RESUMO
A capillary tube feeding (CTF) system was adapted for studying the interaction between Dermacentor variabilis (Say) and the rickettsial cattle pathogen Anaplasma marginale Theiler. A. marginale undergoes a complex developmental cycle in ticks that begins in midguts and ends by transmission from salivary glands. In this CTF system, male D. variabilis were fed A. marginale-infected blood or cultured tick cells. Ticks that fed on highly rickettsemic calves developed midgut and salivary gland infections as detected by PCR, whereas ticks that were fed from capillary tubes on the same blood developed only midgut infections. An unexpected result of capillary tube feeding was that antibodies against the A. marginale adhesin, major surface protein la, enhanced midgut infections and caused cell culture-derived A. marginale to infect midguts. Another unexpected result was the infection of the midguts of the nonvector tick Amblyomma americanum (L.), after capillary tube feeding on infected bovine blood. The gut cell response of ticks to A. marginale, as determined from SDS-polyacrylamide gel electrophoresis protein profiles, did not differ when ticks were fed infected or uninfected cells from capillary tubes. Selected protein bands, as identified by tryptic digestion-mass spectrometry, contained mostly proteins of bovine origin, including bovine albumin, undigested alpha- and beta-chain hemoglobin and hemoglobin fragments. Although infection of ticks by A. marginale CTF system was not the same as infection by feeding on cattle, the results obtained demonstrated the potential use of this system for identifying aspects of pathogen-vector interactions that are not readily recognized in naturally feeding ticks.
Assuntos
Anaplasma marginale/imunologia , Anaplasma marginale/fisiologia , Anticorpos Antibacterianos/imunologia , Dermacentor/microbiologia , Métodos de Alimentação/instrumentação , Adesinas Bacterianas/imunologia , Animais , Proteínas da Membrana Bacteriana Externa/genética , Proteínas da Membrana Bacteriana Externa/metabolismo , Cromatografia Líquida de Alta Pressão , Clonagem Molecular , Dermacentor/imunologia , Sistema Digestório/microbiologia , Eletroforese em Gel de Poliacrilamida , Ensaio de Imunoadsorção Enzimática , Escherichia coli , Interações Hospedeiro-Parasita/imunologia , Espectrometria de Massas , Glândulas Salivares/microbiologiaRESUMO
Morphological and discrete genetic differences are found between geographically isolated, allopatric, tick populations. However, we have found differences in sympatric tick populations. Notable differences were found in the body size and weight of Dermacentor andersoni collected from a single location in Montana, USA. These ticks were separated in groups consisting of big (B) and small (S) individuals. The objectives of this study were: (a) to characterize genetic diversity in B and S D. andersoni individuals, (b) to evaluate transmissibility of the character associated with body size and weight, and (c) to correlate morphological differences with biological, physiological, and behavioral characteristics. We found extensive genetic variation in 16S rDNA and ITS2 loci in B and S ticks and demonstrated genetic differentiation between B and S individuals. We further provide some support for Mendelian autosomal dominant transmission of characters associated with tick body size and weight. The results reported herein show that B ticks have a better reproductive success than S ticks and suggest partial reproductive isolation of S ticks.
Assuntos
Dermacentor/anatomia & histologia , Dermacentor/genética , Variação Genética/fisiologia , Animais , Sequência de Bases , Tamanho Corporal/genética , Peso Corporal/genética , DNA Mitocondrial/química , DNA Ribossômico/química , DNA Espaçador Ribossômico/química , Dermacentor/fisiologia , Feminino , Masculino , Dados de Sequência Molecular , Montana , Polimorfismo Genético , RNA Nuclear/química , RNA Ribossômico 16S/genética , Alinhamento de Sequência , Comportamento Sexual AnimalRESUMO
cDNA expression library immunization (ELI) and analysis of expressed sequenced tags (EST) in a mouse model of tick infestations was used to identified cDNA clones that affected I. scapularis. Three protective antigens against larval tick infestations, 4F8, with homology to a nucleotidase, and 4D8 and 4E6 of unknown function, were selected for further characterization. All three antigens were expressed in all I. scapularis stages and localized in adult tick tissues. 4D8 was shown to be conserved in six other tick species. Based on immunization trials with synthetic polypeptides against larvae and nymphs and on artificial feeding experiments of adults, these antigens, especially 4D8, appear to be good candidates for continued development of a vaccine for control of tick infestations and may be useful in a formulation to target multiple species of ticks.