Study reveals how Helicobacter pylori "goes out of Africa"

On November 1, Daniel Falush, a researcher at the Shanghai Pasteur Institute of the Chinese Academy of Sciences, collaborated with the University of Oslo in Norway to publish an online report entitled Repeated out-of-Africa expansions of Helicobacter pylori driven by replacement of in Nature Communications The research paper on deleterious mutations reports the unique evolutionary history
of several new Helicobacter pylori African lineages "out of Africa" and gradually replacing local lineages in Europe and the Middle East.
The study confirms that the accumulation of harmful mutations caused by the "bottleneck effect" in the process of "going out of Africa" is responsible for
subsequent migration and the replacement of local lineages in other regions.

Helicobacter pylori is a bacterium that parasitizes the human stomach and is one of
the bacteria with a high infection rate in the world.
Helicobacter pylori infection causes chronic gastritis and peptic ulcers and significantly increases the risk of
stomach cancer.
Previous studies have generally suggested that Helicobacter pylori has a similar evolutionary history to its host humans, and was spread around the world
50,000 years ago by human ancestors through a "out of Africa" event.

The study, which analyzed Helicobacter pylori genome sequences from Africa, Europe and Asia, found at least three separate "out of Africa" events
.
The study further showed that Eurasian strains accumulated more nonsynonymous mutations compared to African strains at similar levels of genetic diversity, demonstrating that initial migration out of Africa had an important impact
on bacterial fitness.
The lack of ancestry in the heterozygous European strain suggests that this part of the lineage is substituted
during subsequent gene fusion.

Studies have shown that although Helicobacter pylori relies on human transmission, its DNA differs in its mode of transmission than human DNA
.
The study demonstrates that important population events, such as "out of Africa", affect bacterial fitness as well as patterns
of change in population dynamics.

The research work is supported
by major science and technology projects at the municipal level of Shanghai.