SANTHE Post-doctoral Alumnus leads expansion into Francophone Africa.

In 2018, the SANTHE network expanded to include a new site in Yaoundé, Cameroon, at the time increasing the network to a total of 13 Sub-Saharan African research sites and claiming Cameroon as its second site in Francophone Africa. “I had the honour and responsibility of returning to my home to lead this venture,” says Marcel Tongo Passo, previous SANTHE Post-doctoral Fellow, now SANTHE Site Principal Investigator (PI) based at the Centre de Recherche sur les Maladies Emergentes et Re-Emergentes (CREMER)/Institut de Recherche Medicale et d’Etude des Plantes Medicinales (IMPM) in Yaoundé, Cameroon. “This followed the completion of my PhD and post-doctoral training which lasted eight years at two centres of excellence in South Africa – the University of Cape Town (UCT) and the University of KwaZulu-Natal (UKZN). One of SANTHE’s key missions is to develop the next generation of leaders of African science and as such, I was awarded a SANTHE Path-to-Independence award to help support the establishment of my own independent research programme in the country of my birth. My work now focusses on investigating the extraordinary diversity of HIV that circulates in Cameroon and the Congo basin as a whole, as well as the biological properties of these viruses, which may explain why so many variants circulating in the region have not spread globally.”

The inclusion of the Cameroon site was a massive step for SANTHE. Not only was Tongo Passo the first SANTHE Fellow to start his own research group in his own country, but scientists in the network now also stood to benefit tremendously from understanding how challenges and problems played out in different contexts, especially with regard to infectious diseases. One of SANTHE’s main objectives was, and still is, to transfer scientific knowledge and strengthen capacity, and the inclusion of a second Francophone country into the network offered numerous new opportunities for SANTHE scientists to collaborate on research. “For SANTHE it is perfect that one of our early-careers scientists is leading this effort. We are proud that Marcel is also one of the first recipients of a SANTHE Path-to-Independence award,” said Professor Thumbi Ndung’u, SANTHE Programme Director, based at the Africa Health Research Institute (AHRI) in Durban, South Africa. “By offering young African scientists the resources they need to get started and the assurance of an international network of support in the long-term, SANTHE hopes to help strengthen and grow science in Africa, and our involvement in this initiative represents our continued commitment to supporting countries throughout Sub-Saharan Africa that wish to develop and enhance their science bases,” he said.  

For Tongo Passo, as with any early investigator, it was extremely difficult competing with established researchers for large grants to begin an independent research career. And this is exactly where the SANTHE Path-to-Independence award came into play. “Such funding provided an excellent resource for a new PI like me to generate promising pilot data and to help extend the SANTHE programme to the French-speaking countries from West-Central Africa.” Contributing further to his work, he was also awarded a SANTHE Collaborative Grant, in conjunction with scientists from UKZN, to work on the full-length sequencing and biological characterisation of early divergent HIV-1 lineages from Cameroon.

Tongo Passo’s scientific career started when, as a young boy, he came across some baby birds that had fallen from their nest. He managed to rescue three of them by feeding them daily until they regained their strength. “This early experience instilled a love of science and a desire to understand how life works and how it adapts to different environments,” he says. “I love science and nature and am fascinated with life.”

He grew up in Cameroon’s predominantly coastal cities: Douala and Nkongsamba. After finishing school, he completed BSc and MSc degrees in Biochemistry at the University of Yaoundé. This was followed by a PhD in Medical Virology from UCT, as well as a post-doctoral position in the Division of Immunology and Division of Computational Biology. In 2016, he was awarded a SANTHE Fellowship to continue his research at the University of KwaZulu-Natal (UKZN) in Durban, South Africa. 

“The turning point in my career came with the shocking realisation that although HIV originated in the Congo basin, there were hardly any scientists from this region to tell the story. This was compounded by the fact that at the many scientific meetings in which I was participating, there were very few renowned Africans presenting their work. I wondered why and realised that I could perhaps play a part in the solution,” explains Tongo Passo. 

“It was not until later in my scientific training that I found supervisors and mentors that really helped me develop my career, and this strongly motivated me to return home to help other budding researchers in their scientific development. Cameroon is endowed with so much potential in young people to solve the problems of infectious diseases, but the country crucially lacks leading scientists to provide post-graduate training and I want to help in any way I can. This will of course require a lot of work and I intend to do a lot of reading and networking with individuals to establish new collaborations, remembering that some ideas to enhance and grow my own research portfolio might come from outside of my immediate field,” he says.

While Tongo Passo’s post-doctoral studies sought to explore the early history of the HIV-1 group M pandemic and provide a better understanding on the origins and spread of different subtypes, his current project focuses on understanding the biological determinants of the heterogeneous distribution of HIV-1 group M viruses circulating in the Congo Basin and worldwide. “This region has an extraordinary and unevenly distributed amount of viral diversity including some unusual and rare strains. Despite this broad spectrum of viral diversity, very little is known about the biological properties of the viruses circulating in the country – properties that could explain the uneven distributions of the diverse Cameroonian HIV-1M lineages,” he says. “I propose to perform comparative studies of HIV-1 biological function, based on HIV-1M variants circulating in the Congo Basin. Data from this study may help explain differences in epidemic spread of HIV-1M subtypes and inform vaccine design, both for the country, and for the Congo basin region in general.”

Following Tongo Passo’s SANTHE Path-to-Independence award, he subsequently received two major grants in 2020. The first one from the French National Research on AIDS Agency as a PI and the second one from the German Research Foundation as a member of a German-Africa consortium. He then recruited three students – two PhDs and one Masters – to join his research efforts. “This was an exciting time for SANTHE and for African-led science. Progress of my work was initially delayed due to challenges imposed by COVID-19, but I caught up rapidly. With the help of my SANTHE Path-to-Independence award, I set up two unique cohorts to answer specific question in the COVID-19 and HIV fields. In the first cohort, we recruited 235 SARS-CoV-2-infected participants in three consecutive years (2020, 2021 and 2022) in Yaoundé, following up a subset of these participants in 2020 and 2021 every month for up to six months to evaluate the state and persistence of humoral immunity. The second cohort consisted of about 7000 individuals living in remote communities of the equatorial rain forest of Cameroon to study their exposure to animal viruses and characterise these emerging or re-emerging viruses. These cohorts have fostered two major collaborations with scientists at the National Insitutes of Health (NIH) in the USA, and at the University Hospital Düsseldorf in Germany.”

In 2021, Tongo Passo was part of the SANTHE team that secured a renewal of the programme’s funding from the Science for Africa (SFA) Foundation and Bill & Melinda Gates Foundation. He now leads the SANTHE site in Cameroon which, in addition to CREMER/IMPM, also includes the Centre International de Référence “Chantal BIYA” pour la recherche sur la prévention et le prix en charge du VIH/SIDA (CIRCB), the Centre Pasteur du Cameroun (CPC), and the Biotechnology Centre (BTC) of the University of Yaoundé 1. His most recent award is a second SANTHE Collaborative Grant entitled, “Characterising Currently Circulating HIV in rural forest areas of Cameroon, where ancestors of HIV-1 have been identified”. “Further biological characterisation of unique Cameroonian HIV strains is vital for developing intervention strategies to curtail HIV-1M virulence or epidemic spread,” he says.