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A morphological and molecular study of Anaplasma phagocytophilum transmission events at the time of Ixodes ricinus tick bite.

ABSTRACT: BACKGROUND: Anaplasma phagocytophilum is the causative agent of human granulocytic anaplasmosis (HGA) in humans and tick-borne fever (TBF) in ruminants. The bacterium invades and replicates in phagocytes, especially in polymorphonuclear granulocytes. METHODS: In the present study, skin biopsies and ticks (Ixodes ricinus) were collected from tick feeding lesions on 38 grazing lambs between two and three weeks after access to pastures. The histopathological changes associated with tick bites and A. phagocytophilum infection, were described. In addition the skin biopsies were examined by immunohistochemistry. Furthermore, samples from blood, skin biopsies and ticks were examined by serology, PCR amplification of msp2 (p44), genotyping of rrs (16S rRNA) variants, and compared with the results obtained from histological and immunohistochemical investigations. RESULTS: Tick bites were associated with chronic and hyperplastic inflammatory skin lesions in this study. A. phagocytophilum present in skin lesions were mainly associated with neutrophils and macrophages. Bacteria were occasionally observed in the Tunica media and Tunica adventitia of small vessels, but were rarely found in association with endothelial cells. PCR and genotyping of organisms present in blood, ticks and skin biopsies suggested a haematogenous and a local spread of organisms at the tick attachment sites. CONCLUSIONS: The present study describes different aspects of A. phagocytophilum infection at the site of tick bite, and indicates that A. phagocytophilum rarely associates with endothelium during the early pathogenesis of infection.

SUBMITTER: Granquist EG

PROVIDER: S-EPMC2904780 | biostudies-literature | 2010

REPOSITORIES: biostudies-literature

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A morphological and molecular study of Anaplasma phagocytophilum transmission events at the time of Ixodes ricinus tick bite.

Granquist Erik G EG Aleksandersen Mona M Bergström Karin K Dumler Stephen J SJ Torsteinbø Wenche O WO Stuen Snorre S

Acta veterinaria Scandinavica 20100617

<h4>Background</h4>Anaplasma phagocytophilum is the causative agent of human granulocytic anaplasmosis (HGA) in humans and tick-borne fever (TBF) in ruminants. The bacterium invades and replicates in phagocytes, especially in polymorphonuclear granulocytes.<h4>Methods</h4>In the present study, skin biopsies and ticks (Ixodes ricinus) were collected from tick feeding lesions on 38 grazing lambs between two and three weeks after access to pastures. The histopathological changes associated with tic ...[more]

PMID: 20565721

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Project description:Ticks are blood feeding arthropod ectoparasites that transmit pathogens, which cause diseases in humans and animals worldwide. In the past ten decades, the continuous human exploitation of environmental resources and the increase in human outdoor activities has promoted contact with arthropod vectors normally present in the wild, resulting in increased transmission of vector-borne pathogens. In addition, vector populations are expanding in response to climate change and human interventions that impact reservoir host movement and human exposure to infected vectors. Among these emerging vector-borne pathogens, Anaplasma phagocytophilum (Rickettsiales: Anaplasmataceae) has become an important tick-borne pathogen in the United States, Europe and Asia, with increasing numbers of infected people and animals every year. Diseases caused by A. phagocytophilum include human granulocytic anaplasmosis (HGA), equine and canine granulocytic anaplasmosis and tick-borne fever (TBF) in ruminants. The natural infection cycle of A. phagocytophilum is dependent upon the presence of infected vertebrate reservoir hosts and Ixodid tick vectors. In the United States and Europe the main vector species are Ixodes scapularis, Ixodes pacificus, and Ixodes ricinus, while a wide range of mammals, lizards, and birds serve as reservoir hosts for various A. phagocytophilum genotypes. A. phagocytophilum initially infects tick midgut cells and then subsequently develops in salivary glands for transmission to susceptible hosts during tick feeding where the pathogen infects granulocytic cells, primarily neutrophils. Anaplasma phagocytophilum develops within membrane-bound inclusions in the host cell cytoplasm. This pathogen has evolved with its tick and vertebrate hosts through dynamic processes involving genetic traits of the pathogen and hosts that collectively mediate pathogen infection, development, persistence, and survival. However, the mechanisms used by A. phagocytophilum for molecular mechanisms involved in tick-pathogen interactions have not been fully characterized. The objective of this study is to characterize the dynamics of the microRNA response in the tick vector Ixodes scapularis in response to A. phagocytophilum infection. To address this objective, the composition of tick microRNAs was characterize using RNA sequencing in I. scapularis tick cells in response to A. phagocytophilum infection. The discovery of these mechanisms provides evidence that a control strategy could be developed targeted at both vertebrate and tick hosts for more complete control of A. phagocytophilum and its associated diseases.

Dataset Information

A morphological and molecular study of Anaplasma phagocytophilum transmission events at the time of Ixodes ricinus tick bite.

Publications

A morphological and molecular study of Anaplasma phagocytophilum transmission events at the time of Ixodes ricinus tick bite.

Similar Datasets

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