Science
Just one mutation can make H5N1 bird flu a threat to humans, California researchers say
California researchers say the world may be just one genetic tweak away from human-to-human transmission of the H5N1 bird flu virus — a worrisome mutation that could open the door to widespread human infections and possibly even a pandemic, according to some experts.
In a study published Thursday in the journal Science, Scripps Research Institute biologists determined that a single mutation of the hemagglutinin protein — the “H” in H5N1 — could transform a virus that has so far sickened or killed mostly birds and cows into a pathogen that targets cells in human beings.
The finding comes amid a growing number of H5N1 outbreaks among California dairy cows, as well as a state-ordered recall of raw milk products. Since the virus began infecting the nation’s dairy stock in March, infectious disease experts have warned that unprotected contact between dairy workers and infected cows could enable the virus to evolve in a manner that threatens humans.
Now, Scripps researchers suggest the path for such a genetic change may be much shorter than state and national health officers anticipated.
“This really surprised us,” said study coauthor James Paulson, a biochemist and molecular biologist. This one mutation “satisfies a requirement for transmission,” he said.
Richard Webby, director of the World Health Organization’s Collaborating Center for Studies on the Ecology of Influenza in Animals and Birds, said the study’s finding countered prevailing thought on the virus — specifically, that it would take multiple mutations for the virus to pose a threat to humans.
“This will likely cause a stir,” said Webby, who is also a researcher in the department of infectious diseases at St. Jude Children’s Research Hospital in Memphis, Tenn., and was not involved in the Scripps research.
“I think most of us thought it would probably need more than one change,” Webby said.
Yoshihiro Kawaoka, a virologist at the University of Wisconsin-Madison and the University of Tokyo, called the Scripps teams’ finding a “significant discovery” and said it was “critical because, given the mutation rate of influenza viruses, one in every 10,000 particles of the bovine H5N1 virus could carry this mutation.”
That means the potential emergence of an H5N1 virus “that can recognize human receptors is closer than we may have thought,” he said.
Several months ago, Paulson and coauthor Ian Wilson, a Scripps structural biologist, decided they’d investigate the current H5N1 strain, and see what it would take for it to cause a human pandemic.
Paulson is an expert in researching where and how different influenza viruses bind to cells when they enter a host. Wilson studies the structure of influenza virus proteins.
The scientists began their research by accessing a global influenza database and locating the genetic sequence for A/Texas/37/2024 — the strain of H5N1 bird flu found in a Texas dairy worker.
They then examined the hemagglutinin proteins, or spikes, on the outer surface of the virus, since those enable it to latch onto the cell membrane of its host. Animals such as birds and humans have different docking stations on their cells — known as sialic acid receptors. In order for a flu virus to open a door into a cell and begin replicating, it needs just the right spike, or key.
Although more than 50 humans have been infected by H5N1, many of these cases involve dairy workers who were likely sprayed in the eyes and nose with milk from infected cows. Researchers postulate that repeated exposure of this sort allowed the virus to push into the cells — a brute force entry more than a lock-picking.
Ordinarily, person-to-person transmission of a flu virus “is mainly through the air from droplets from a sneeze or cough, which contains very little virus,” Paulson said. “In this context, the virus needs to be able to recognize human-type receptors to bind to cells in the human airway in amounts sufficient to cause infection.”
In order to figure out what it would take for the virus to gain the right docking equipment to unleash a human pandemic, Paulson, Wilson and their team looked at previous flu outbreaks that had jumped the bird-human divide, including the influenza outbreaks of 1918, 1957, 1968 and 2009 — as well as some earlier research.
They “selected a number of positions” on the hemagglutinin protein “to mutate, one at a time” with amino acids they knew had been implicated in previous pandemics.
Then they attempted to bind these altered “H” proteins with human and bird receptor analogues.
Lo and behold, when they switched a glutamine to a leucine at position 226, it no longer bound to the bird receptors, but instead exclusively to those of humans.
Paulson said it was especially interesting because this mutation had occurred before in earlier strains of H5N1, including one from around 2010 — but “at that time, that single mutation was not sufficient to change receptor specificity. So, the unexpected thing is that virus has changed in subtle ways — evolved, if you will — so that now that single mutation does change the receptor specificity.”
Although the researchers demonstrated that it was possible for the virus to become a threat to humans with just one genetic change, that does not mean nature will follow that specific path. A multitude of factors can influence the evolution of an organism, and they are not easily predicted. This may be why the virus has not yet gained the ability to widely infect humans, some say.
