Scientists in Houston on Wednesday released a study of more than 5,000 genetic sequences of the coronavirus that reveals the virus’s continual accumulation of mutations, one of which may have made it more contagious. The new report, however, did not find that these mutations have made the virus deadlier or changed clinical outcomes. All viruses accumulate genetic mutations, and most are insignificant, scientists say.

Coronaviruses such as SARS-CoV-2 are relatively stable as viruses go, because they have a proofreading mechanism as they replicate. But every mutation is a roll of the dice, and with transmission so widespread in the United States — which continues to see tens of thousands of new, confirmed infections daily — the virus has had abundant opportunities to change, potentially with troublesome consequences, said study author James Musser of Houston Methodist Hospital.

The tiny mutation found in the dominant coronavirus variant

Like all coronaviruses, SARS-CoV-2 has a series of characteristic spikes surrounding its core. These spikes are what allow the virus to attach to human cells.

SPIKE

Spike

SARS-CoV-2

Amino acid 614

A mutation affecting the spike protein changed amino acid 614 from “D” (aspartic acid) to “G” (glycine). Research suggests that this small change — which affects three identical amino acid chains — might enhance the virus’s transmissibility.

Source: Global Initiative on Sharing All Influenza Data

Scientists from Weill Cornell Medicine, the University of Chicago, Argonne National Laboratory and the University of Texas at Austin also contributed to the study.

The new study, which has not been peer-reviewed, was posted Wednesday on the preprint server MedRxiv. It appears to be the largest single aggregation of genetic sequences of the virus in the United States thus far. A larger batch of sequences was published earlier this month by scientists in the United Kingdom, and, like the Houston study, concluded that a mutation that changes the structure of the “spike protein” on the surface of the virus may be driving the outsized spread of that particular strain.