Introduction

    White-Nose Syndrome affects five of the nine bat species located in Michigan: the Little Brown bat, the Big Brown Bat, the Tricolored bat, the Indiana bat, and the Northern Long-Eared bat1. The disease is caused by the fungus Pseudogymnoascus destructans, which infects bats during their hibernation period, causing the collagen in their noses to slowly degrade due to proteolytic enzymes produced by the fungus. This causes the bats to become active from hibernation prematurely, which results in lethargy due to the limited resources. Without the necessary means to sustain life available in the winter season, death is often a result. There is currently no widespread treatment to prevent P. destructans infections in bats. There has been over 90% mortality of Northern Long-Eared, Little Brown, and Tri-colored bat populations in less than a decade2.

    Figure 1: Areas where one or more bats have been documented showing symptoms of White-Nose Syndrome. The X indicates where the first sighting occurred in the United States. Colors represent the years that area had indicated one or more bats with White-Nose Syndrome3.

Figure 2: Northern Long-Eared Bat with White-Nose Syndrome4.

Problems:

  • Bats affected by White-Nose Syndrome wake from hibernation too early; due to the lack of food availability, bats resort to utilizing their fat reserves for energy. This often leads to starvation and eventually death.
  • As pollinators, bats feed on nectar, benefiting many plants. Hundreds of plants, like fruits, nuts, figs, and cacao depend on bats for pollination and seed dispersion5. Due to the lack of pollinators in hot, dry, environments, the presence of agave and saguaro cacti can be attributed to these nocturnal pollinators4,5. Seed dispersion occurs through the consumption of seeds, which eventually reenters the environment through bat droppings. Through the decline of bat species, one can expect reduced biodiversity and forestry cover due to the lack of pollination and seed dispersal.
  • In the United States alone, bats are estimated to save farmers at least $3.7 billion per year in pest control services6. Bat species are very important pest controllers on agricultural farms due to their tendency to eat insects that damage crops and trees. The loss of these nocturnal predators can result in major effects on the environment, with the potential to affect forestry, agriculture, and human health.

Figure 3: Bats play important ecological roles in the environment, such as pest control and pollination.

Current Solutions:

Most current solutions are being tested for effectiveness; however, some data and progress toward a permanent solution have been recorded. An oral vaccine is one of two treatments that express an antigen that targets the fungus7. It is administered via a liquid dose into the bat’s mouth. The vaccine was developed by Dr. Tonie Rocke, in partnership with Dr. Bruce Klein and Dr. Jorge Osori. Developed at McMaster University and Thompson Rivers University, the second treatment is a probiotic aimed at slowing the growth of the fungus on the bat’s skin7. Both treatments still need to be adjusted and there is not enough sufficient data to confirm their effectiveness. Administering treatments to the bats can be difficult due to the lack of accessibility in areas where the bats inhabit.

Our Solution:

P. destructans has a critical enzyme called Destructin-1, a serine protease that allows it to degrade collagen8. This allows the fungus to create deeper infection sites on bats by destroying the skin's structural strength along with 5 other endopeptidases that break down other proteins. We aim to engineer E. coli that secrete a serine protease inhibitor(s) to prevent collagen degradation.

Specifically, the goal is to have a singular construct, a device that allows E. coli to secrete the most effective serine protease inhibitor(s) to combat Destructin-1. Secretion is achieved by using the type 1 Secretion system naturally in E. coli9. Attaching the Hly-A peptide signal to the inhibitors causes the bacteria to recognize and export through the channel complex of HlyB, HlyD, and TolC. After being exported an additional protease is generated by the device that is called TEV(tobacco etch virus) that recognizes a certain signal peptide and cleaves the protein. This allows for the separation of the Hly-A signal which will prevent unwanted confirmations of the inhibitors. These serine protease inhibitors are then free to bind to Destructin-1 and possibly other endopeptidases produced by P. destructans.

Figure 4: An example model of a secretion device producing enzymes in bacteria and then secreting them to be used against Destructin-1.

The end goal is to have a bacteria spray that could be produced cheaply to be sprayed in critical bat habitats. This would allow the bacteria to thrive and actively combat the enzyme(s) produced by P. destructans. This would allow active bats to potentially carry the bacteria with them to other habitats that humans have not found or can access. In addition, live bacteria sprays will only be used if they are proven to be safe to release in the environment for remediation.

References

  1. “Bats Affected by WNS.” White-Nose Syndrome, n.d. https://www.whitenosesyndrome.org/static-page/bats-affected-by-wns.
  2. United States Geological Survey. “White-Nose Syndrome Killed Over 90% of Three North American Bat Species | U.S. Geological Survey.” USGS.gov, 21 April 2021, https://www.usgs.gov/news/national-news-release/white-nose-syndrome-killed-over-90-three-north-american-bat-species.
  3. ArcGIS web application. Available at: https://midnr.maps.arcgis.com/apps/webappviewer/index.html?id=12a083be8ea14d4d9e9e8fdb91a8f09d
  4. Northern long-eared bat (Myotis septentrionalis): U.S. Fish & Wildlife Service FWS.gov. Available at: https://www.fws.gov/species/northern-long-eared-bat-myotis-septentrionalis.
  5. “13 Awesome Facts About Bats.” U.S. Department of the Interior, 20 October 2021, https://www.doi.gov/blog/13-facts-about-bats.
  6. Celley, Courtney. “Bats are one of the most important misunderstood animals | U.S. Fish & Wildlife Service.” U.S. Fish and Wildlife Service, 11 June 2021, https://www.fws.gov/story/bats-are-one-most-important-misunderstood-animals.
  7. Vachula, Laura. “Preventing and treating white-nose syndrome | U.S. Fish & Wildlife Service.” U.S. Fish and Wildlife Service, 23 May 2024, https://www.fws.gov/story/preventing-and-treating-white-nose-syndrome.
  8. O’Donoghue, A.J. et al. (2015) ‘Destructin-1 is a collagen-degrading endopeptidase secreted by Pseudogymnoascus destructans, the causative agent of white-nose syndrome’, Proceedings of the National Academy of Sciences, 112(24), pp. 7478–7483. doi:10.1073/pnas.1507082112.
  9. Thomas, S., Holland, I.B. and Schmitt, L. (2014) ‘The type 1 secretion pathway — the hemolysin system and beyond’, Biochimica et Biophysica Acta (BBA) - Molecular Cell Research, 1843(8), pp. 1629–1641. doi:10.1016/j.bbamcr.2013.09.017.