RESUMO
Anaplasma phagocytophilum causes human granulocytic anaplasmosis. Infection with this zoonotic pathogen affects gene expression in both the vertebrate host and the tick vector, Ixodes scapularis. Here, we identified new genes, including spectrin alpha chain or alpha-fodrin (CG8) and voltage-dependent anion-selective channel or mitochondrial porin (T2), that are involved in A. phagocytophilum infection/multiplication and the tick cell response to infection. The pathogen downregulated the expression of CG8 in tick salivary glands and T2 in both the gut and salivary glands to inhibit apoptosis as a mechanism to subvert host cell defenses and increase infection. In the gut, the tick response to infection through CG8 upregulation was used by the pathogen to increase infection due to the cytoskeleton rearrangement that is required for pathogen infection. These results increase our understanding of the role of tick genes during A. phagocytophilum infection and multiplication and demonstrate that the pathogen uses similar strategies to establish infection in both vertebrate and invertebrate hosts.
Assuntos
Anaplasma phagocytophilum/patogenicidade , Apoptose , Proteínas de Transporte/metabolismo , Citoesqueleto/metabolismo , Ixodes/microbiologia , Proteínas dos Microfilamentos/metabolismo , Anaplasma phagocytophilum/genética , Animais , Proteínas de Transporte/genética , Caspase 9/genética , Caspase 9/metabolismo , Linhagem Celular , Comportamento Alimentar , Feminino , Trato Gastrointestinal/microbiologia , Regulação da Expressão Gênica , Técnicas de Silenciamento de Genes , Interações Hospedeiro-Patógeno , Ixodes/genética , Ixodes/metabolismo , Masculino , Proteínas dos Microfilamentos/genética , Proteínas de Transporte da Membrana Mitocondrial/genética , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Filogenia , Interferência de RNA , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Glândulas Salivares/microbiologia , Espectrina/genética , Espectrina/metabolismo , Canais de Ânion Dependentes de Voltagem/genética , Canais de Ânion Dependentes de Voltagem/metabolismoRESUMO
Anaplasma phagocytophilum, first identified as a pathogen of ruminants in Europe, has more recently been recognized as an emerging tick-borne pathogen of humans in the U.S. and Europe. A. phagocytophilum is transmitted by Ixodes spp., but the tick developmental cycle and pathogen/vector interactions have not been fully described. In this research, we report on the experimental infection of sheep with the human NY-18 isolate of A. phagocytophilum which then served as a host for infection of I. scapularis nymphs and adults. A. phagocytophilum was propagated in the human promyelocytic cell line, HL-60, and the infected cell cultures were then used to infect sheep by intravenous inoculation. Infections in sheep were confirmed by PCR and an Anaplasma-competitive ELISA. Clinical signs were not apparent in any of the infected sheep, and only limited hematologic and mild serum biochemical abnormalities were identified. While A. phagocytophilum morulae were rarely seen in neutrophils, blood film evaluation revealed prominent large granular lymphocytes, occasional plasma cells, and rare macrophages. Upon necropsy, gross lesions were restricted to the lymphoid system. Mild splenomegaly and lymphadenomegaly with microscopic evidence of lymphoid hyperplasia was observed in all infected sheep. Female I. scapularis that were allowed to feed and acquire infection on each of the 3 experimentally infected sheep became infected with A. phagocytophilum as determined by PCR of guts (80-87%) and salivary glands (67-100%). Female I. scapularis that acquired infection as nymphs on an experimentally infected sheep transmitted A. phagocytophilum to a susceptible sheep, thus confirming transstadial transmission. Sheep proved to be a good host for the production of I. scapularis infected with this human isolate of A. phagocytophilum, which can be used as a model for future studies of the tick/pathogen interface.
Assuntos
Anaplasma phagocytophilum/fisiologia , Vetores Aracnídeos/microbiologia , Ehrlichiose/microbiologia , Ixodes/microbiologia , Infestações por Carrapato/parasitologia , Anaplasma phagocytophilum/genética , Anaplasma phagocytophilum/imunologia , Animais , Antígenos de Bactérias/imunologia , Vetores Aracnídeos/virologia , Linhagem Celular , DNA Bacteriano/genética , Ehrlichiose/complicações , Ensaio de Imunoadsorção Enzimática , Feminino , Trato Gastrointestinal/microbiologia , Humanos , Ixodes/virologia , Masculino , Modelos Animais , Neutrófilos/microbiologia , Ninfa , Reação em Cadeia da Polimerase , Glândulas Salivares/microbiologia , Ovinos , Infestações por Carrapato/complicaçõesRESUMO
Ticks are ectoparasites of animals and humans that serve as vectors of Anaplasma and other pathogens that affect humans and animals worldwide. Ticks and the pathogens that they transmit have coevolved molecular interactions involving genetic traits of both the tick and the pathogen that mediate their development and survival. In this paper, the expression of heat shock proteins (HSPs) and other stress response proteins (SRPs) was characterized in ticks and cultured tick cells by proteomics and transcriptomics analyses in response to Anaplasma spp. infection and heat shock. The results of these studies demonstrated that the stress response was activated in ticks and cultured tick cells after Anaplasma spp. infection and heat shock. However, in the natural vector-pathogen relationship, HSPs and other SRPs were not strongly activated, which likely resulted from tick-pathogen coevolution. These results also demonstrated pathogen- and tick-specific differences in the expression of HSPs and other SRPs in ticks and cultured tick cells infected with Anaplasma spp. and suggested the existence of post-transcriptional mechanisms induced by Anaplasma spp. to control tick response to infection. These results illustrated the complexity of the stress response in ticks and suggested a function for the HSPs and other SRPs during Anaplasma spp. infection.