実は、コウモリ研究は、ヒトの病気を知る上で、貴重な知見を提供してくるそうです。 コウモリは、体の大きさと比べて寿命が長く、かつ、腫瘍形成性が低いそうです。 Many bat species studied exhibit an extremely long lifespan relative to body size and a suspected low tumorigenesis rate. コウモリは、その遺伝子内に多くのウイルスゲノム（主としてレトロウイルス）をため込んでいるそうです。
その疑問にせまった論文を紹介します。 タイトル：Bat pluripotent stem cells reveal unusual entanglement between host and viruses PMCID: PMC10085545 NIHMSID: NIHMS1865119 PMID: 36812912
We conjectured that pluripotent stem cells would be an ideal experimental system for addressing this question. Given that pluripotent stem cells are the founding cells of the entire embryo, their cellular ground state provides an exclusive reference point for comparative studies, as all mammals must complete this stage in a similar manner.47 Importantly, the global epigenetic resetting that occurs as cells reprogram to pluripotency causes the transcriptional reactivation of endogenous viruses.48–51 As such, it would present a distinctive window into the abundant endogenized viral diversity within bat genomes, allowing the broad cataloging of active viruses and, in turn, the study of how viruses interface with host cell programs.
論文の主旨の総まとめの短文は、以下です。 Generation of induced pluripotent stem cells from two diverse bat species opens the door to functional studies of bat cell biology, including the question of why they are distinctively able to harbor viruses of importance to human health.
SUMMARY Bats are distinctive among mammals due to their ability to fly, use laryngeal echolocation, and tolerate viruses. However, there are currently no reliable cellular models for studying bat biology or their response to viral infections. Here, we created induced pluripotent stem cells (iPSCs) from two species of bats: the wild greater horseshoe bat (Rhinolophus ferrumequinum) and the greater mouse-eared bat (Myotis myotis). The iPSCs from both bat species showed similar characteristics and had a gene expression profile resembling that of cells attacked by viruses. They also had a high number of endogenous viral sequences, particularly retroviruses. These results suggest that bats have evolved mechanisms to tolerate a large load of viral sequences and may have a more intertwined relationship with viruses than previously thought. Further study of bat iPSCs and their differentiated progeny will provide insights into bat biology, virus host relationships, and the molecular basis of bats’ special traits.
Bats have evolved an unusual lifestyle among mammals as they fly, use echolocation, and have a curious affinity for viruses. One possibility is that bats evolved a tolerance for viruses by evolving changes in their innate immunity resembling the virus evasion mechanisms of the mammalian immune response. Another possibility is that bats evolved mechanisms for a cellular program to support viral replication and persistence, comparable to how viruses manipulate the host cell. Our results support both perspectives.
Our bat stem cell system will also provide insights into bats’ potential role as virus reservoirs and the relationship between bats and viruses. In vitro differentiation into immune cells and tissues, such as lung or gut epithelium, will illuminate emerging viruses, develop bats as new model study systems, provide new insights into how bats tolerate viral infections, and, in turn, allow us to better prepare for future pandemics.
One possibility is that bats evolved a tolerance for viruses by evolving changes in their innate immunity resembling the virus evasion mechanisms of the mammalian immune response. Another possibility is that bats evolved mechanisms for a cellular program to support viral replication and persistence, comparable to how viruses