INTERVIEW: The First Proof of Zika Virus and Microcephaly Association

Prof. Dr. Tatjana AvšičMeet Prof. Dr. Tatjana Avšič, the leading scientist behind the first proof of the association between Zika virus and microcephaly in the world.After 35 years of her recognized career as a virologist, she is still curious and admits that this last discovery about the Zika is a once-in-a-lifetime opportunity. We talked about the Zika research, conspiracy theories and her plans for the future. And how she manages to balance her career and family life.


JANA: Hello Splice. I am here with a renowned virologist Prof. Dr. Tatjana Avšič. She is the Head of the Laboratory for diagnosis of Zoonoses at the Institute of Microbiology and Immunology, Faculty of Medicine, University of Ljubljana, Slovenia. Prof. Avšič has been a leading senior scientist behind the research paper published in New England Journal of Medicine in which they confirmed that Zika is transmitted from the infected mother to a fetus. Hello Prof. Avšič.


JANA: It is amazing that you were the first who discovered transmission of Zika virus from woman/mother (who was infected with Zika) to fetus having in mind that Slovenia is not even close to the region of Zika virus outbreak. What raised your suspicion that the reason for microcephaly in fetus may be related to mother’s Zika infection?

TATJANA: Actually, our results were another proof of the association between the Zika virus and microcephaly. Because there has been a suspicion that Zika virus infection could cause microcephaly in fetus. We were suspicious because the expectant mother lived in Brazil for a year and a half when she actually got pregnant. During her pregnancy in the first trimester she got a viral infection which was not diagnosed at the time (the end of May 2015) but with a very clear clinical picture and symptoms that are consistent with Zika virus infection. When she came to our facility center she told us that she had the very symptoms of Zika virus infection.

I have received almost 500 emails in less than 2 days after the paper was published.

JANA: The research has been done in collaboration with different departments and institutes of the University Medical Centre of Ljubljana and Faculty of Medicine. A really nice example of good collaboration. How long did it take from the start of the research to the publication of the paper?

TATJANA: It was actually a very short period of time, because this was a single case. Still it took us about two to three months to compile all the results and to put the manuscript together. It could have been even shorter but there are some particular techniques that require longer time, such as fixation in pathology, which usually takes three to four weeks.

JANA: We know that viruses are constantly changing. How did you decide which methods will you use to detect Zika virus and which was the first method you used and also detected virus with it?

TATJANA: The viruses are constantly changing but not that fast as people have in mind, so it is not necessary for us virologists to change our techniques on a monthly base, particularly the molecular techniques. We used qPCR and reverse transcription qPCR (RT-qPCR) targeting specific protein 5 of the Zika virus genome and this one appeared to be positive. Since I am usually suspicious of the first results I wanted to confirm these first results with another gene, so we then targeted an envelope protein of the virus. We used the methods of molecular detection that have been published two years ago.

First result was surprising, since I was expecting to get all other organs positive or at least the placenta but we received only positive reaction in the brain tissue.

JANA: Were you searching for virus only in fetus brain or also in other organs and which?

TATJANA: At the beginning we knew there is a sort of probability that the mother has been infected with Zika virus during her first trimester of the pregnancy. But at the time there has been a very few rare reports of the possibility of the association of Zika and microcephaly in Brazil. That was in the mid October last year. With the agreement a pathologist asked for many different organs, beside the brain we checked the placenta, lungs, heart, spleen, thymus, liver, kidney and the cortex of the brain. We have looked for the different viruses and we thought of Zika, because as you know the Brazil is endemic particularly for Dengue and Chikungunya. The two infections have very similar clinical signs and symptoms as Zika, so at the beginning we did in parallel PCRs for all three pathogens on all 9 tissue samples from the fetus. Very surprisingly we got only brain tissue positive and it was positive only for Zika virus.

JANA: You have already answered my next question. I believe you have done a great job by including also many other organs and also many negative tests. Were you surprised by any results during the investigation?

