Ferrier Public Lecture—The sweet, the sour, and the spicy sides of microbial glycans
The 2025 Ferrier Public Lecture was delivered by Professor Cristina De Castro, a professor of organic chemistry, from the University of Napoli, Italy.
Now in its 12th year, the annual Ferrier Public Lecture honours the late Professor Robin Ferrier, a world-renowned chemist and esteemed member of Te Herenga Waka—Victoria University of Wellington. Established to recognise his significant contributions to chemistry locally and globally, it also serves as a tribute from his university, friends, and colleagues.
Professor De Castro’s lecture, ‘The sweet, the sour, and the spicy sides of microbial glycans’, explored how bacteria and viruses use sugars to their advantage—sometimes in beneficial (sweet) ways, and other times in harmful (sour) or yet-to-be-defined (spicy) ways. More than 100 attendees gained insights into the fascinating role of microbial glycans in health and disease.
The lecture underscored the vital role of carbohydrate chemistry, highlighting advancements in research set to unlock new scientific and medical responsibilities.
Professor De Castro first explored the question of how humans and bacteria coexist. She demonstrated how small changes in the structure of lipid A, an important molecule in bacterial membranes, can drastically influence immune responses. Indeed, lipid A’s from different bacterial strains present tiny structural differences that lead to a range of outcomes. Even small differences—a missing phosphate group or the length of a lipid tail, for example—could spark or dampen inflammation.
Throughout her talk, she highlighted how molecular level changes drove major biological outcomes. She reported that the differences in lipid A structures were connected to our beneficial relationship with gut bacteria. The variety of bacterial species in our gut produces a mixture of lipid A variants that have a combined effect to keep the immune system in check.
Professor De Castro also demonstrated how chemists use advanced tools like nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry to determine the molecular structure, and how they combine these pieces of information with molecular modeling to disclose the way cell receptors interact with glycans. The combination of these tools is key to investigating how subtle structural changes lead to differing biological outcomes—ultimately revealing how our immune system could discriminate between pathogens or commensals. Applying chemical tools to understand how the immune system interacts with pathogens is essential to develop new medicines and vaccines in the future.
Next, she described viruses that are human pathogens as the perfect parasites, able to invade a host cell and hijack the host’s cellular machinery for their own benefit. She presented examples of how these viruses exploit the host glycosylation machinery to hide themselves from the immune system or enhance their infectiousness. Finally, she shared stories about her favourite ‘fascinating entities’, giant viruses. She introduced the audience to these special viruses by highlighting their peculiarities and divergencies with the previous virus types. For instance, some of these giant viruses were discovered in Siberian ice cores, and they could still infect their host after having been frozen for 30,000 years.
Professor De Castro uncovered the unique glycosylation pattern in one of these special viruses, the chlorovirus PBCV-1. This virus does not exploit the host's sugar-producing machinery since it encodes most, if not all, of the enzymes required to glycosylate its capsid. As a result, its glycan has a unique structure, and the glycosylation site on the capsid protein doesn’t match the sequon conserved in all forms of life. These remarkable features were important discoveries that trigger questions about the giant virus’ evolution and highlight the critical importance of fundamental research in understanding the natural world. Discoveries like these give a ‘spicy’ flavour to science and can lead to future developments and can ultimately be exploited for our benefit.
During her visit to New Zealand, Professor De Castro has been engaging with staff and postgraduate students at Te Kāuru—Ferrier Research Institute, providing an opportunity for them to share their work and receive valuable feedback. These interactions are helping to build connections for future collaboration.
Vice-Chancellor Professor Nic Smith spoke at the lecture, acknowledging the impact and contributions of Professor Robin Ferrier. He also expressed gratitude to Dr Peppi Prasit, a former student of Ferrier, for generously sponsoring the lecture series.
Professor Ferrier’s legacy continues at the University, having nurtured a generation of New Zealand carbohydrate chemists. Among those in attendance were two of his distinguished alumni—Professor Richard Furneaux, former director of Ferrier Research Institute, and Professor Peter Tyler—both of whom continue to drive innovation in carbohydrate chemistry. Professor Ferrier’s son, Duncan Ferrier, was also present, reflecting the family’s ongoing support for the lecture series.