British cybersecurity start-up Darktrace has raised $50 million in a funding round that values the firm at $1.65 billion.

The investment, announced on Thursday, was led by European private equity firm Vitruvian Partners and includes backing from existing investors KKR and TenEleven Ventures.

Cambridge-headquartered Darktrace, founded in 2013, uses artificial intelligence (AI) and machine-learning technology to detect and counter cyber threats. The investment is a Series E round, which is the fifth major funding round of a venture.

Darktrace says its technology, called the Enterprise Immune System, acts similarly to a human immune system. It uses a computer algorithm to monitor patterns and adapt to understand what constitutes normal and suspicious cyber behavior.

It further uses what is known as autonomous response technology to respond to any threats automatically, either slowing or shutting down a device or connection that has been compromised. The firm recently released the second version of its autonomous response system, called Antigena, which is aimed at targeting malicious emails.

Darktrace deploys this technology in a number of environments, including cloud, so-called internet of things and industrial control systems. Its clientele ranges from Britain's London Gatwick Airport to American insurance giant AIG. The firm disclosed Thursday that its technology is now being used across 7,000 networks around the world.

Darktrace first passed the $1 billion valuation mark in May, when it reached a market value of $1.25 billion, elevating it into the ranks of the world's so-called unicorns. The firm's most recent valuation of $1.65 billion marks a 32 percent increase in the last four months.

The funding comes at a time of rapid growth for both the cybersecurity and AI industries. IT research group Gartner forecasts that spending in the cybersecurity sector will grow to $114 billion this year, a rise of 12.4 percent from the previous year, and that the total business value of AI will hit $1.2 trillion this year, spiking 70 percent from 2017.