TATJANA: Yes, like you mentioned, we have done a lot of tests, as we call it in microbiology, differential diagnostic methods, since we needed to rule out other possible causes of infection in mother and particularly other possible causes by known pathogens that can be teratogenic or that can be transmitted vertically from the mother to the fetus. We had to rule out Toxoplasma gondii, Rubella, Cytomegalovirus, Herpes virus, Parvovirus B19, Lymphocytic choriomeningitis, West Nile encephalitis and a bunch of other viruses that could go through the placenta and infect the fetus. For me personally the first results were surprising, since I was expecting to get all other organs positive or at least the placenta but we received only positive reaction in the brain tissue. Therefore I insisted that we have to look for the other genes and confirm that with the sequencing.

We have combined the 35 years of experience with a great opportunity that we had with a patient and also with a little luck as well.

JANA: Why is Zika targeting only the brain tissue is something that would be important to understand as well.


Zika virus under the transmission electron microscope. A group of Slovenian researchers was the first to show the association between Zika virus and damages in fetal brain. Authors: Marko Kolenc, Mateja Poljšak-Prijatelj, Katarina Resman Rus, Miša Korva, Miroslav Petrovec and Tatjana Avšič Županc

TATJANA: Exactly. This is the future research for all the researching groups at the moment from all around the world. We have to confirm that Zika is neuropathogenic virus, a virus that has a tendency to infect some brain cells, probably neurons, who knows which ones. We also want to know how it enters through the placenta and blood-brain barrier.

JANA: Have you encountered any problems during investigation of Zika virus and can you highlight the most important one?

TATJANA: During this case report we didn’t have any real problem by searching the virus. It was more of a problem from my part when I had to convince my colleagues from the pathology and gynecology that this is very important case and we need to investigate it further, then to write and publish a manuscript fast . I said ‘We will try to send it to the best medical journal. If this is what I think it is, they will accept it’.

JANA: Many laboratories in the world are investigating Zika. I guess it is really hard to be the first one in confirming such an important fact.

TATJANA: That is true but in our group of researchers, that are also co-authors of this case report, there are some people like me that have more than 35 years of experience in virology and pathology. This means that we have combined the years of experience with a great opportunity that we had with a patient and with a little luck as well. For me personally this discovery was very important for so many women in South America. With this report we started a long way to go, to help a lot of people in future, we added an important knowledge to the medical science.

JANA: How is Zika virus different from other mosquito transmitted viruses?

TATJANA: A lot of viruses are mosquito transmitted. The one that I already mentioned, which is the most known globally expanded, is Dengue virus that is transmitted with the same vector. The second one may be Yellow fever virus, which is one of the oldest known one, and then Chikungunya, which has just recently became more important as it is also present in South East Asia and South and Middle America. The other one is West Nile virus that has been known particularly in Africa or Mediterranean countries before the year of 1999/2000 when it spread to the Western Hemisphere to North America.

If there are other species of mosquitoes competent enough to efficiently transmit the Zika virus then the virus can be easily spread to North America or to other continents.

JANA: We know that many infections by Zika virus have been confirmed during the last year in South America. Can we speak about Zika virus epidemic?

TATJANA: Definitely, this is Zika virus epidemic. What was happening in the island of Yap in Micronesia in 2007 was an outbreak. It was only this island affected and a few thousand of people that were infected. The French Polynesia episode was already an epidemic and what is happening now is South America and further around in Middle America, we can talk about an epidemic. Definitely we talk about hundreds of thousands of cases.

JANA: What do you think are the chances that Zika virus will spread to United States or maybe even other continents? In your opinion when can this happen?

TATJANA: It is difficult to predict. Up until now we can talk that the main transmission of Zika virus is by its vectors. I particularly emphasize vectors in plural because we are not sure that Aedes aegypti mosquito is the only vector. We do not know yet but definitely this mosquito is the competent vector for Zika virus. On the other hand it is Aedes albopictus (tiger mosquito) that probably can also be sufficiently transmitting the virus and may be competent also for Zika virus. Tiger mosquito is present everywhere, in all continents, including all the Mediterranean countries of the Europe and can spread even further on because its eggs can sustain during the winter climate and low temperatures. Some researchers think that mosquitoes from the genus Culex can transmit the Zika virus. If there are other species of mosquitoes competent enough to efficiently transmit the Zika virus then the virus can be easily spread to North America or to other continents with infected people.

