Persistence of Infection in Mosquitoes Injected with Bacteria

Gorman, Maureen J.; Paskewitz, Susan M.

doi:10.1006/jipa.2000.4930

Cited by 21 publications

(14 citation statements)

References 6 publications

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“…Even though we observed that mosquitoes are impressively equipped to kill large numbers of E. coli , only three of the 150 mosquitoes surveyed completely cleared the infection, and all three mosquitoes were injected with the lowest E. coli dose (5K). These results are in accord with experiments in A. gambiae that showed mosquitoes can successfully clear M. luteus but not E. coli infections (Gorman and Paskewitz, 2000).…”

Section: Resultssupporting

confidence: 90%

Age-associated mortality in immune challenged mosquitoes (Aedes aegypti) correlates with a decrease in haemocyte numbers

Hillyer

Schmidt

Fuchs

et al. 2004

Cellular Microbiology

113

139

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SummaryMosquitoes vector pathogens. One aspect that has been overlooked in mosquito-pathogen relationships is the effect of host age on immune competence. Here, we show that there is age-associated mortality following immune challenge with Escherichia coli . This mortality correlates with a decrease in haemocyte numbers (blood cells) and a decreased ability to kill E. coli . Although the number of haemocytes decreases, the available haemocytes retain their phagocytic ability regardless of age, and we estimate that individual granulocytes can phagocytose approximately 1500 E. coli . Moreover, transcription profiles for cecropin, defensin and gambicin in E. coli challenged mosquitoes do not change with age, indicating that the increased susceptibility is not attributed to fewer humoral antimicrobial peptides. These results suggest that a contributing factor for the age-associated mortality is the decrease in circulating haemocytes, which reduces the overall phagocytic capacity of mosquitoes. To our knowledge, this is the first report detailing an age-associated decline in the immunological capabilities of mosquitoes following challenge with an infectious agent. These data also call for caution in the analysis and interpretation of experimental results when mosquito age has not been closely monitored. Lastly, a model for haemocyte function is presented.

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Section: Resultssupporting

confidence: 90%

Age-associated mortality in immune challenged mosquitoes (Aedes aegypti) correlates with a decrease in haemocyte numbers

Hillyer

Schmidt

Fuchs

et al. 2004

Cellular Microbiology

113

139

View full text Add to dashboard Cite

show abstract

“…All mosquitoes assayed at 12 days post challenge had live E. coli in their hemocoels (and periostial regions; Figure 7B), and the amount of melanin deposition in the periostial regions also increased as mosquitoes aged. Thus, the maintenance of elevated numbers of periostial hemocytes may be due to the continued need of cellular antimicrobial activity, as mosquitoes appear to be incapable of completely clearing an E. coli bacterial infection [24], [25]. Finally, based on the number of circulating hemocytes [17], [19]–[23], the periostial hemocyte population represents between 10% and 25% of the total hemocyte population post-infection, which highlights the importance of pathogen sequestration in these areas of high hemolymph flow.…”

Section: Resultsmentioning

confidence: 99%

Infection-Induced Interaction between the Mosquito Circulatory and Immune Systems

King¹,

2012

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Insects counter infection with innate immune responses that rely on cells called hemocytes. Hemocytes exist in association with the insect's open circulatory system and this mode of existence has likely influenced the organization and control of anti-pathogen immune responses. Previous studies reported that pathogens in the mosquito body cavity (hemocoel) accumulate on the surface of the heart. Using novel cell staining, microdissection and intravital imaging techniques, we investigated the mechanism of pathogen accumulation in the pericardium of the malaria mosquito, Anopheles gambiae, and discovered a novel insect immune tissue, herein named periostial hemocytes, that sequesters pathogens as they flow with the hemolymph. Specifically, we show that there are two types of endocytic cells that flank the heart: periostial hemocytes and pericardial cells. Resident periostial hemocytes engage in the rapid phagocytosis of pathogens, and during the course of a bacterial or Plasmodium infection, circulating hemocytes migrate to the periostial regions where they bind the cardiac musculature and each other, and continue the phagocytosis of invaders. Periostial hemocyte aggregation occurs in a time- and infection dose-dependent manner, and once this immune process is triggered, the number of periostial hemocytes remains elevated for the lifetime of the mosquito. Finally, the soluble immune elicitors peptidoglycan and β-1,3-glucan also induce periostial hemocyte aggregation, indicating that this is a generalized and basal immune response that is induced by diverse immune stimuli. These data describe a novel insect cellular immune response that fundamentally relies on the physiological interaction between the insect circulatory and immune systems.

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“…Rather, we suggest that the positive correlation between the melanization of beads and the antibacterial response is due to shared genes and pathways that regulate these two effector mechanisms. Indeed, immune responses appear to share several regulating pathways, for example the use of serine proteases in the cascades (Gorman and Paskewitz 2001). Therefore, different immunological processes cannot be regulated independently of each other, but respond to difference in regulatory processes in a correlated fashion.…”

Section: Discussionmentioning

confidence: 99%

“…The antibacterial response was measured as the persistence of a bacterial infection with Escherichia coli strain CIP 103470 (Pasteur Institute Collection, Paris) as described in Gorman and Paskewitz (2000). Three days after emergence, mosquitoes were immobilized on ice and inoculated with 200 bacteria by intrathoracic injection of 0.1 l of a diluted bacterial suspension.…”

Section: Antibacterial Responsementioning

confidence: 99%

Genetic Correlation Between Melanization and Antibacterial Immune Responses in a Natural Population of the Malaria Vector Anopheles Gambiae

2004

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The immune system of invertebrates can mount different responses, including melanotic encapsulation and several antibacterial defense mechanisms. Variation of the efficacies of these responses is generally considered to be a product of the evolutionary pressure on each response due to infection by parasites. However, potential interactions and trade-offs among the different responses of the immune system could constrain the evolutionary potential of each response. In a natural population of the mosquito Anopheles gambiae, we measured the genetic association between the melanization response and an antibacterial response in two environmental qualities (well-fed and undernourished larvae). In both environments the two immune responses were positively genetically correlated: in full-sib families that were most likely to melanize a bead, injected bacteria were most likely to be cleared. Thus, our data do not support the idea of a trade-off among different outcomes of the invertebrate immune system, but rather that some families are overall immunologically superior to others.

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Persistence of Infection in Mosquitoes Injected with Bacteria

Cited by 21 publications

References 6 publications

Age-associated mortality in immune challenged mosquitoes (Aedes aegypti) correlates with a decrease in haemocyte numbers

Age-associated mortality in immune challenged mosquitoes (Aedes aegypti) correlates with a decrease in haemocyte numbers

Infection-Induced Interaction between the Mosquito Circulatory and Immune Systems

Genetic Correlation Between Melanization and Antibacterial Immune Responses in a Natural Population of the Malaria Vector Anopheles Gambiae

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