The boss of e-cigratte maker Juul stepped down on Wednesday in the face of a regulatory backlash and a surge in mysterious illnesses linked to vaping products.

Chief Executive Kevin Burns will be replaced immediately by KC Crosthwaite, an executive from Altria, the tobacco giant behind Marlboro cigarettes that owns a 35 percent stake in Juul.

News of the C-suite switch came as Altria disclosed separately Wednesday that it has scrapped its talks to reunite with Philip Morris as concerns about the vaping crisis have hammered its stock.

As reported by The Post, Altria’s Juul stake, for which it paid $12.8 billion, has since dropped by more than a third as the company faces growing heat from federal officials over vaping-related illnesses and widespread use of Juul products by teens.

The Wednesday announcements came a day after Juul said it was weighing layoffs and yanking all broadcast, print and digital product advertising in the US. On Monday, federal prosecutors in California launched a criminal investigation into Juul.

Juul said this week it won’t oppose the Trump administration’s proposed ban on flavored e-cigarettes, which account for most of its sales. In a statement, Juul’s new CEO said he’s always believed in a future where adult smokers choose “alternative products like Juul.”

“Unfortunately, today that future is at risk due to unacceptable levels of youth usage and eroding public confidence in our industry,” Crosthwaite said. “Against that backdrop, we must strive to work with regulators, policymakers and other stakeholders, and earn the trust of the societies in which we operate.”

At least eight people have died from vaping, while more than 500 others have become sickened with lung issues, according to the Centers for Disease Control and Prevention.

Juul sales at US convenience stores fell 1.5 percent in the week ended Sept. 14 from the same week a year ago, according to Nielsen. During the four weeks ended Sept. 7, Juul’s US sales fell from $294 million to $278 million, or 5.4 percent, according to a Wells Fargo analysis of Nielsen data.

Shares in Philip Morris rose 5.2 percent on Wednesday, while those of Altria fell 0.4 percent.

Philip Morris and Altria, announcing the end of their talks, said they would instead focus on the joint launch of tobacco-heating product iQOS in the United States.

The iQOS heat-not-burn product is not a typical vaping device but instead heats packages of ground-up tobacco into a nicotine-filled aerosol.

Juul’s devices, though, vaporize a liquid containing nicotine, and such e-cigarettes have borne the brunt of the regulatory crackdown.

With Richard Morgan and Post wires