“Despite more than 50 human infections with bovine H5N1, we have not seen evidence of this virus adapting to humans on a larger scale,” Kawaoka said. “This suggests that … additional mutations are likely required for the virus to become fully transmissible between humans.”
Paulson acknowledged that the “context of the total biological picture is extremely important.”
He said the research focused on just “one property that is important for the virus to be successful when adapting to a new host,” but there are others that may also be important.
For instance, H5N1 in the past was known to cause severe respiratory disease. But recently, it’s mostly been associated with conjunctivitis and only occasionally with mild, upper respiratory disease in people.
“Why is that? I don’t think anybody knows,” Paulson said.
What is known is that the virus is moving swiftly through a variety of species around the globe — with ample opportunity to mutate and adapt.
As of Thursday, the Centers for Disease Control and Prevention had confirmed H5N1 infections in 58 people: 35 as a result of working with infected dairy cows, 21 from infected poultry, and in two cases, the source is unknown.
In addition, 707 dairy herds across 15 states have also been infected. And in just the last 30 days, 23 commercial poultry farms in California have come down with the virus — affecting more than 5.6 million birds.
Science
Video: NASA Announces Artemis III Crew
new video loaded: NASA Announces Artemis III Crew
transcript
transcript
NASA Announces Artemis III Crew
NASA announced the crew of Artemis III mission, which will fly to low-Earth orbit to test rendezvous and docking maneuvers with one or two lunar landers.
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“I am excited to welcome you as the next crew in the Artemis journey to successfully return to the moon — this time to stay.” “I’m honored by the role that I’ve been given. I’m also very humbled by the task in front of us. But first and foremost, I’m grateful.” “So with that, the Artemis II crew, comrade, hands you the baton. You got the controls.” “As you know, we had a significant anomaly at our Launch Complex 36A on May 28. We’ve redoubled our efforts and are moving forward.”
By Alisa Shodiyev Kaff
June 9, 2026
Science
Santa Monica Mountains’ last steelhead trout survived the Palisades fire — and even had babies
Scientists feared the Santa Monica Mountains’ last remaining steelhead trout were dead, smothered by debris flows unleashed by the Palisades fire.
But the endangered fish surprised them: A team of biologists recently spotted 30 of the rare trout — and 21 babies — in Topanga Creek.
“There was a lot of happy dancing in the creek,” said Rosi Dagit, principal conservation biologist for the Resource Conservation District of the Santa Monica Mountains, which works with public and private landowners to conserve natural resources.
That’s because the steelhead here are endangered, at both the state and federal levels. Once, they swam in most streams of the Santa Monicas, but their numbers plummeted amid overfishing and coastal development. Increasingly frequent wildfire has further stressed their habitat. Topanga Creek, a biodiversity hot spot, is home to their last known population in the mountains that stretch from the Hollywood Hills to Point Mugu in Ventura County.
The trout that were spotted, including this one, are part of a distinct Southern California population that’s listed as endangered at the state and federal levels.
(RCDSMM Stream Team)
The California Department of Fish and Wildlife spearheaded a complex mission to rescue trout threatened by the Palisades fire that sparked in January 2025.
Time was of the essence. The fire hadn’t yet been fully contained. But rain was on the way, which would sweep massive amounts of sediment from the denuded hillsides into the water. Fish are often killed this way.
Crews stunned the fish with electricity, scooped them up in buckets, trucked them to a hatchery and ultimately moved them to Arroyo Hondo Creek in Santa Barbara County.
Within days, Topanga Creek was choked with mud. Some assumed the fish left behind were goners.
But in March, the conservation district’s team found four. The following month, when water conditions were clearer, they saw more.
“These fish continue to amaze me,” said Kyle Evans, environmental program manager for the state Department of Fish and Wildlife, who had seen the damage to the creek. “I had seen populations get wiped out in similar situations. So when I heard, I was thrilled.”
Evans surmises the fish that survived were in an area of the creek where less charred material and sediment were swept in.
“These fish likely hunkered down, were hiding under some rocks or places to try to get away from the main concentration of flow,” he said. “And luckily they weren’t buried.”
The ones that were spotted were fairly small, around 6 to 14 inches. Rainbow trout and steelhead trout are the same species, but with different lifestyles. If the fish remain in freshwater, they’ll be considered rainbows. However, they can migrate to the ocean and become steelhead, where they typically grow larger before returning to their natal waters to spawn.
Topanga Creek hasn’t fully recovered from the damage it sustained, but scientists say it’s looking better. Surveys last year were “so depressing,” Dagit said, with very few animals, and stretches that were essentially transformed into flat roads from all the sediment buildup. Some of the riparian canopy burned right down to the creek.
