The plague, caused by the bacterium Yersinia pestis, has been a persistent threat to human populations for centuries. A recent study published in the journal Science sheds light on how a single gene in the bacterium allowed it to adapt and survive for hundreds of years. The research, conducted by scientists at McMaster University and France’s Institut Pasteur, reveals that changes in the copy number of the pla gene led to a reduction in virulence and an increase in the length of time it took to kill its victims.

The study examines the evolution of the plague during three major pandemics: the Plague of Justinian, the Black Death, and the third plague pandemic. The researchers found that strains of the Justinian plague became extinct after 300 years of ravaging European and Middle Eastern populations. Strains of the second pandemic emerged from infected rodent populations, causing the Black Death, before breaking into two major lineages.

One lineage is the ancestor of all present-day strains, while the other re-emerged over centuries in Europe and ultimately went extinct by the early 19th century. The researchers used hundreds of samples from ancient and modern plague victims to screen for the pla gene and perform extensive genetic analysis.

Their findings suggest that a reduction in the copy number of the pla gene led to a decrease in virulence and an increase in the length of time it took to kill its hosts. In mice models of bubonic plague, this change resulted in a 20% reduction in mortality and increased the length of infection, allowing the hosts to live longer before dying.

The scientists also identified a striking similarity between the trajectories of modern and ancient strains, which independently evolved similar reductions in pla in the later stages of the first and second pandemic. This suggests that when the gene copy number dropped, the infected rats lived longer, spreading the infection farther and ensuring the reproductive success of the pathogen.

The researchers propose that this evolutionary change may reflect the changing size and density of rodent and human populations. They also found three contemporary strains with pla depletion in a collection at the Institut Pasteur.

This study provides valuable insights into the evolution of the plague and its impact on human history. It highlights the importance of understanding the complex relationships between pathogens, their hosts, and their environments, as well as the need for continued research into the causes and consequences of pandemics.

The findings also underscore the ongoing threat posed by the plague in regions like Madagascar and the Democratic Republic of Congo, where cases are regularly reported.

Overall, this study sheds new light on the evolution of a single gene that allowed the plague to adapt and survive for centuries. It emphasizes the importance of continued research into the causes and consequences of pandemics and highlights the need for effective strategies to combat infectious diseases that continue to pose significant threats to global health.

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Ancient Arctic Nursery: 73 Million-Year-Old Bird Fossils Discovered in Alaska

For half of the time birds have existed on Earth – a staggering 150 million years – they’ve been nesting in the Arctic, according to a groundbreaking paper featured in Science. The study reveals that millions of birds gathered in the polar regions 73 million years ago, raising their young amidst dinosaurs and other prehistoric creatures.

The research, led by Lauren Wilson from Princeton University, is based on dozens of tiny fossilized bones and teeth found at an Alaska excavation site. These ancient bird fossils, which include diving birds resembling loons, gull-like birds, and various types of ducks and geese, push back the record of birds breeding in the polar regions by 25 to 30 million years.

Prior to this study, the earliest known evidence of birds reproducing in either the Arctic or Antarctic was about 47 million years ago. This new discovery sheds light on the evolution of modern bird species and highlights the importance of the Arctic as a nursery for these animals.

The fossil collection is part of the University of Alaska Museum of the North’s collections, and the research team used an uncommon excavation and analysis approach to recover the tiny bones and teeth. By examining every bone and tooth they could find, from the visible to the microscopic, the scientists were able to identify multiple types of birds that coexisted with dinosaurs in the Arctic.

This study has significant implications for our understanding of bird evolution and the behavior of ancient species. As Pat Druckenmiller, senior author of the paper and director of the University of Alaska Museum of the North, notes, “The Arctic is considered the nursery for modern birds. It’s kind of cool when you go to Creamer’s Field [a Fairbanks-area stopover for migrating geese, ducks, and cranes] to know that they have been doing this for 73 million years.”

While further research is needed to confirm whether these ancient bird fossils belong to the Neornithes group (which includes all modern birds), this study has already pushed back the record of birds breeding in the polar regions by millions of years. The findings are a testament to the value of an uncommon approach to fossil hunting and highlight the importance of continued research into the evolution and behavior of ancient species.

The recent global outbreak of mpox, a disease caused by the monkeypox virus, has raised concerns about its transmission dynamics. Historically, most human infections have resulted from zoonotic transmission – from animals to humans – but during the 2022 global outbreak, the virus began spreading readily between people. A new study published in Nature has now shown that the virus was circulating long before then.

Using genomic tracing, researchers estimated that the virus’ ancestor first emerged in southern Nigeria in August 2014 and spread to 11 states before human infections were detected in 2017. The findings highlight the need for improved global surveillance and medicines, given the threat of impending pandemics.

“We could have very easily prevented the 2022 multi-country outbreak if countries in Africa were given better access to therapeutics, vaccines, and surveillance technologies,” says Edyth Parker, a professional collaborator in the Kristian Andersen Lab at Scripps Research and one of the paper’s first authors. “In a vulnerably connected world, we cannot neglect epidemics until they get exported to the Global North.”

The study’s senior author, Christian Happi, director of the Institute of Genomics and Global Health at Redeemer’s University in Nigeria, organized a Pan-African consortium to share and generate mpox genomic data. The consortium involved researchers and public health agencies in West and Central Africa, with support from international collaborators including Scripps Research.

By pooling samples and laboratory methods, the group generated a genomic dataset that is around three times larger than any previous mpox dataset. Altogether, the team analyzed 118 viral genomes from human mpox cases that occurred in Nigeria and Cameroon between 2018 and 2023. All of the sequences were identified as Clade IIb – the mpox strain endemic to West Africa.

The researchers created a phylogenetic tree, which estimates how related the different viruses are, and how recently they evolved. They found that most of the viral samples from Nigeria were the result of human-to-human transmission (105/109), while the remaining four were caused by zoonotic spillover. In contrast, all nine mpox samples from Cameroon were derived from isolated zoonotic spillover events.

“Mpox is no longer just a zoonotic virus in Nigeria; this is very much a human virus,” says Parker. “But the fact that there’s ongoing zoonotic transmission means there’s also a continual risk of re-emergence.”

The team estimated that the ancestor of the human-transmitting mpox virus emerged in animals in November 2013 and first entered the human population in southern Nigeria in August 2014. They also showed that southern Nigeria was the main source of subsequent cases of human mpox: though the virus spread throughout Nigeria, continual human-to-human transmission only occurred in the country’s south.

The study highlights the need for better wildlife surveillance, as well as better surveillance in the human populations that interface with animals in that forested border region. It also emphasizes the importance of better access to diagnostics, vaccines, and therapeutics in Africa.

“Global health inequities really impede our ability to control both zoonotic and sustained human transmission,” says Parker. “We cannot continue to neglect either the human epidemics in Africa or the risk of re-emergence – not only does it perpetuate suffering in these regions, it means that inevitably there will be another pandemic.”