Lightning Talk Tsetse Flies and their associated microorganisms by Brian Weiss
March 21, 2024Information
Brian Weiss, PhD, Senior Research Scientist in Epidemiology and Lecturer (Microbial Diseases); Affiliated Faculty, Yale Institute for Global Health
Tsetse flies are obligate vectors of pathogenic African trypanosomes. Tsetse also harbor a population-specific assortment of bacterial endosymbionts that mediate many aspects of the fly’s physiology, including susceptibility to infection with trypanosomes and reproduction. The ultimate goal of my research is interrupt the tsetse fly-endosymbiont association in an effort to reduce disease control.
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- 00:00All right. So thank you seminar committee for
- 00:04giving me this opportunity to talk, right.
- 00:07I'm a senior research
- 00:09scientist in the department.
- 00:10I also Co teach the vector biology
- 00:13course with Doctor Axoy.
- 00:15My interests are arthropod disease
- 00:17vectors and they're microorganisms and
- 00:20I work specifically with TETSI fly.
- 00:22So this is a TETSI fly down here.
- 00:25Many of you may not have seen one before.
- 00:27From from a size perspective,
- 00:29they're about the size of a large house
- 00:31fly and they're found exclusively in
- 00:33tropical and parts of subtropical Africa.
- 00:36In the wild,
- 00:37I should point out now we have a
- 00:39colony of these flies right in this
- 00:41building on the 6th floor here.
- 00:44It's the only self-sustaining taxi
- 00:46colony in the Western Hemisphere.
- 00:48You're a vector biology nerd like myself,
- 00:51that's pretty cool.
- 00:53So this is what we used to do
- 00:54all of our work.
- 00:55And then we also go into the field in
- 00:57Africa and work with these flies as well.
- 01:00All right,
- 01:01so Tetsi flies are most well known as the
- 01:04vectors of pathogenic African turpanosomes.
- 01:07These are some here circulating
- 01:09with some red blood cells,
- 01:11and these parasites are the
- 01:13causative agents of human and
- 01:16animal African Turpanosomyces.
- 01:18Some of the more epidemiologically
- 01:21important species are here.
- 01:23They're very interesting creatures.
- 01:24I'm not going to talk about them at all,
- 01:26but if you're interested in parasites,
- 01:29they're they're the most
- 01:30interesting ones in my opinion,
- 01:33right? So if you go out into
- 01:35the field and you sample,
- 01:36let's say in Africa, you sample 100 flies,
- 01:39you might find a couple,
- 01:41you know, maybe 20 at the most,
- 01:44that are infected with trepanosomes.
- 01:46But every single Tetsi fly that you
- 01:49collect and that you find houses a
- 01:52consortium of endosymbiotic bacteria
- 01:54that reside exclusively within it.
- 01:57And there's four of them
- 01:58that we know about so far.
- 01:59There could be more, and they're listed here.
- 02:03So every single Tetsi fly has the
- 02:05bacterium from the genus Wigglesworthia,
- 02:08and that's an obligate symbiosis.
- 02:10So neither Organism can live
- 02:11in the absence of the other.
- 02:13And then depending on environmental cues and,
- 02:17you know, temperature, humidity,
- 02:19so on, there might be some combination
- 02:22of the other three endosymbiotes.
- 02:24And these organisms,
- 02:25this fly and these microbes are
- 02:28very intimately associated with
- 02:30one another from a physiological
- 02:33and biological perspective.
- 02:35So touchy flies are also very
- 02:37unique because unlike basically
- 02:38every other insect they give,
- 02:40they give birth to live young and these,
- 02:43these endosymbiotic bacteria
- 02:45are maternally transmitted from
- 02:47the mom to these offspring.
- 02:49That's a larval,
- 02:51A larval tessie fly right there while
- 02:53it's developing within the mom.
- 02:55So that's how they're transmitted and
- 02:58if you interrupt that transmission,
- 03:01this offspring and it develops without them,
- 03:04it's biologically compromised
- 03:07in many ways and that's what we
- 03:09look at in in our group.
- 03:11So the ultimate goal of the research
- 03:13that we do in our in our group is
- 03:15to kind of decipher just the basic
- 03:17molecular mechanisms that underlie
- 03:19Tetsy fly endosymbiont interactions,
- 03:21because it's just very
- 03:23interesting biologically.
- 03:24And then also of course we want to
- 03:27try and use this knowledge that we
- 03:29learn to develop novel ways to control
- 03:32the spread of Tetsy borne diseases.
- 03:36All right.
- 03:37So over the years we have come up
- 03:40with ways to eliminate either all
- 03:43of these symbionts or you know,
- 03:46different ones, different combinations.
- 03:47And then we can by doing that,
- 03:49we can look at the phenotypes of
- 03:52these flies and determine, you know,
- 03:55you know, the nature of these interactions.
- 03:57And to make a very long story very short,
- 04:00these are some of the main things we found.
- 04:02We found that when flies are dysbiotic,
- 04:05so when they're symbiotes are,
- 04:08you know, altered by us experimentally,
- 04:10they can't find hosts and they they,
- 04:13they don't find mates as well.
- 04:15They become reproductively sterile
- 04:17because the symbiotes provide
- 04:19nutrients if they need.
- 04:21They're they're immunocompromised.
- 04:22And also depending on which one's missing,
- 04:25they're either more or less
- 04:28susceptible to trepanosomes.
- 04:29And the more we learn about this,
- 04:31you know, the more we,
- 04:32again,
- 04:32we can apply this information to developing
- 04:34these novel Disease Control strategies.
- 04:37So for example,
- 04:38you could,
- 04:39you know,
- 04:40you could figure out how to inhibit
- 04:43the the symbionts ability to
- 04:45produce vitamins and you would lower
- 04:47fecundity of the fly and fewer flies,
- 04:49less disease transmission.
- 04:51That's just one example.
- 04:52So I like to just conclude with this,
- 04:55this is just a really interesting
- 04:58diagram of physiological similarities
- 05:00between humans and fruit flies.
- 05:03And I cheated and added Tetsy
- 05:05fly because it's the same also,
- 05:07but they're very similar actually,
- 05:09you know, they they share similar
- 05:11organ systems and similar cell types.
- 05:13And what we can learn from these flies,
- 05:15you know, it's conspicuously
- 05:18applicable to developing hypothesis
- 05:20for more advanced systems.
- 05:23And case in point is the 2011 Nobel
- 05:26Prize in Physiology and Medicine was
- 05:28awarded to a group that deciphered the
- 05:30innate immune system of a fruit fly.
- 05:33And as it turns out,
- 05:34it's highly conserved in all animals.
- 05:36And what we know about human innate
- 05:38immunity kind of came from that work.
- 05:40All right. So I thank you for listening.
- 05:42This is my wonderful group of colleagues.
- 05:45That's how you can reach me if you want
- 05:47to talk or see the flies or anything.
- 05:50Thank you.