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Concept art of the Blacklight virus.

The Blacklight virus, dubbed now as the Mercer Virus by the general public, is an evolutionary chimeric mutation-causing infectious agent that can reproduce only inside the living cells of other biological organisms. It was extracted and synthesized by Gentek, using a sample of Elizabeth Greene's blood, which had been infected with the Redlight virus years previously.[1]


"[The Virus] enters, re-purposes and changes the cell. The new cell replicates with formerly dormant non-encoding regions active, causing drastic biological changes."
―Node of Intrigue, Claude Cavillo.[src]

After infection, the virus "plugs in" and activates the 'junk' DNA in its victim, resulting in several biological changes that create (and recreate) sentience within the infected creature's cellular makeup. It acts by affecting the protein encoding regions of the promoter introns in each cell. As a retrovirus, it contains both RNA and the reverse transcriptase enzyme, allowing it to insert its own genetic codes into the host's cells. It enters, re-purposes and changes the cell, replicating previously dormant non-coding segments of the organism's DNA.[1]

A Blacklight bacterial organism entering a host's cells.

More often than not, these changes are too drastic and 99.99% of all infected organisms die from massive organ failure and cell saturation. However, few variants have yielded other beneficial results, endowing the infected organisms with incredible superhuman genetic prowess that greatly increase their natural abilities to levels far exceeding human capability; these variants include DX-1120 and DX-1118 C.[1]


The virus is highly contagious and can infect organisms through a multitude of means:

  • Physical Contact: If a non-infected person is bitten or scratched by an Infected person or a Hunter, the virus can spread directly to the victim resulting in their infection.
  • Exposure: Coming into contact with an Infected Water Tower or a Hive can result in the infectious agents spreading to nearby humans.
  • Bodily Fluid Contact: Infectious bodily fluids and materials are capable of infection through open wounds.[2]
  • Injection: As demonstrated by the Project D-Code soldiers, the virus can be spread through direct application via injection.


Blacklight (DX-1118 C)

"When it DOES manifest, it makes the Idaho strain look like the common cold."
Raymond McMullen describes the Blacklight virus.[src]

The vial, taken and destroyed by Alex Mercer, containing the Blacklight virus.

A group of scientists led by Dr. Alex Mercer managed to synthesize a new virus strain which they named 'Blacklight'. They were trying to use it to cure global diseases such as cancer (unbeknownst of the real goal, to engineer a new version of the Redlight virus that could copy and combine genetic traits to re-write living creatures).[3] The scientists soon became suspicious, noting that a large portion of virus variants had deadly effects on the test animals.

The Blacklight virus' effects are variable and far more infectious than the Redlight strain. The Blacklight virus outbreak does not follow the pattern of the Hope outbreak: it causes too many infections, spreads over too wide an area, and leaves very few 'clean' entities. The mortality rate of the Blacklight virus is lower than that of the Redlight virus, and the incubation period of it is much longer. The full capabilities of the Blacklight virus were unknown, even to the scientists who synthesized it.[4]

Mercer attempting to kill James Heller by manipulating the virus within him.

Thankfully, the Blacklight virus is incapable of crossing large water bodies, leaving it stranded on Manhattan Island. The Blacklight virus can make Walkers, but it's unknown if Greene or Alex could control these Walkers with the Hive Mind ability.


"Sir, their testing is off the charts. No ill effects at present. No evidence of the un-modified virus!"
William Demeza informing General Peter Randall about the effects of the virus.[src]

One hundred and sixty-one soldiers were injected with this variant in Project D-Code. This variant caused no deaths or side effects. The virus' replication and re-growth within the organism was completed in less than two days. The subjects showed dramatic increases in metabolic rate, strength, and reaction times. This variant was only three weeks old and was responsible for creating the Super Soldiers: agile, strong, and formidable foes to the Blacklight beings.[1]


  • As stated in the Web of Intrigue, the virus changes on a rapid scale, changing and evolving into something else.