During the 2150s, Antaak was involved in mutagenic research. When the Klingons recovered several human augment embryos from a wrecked bird-of-prey in 2154, Antaak and his fellow researchers seized upon an opportunity to develop their own augments. Their efforts failed, with a virus unleashed on many Klingons which threatened the Klingon race with extinction. Thanks to the efforts of the Denobulan physician Phlox and Antaak, the disease was contained, but millions of Klingons were affected - losing their cranial ridges and becoming more human-like in attitude and appearance. (ENT episodes: "Affliction", "Divergence")
In 2165, after the death of Chancellor M'Rek, he and Phlox discovered that the Chancellor's death wasn't of natural causes. He had been murdered none other by one of Antaak's own sons, Krit who followed in his father's footsteps and became a geneticist himself. Antaak and Phlox revealed their findings to the Klingon High Council, who sentenced Krit to be executed. (ENT - Rise of the Federation novel: Live by the Code)
Antaak spent the remainder of his life attempting to find a cure for the disease. In 2173 he believed that he had succeeded, and released a retrovirus at the Qu'Vat colony designed to reverse the effects of the augment virus. While the virus did restore the appearance of some Klingons, it killed them within minutes. Antaak himself died from this new plague he had accidentally unleashed on the Klingons living on Qu'Vat. (ST novel: Excelsior: Forged in Fire)
It was not until the late 23rd century that the Klingons were able to purge this augment DNA from their genome, thanks in part to the efforts of Antaak's grandson Hurghom. (ST novel: Excelsior: Forged in Fire)
- ENT episode: "Affliction"
- ENT episode: "Divergence"
- TOS comic: "Against Their Nature" - Brief cameo in the form of a flashback to the events of Divergence.
- ENT - Rise of the Federation novel: Live by the Code
- ST novel: Excelsior: Forged in Fire