Lymphocytic encephalitis

An actual LCMV specimen, as observed under a light microscope

Lymphocytic encephalitis is a viral infectious disease caused by the Lymphocytic Choriomeningitis Virus (LCMV). Originally carried by rodents, primarily rats, LCMV is no longer lethal to humans of The Twelve Colonies of Kobol, who have developed an immunity to the virus several hundred years ago.

Potential as Biological Weapon

A beacon, believed to have been left by the Thirteenth Tribe on their way to Earth, was contaminated by LCMV. When a basestar discovers the beacon while exploring the Lion's Head Nebula circa 3 ACH (2002BYR), the Cylons bring the device on board that exposes that basestar's Humanoid Cylons and the organic components of the basestar itself to the virus ^{(TRS: "Torn")}. Some time later, a team of Colonial marines from Galactica discovers the drifting basestar and board the ship, finding everything save for a small group of humanoids, dead. They take the ill Cylons (a Two, a Four, a Five, a Six, and an Eight) prisoner and return to Galactica just as the basestar's self-destruct mechanism activates and destroys the ship ^{(TRS: "A Measure of Salvation")}.

Though humans are immune, the virus is highly lethal to Cylons because of a bio-electric component that causes a fatal system error within the host. It is theorized that this system error disrupts the management of a humanoid Cylon's immune system, progressively weakening and eventually killing the infected individual. Furthermore, the Cylons speculate that if an infected host is resurrected, the system error will follow, potentially afflicting the Resurrection Ship and eventually the entire Cylon fleet ^{(TRS: "Torn")}.

This theory forms the basis of a plan devised by Lee "Apollo" Adama to eradicate the Cylon race. By killing the infected Cylons prisoners near a Resurrection Ship, the aforementioned bio-electrical effect would be spread to all Cylons upon download. Ultimately, the plan is thwarted when Karl "Helo" Agathon kills the prisoners before Galactica can penetrate the Resurrection Ship's upload radius. Agathon does this despite the risk of being executed for treason, as he feels that the genocide of the Cylon race, despite the fact that they had tried to do the same to mankind, is morally wrong ^{(TRS: "A Measure of Salvation")}.

Cylon Treatment

During the time that the infected Cylons are held captive aboard Galactica, Dr. Sherman Cottle creates a simple vaccine that dramatically reverses the effect of the virus on said Cylons. However, an antibody in their blood breaks down the vaccine's RNA backbone, rendering the permanence of said treatment ineffectual. As such, the Cylons require regular close interval injections of the vaccine, or their condition significantly worsens. With a regimen of regular injections, an infected Cylon could be kept alive indefinitely.

Unlike the other Cylons Sharon "Athena" Agathon displays immunity to the virus—while exposed to LCMV, the pathogen does not adversely affect her. Cottle postulates that human antibodies were transferred over to Sharon during her pregnancy with her half-human daughter Hera, and that these antibodies subdue the virus ^{(TRS: "A Measure of Salvation")}.

Cylon Deception and Prisoner Manipulation

During his six-year captivity aboard a Cylon Basestar, Novacek reported that his captors became severely ill from what they claimed was a spreading virus, with many Cylons appearing to be dying from the disease.

However, Novacek's "escape" was later revealed to be an elaborate Cylon manipulation designed to send him back to the Colonial Fleet with specific disinformation. The apparent viral outbreak among his captors is staged as part of this deception, giving credence to Novacek's story given the Colonials' recent experience with the virus ^{(TRS: "Hero")}.

Notes

• Lymphocytic choriomeningitis (of which encephalitis is one form) is an actual disease. As in the episode, the illness was spread through rodents on the real-world Earth. The effects on the Cylons appear similar to the symptoms in this CDC document.
• Arguably, the plan to kill all Cylons by exposing the Resurrection ship to the disease is ill-conceived; there is nothing to stop the Cylons from destroying the vessel after it is infected. The plan seems to hinge on the posit that once in the Resurrection Ship, the disease would spread throughout the Cylon fleet and perhaps even the whole of Cylon-inhabited space.
• After her death and resurrection in "Rapture," Sharon Agathon presumably no longer possesses an immunity to this virus.

From Script to Screen

• The October 25, 2006 "Full Collated" version of the "Hero" script contains more detailed descriptions of Novacek's account of Cylon illness, including specific dialogue about the virus "spreading" and "getting worse" among his captors. The aired episode condenses this exposition while maintaining the essential plot point about Cylon vulnerability to disease.

References