"Vampire Viruses" Found for the First Time in US

In a groundbreaking scientific revelation, researchers have identified peculiar "vampire viruses" in soil samples from Maryland and Missouri in the United States. While the existence of these intriguing entities, known as mobile genetic elements (MGEs), has been acknowledged by scientists for decades, this marks the first instance of their discovery in soil samples.

At the University of Maryland Baltimore County, researchers made a significant observation as they detected virus-like entities, MGEs, attaching themselves to helper viruses during the infection of bacterial cells. These MGEs, often referred to as vampire viruses, are pathogens that rely on other viruses to facilitate their replication.

This unique relationship unfolds when a bacteriophage attaches to a soil-based virus, essentially utilizing the viral host resources for its independent survival. The intricate dynamic between these two pathogens is termed a "satellite and a helper." The satellite, an infectious strand, depends on the helper throughout its life cycle. This reliance extends to the construction of a protective shell, known as a capsid, around its genetic material, as well as assistance in DNA replication.

Notably, most satellite viruses carry a gene that enables them to integrate into the host cells genetic material upon entry, allowing them to reproduce whenever a helper virus enters the cell. The host cell, in turn, replicates both the satellite DNA and its own during cell division.

The concern arises from the fact that vampire viruses latch onto helper viruses to insert their genes into host cells. This process requires both viruses to infect the cell simultaneously, necessitating close proximity during the event. The recent discovery, made possible through the use of an electron microscope emitting beams of electrons, revealed a unique attachment of the satellite virus to the helper virus at the neck, where the outer shell of the helper virus connects to its tail.

This unprecedented observation was documented in a study published on October 31 in the Journal of the International Society for Microbial Ecology.

Initiated as part of a routine undergraduate project, the research involved isolating bacteriophages – viruses targeting bacteria – from environmental samples for sequencing in labs. The researchers uncovered that, to ensure the satellite-helper pair enters the host cell simultaneously, the satellite employs a distinctive adaptation to attach to the helper using its tail. The consistency of these findings across multiple experiments underscores the significance of this newfound understanding of vampire viruses in the microbial world.