1
|
Zhao D, Ali A, Zuck C, Uy L, Morris JG, Wong ACN. Vibrio cholerae Invasion Dynamics of the Chironomid Host Are Strongly Influenced by Aquatic Cell Density and Can Vary by Strain. Microbiol Spectr 2023; 11:e0265222. [PMID: 37074192 PMCID: PMC10269514 DOI: 10.1128/spectrum.02652-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 03/24/2023] [Indexed: 04/20/2023] Open
Abstract
Cholera has been a human scourge since the early 1800s and remains a global public health challenge, caused by the toxigenic strains of the bacterium Vibrio cholerae. In its aquatic reservoirs, V. cholerae has been shown to live in association with various arthropod hosts, including the chironomids, a diverse insect family commonly found in wet and semiwet habitats. The association between V. cholerae and chironomids may shield the bacterium from environmental stressors and amplify its dissemination. However, the interaction dynamics between V. cholerae and chironomids remain largely unknown. In this study, we developed freshwater microcosms with chironomid larvae to test the effects of cell density and strain on V. cholerae-chironomid interactions. Our results show that chironomid larvae can be exposed to V. cholerae up to a high inoculation dose (109 cells/mL) without observable detrimental effects. Meanwhile, interstrain variability in host invasion, including prevalence, bacterial load, and effects on host survival, was highly cell density-dependent. Microbiome analysis of the chironomid samples by 16S rRNA gene amplicon sequencing revealed a general effect of V. cholerae exposure on microbiome species evenness. Taken together, our results provide novel insights into V. cholerae invasion dynamics of the chironomid larvae with respect to various doses and strains. The findings suggest that aquatic cell density is a crucial driver of V. cholerae invasion success in chironomid larvae and pave the way for future work examining the effects of a broader dose range and environmental variables (e.g., temperature) on V. cholerae-chironomid interactions. IMPORTANCE Vibrio cholerae is the causative agent of cholera, a significant diarrheal disease affecting millions of people worldwide. Increasing evidence suggests that the environmental facets of the V. cholerae life cycle involve symbiotic associations with aquatic arthropods, which may facilitate its environmental persistence and dissemination. However, the dynamics of interactions between V. cholerae and aquatic arthropods remain unexplored. This study capitalized on using freshwater microcosms with chironomid larvae to investigate the effects of bacterial cell density and strain on V. cholerae-chironomid interactions. Our results suggest that aquatic cell density is the primary determinant of V. cholerae invasion success in chironomid larvae, while interstrain variability in invasion outcomes can be observed under specific cell density conditions. We also determined that V. cholerae exposure generally reduces species evenness of the chironomid-associated microbiome. Collectively, these findings provide novel insights into V. cholerae-arthropod interactions using a newly developed experimental host system.
Collapse
Affiliation(s)
- Dianshu Zhao
- Entomology and Nematology Department, University of Florida, Gainesville, Florida, USA
| | - Afsar Ali
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, USA
- Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, Gainesville, Florida, USA
| | - Cameron Zuck
- Entomology and Nematology Department, University of Florida, Gainesville, Florida, USA
| | - Laurice Uy
- Entomology and Nematology Department, University of Florida, Gainesville, Florida, USA
| | - J. Glenn Morris
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, USA
| | - Adam Chun-Nin Wong
- Entomology and Nematology Department, University of Florida, Gainesville, Florida, USA
- Genetics Institute, University of Florida, Gainesville, Florida, USA
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, USA
| |
Collapse
|
2
|
McDonald ND, Rosenberger JR, Almagro-Moreno S, Boyd EF. The Role of Nutrients and Nutritional Signals in the Pathogenesis of Vibrio cholerae. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1404:195-211. [PMID: 36792877 DOI: 10.1007/978-3-031-22997-8_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Vibrio cholerae, the agent of cholera, is a natural inhabitant of aquatic environments. Over the past decades, the importance of specific nutrients and micronutrients in the environmental survival, host colonization, and pathogenesis of this species has become increasingly clear. For instance, V. cholerae has evolved ingenious mechanisms that allow the bacterium to colonize and establish a niche in the intestine of human hosts, where it competes with commensals (gut microbiota) and other pathogenic bacteria for available nutrients. Here, we discuss the carbon and energy sources utilized by V. cholerae and what is known about the role of nutrition in V. cholerae colonization. We examine how nutritional signals affect virulence gene regulation and how interactions with intestinal commensal species can affect intestinal colonization.
