Scientists map body-wide production of protein with "important role" in COVID-19
London: Scientists have analysed the presence throughout the human body of a protein which the novel coronavirus uses to enter host cells, and have found that it is produced only at "very low levels, if at all," in the respiratory system, an advance which highlights the need for further studies to reassess the biological mechanisms responsible for COVID-19.
The study, published in the journal Molecular Systems Biology, presented a systematic evaluation of the production of ACE2 -- the 'coronavirus entry gate' protein -- in more than 150 cell types in the human body.
It noted that the protein expression was consistently high in the intestines, kidney, gallbladder, heart, male reproductive organs, placenta, eye and vascular tissues, while it was limited in the respiratory system.
"Previous studies have indicated that ACE2 protein is highly expressed in the human lung. But these expression profiles have not been reliably presented along with tissues and organs from the entire human body, or based on several different datasets," said study senior author Cecilia Lindskog from Uppsala University in Sweden.
"Here, in contrast to previous studies, we were able to confidently show that no ACE2 protein is present, or that it occurs at only very low levels, in the normal respiratory system," Lindskog said.Earlier studies had suggested that the novel coronavirus SARS-CoV-2 employs ACE2 for host cell entry, and that penetration of the virus via this receptor would explain the severe clinical manifestations observed in various tissues and organs, including the respiratory system.
"Considering the clinical manifestations of COVID-19, with acute respiratory distress syndrome and extensive damage to the lung parenchyma, the results highlight the need for further study of the biological mechanisms responsible for COVID-19 infection and disease progression," Lindskog said.
"Further studies addressing the dynamic regulation of ACE2, and to confirm whether the low ACE2 expression in the human respiratory system is sufficient for SARS-CoV-2 infection, or whether other factors are needed for host cell entry, are urgently needed," she added.
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3 US troops killed, 5 seriously wounded during Iran attacks, military says
Washington (AP): Three American service members have been killed and five others seriously wounded during the US attacks on Iran, the military said Sunday, marking the first American casualties in a major offensive that has sparked retaliation from the Islamic Republic.
US Central Command, which oversees the Middle East, announced the deaths in a post on X but did not say when and where they occurred. The statement said “several others sustained minor shrapnel injuries and concussions” and were going to return to duty.
Central Command described the situation “as fluid” and said it would withhold the identities of the service members who were killed for 24 hours after their families were notified.
The US military also denied Iranian claims that the USS Abraham Lincoln aircraft carrier was struck with ballistic missiles, saying on X that the “missiles launched didn't even come close.”
President Donald Trump had warned that American troops could be killed or injured in the operation.
“The lives of courageous American heroes may be lost, and we may have casualties,” the Republican president said in a video address released early Saturday. “That often happens in war. But we're doing this not for now. We're doing this for the future.”
Following the US-Israeli strikes that killed Iran's supreme leader, Ayatollah Ali Khamenei, and other leaders, Iran's counterattacks have struck US bases in Bahrain and the United Arab Emirates.
Iran's paramilitary Revolutionary Guard has threatened to launch its “most intense offensive operation” ever targeting Israeli and American military installations.
Before the strikes, Trump had built up the largest US military presence in the Middle East in decades. The arrival of the Lincoln and three accompanying guided-missile destroyers at the end of January bolstered the number of warships in the region.
The world's largest aircraft carrier, the USS Gerald R. Ford, and four accompanying destroyers later were dispatched from the Caribbean Sea to head to the Middle East.
The Ford was part of the US raid in Venezuela that captured leader Nicolás Maduro, who was brought to New York to face drug trafficking charges. The operation in January claimed no American lives but left seven US troops with gunshot wounds and shrapnel-related injuries.
One of those injured received the Medal of Honor during Trump's State of the Union address last week. Trump said Army Chief Warrant Officer 5 Eric Slover piloted the lead CH-47 Chinook helicopter that descended on the “heavily protected military fortress” where Maduro was staying.
Trump has launched several military operations during his second term, including strikes on members of the Islamic State group in Syria in retaliation for an ambush attack that killed two US troops and an American civilian interpreter in December.
The US military has also struck IS forces in Nigeria, after Trump accused the West African country's government of failing to rein in the targeting of Christians.
