Histologie des M�ckenstiches (Aedes aegypti)

Bandmann, Hans‐Jürgen; Bosse, K

doi:10.1007/bf00501526

Cited by 5 publications

(3 citation statements)

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“…(i) Antigen-antibody complexes in the skin stimulate platelet aggregation and subsequent hemostasis. (ii) Mosquito bites on sensitized animals lead to a reduction in the local blood flow by constriction of blood vessels during local cutaneous anaphylaxis and to occlusion of the blood vessels by local edema (5,42). Such hemostatic events may hinder mosquito feeding.…”

Section: Discussionmentioning

confidence: 99%

Neither Mosquito Saliva nor Immunity to Saliva Has a Detectable Effect on the Infectivity ofPlasmodiumSporozoites Injected into Mice

2010

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Malaria infection is initiated when a female Anopheles mosquito probing for blood injects saliva, together with sporozoites, into the skin of its mammalian host. Prior studies had suggested that saliva may enhance sporozoite infectivity. Using rodent malaria models (Plasmodium berghei and P. yoelii), we were unable to show that saliva had any detectable effect on sporozoite infectivity. This is encouraging for plans to immunize humans with washed, attenuated P. falciparum sporozoites because many individuals develop cutaneous, hypersensitivity reactions to mosquito saliva after repeated exposure. If washed sporozoites have no appreciable loss of infectivity, they likely do not have decreased immunogenicity; thus, vaccinees are unlikely to develop cutaneous reactions against mosquito saliva during attempted immunization with such sporozoites. Earlier studies also suggested that repeated prior exposure to mosquito saliva reduces infectivity of sporozoites injected by mosquitoes into sensitized hosts. However, our own studies show that prior exposure of mice to saliva had no detectable effect on numbers of sporozoites delivered by infected mosquitoes, the rate of disappearance of these sporozoites from the skin or infectivity of the sporozoites. Under natural conditions, sporozoites are delivered both to individuals who may exhibit cutaneous hypersensitivity to mosquito bite and to others who may have not yet developed such reactivity. It was tempting to hypothesize that differences in responsiveness to mosquito bite by different individuals might modulate the infectivity of sporozoites delivered into a milieu of changes induced by cutaneous hypersensitivity. Our results with rodent malaria models, however, were unable to support such a hypothesis.The malaria infection is initiated when a female Anopheles mosquito probing for a blood meal injects saliva, together with sporozoites into the skin of its mammalian host (18, 39). Mosquito saliva is known to enhance the ability of the mosquito to locate a blood source and to inhibit hemostasis by any of several mechanisms. These include injection of an anticoagulant factor (34), inhibition of platelet aggregation by salivary apyrase (29) or a salivary factor that inhibits collagen-induced platelet aggregation (43), inhibition of thrombin activity (14), and vasodilation of host blood vessels (30). Arthropod saliva has been shown to enhance the infectivity of several different pathogens introduced into hosts by arthropods; these include sandfly transmission of Leishmania, tick transmission of viruses and spirochetes, and mosquito transmission of viruses (for a review, see reference 36). Enhancement of Plasmodium sporozoite infectivity by mosquito saliva has also been reported (12, 36) based on a prior study (41), but we felt that this study needed to be reassessed.In addition to these studies on the direct effect of arthropod saliva on infectivity of pathogens injected by arthropods into immunologically naive hosts, studies have also been done on the role of prior exposure...

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Section: Discussionmentioning

confidence: 99%

Neither Mosquito Saliva nor Immunity to Saliva Has a Detectable Effect on the Infectivity ofPlasmodiumSporozoites Injected into Mice

2010

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“…Remarkably few studies, however, have been published describing the morphological features of this frequent entity. Most of them are of older date 1–5 or emphasize arthropod assault reactions with unusual histopathological features occurring in specific clinical settings, such as those observed in patients with hematologic disorders 6–8 …”

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confidence: 99%

“…Remarkably few studies, however, have been published describing the morphological features of this frequent entity. Most of them are of older date [1][2][3][4][5] or emphasize arthropod assault reactions with unusual histopathological features occurring in specific clinical settings, such as those observed in patients with hematologic disorders. [6][7][8] Almost all textbooks of dermatopathology [9][10][11][12] and occasional review articles 13 but actually only few original papers 5,14 emphasize the presence of a triangular, wedge-or V-shaped inflammatory infiltrate as an important clue to the diagnosis of arthropod assault reaction on scanning magnification.…”

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confidence: 99%