Collapse
Affiliation(s)
- N D McDonald
- Department of Biological Sciences, University of Delaware, Newark, DE, USA
| | - J R Rosenberger
- Department of Biological Sciences, University of Delaware, Newark, DE, USA
| | - S Almagro-Moreno
- Burnett School of Biomedical Sciences, University of Central Florida, Orlando, FL, USA.,National Center for Integrated Coastal Research, University of Central Florida, Orlando, FL, USA
| | - E Fidelma Boyd
- Department of Biological Sciences, University of Delaware, Newark, DE, USA.
| |
Collapse
|
3
|
Laviad-Shitrit S, Sela R, Thorat L, Sharaby Y, Izhaki I, Nath BB, Halpern M. Identification of chironomid species as natural reservoirs of toxigenic Vibrio cholerae strains with pandemic potential. PLoS Negl Trop Dis 2020; 14:e0008959. [PMID: 33362241 PMCID: PMC7757795 DOI: 10.1371/journal.pntd.0008959] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 11/06/2020] [Indexed: 11/24/2022] Open
Abstract
Vibrio cholerae causes the fatal cholera diarrhea. Chironomids (Diptera; Chironomidae) are abundant in freshwater aquatic habitats and estuaries and are natural reservoirs of V. cholerae. Until now, only the non-O1/O139 serogroups of V. cholerae were identified in chironomids. Here, we explored whether chironomids are natural reservoirs of V. cholerae O1/O139 serogroups, which are associated with cholera endemics and pandemics. All four life stages of chironomids were sampled from two rivers, and a laboratory culture in Pune, India, and from a pond in Israel. In total, we analyzed 223 chironomid samples. The presence of V. cholerae O1/O139 serogroups was verified using molecular tools. Nine chironomid species were identified; of them, Chironomus circumdatus was the most abundant. The presence of V. cholerae serogroup O1 and the cholera toxin genes were detected in samples from all chironomid species. However, serogroup O139 was detected in only two chironomid species. Besides PCR to detect specific genes, a metagenomic analysis that was performed in three selected C. ramosus larvae, identified a list of virulence genes associated with V. cholerae. The findings provide evidence that chironomids are natural reservoirs of toxigenic V. cholerae O1/O139. Chironomid populations and V. cholerae show biannual peak patterns. A similar pattern is found for cholera epidemics in the Bengal Delta region. Thus, we hypothesize that monitoring chironomids in endemic areas of the disease may provide a novel tool for predicting and preventing cholera epidemics. Moreover, serogroup O139 was detected only in two chironomid species that have a restricted distribution in the Indian subcontinent, possibly explaining why the distribution of the O139 serogroup is limited.
