Anthropic Says Claude Found a New Enzyme System in Bacterial Viruses

Claude agents searching DNA data identified what Anthropic calls a previously uncharacterized enzyme system in viruses that infect bacteria. In a new preprint, the company describes the pattern that drew the agents’ attention and the first lab result supporting further study. The finding puts AI-led searching in the spotlight, but the system’s biological function is still unknown.

The clue was beside a known enzyme

Anthropic calls the system array-associated reverse transcriptases, or ART. A reverse transcriptase copies RNA into DNA. Researchers had identified the underlying enzyme in an earlier study of a jumbo phage, a virus that infects bacteria. Anthropic says Claude’s contribution was spotting features around that enzyme that appeared to mark a system no one had characterized.

The scientists started the search with a prompt asking Claude to find interesting reverse transcriptases in a large DNA database. Anthropic says agents gathered more than 200,000 of the enzymes, selected 3,500 candidate systems and narrowed those to 20 for detailed reports. One agent examined DNA beside an unusual enzyme and noticed a long, orderly run of repeats.

Roughly 950Claude agents

Anthropic says roughly 950 Claude agents worked on the DNA-data search.

21 hoursSearch time

Anthropic says the agents spent 21 hours searching the data.

210 millionTokens used

Anthropic reports that the search used 210 million tokens.

The agent counted the repeats, checked their spacing, compared the layout with known systems and searched for earlier descriptions before submitting a report for human review. Anthropic says scientists supplied the initial prompt and performed all laboratory work; the agents handled the database search and proposed which leads deserved attention.

A resemblance, not a CRISPR tool

ART has three parts, according to Anthropic: the reverse transcriptase, a neighboring partner gene and an array of evenly spaced DNA repeats. It occurs mainly in bacteriophages. The repeats resemble a feature of CRISPR systems, whose arrays hold sequences that help make those systems programmable. A similar-looking layout is a reason to investigate ART, not evidence that it can edit genes.

The first experiments found that the ART array produces distinct short RNAs. That adds a laboratory observation to the sequence-based finding, but it does not settle what those RNAs do or what the enzyme system is for. Anthropic says experiments to determine ART’s primary function are continuing.

Finding leads is not finishing the experiment

The result comes from a biology research group Anthropic formed in spring 2026, with its own laboratory for testing AI-generated ideas. In the workflow Anthropic describes, Claude surveys scientific literature and DNA data, writes reports on possible systems, then reassesses its evidence. Scientists review promising candidates before testing proteins in the lab. Many proposed leads fall away before that stage.

Anthropic says a single campaign can yield hundreds or thousands of candidate reports. Its researchers study which proposals they consider worth testing, then use those judgments to refine Claude’s instructions. ART shows why that filter matters: an agent can notice a pattern humans want to pursue, while experiments still have to establish whether the pattern points to a useful biological mechanism.