Then came 32 inches of rain over the last nine months, scouring out and moving sediment, creating deeper pools. Dagit said they recently found newt egg masses for the first time in years, as well as a few adult newts and many frogs. Plants that provide cover are starting to recover.
She provided photos comparing certain pools last year and this year, some dramatically transformed. In September 2025, the Shrine Pool could have been an overgrown hiking trail. This April, it was filled with shallow water.
The Shrine Pool in September 2025, left, and the same location in April 2026, right, with RCDSMM’s Isaac Yelchin donning a wetsuit.
(RCDSMM Stream Team)
Topanga Creek is home to another endangered fish, the small but hardy northern tidewater goby, often described as cute. Not long before the trout operation, Dagit led a rescue of hundreds of these fish too. Many were repatriated to the lagoon at the mouth of the creek in a moving ceremony last June.
There’s still the matter of what to do with the trout that were moved to Santa Barbara County last year. Evans would like to bring them home to the Santa Monicas at some point, but isn’t sure if it will happen. On one hand, they could bolster the small, genetically isolated surviving population. On the other, they might inadvertently bring in a disease or bacteria. There is some time to decide. Evans estimates the creek still needs to recover for two to three more years.
For now, the fish are functioning fine in their adopted creek. Experts worried the trauma wrought by the move would disrupt their spawning process, but they had babies that spring. This year, they spawned again.
Science
Pacifica pier cracks, another coastal casualty as seas continue to rise
The Pacifica Municipal Pier was shut down and taped off Thursday after city workers noticed cracks running through the landmark structure and concrete chunks falling into the ocean.
It’s just one of many coastal California structures that have recently crumbled under pressure from a rising and relentless ocean.
Officials from the small, beach city south of San Francisco said the pier was closed due to “cracking, separation, and displacement of the concrete walkway and structural elements.”
It will stay closed while structural engineers asses its safety.
Photos taken by city employees show a wide crack that runs from top to bottom and across the structure as well. Other photos show a large horizontal crack under the foundation of a small restaurant on the pier, the Chit Chat Cafe.
The cafe was also shut down.
This is not the first time the 53-year-old pier has shown signs of stress. In 2021, part of it was shut down after handrails along the edge collapsed. And in 2023, after a series of storms pummeled the Central California coast, damaging parts of the pier, the structure was partially closed for more than year.
Those same storms caused extensive damage in Aptos and Capitola, 70 miles south, where piers and waterfront infrastructure were swept away or damaged.
In 2024, a 150- to 180- foot section of the Santa Cruz wharf was ripped off by powerful waves.
At least 10 of the state’s dozens of coastal public piers were closed for part or all of 2024 due to structural damage sustained in winter storms since 2022. At least five others have longer-term upgrades planned to address structural issues.
“These things are costly to maintain,” said Zach Plopper, senior environmental director at Surfrider. “They are a part of our California coastal culture in many ways, but we’re going to need to reckon with, one, the state that they’re in, and two, the continuous and worsening threats they’re going to experience,”
He said most of the piers were constructed in the early 1900s, and they weren’t built to withstand decades of rough seas, storms and rising sea level.
“With this incoming El Niño, which is forecasted to be significant, and this marine heat wave we’re in the midst of, we’re kind of in uncharted waters as far as what this winter could bring in terms of storms and swells to the California coast, and we’re likely going to see a lot more damage,” he said. “Not just piers, but roads and other coastal infrastructure up and down the state.”
There was no storm in Pacifica earlier this week, so no single event could be blamed for the destruction.
However, a 2025 report from an outside engineering firm, GHD, found that several sections of the pier were in “poor” or “serious” condition, and they recommended closure before anticipated storms or events that could “subject the piles to high winds, swells and large waves.”
The firm found several areas of the pier where concrete was missing and rebar was exposed and corroding.
“The pier has continued to experience high winds and large waves in a harsh marine environment,” the engineers wrote in the report, noting that continuous exposure to seawater or marine spray was “detrimental” to the structure.
A 2023 city report estimated it would cost $19 million to repair.
That same year, a state law was enacted to require local governments along the California coast to plan for sea level rise in the coming decades.
Sea level has risen some 8 inches, on average, along the coast in the past 150 years, Plopper said, and researchers anticipate another foot in the next 25 years.
“We’re going to see profound shifts on our coastline, none that we have ever experienced before, and building static structures on the coast just doesn’t work all that well,” he said. “We’re going to have to make some really hard decisions.”
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