{"id":1680,"date":"2024-11-22T11:40:07","date_gmt":"2024-11-22T11:40:07","guid":{"rendered":"https:\/\/retirednurseblog.com\/index.php\/2024\/11\/22\/bird-flu-virus-isolated-from-hospitalized-canadian-teen-shows-signs-of-human-adaptation\/"},"modified":"2024-11-22T11:40:07","modified_gmt":"2024-11-22T11:40:07","slug":"bird-flu-virus-isolated-from-hospitalized-canadian-teen-shows-signs-of-human-adaptation","status":"publish","type":"post","link":"https:\/\/retirednurseblog.com\/index.php\/2024\/11\/22\/bird-flu-virus-isolated-from-hospitalized-canadian-teen-shows-signs-of-human-adaptation\/","title":{"rendered":"Bird flu virus isolated from hospitalized Canadian teen shows signs of human adaptation"},"content":{"rendered":"

The avian flu virus isolated from a hospitalized teenager in Vancouver has mutations in key areas that could help the virus spread more easily in humans, scientists say. <\/p>\n

There is no indication that the mutated virus has traveled beyond this patient. After monitoring of dozens of potential contacts among the teen\u2019s friends, family and health care providers, \u201cno further cases have been identified,\u201d Dr. Bonnie Henry, provincial health officer for British Columbia, said in a written statement. That means the mutated virus is not spreading or a threat to anyone else. <\/p>\n

But scientists say the genetic changes are a reminder of what the virus is capable of if it continues to spread. <\/p>\n

\u201cCertainly, this is one of the first times that we\u2019ve really seen evidence of these sort of adaptation mutations in H5,\u201d said Dr. Jesse Bloom, a computational virologist at the Fred Hutchinson Cancer Center. <\/p>\n

The H5N1 bird flu virus that infected the teen, who is in critical but stable condition, is not the same strain that is transmitting in dairy cattle in the United States. It is more closely related to an H5N1 strain that is circulating in wild birds such as geese in the Pacific Northwest. Although both strains are H5N1, they are distinct, the same way Delta and Omicron were different versions of the SARS-CoV-2 virus that causes Covid-19. <\/p>\n

Disease detectives who are investigating the case still don\u2019t know how the teen was infected, since they had no known contact with wild birds. <\/p>\n

The three mutations are at positions in the virus\u2019 genome that Bloom and other scientists have determined would allow it to attach more easily to human cells. <\/p>\n

\u201cIt\u2019s caught the attention of a lot of flu virologists, including myself, because some of the sequence has evidence of some of the types of mutations we worry about,\u201d he said. <\/p>\n

Flu viruses enter cells by attaching to sugars that stick up from their surfaces called sialic acids. Birds have an abundance of a kind of sialic acid called alpha 2,3, but humans primarily have alpha 2,6 sialic acids, particularly in the nose, throat and lungs. <\/p>\n

Dr. Scott Hensley, a microbiologist and immunologist at the University of Pennsylvania who specializes in the study of flu viruses, says decades of basic research have shown scientists which mutations to watch for. <\/p>\n

And Hensley said that on Saturday morning, when he looked up the sequence from the Canadian patient that had been newly uploaded to the international genome sharing database GISAID, he saw exactly the changes that would enable the virus to switch from preferring the alpha 2,3 receptor plentiful in birds to the alpha 2,6 sialic acids plentiful in the human nose, throat and lungs. <\/p>\n

One place in the human body where alpha 2,3 receptors are plentiful is the eye, he said. Most of the human H5N1 infections reported in the United States have had red, inflamed <\/strong>eyes as an early symptom, suggesting that\u2019s where the virus entered the body. <\/p>\n

The Canadian youth also had red eyes as one of their first symptoms, so Hensley thinks it\u2019s possible that\u2019s how the virus got in. However, the patient developed severe breathing problems called acute respiratory distress syndrome, or ARDS, perhaps as a result of the mutations the virus began to acquire as it copied itself in the body, Hensley said. <\/p>\n

Still, this is not the beginning of a pandemic, he stressed. The virus becoming better adapted to the human cells is a start, but it wouldn\u2019t necessarily be enough on its own to ignite an outbreak. <\/p>\n

\u201cWe need to do a lot of studies at this point. We have to try to understand if this particular virus does have properties of effective transmission,\u201d he said. <\/p>\n

Each of the mutations is ambiguous, meaning when scientists read the sequence of letters that make up the virus\u2019 genome, they weren\u2019t able to determine which of two letters, or nucleotides, should be in that position. <\/p>\n

Bloom explains that this can happen when a virus is evolving in its host and present in the body in different forms. <\/p>\n

\u201cIt\u2019s commonly observed, when you look at sort of this sequencing of how a virus is evolving within a single host, that after an infection is gone for a couple of weeks, you\u2019ll see a mix of different mutations,\u201d he said. <\/p>\n

The Canadian teen began having symptoms a week before they were admitted to the hospital, which may have been enough time for the virus to grow better at infecting the cells it was trying to enter. <\/p>\n

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