Unraveling Rabies Virus: Evolutionary History in Multiple Hosts

What is it about?

Researchers investigated the evolution of rabies virus (RABV) across multiple host species, using 321 genome sequences spanning different continents. They identified two major phylogenetic groups: bat-related RABV and dog-related RABV. While bat-related RABV didn't show a clear correlation between time and genetic divergence, dog-related RABV followed a generally clock-like structure, although with a relatively low evolutionary rate. Molecular clock dating indicated that dog-related RABV likely underwent rapid global spread following the intensification of intercontinental trade starting in the 15th century. The study found no clear evidence of adaptive evolution in RABV host-jumping events, suggesting that ecological processes also play a role in shaping emergence patterns. Some host shifts were associated with increases in evolutionary rate, especially in ferret-badgers and mongooses. The study's findings provide insights into the impact of cross-species transmission on RABV evolution.

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Why is it important?

This study is important because it provides valuable insights into the evolutionary dynamics of the rabies virus (RABV) and the impact of cross-species transmission on viral emergence. By analyzing 321 RABV genome sequences, the researchers were able to determine the mechanisms that underpin viral emergence, identify different evolutionary rates and selection pressures, and uncover patterns that have significant implications for disease control and prevention. Key Takeaways: 1. The study presents the largest phylogenomic analysis of RABVs circulating worldwide, providing a more comprehensive and precise reconstruction of the virus's evolutionary history. 2. The analysis reveals that RABV undergoes frequent cross-species transmission, which offers an opportunity to determine whether host jumping impacts rates of evolutionary change. 3. Although bat-related RABV does not follow a clock-like structure in terms of genetic divergence and sampling time, dog-related RABV exhibits a generally clock-like structure, with a relatively low evolutionary rate. 4. Specific amino acid changes were associated with the parallel emergence of RABV in ferret-badgers in Asia, suggesting that changes in host species can have significant impacts on evolutionary dynamics. 5. The study provides a time-scale for the evolution of the principal geographical clusters of dog-related RABV, which coincides with the development of the world's first global trade network following the explorations of Columbus, Vasco da Gama, and Zheng He. This example highlights the early human-mediated dissemination of a zoonotic disease.