. “As of this morning, such interest for cooperation has been expressed by researchers from Australia, Great Britain, Spain, Brazil and Sweden,” says Ustav.
“In addition to that, yes, we want to make vaccine candidates ourselves too.”
In order to construct a functioning vaccine candidate, it does not necessarily take decades of experience in working with a pathogen. In order to come up with rational solutions, you need to know the general principles and have molecular biology skills.
“We know very well what a good vaccine should be like. It needs to be able to activate all three constituents of the immune system from beginning to end. This vaccine has to be able to correctly present all immunogenic parts of the virus and, in addition to innate immunity, also activate the adaptive (humoral and cellular) immune response, which can eliminate the pathogen from the organism. At the same time, the vaccine cannot be too dangerous for humans,” list the researchers.
“True, there are about 40 reasonable options for doing all this. I am certain many teams are working on this right now; we want to come up with three different types of vaccine candidates,” says Merits.
In order to achieve this, he intends to construct the yellow fever 17D vaccine—named the most effective vaccine in the world—and a Zika virus chimera. “It is relatively easy, we know it works for some other viruses and it is very likely that it will work here as well.”
“Secondly, I want to use alphaviruses, which I have good knowledge of, as carriers of vaccine antigens. I will take three very different antiviruses—Chikungunya, Ross River and Semlik Forest virus—and make them produce the three structural proteins of the Zika virus—capsid, matrix protein and membrane protein. The sequences that code for these proteins fit nicely in the genome of the alphavirus based replicon vectors, we create virus-like particles and see what comes out.” Merits added that the third method for creating a vaccine candidate is called codon de-optimization.
“The vaccine candidates are partly necessary because Mart Ustav will be creating antibodies for the Zika virus. By immunising an animal or human with a vaccine, antibodies form and the genes of these antibodies can be isolated from the B-cells of a vaccinated human or animal,” adds Merits.
“There is always the chance that a good idea bogs down. It is a contest in essence: if we do nothing, we are bound to lose,” thinks the professor of applied virology.
“EU grants bring together various researchers with various ideas. Those who do not have an idea do not participate and they are out of the contest.”
Once research groups have put together Zika vaccine candidates, a large consortium should compare them at some point. This is to select the best to carry out clinical trials with them.
“Ebola and Zika are major global problems—if you see people suffer and you have a rational idea how to avoid this… We have good ideas and we want to play in the big league,” say Mart Ustav and Andres Merits.