Certain funguses are deadly for frogs. Could ‘vaccinating’ them help?

Certain funguses are deadly for frogs. Could ‘vaccinating’ them help?

This article was originally published on The Conversation.

Many people were shocked when the COVID-19 pandemic began. Wildlife disease researchers like me They were not surprised. Some were surprised that it hadn’t happened sooner. After all, it is our job as scientists to study and observe pandemic dynamics in animals.

For decades, amphibians have been suffering from a global pandemic (the animal version of a pandemic) that has been going on for decades. Researchers identified the Amphibian chytrid fungusThis is the most deadly form of the disease. ChytridiomycosisAs the likely culprit behind the declines in salamander and frog numbers and subsequent extinctions Australia To Central America And elsewhere that started 10, 20, or even 30 years ago.

Scientists have identified this pathogen. Every continent amphibians have ever lived onThe extensive Global amphibian trade It is likely that the virus has spread deadly strains all over the globe. Some countries are home to the amphibian-chytrid fungus. Geographic regionsIt can, just like the virus that causes COVID-19. mutate rapidly You can also try new forms that may cause different degrees of disease.

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Many amphibians are in danger of disappearing all over the globe.

Conservation translocation This is a popular way to save species that have suffered significant population declines. It involves moving organisms to reestablish extinct populations, supplement existing ones, or establish new species in areas where they are not already present. The amphibian chytrid fungal infection can make it difficult for translocation to succeed.

Researchers are working to avoid the setbacks caused by disease. Use a tool Often used against human pandemics Inoculations are similar to vaccinations.

In Our recent studyMy research team and I inoculated threatened California red-legged Frogs By exposing them to the chytrid yeast in the laboratory, we were able to protect them against the chytrid fungal infection. We wanted to test their immune systems and give them an advantage against the fungus once they were released. Our results were surprising.

A cocktail is the best medicine.

Yosemite National Park has been actively translocating California red frogs since 2017. Yosemite Valley, where the chytrid fungal infection is already present. We used a A small subset These frogs were translocated in our study.

We collected wild frog eggs from a location where the species is thriving, approximately 100 miles northwest of Yosemite Valley. Then, we raised them in captivity at San Francisco Zoo. After they became juvenile frogs, the group bathed them in a “cocktail”, which contained four active strains of fungus. To stop the infection, they were given an antifungal bath after three weeks. Forty-eight other frogs were also bathed with an antifungal drug to stop the infection.

We then exposed the 20 infected frogs to fungus again, while the uninfected frogs were first exposed to the fungus. We wanted to compare the frogs that had been infected twice with those that had not been.

Surprisingly, 35% of the frogs that were infected with the disease had their infection cleared without any vaccination or antifungal drugs. This suggests that they may have some degree of immunity. Inborn immunityThis means that their immune system was able to fight the fungus. A third infection rate was 31% lower in frogs that were infected twice than infected once. This suggests that vaccine-like treatment works by stimulating the immune system. Adaptive immunityThis means that their immune system was able to recognize the fungus and fight it off more effectively. Their fungal infections did not cause any deaths in the frogs.

We treated the frogs using an antifungal drug before releasing them into the wild. We also monitored their health to ensure they were healthy. We placed tiny transmitters with beaded belts around the waists of the frogs to track their survival and infections over three months.

Unexpectedly, there was no difference in disease burden between frogs that were never infected and those who had been infected in the laboratory. This suggests that immunizing this species for chytrid fungal disease, at least in Yosemite may not be necessary to ensure their survival after reintroduction.

The California red-legged Frogs have been thriving in Yosemite Valley three years after our experiment, and six years after their first translocation. They are hibernating well through the cold winters, and emerge early in the spring to reproduce.

We have hope for the future

Our study focuses on the new tool of inoculation against chytrid. We combined ex situ (or laboratory) experiments with in situ (or in the field) implementation to put our lab observations to the real-world test. This type of work helps strengthen collaborations between wildlife managers, zoos and other zoos. The biodiversity crisis is intensifying.

Although California red-legged Frogs in Yosemite Valley did not seem to require vaccinations, it doesn’t necessarily mean that other imperiled amphibian species do not. Research on chytrid vaccinations in other species has had mixed results. They range from Not improving survival To reducing infection burden Vaccination is associated with higher survival rates. This conservation approach has one major problem: even if vaccination increases survival following initial release, this immunity doesn’t carry forward to subsequent generations.

There is still hope. Researchers are trying to find the right answer. Genetic signatures associated immunity to the chytrid fungal infection. If breeding programs are successful, they can artificially select for – or even gene-edit Protective traits that give frogs an advantage over a pathogen that has decimated amphibian populations around the world.The Conversation

Andrea Adams is a Researcher on Ecology at the University of California Santa Barbara. Andrea Adams was previously funded by the Yosemite Conservancy to conduct this research as a postdoctoral researcher in Yosemite National Park. The U.S. provided funding for her current academic appointment. Fish and Wildlife Service.

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