Featured Research

from universities, journals, and other organizations

Hitting snooze on the molecular clock: Rabies evolves slower in hibernating bats

Date:
May 18, 2012
Source:
University of Georgia
Summary:
The rate at which the rabies virus evolves in bats may depend heavily upon the ecological traits of its hosts, according to new research. Rabies viruses in tropical and sub-tropical bat species evolved nearly four times faster than viral variants in bats in temperate regions.

The rate at which the rabies virus evolves in bats may depend heavily upon the ecological traits of its hosts, according to researchers at the University of Georgia, the U.S. Centers for Disease Control and Prevention and Katholieke Universiteit Leuven in Belgium. Their study, published May 17 in the journal PLoS Pathogens, found that the host's geographical location was the most accurate predictor of the viral rate of evolution. Rabies viruses in tropical and sub-tropical bat species evolved nearly four times faster than viral variants in bats in temperate regions.

"Species that are widely distributed can have different behaviors in different geographical areas," said Daniel Streicker, a postdoctoral associate in the UGA Odum School of Ecology and the study's leader. "Bats in the tropics are active year-round, so more rabies virus transmission events occur per year. Viruses in hibernating bats, on the other hand, might lose up to six months' worth of opportunities for transmission."

Understanding the relationship between host ecology and viral evolution rates could shed light on the transmission dynamics of other viruses, such as influenza, that occur across regions, infect multiple host species or whose transmission dynamics are impacted by anthropogenic change.

The team's findings could eventually help public health officials better predict when rabies virus transmission could happen in different environments and as environments change, but Streicker cautions that more research into the rabies virus genome and bats' overwintering ecology is needed.

"If viral evolution is faster, it could potentially lead to greater genetic diversity in crucial parts of the viral genome that allow it to shift hosts," he said. "For rabies, we don't yet know what those are, so identifying them will be key. Similarly, before understanding whether climate change will speed viral evolution, we need a better idea of how environmental changes will influence host ecology and behavior."

Evolutionary biologists have long recognized that molecular evolution proceeds in a largely clock-like manner, with mutations accumulating at a fairly constant rate over time. This "molecular clock" allows for powerful inferences -- from dating the origins of species to the origins of epidemics. However, the rate at which the clock ticks varies dramatically among species; much research has focused on what causes these differences.

For RNA viruses such as rabies, understanding the rate variability has practical implications, since faster evolution can enable viral emergence in new species or allow a virus to evade its host's immune defenses. However, nearly all past studies compared viruses of completely different families and were therefore limited to focusing on viral structural traits. Since few opportunities existed to study the evolution of similar viruses in different host species, the role of the host had been almost completely neglected.

Streicker set out to better understand the tempo of the evolution of rabies viruses in bats, and specifically what, if any, role the host species played.

To conduct the study, Streicker and his colleagues compiled a database of rabies virus genetic sequences from infected bats in the U.S. and South America, representing 21 different variants of the virus. They also collected information on the biology and ecology of the different bat species that served as viral hosts. They looked at the evolutionary history of the different bat species; their overwintering behavior (whether the bats hibernated, went through periods of torpor or remained active during the winter); their metabolic rates; and their migration habits (whether they engaged in long distance migration). They also classed the bats by climatic region and whether they were solitary or roosted in colonies.

Their analysis of this enormous database revealed extreme variability in the rate of evolution in different rabies viruses, comparable to the differences seen between viruses of entirely different families. The analysis also suggested that viral genetic traits were not chiefly responsible for this variation since rates seemed to shift freely throughout the ancestral history of the rabies virus as it jumped into new bat species.

"Earlier studies led to the conclusion that viral genomic traits are driving the evolution rate," Streicker said. "It turns out that's not the whole story. In this case, host biology plays an important role."

The trait that best correlated with the rate of viral evolution was not the host's evolutionary history. It was its climatic region, which affects the bats' behavior.

Rabies in tropical bats goes through more generations per year than in temperate bats, a mechanism also hypothesized to accelerate how quickly the molecular clock ticks in free-living tropical plants and animals. The rapid evolution in rabies viruses provided the researchers with an opportunity to examine one of the mechanisms thought to drive the differences in evolution and species diversity across latitudes from the poles to the tropics.

"This is just another example of how the fast pace of evolution in RNA viruses makes them exceptional tools for understanding simultaneously ecological and evolutionary processes," Streicker said.

The paper's coauthors were Philippe Lemey of KU Leuven and Andres Velasco-Villa and Charles E. Rupprecht of the CDC's Rabies Program. The research was supported by grants from UGA, the National Science Foundation and the European Research Council.


Story Source:

The above story is based on materials provided by University of Georgia. The original article was written by Beth Gavrilles. Note: Materials may be edited for content and length.


Journal Reference:

  1. Daniel G. Streicker, Philippe Lemey, Andres Velasco-Villa, Charles E. Rupprecht. Rates of Viral Evolution Are Linked to Host Geography in Bat Rabies. PLoS Pathogens, 2012; 8 (5): e1002720 DOI: 10.1371/journal.ppat.1002720

Cite This Page:

University of Georgia. "Hitting snooze on the molecular clock: Rabies evolves slower in hibernating bats." ScienceDaily. ScienceDaily, 18 May 2012. <www.sciencedaily.com/releases/2012/05/120518132708.htm>.
University of Georgia. (2012, May 18). Hitting snooze on the molecular clock: Rabies evolves slower in hibernating bats. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/2012/05/120518132708.htm
University of Georgia. "Hitting snooze on the molecular clock: Rabies evolves slower in hibernating bats." ScienceDaily. www.sciencedaily.com/releases/2012/05/120518132708.htm (accessed July 25, 2014).

Share This




More Plants & Animals News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Boy Attacked by Shark in Florida

Boy Attacked by Shark in Florida

Reuters - US Online Video (July 24, 2014) An 8-year-old boy is bitten in the leg by a shark while vacationing at a Florida beach. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Goma Cheese Brings Whiff of New Hope to DRC

Goma Cheese Brings Whiff of New Hope to DRC

Reuters - Business Video Online (July 24, 2014) The eastern region of the Democratic Republic of Congo, mainly known for conflict and instability, is an unlikely place for the production of fine cheese. But a farm in the village of Masisi, in North Kivu is slowly transforming perceptions of the area. Known simply as Goma cheese, the Congolese version of Dutch gouda has gained popularity through out the region. Ciara Sutton reports. Video provided by Reuters
Powered by NewsLook.com
Dogs Appear To Become Jealous Of Owners' Attention

Dogs Appear To Become Jealous Of Owners' Attention

Newsy (July 23, 2014) A U.C. San Diego researcher says jealousy isn't just a human trait, and dogs aren't the best at sharing the attention of humans with other dogs. Video provided by Newsy
Powered by NewsLook.com
Professor Creates Site Revealing Where People's Cats Live

Professor Creates Site Revealing Where People's Cats Live

Newsy (July 23, 2014) ​It's called I Know Where Your Cat Lives, and you can keep hitting the "Random Cat" button to find more real cats all over the world. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

    Health News

      Environment News

        Technology News



          Save/Print:
          Share:

          Free Subscriptions


          Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

          Get Social & Mobile


          Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

          Have Feedback?


          Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
          Mobile: iPhone Android Web
          Follow: Facebook Twitter Google+
          Subscribe: RSS Feeds Email Newsletters
          Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins