“HIV is still a huge global challenge” – In conversation with Christian Gaebler, the physician-scientist promoting HIV research in Berlin

A well-known example would be the antibodies from pharmaceutical companies such as Regeneron, Eli Lilly, and VIR, which were widely used to treat COVID-19. These pharmaceutical drugs were produced using methods that we pioneered in our HIV research.

Fascinating! Now let’s jump forward in time. You became Professor for Translational Immunology of Viral Infections in November 2023 and we supported the process with a Recruiting Grant. How would you describe your first two years back at the Charité?  Do you feel that you have settled in well?

Yes, I think so! I’ve actually been here since January 2023 and spent the first months building up my lab – recruitment took a little while. But yes, I’ve been leading my own research group for almost exactly two years now. My job description has totally changed. The switch from assistant professor in New York to group leader and professor in Berlin was challenging – I had to navigate a new role and work environment, even though I already knew the Charité from my time as a resident physician. But of course, a lot also changed between 2018 and 2023! I used to be very much a clinician whereas now I am more of a scientist. The start of my new role was also impacted by the tail end of the pandemic, although building a research group is always complicated: you’ve got to recruit the right people, put structures in place, get to grips with internal bureaucracy and, of course, secure funding. The first year is bound to be bumpy, as my mentors also confirmed based on their own experiences.

Today I’m proud to say that we have a very strong team which has in turn created a great working environment. Now we can concentrate on our field of research which I feel is still neglected in Berlin, despite the fact that the city has the largest community of people living with HIV in Germany. That was partly why I decided to come back. The Charité has also played a major role in real scientific breakthroughs like the curing of the first and second ‘Berlin patients’. But in recent years, HIV research seems to have dropped off the radar a bit. That’s what I am here to change.

‘Community’ is key in your field of research. Can you give some examples of the role played by people living with HIV? 

Our relationship to the community is crucial. It is mirrored in the language we use, which is why we refer to ‘people living with HIV’ rather than ‘people infected with HIV’, for example. We want to show respect and avoid stigma. I do think we should still be able to refer to cells as being infected with HIV – that’s just scientific language – but we should not do so in relation to people. Today we have clear language guidelines which reflect our sensitivity towards patients. But it was not always that way. The situation in the 1980s and 1990s was absolutely hopeless: scientific research was largely carried out without the involvement of those affected and there was a huge social stigma. It has been a long and arduous road for people living with HIV to get to where they are now. 

We get important feedback from members of the community. They let us know, for example, when scientific publications use insensitive language. Avoiding these mistakes is not always easy for those of us working in science as we have not necessarily been trained in how to communicate with stakeholders outside of academia – making it all the more essential that we include people living with HIV in our work.

How have these values shaped your actions? 

As a new arrival in Berlin, I feel that it is my job to communicate who I am, what my team and I want, and what our goals are. We need to communicate this to the other groups of scientists with whom we come into contact and, of course, to patients, their loved ones, and their wider communities. Although a lot now happens in specialist medical practices instead of the university hospital, the Charité is still involved in treating patients. We still see complex cases and unfortunately – although rare – full progression from HIV to AIDS.

That’s why we collaborate closely with organizations like Berlin AIDS Help, German AIDS Help, Checkpoint Berlin, and other healthcare facilities to maintain contact with the community. Our outreach work ranges from film screenings to discussion sessions. This is particularly important for our research as we want to find really motivated participants for our clinical studies. I am always impressed by the generosity of people living with HIV: they are acutely aware of how much they have personally benefited from previous clinical studies and therefore want to contribute towards the treatments of the future.

Our relationship really is a two-way street: we are constantly learning from members of the community and they support us in our research too.

Many people view HIV as a problem that has more or less been solved. Media coverage and public interest seem to be limited to anniversaries and major research breakthroughs. Which aspects of the virus, disease, or HIV/AIDS research do you believe deserves more attention?

We should take care not to consider HIV to be a closed chapter just because good treatment options are now available. Even today, it is not generally possible to cure people! The breakthroughs in HIV treatment are extremely hard won and are not set in stone. HIV is still a huge challenge around the world and we are sadly witnessing a resurgence in anti-scientific claims and political decisions which put these achievements at risk and ultimately cost lives.

In answer to your question: one especially important yet overlooked issue is gender bias in HIV research. In the Global North, we often focus on men living with HIV, even though more women are affected by it around the world. I also feel that greater attention should be paid to ethnic diversity among research study participants. The HIV subtypes that we focus on in western countries are different to those most widespread across the world, especially in the Global South. HIV is a very variable virus and this impacts research insights, treatment, and preventive measures.

