Retrovirus
A retrovirus was a biological particle that infected s. This form of virus reproduced itself by converting its RNA to DNA and incorporating that code into its host cell's genome. The host cell then produced more copies of the retrovirus, possibly leading to its destruction.

After a pair of Tarkaleans had been infected with Borg nanoprobes in 2153, Phlox attempted to slow the devices' progress with a modified retrovirus, with no appreciable affect. ()

In 2370, Data created a retrovirus from amniotic fluid to combat an outbreak of Barclay's Protomorphosis Syndrome. ()

The same year, the Pakleds crossed the Demilitarized Zone to supply the Cardassians with a shipment of retrovirus vaccines. ()

Retroviruses could be used as a vector to introduce foreign genes into a cell. After Taresian DNA was introduced in Harry Kim, The Doctor hypothesised that a retrovirus was most likely responsible. ()

In 2375, The Doctor's annual physicals found a nascent alien retrovirus "bouncing" between  personnel on decks 10 and 11. He successfully halted its progress. ()

In an illusory future set in 2383, Beverly Crusher described William T. Riker's memory loss as the result of Altarian encephalitis, a retrovirus. This later proved to be, seemingly, part of the Romulan equivalent of a holoprogram. ()

See also 
 Mutagenic retrovirus

External link 
 

de:Retrovirus
Microorganisms