Researchers from the Chinese Academy of Sciences in Beijing recently reported intriguing new evidence for a possible mouse origin of the Omicron variant. Their paper, posted on the BioRxiv preprint server, was quickly picked up and published a few days later by the Journal of Genetics and Genomics, and defies the prevailing theory which claims that the polymutant spike sequence of Omicron must have evolved under protracted infection in a severely immunocompromised patient.

Their main idea is that a mouse could have somehow been infected with the human virus by “reverse zoonotic transfer,” whereupon the virus evolved all or many of its 45 novel mutations, and then subsequently was transferred back to humans. While this theory might explain why Omicron appears so anomalous when plotted on a phylogenetic tree against the usual suspects, there is one major problem: The mouse homolog of the human ACE2 receptor (hACE2), which the virus typically uses to gain entry into cells, has little affinity for the standard issue SARS-CoV-2 spike protein.

So little in fact, that in order to study the virus in this preferred research animal, scientists must artificially introduce hACE2 in order to create mice that show any significant respiratory distress upon infection. These transgenic mice are made in several ways, each showing unique tissue tropisms, penetrance and correspondingly different effects. Researchers have conducted knock-in experiments in which the human hACE2 sequence is integrated into the host genome and induced under the control of a number of different promoters. Adenoviruses can also be used to infect cells and create replicating plasmids that propagate the hACE2 code.

More than fine, actually. Much more, she says.

“This is major for me and my family,” she says. “Two years without me being in the hospital? Wow. We just can’t believe it. But we’re so grateful.”

She’s doing so well for so long that she’s officially no longer in the landmark study she volunteered for. That involved doctors taking cells out of her bone marrow, and editing a gene in the cells in their lab, using the revolutionary gene-editing technique known as CRISPR. CRISPR allows scientists to make very precise changes in DNA much more easily than ever before. Many think it will revolutionize medicine.

New technique means head lice can provide clues about ancient people and migration.

Human DNA

DNA, or deoxyribonucleic acid, is a molecule composed of two long strands of nucleotides that coil around each other to form a double helix. It is the hereditary material in humans and almost all other organisms that carries genetic instructions for development, functioning, growth, and reproduction. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).

A major new study of ancient DNA has traced the movement of people into southern Britain during the Bronze Age.

In the largest such analysis published to date, scientists examined the DNA of nearly 800 ancient individuals.

The new study, led by the University of York 0, Harvard Medical School, and the University of Vienna, shows that people moving into southern Britain around 1300‒800 BC were responsible for around half the genetic ancestry of subsequent populations.