Researchers from the Center for Microbiology and Environmental Systems Science at the University of Vienna have made a groundbreaking discovery in the field of virology. In an international collaboration, they have identified giant viruses that infect the deadly human parasite, Naegleria fowleri. The findings, published in Nature Communications, shed light on the unique features of these viruses and their potential implications for understanding Naegleria biology.

Naegleria fowleri is a single-celled organism and one of the most dangerous human parasites. It thrives in warm waters above 30°C and causes a rare but almost always fatal brain infection known as primary amoebic meningoencephalitis (PAM). Researchers led by Patrick Arthofer and Matthias Horn from the University of Vienna's Center for Microbiology and Environmental Systems Science have successfully isolated giant viruses that infect various Naegleria species.

Giant viruses, also known as Nucleocytoviricota, were only discovered two decades ago and primarily infect single-celled organisms. These viruses possess unusually large particles and complex genomes, rivaling the size of bacteria. Their discovery has sparked debates over the definition of viruses and the origins of life.

The newly discovered viruses, named Naegleriaviruses, were isolated from a wastewater treatment plant in Klosterneuburg near Vienna. These viruses belong to a group called Klosneuviruses and represent only the fourth isolate from this group. The research team collaborated with scientists from the universities in Poitiers, the Canary Islands, and the US-based Joint Genome Institute to characterize and study these viruses.

Naegleriaviruses infect their amoeba hosts by using a unique structure called a stargate. This structure facilitates the entry of viral DNA into host cells. Within a few hours, a virus factory forms inside the amoeba cell, where viral genetic material is replicated outside the nucleus, and hundreds of new virus particles are assembled. To keep the host cell alive during this process, Naegleriaviruses likely employ special proteins that suppress the cell's natural immune response, preventing premature cell death. Only after successful viral replication does cell destruction and virus release occur.

Although the newly identified Naegleriaviruses may not be suitable for treating Naegleria infections in the brain due to the challenging accessibility of this organ, their discovery opens the possibility of preventative treatment for at-risk water bodies. For example, swimming pool water treatment could potentially benefit from further research based on these findings. Additionally, this discovery enhances our understanding of Naegleria biology and the viruses that infect them, contributing to the broader field of virology.

This groundbreaking research, published in Nature Communications, provides valuable insight into the complex relationships between giant viruses and their microbial hosts. As scientists continue studying these mysterious organisms, further breakthroughs could be achieved in treating and preventing deadly infections caused by parasites like Naegleria fowleri.

Source: Nature Communications. DOI: 10.1038/S41467-024-47308-2