JANA: Can we predict that in a laboratory? Can we use different species of mosquitoes in a laboratory and test it?

TATJANA: Yes, those experiments are now undergoing by some research groups that are experts in this field. You may also be aware that when you have an experiment in a laboratory controlled conditions with the right animals (models) and very predictive conditions it is very difficult to compare to what is going on in the nature. We know that some abiotic factors like temperature and humidity usually effect very much the population of mosquitoes, so it is really difficult to predict this. Although there are some people working with prediction maps and modeling programs that can predict how the vectors, the viruses and the diseases will spread in the future but I think it is too risky to say anything.

There are at least 12 to 15 groups working on the vaccine development at the moment.

JANA: Is it possible that Zika virus will use a vector other than a mosquito?

TATJANA: I think Zika virus won’t need another vector. There are so many different species of mosquitoes that Zika can probably survive in the nature with mosquito. But if you think if Zika can be transmitted on some other way than a mosquito bite it can be sexually transmitted among people and by saliva and definitely with a transfusion. Nevertheless, these are not so important transmission routes than the one with mosquito bite and are easier to be prevented and/or controlled.

JANA: You have learned many things about Zika virus now. Do you think you can apply this knowledge to any other pathogenic viruses?

TATJANA: Definitely. For example in Slovenia we have a very important Flavivirus called tick-borne encephalitis virus (TBEV) which in difference to Zika or Dengue is tick transmitted and our country is highly endemic for this virus. Still it is a Flavivirus, so the knowledge that I have from TBEV I could already use for Zika and now some new knowledge from Zika I can use for TBEV and other viruses like Dengue. You can always use methodology knowledge from one virus to another.

JANA: How do you think your discovery will affect Zika research at other institutions? Is it too soon to speak about the development of new vaccine?

TATJANA: Our results and case report that we have published were extremely well accepted from almost around the globe research groups. The reason was because it was the first proof of the association between Zika virus and microcephaly. Before that there were only suspicions people did not want to believe. Now we have more and more information and other studies are starting to confirm the same results which is good for many reasons, one of them is of course the search for a vaccine. There are at least 12 to 15 groups working on the vaccine development at the moment.

JANA: There are many conspiracy theories regarding Zika and other viruses, such as that it has been intentionally released to the environment. As a virologist, how do you look at these rumors?

TATJANA: Well, these conspiracy theories are to me like science fiction movies which I don’t like to watch and being a virologist and a researcher at the same time I believe only what I see, what I touch and what my results can show me. And even so I have to confirm my own results two or three times before I really believe them to be true.

JANA: Probably you are continuing with investigation of Zika virus, what are the next steps?

TATJANA: We are applying now as a partner in a consortium, since the European Commission has just released Research and Innovation programme, posting 10 million euros for the Zika virus research until 2020. We would like to continue our research work particularly on histopathology of brain tissue of the fetuses and mainly we would like to continue our research on pathogenesis in the brain tissue.

JANA: Your everyday schedule must be completely full. How do you balance your career and private life? How do you relax and what do you enjoy most?

TATJANA: It is true that the last months have been very busy but I still had a chance to go skiing for 5 days in Tyrol (Austria), since skiing is one of my favorite sports. Sometimes there are periods when I don’t have much time for my private life then in the summer I usually have more free time. I really like cycling, hiking, skiing and just being with my friends and particularly I like to spend as much as possible my time with my three grandchildren which I love the most.

JANA: Thank you Prof. Avšič for your time. Splice wishes you and your team a lot of success in the future research.

TATJANA: Thank you very much.



Leave us a comment:

2 Comments Published

[…] Top Science News: The First Proof of Zika Virus and Microcephaly Association (Interview) […]

[…] has already featured some other discoveries about Zika virus such as the first proof of the association between Zika virus and microcephaly, low-cost paper based test for Zika virus detection and effective vaccination against […]

Splice supporters