A fungal disease known to kill millions of bats in North America can now be tracked using a newly identified fungus-infecting virus.
In a study featured in the journal PLOS Pathogens, researchers from Pennsylvania State University discussed how they were able to identify a virus harbored by the Pseudogymnoascus destructans fungus.
P. destructans is known to be the cause of the white-nose syndrome (WNS) among bats, which has already killed as many as 6 million of the flying mammals in North America since it was first discovered in 2006.
Prof. Marilyn Roossinck and her colleagues at Penn State believe that the virus that they isolated could be used as a marker to monitor the spread of WNS to other bats.
According to the U.S. Geological Survey's National Wildlife Health Center, WNS is a highly contagious disease known to affect hibernating bats. It gets its name from the white fungus P. destructans that infects the skin on the ears, muzzle, and wings of the animals.
Millions of insect-eating bats have already been killed by the disease in 29 U.S. states and five Canadian provinces since the winter of 2007 to 2008. Researchers have now also detected WNS in Rhode Island and Washington.
While WNS can infect several bat species, those living in the northeast have been found to be particularly at risk. The mortality rate for the disease can reach as high as 99 percent among these species.
Animal conservationists are concerned that the high mortality rate could severely affect the ecological balance in the country since bats help keep populations of insect pests, such as mosquitoes, in check.
To help understand more about the white-nose syndrome, Roossinck and her team analyzed 62 isolates of P. destructans, including 35 collected from the U.S., 17 from Europe, and 10 from Canada. They discovered that only samples taken from North America have the virus infection they were looking for.
Since the P. destructans fungus is clonal, Roossinck said it is identical wherever the organism exists in North America. This makes it difficult for researchers to determine how it is able to spread.
However, the researchers found that the virus the fungus harbors has several variations. While the viruses in the isolates they examined from Pennsylvania were similar, those found in isolates taken from Canada and other areas differed from each other.
The researchers said fungi are not readily affected by fungal viruses. This means that the differences in viral genome they identified could occur after the virus begins to evolve within fungal isolates, making it a good candidate as a marker.
"We believe the differences in the viruses reflect the movement of the fungus, and this viral variability should enable us to get a better handle on how the disease is spreading," Roossinck pointed out.
The identified virus is not known to cause white-nose syndrome. However, the researchers have yet to prove that it influences the virulence of the disease.
Roossinck said it is difficult to determine the virulence of WNS in terms of bat infection since there are only a few of the animals left to study. They also have yet to devise an experimental system that would work for such an endeavor.
The researchers were able to eliminate the virus from one of the fungal isolates they retrieved. This has given them a virus-free isolate that they can use to compare biochemical changes in the virus-infect isolates they still have.
Roossinck and her colleagues now plan to use their findings to come up with strategies on how to control the spread of white-nose syndrome in North America and help save the bats that are still left.