Gender bias is particularly evident in clinical studies. When we wanted to lead an observational study in Berlin, the ethics commission told us that we were not allowed to include pregnant women living with HIV. That's despite the fact that every year, around 160,000 newborns across the world are infected with HIV as a result of mother-to-child vertical transmission. Excluding pregnant women from our studies creates and widens gaps in our understanding of this population. I don’t mean to criticize the ethics commission – it is only doing its job and the risks must always be weighed up against the potential for new insights. But we must also consider the negative impact of categorically excluding women in this way.

Can you elaborate on this?

Sure. Every year, we treat 50 to 70 pregnant women living with HIV at the Charité. I was surprised by this figure the first time I heard it as it is pretty high! All the female patients from the greater Berlin area essentially come to us because of our excellent treatment facilities here: at the Charité Campus Virchow-Klinikum we have departments for infectious diseases, neonatal care, and pediatrics which all work closely with one another. This is also a good argument for why we should have a mother-child study cohort: we want to understand how a chronic HIV infection manifests itself during pregnancy. This could then help to improve treatments designed to prevent mother-to-child transmission, an issue which is crucial in parts of the world that are experiencing high rates of new infections.

What would you say has been your greatest career success? Have you experienced any serious lows too?

For me, success is not just about publishing papers. Instead, my proudest achievement is having successfully brought together academic and clinical research. Many of my mentors felt that this would be difficult in the long term – but uniting these two sides is second nature to a physician-scientist like me. In the USA, I saw that it was possible to carry out research in both the clinic and the lab, all while maintaining a focus on translational medicine as the overarching goal. I’ve managed to achieve this so far.

The beginning of the COVID-19 pandemic in New York was my greatest challenge to date. Life with a small child in a city that was badly affected by the pandemic while also dealing with urgent scientific questions made this a very difficult time.

You had an unusual perspective on the pandemic as an HIV/AIDS doctor. What insights did you gain during this time?

At the start of the pandemic, we were quickly able to apply our expertise and experience with other viruses to this new situation – our knowledge spanned infection trajectories, research methods, and practical matters like workflows. Although many other labs also shifted their focus to COVID-19 at the time, our background in HIV research allowed us to react especially fast. The pandemic was, however, also a humbling experience. On the one hand, we were able to learn a lot in a short space of time, but on the other, we were continually confronted with the fact that we were only scratching the surface. The scientific process itself was particularly impressive: the entire scientific community worked together on this one urgent issue and we made huge leaps forward.

Collaborating with a gastroenterologist in summer 2020 was a very formative experience for me. We examined biopsies taken during routine gastro- and colonoscopies from people who had luckily survived being infected with COVID-19. Under the electron microscope, we were surprised to find viruses months after infection. Coronaviruses have a different biological structure compared to human immunodeficiency viruses, so we really did not think that they would persist for so long. This discovery raised a whole range of questions and is perhaps a good example of how important it is to always question your scientific assumptions and be open to new insights. That was the most important lesson I learned from the pandemic.

How does our pandemic preparedness look today? It doesn’t seem as though we have entirely come to terms with the COVID-19 pandemic – what is your take?

From a scientific perspective, the pandemic was an impressive example of what international research collaboration can achieve. We not only achieved major breakthroughs with COVID-19 – like vaccine development – but also gained so much insight that can be applied to other infectious diseases too. The pandemic showed us what is possible when the entire scientific community works together.

The societal dimension is far more complex. We are all exhausted by the pandemic but that doesn’t change the biological reality that the risk of new pandemics remains just as high. I believe that we are well equipped from a scientific point of view and could respond quickly in another emergency. The social and political aspects probably pose the greater challenge.

There’s a black-and-white print on the wall above the table we're sat at, depicting a stylized map of Manhattan. It makes me wonder: What do you miss from all those years at The Rockefeller University in New York, and how are things different in Berlin and at the Charité?

It’s like comparing apples and pears! The Rockefeller University is a small, highly specialized research institute, while the Charité is a huge university hospital. Sometimes I miss the ease of communication and close-knit nature of the smaller institution. But at the Charité you get to have direct contact with patients, so there are pros and cons to both.

It’s a similar story when you compare the cities too. New York is more than just the place I used to work: it’s where my children were born and where I spent half my life over the last 15 years. It’s a city that has played a huge role in the story of my life so far. New York is a worldly metropolis – and you maybe can’t quite say the same for Berlin… yet.

Gaebler laughs.

But there’s a lot to be said for that too, of course!

Dr. Nina Schmidt
January/February 2025