The surprising discovery of entities smaller than viruses raises profound questions about what life is and how it got started ...

New discovery reveals an entire new world smaller than viruses and bacteria.

There is growing evidence that small RNA's believed to play an antiviral defense role in many organisms, may be acting as doubleagents. In March 2004, an international team of scientists reported that ...

Their unique characteristics place them between viruses and tiny viroids, without being either type of infectious agent. These RNA circles are highly self-complementary, allowing them to adopt a ...

Obelisks share some traits with viroids—infectious RNA loops known to affect plants—but exist in human-associated bacteria. These RNA-based structures lack the protective protein shells seen ...

William A. Haseltine, Ph.D., covers genomics and regenerative medicine This story is part of a larger series on viroids and virusoids, small infectious RNAs. It is also the eighth installment in a ...