Evolution of guanylate binding protein genes shows a remarkable variability within bats (Chiroptera).

Background: s (guanylate binding proteins), an evolutionary ancient protein family, play a key role in the host's innate immune response against bacterial, parasitic and viral infections. In Humans, seven genes have been described (). Despite the interest these proteins have received over the last years, evolutionary studies have only been performed in primates, and rodents. These have shown a pattern of gene gain and loss in each family, indicative of the birth-and-death evolution process.

Results: In this study, we analysed the evolution of this gene cluster in several bat species, belonging to the Yangochiroptera and Yinpterochiroptera sub-orders. Detailed analysis shows a conserved synteny and a gene expansion and loss history. Phylogenetic analysis showed that bats have s , and -. has been lost in several bat families, being present only in Hipposideidae and Pteropodidae. s, and are present mostly as single-copy genes in all families but have suffered duplication events, particularly in and Most interestingly, we demonstrate that duplicated in a Chiroptera ancestor species originating two genes, which we named and , with different subsequent evolutionary histories. 6a underwent several duplication events in all families while 6b is present as a single copy gene and has been lost in Pteropodidae, Miniopteridae and , a Phyllostomidae. With 14 and 15 genes, and stand out as having far more copies than all other studied bat species. Antagonistically, Pteropodidae have the lowest number of genes in bats.

Conclusion: Bats are important reservoirs of viruses, many of which have become zoonotic diseases in the last decades. Further functional studies on bats s will help elucidate their function, evolutionary history, and the role of bats as virus reservoirs.