An international team of scientists led by Nobel laureate Andrew Fire has identified a new biological entity in the human microbiome, termed "obelisk" due to its elongated rod-like shape. This discovery, published in the journal Cell, reveals an agent with a simpler genome than viruses, raising questions about its function and impact on human health.
The research, conducted through bioinformatics analysis of genetic sequences from human fecal samples, found that approximately 7% of the 440 samples contained these novel agents. The study also uncovered nearly 30,000 species of obelisks in various biological samples collected globally, including ecosystems such as soils, rivers, and oceans.
Obelisks are characterized by their tiny circular RNA genomes of about 1,000 nucleotides, significantly smaller than those of some known viruses. They lack the protein coat typical of viruses but can still code for proteins. The findings suggest that obelisks may play a role in regulating cellular activity, with potential implications for health, as the microbiomes harboring these bacteria influence various physiological aspects, from digestion to immune response.
Marcos de la Peña, a co-author of the study, noted that this discovery challenges existing classifications of biological entities, positioning obelisks between viruses and viroids—subviral agents that infect plants. The study emphasizes the complexity of the microbial world and its impact on our understanding of virology, biology, and the origins of life on Earth.