Study details how some fish cope with parasites, with implications for
human health
New research on how parasite resistance in threespine stickleback fish
may lead to a better understanding of human diseases.

Date:
March 2, 2022
Source:
University of Minnesota
Summary:
Parasitic tapeworms have a complex life cycle moving from plankton
to fish and then fish-eating birds. New research on how parasite
resistance in threespine stickleback fish may lead to a better
understanding of human diseases such as cystic and liver fibrosis.



FULL STORY ==========================================================================
They thrive everywhere from bustling cities to remote rainforests --
even in our own backyards. Pervasive and unapologetic mooches, parasites
rely on other organisms for their survival.


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How parasites impact their host varies broadly, from causing minor
irritation to death. Even among host populations that are closely
related, the response to an infection by a parasite can differ
dramatically. Frequently, populations are classified as either "resistant"
or "susceptible" to a parasite. However, this simplified framework
doesn't tell the whole story.

In a recent study published in Evolution Letters, a team of researchers
led by Amanda Hund, a postdoctoral researcher in the University of
Minnesota's College of Biological Sciences, details how parasite
resistance in hosts arises.

To understand how related hosts respond differently to parasitic
infection, researchers closely monitored threespine stickleback fish
that live in isolated lakes on the western coast of Canada.

"Mature tapeworms can make it difficult for the fish to swim or
reproduce. It can even manipulate the fish's behavior to increase the
odds that it will be eaten by a bird, where the tapeworm reproduces,"
says Hund.

The interaction between a host and a parasite can be broken down into
several different steps. Understanding where populations differ in
these steps shows scientists where evolution is happening and often
determines whether the population is resistant or susceptible to the
parasite. Researchers found the ability to detect a parasite and launch
an immune response quickly is the most important factor in determining if
the host can resist the parasite or limit parasite growth. "Applying this approach to more hosts and parasites will allow us to better understand
why parasite resistance varies and how it evolves," says Hund.

The findings could have further implications for human conditions that
generate scar tissue which is similar to the mesh of tissue that resistant
fish use to trap the parasite. Hund's collaborator Daniel Bolnick, a
professor at the University of Connecticut, is continuing work in this
system to better understand how it connects with human diseases such as
cystic fibrosis and liver fibrosis.

"We found naturally-evolved genetic variation in how quickly fish
initiate and recover from a self-harming immune response. That same
harmful immune response exists in humans, so the discoveries in fish
have the potential to teach us how our own bodies might recover faster
from damaging conditions" says Bolnick.

Funding and support for this work was provided by a James S. McDonnell Foundation Postdoctoral Fellowship (to AKH), an American Association of Immunologists Intersect Postdoctoral Fellowship (to LEF), University of Connecticut (startup to DIB), and National Institutes of Health NIAID
grant 1R01AI123659-01A1 (to DIB).

========================================================================== Story Source: Materials provided by University_of_Minnesota. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Amanda K. Hund, Lauren E. Fuess, Mariah L. Kenney, Meghan
F. Maciejewski,
Joseph M. Marini, Kum Chuan Shim, Daniel I. Bolnick.

Population‐level variation in parasite resistance due to
differences in immune initiation and rate of response. Evolution
Letters, 2022; DOI: 10.1002/evl3.274 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220302185952.htm

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