Collapse
Affiliation(s)
- Sivan Laviad-Shitrit
- Department of Evolutionary and Environmental Biology, University of Haifa, Haifa, Israel
| | - Rotem Sela
- Department of Evolutionary and Environmental Biology, University of Haifa, Haifa, Israel
| | - Leena Thorat
- Department of Zoology, Savitribai Phule Pune University, Pune, India
- Department of Biology, York University, Toronto, Canada
| | - Yehonatan Sharaby
- Department of Evolutionary and Environmental Biology, University of Haifa, Haifa, Israel
| | - Ido Izhaki
- Department of Evolutionary and Environmental Biology, University of Haifa, Haifa, Israel
| | - Bimalendu B. Nath
- Department of Zoology, Savitribai Phule Pune University, Pune, India
| | - Malka Halpern
- Department of Evolutionary and Environmental Biology, University of Haifa, Haifa, Israel
- Department of Biology and Environment, University of Haifa, Oranim, Tivon, Israel
| |
Collapse
|
4
|
Sela R, Halpern M. Seasonal dynamics of Chironomus transvaalensis populations and the microbial community composition of their egg masses. FEMS Microbiol Lett 2020; 366:5700282. [DOI: 10.1093/femsle/fnaa008] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 01/09/2020] [Indexed: 12/27/2022] Open
Abstract
ABSTRACT
Chironomids (Diptera; Chironomidae) are the most abundant insects in freshwater environments and are considered natural reservoirs of Vibrio cholerae. We monitored the annual dynamics of chironomid populations along with their microbiota in order to better understand host–microbiota interactions. Chironomus transvaalensis populations peaked biannually in August and May–June. The composition of the endogenous bacterial communities of their egg masses clustered in two groups according to the sampling periods August–November and May–July. Nevertheless, a core bacterial community (43%) was present in all egg-mass samples. The most abundant phyla were: Proteobacteria, Firmicutes, Cyanobacteria and Bacteroidetes. The abundance of several genera (e.g. Rheinheimera and Pseudomonas) was positively correlated with C. transvaalensis population dynamics, while a predator–prey interaction was observed between the relative abundance of Vibrio OTUs and C. transvaalensis population size. Chironomids are known to tolerate toxic and stress conditions, and our results demonstrated that bacterial genera that may protect the insect under these conditions are present in the egg masses. After hatching, the first larval meal is the gelatinous matrix that surrounds the eggs. This meal contains a probiotic consortium that may protect the larva during its metamorphosis. The results provide important insights into the host–microbe interactions of chironomids.
Collapse
Affiliation(s)
- Rotem Sela
- Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa, 199 Abb Khoushi Ave. Mt. Carmel, Haifa, 3498838, Israel
| | - Malka Halpern
- Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa, 199 Abb Khoushi Ave. Mt. Carmel, Haifa, 3498838, Israel
- Department of Biology and Environment, Faculty of Natural Sciences, University of Haifa, Oranim, Derech Kiryat Amal, Tivon, 3600600, Israel
| |
Collapse
|
5
|
Halpern M, Senderovich Y. Chironomid microbiome. MICROBIAL ECOLOGY 2015; 70:1-8. [PMID: 25421389 DOI: 10.1007/s00248-014-0536-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 11/11/2014] [Indexed: 06/04/2023]
Abstract
Chironomids are abundant insects in freshwater habitats. They undergo a complete metamorphosis of four life stages: eggs, larvae, and pupae in water, and a terrestrial adult stage. Chironomids are known to be pollution-tolerant, but little is known about their resistance mechanisms to toxic substances. Here we review current knowledge regarding the chironomid microbiome. Chironomids were found as natural reservoirs of Vibrio cholerae and Aeromonas spp. A stable bacterial community was found in the egg masses and the larvae when both culture-dependent and -independent methods were used. A large portion of the endogenous bacterial species was closely related to species known as toxicant degraders. Bioassays based on Koch's postulates demonstrated that the chironomid microbiome plays a role in protecting its host from toxic hexavalent chromium and lead. V. cholerae, a stable resident in chironomids, is present at low prevalence. It degrades the egg masses by secreting haemagglutinin/protease, prevents eggs from hatching, and exhibits host pathogen interactions with chironomids. However, the nutrients from the degraded egg masses may support the growth of the other microbiome members and consequently control V. cholerae numbers in the egg mass. V. cholerae, other chironomid endogenous bacteria, and their chironomid host exhibit complex mutualistic relationships.
Collapse
Affiliation(s)
- Malka Halpern
- Department of Biology and Environment, Faculty of Natural Sciences, University of Haifa, Oranim, Tivon, Israel,
| | | |
Collapse
|
6
|
Ceccarelli D, Spagnoletti M, Bacciu D, Danin-Poleg Y, Mendiratta DK, Kashi Y, Cappuccinelli P, Burrus V, Colombo MM. ICEVchInd5 is prevalent in epidemic Vibrio cholerae O1 El Tor strains isolated in India. Int J Med Microbiol 2011; 301:318-24. [DOI: 10.1016/j.ijmm.2010.11.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Revised: 11/15/2010] [Accepted: 11/21/2010] [Indexed: 01/01/2023] Open
|