Browsing by Author "Pascoal da Silva, L."
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- Host dispersal shapes the population structure of a tick-borne bacterial pathogenPublication . Norte, A.C.; Margos, G.; Becker, N.S.; Albino Ramos, J.; Núncio, M.S.; Fingerle, V.; Araújo, P.M.; Adamík, P.; Alivizatos, H.; Barba, E.; Barrientos, R.; Cauchard, L; Csörgő, T.; Diakou, A.; Dingemanse, N.J.; Doligez, B.; Dubiec, A.; Eeva, T.; Flaisz, B.; Grim, T.; Hau, M.; Hornok, S.; Kazantzidis, S.; Kováts, D.; Krause, F.; Literak, I.; Mänd, R.; Mentesana, L.; Morinay, J.; Mutanen, M.; Neto, J.M.; Nováková, M.; Sanz, J.J.; Pascoal da Silva, L.; Sprong, H.; Tirri, I.S.; Török, J.; Trilar, T.; Tyller, Z.; Visser, M.E.; Lopes de Carvalho, I.f ticks and their associated pathogens. The life cycle of tick-borne pathogens is complex and their evolutionary ecology is shaped by the interactions with vertebrate hosts and tick vectors (Kurtenbach et al., 2006). This study focused on the ecology and genetic diversity of B. burgdorferi s.l. as a model to investigate the drivers of the population structure and to understand the role of host- associated dispersal on the evolution of tick-borne pathogens. This represents a consequential question in the ecology and evolution of any pathogen. Borrelia burgdorferi s.l. is a bacterial complex of over 20 known genospecies, including the etiologic agents of Lyme borreliosis (Casjens et al., 2011; Margos et al., 2015), whose main vectors are ticks of the genus Ixodes (Eisen & Lane, 2002). These bacteria are widespread in Europe, Asia and North America and are also present in North Africa (Margos, Vollmer, Ogden, & Fish, 2011; Zhioua et al., 1999). Different Borrelia genospecies have different patterns of association with vertebrate reservoir hosts (Humair & Gern, 2000; Kurtenbach, Peacey, et al., 1998) because of the immunological host response, mediated by the action of the host's complement system (Kurtenbach et al., 2002). While B. burgdorferi sensu stricto (s.s.) is a generalist genospecies, Borrelia afzelii is mostly associated with mammalian hosts such as rodents, whereas Borrelia valaisiana, Borrelia garinii and Borrelia turdi are mostly associated with birds (Heylen, 2016; Margos et al., 2011). Because tick vectors cannot move large distances independent of hosts, it has been suggested that host specialization determines the spread and dispersal of B. burgdorferi s.l. genospecies (Kurtenbach et al., 2010; Sonenshine & Mather, 1994). Because birds are both important hosts for some Borrelia genospecies and for various species of vector ticks, they act as a driving force shaping B. burgdorferi s.l. distribution and phylogeographical patterns (Margos et al., 2011; Vollmer et al., 2011). Here, we assessed the role of passerine birds as hosts and dispersers of B. burgdorferi s.l. We tested the hypothesis that infection prevalence with Borrelia genospecie
- A importância das aves como hospedeiros de carraças e no ciclo enzoótico da Borrelia burgdorferi s.l. em PortugalPublication . Norte, A.C.; Ramos, J.A.; Araújo, P.M.; Pascoal da Silva, L.; Tenreiro, P.Q.; Escudero, R.; Anda, P.; Gern, L.; Zé-Zé, L.; Núncio, M.S.; Lopes de Carvalho, I.As aves selvagens são frequentemente infestadas por carraças e são consideradas reservatório da Borrelia burgdorferi s.l. (sensu lato), um complexo de bactérias transmitidas por carraças, que causam a borreliose de Lyme. De 2010 a 2014 recolhemos 2820 carraças de 690 aves infestadas pertencentes a 40 espécies, e avaliámos a infecção por B. burgdorferi s.l. por nested PCR nestas carraças. Oito espécies de carraças foram identificadas, sendo, Ixodes frontalis (37%) e I. ricinus (34%) as espécies mais comuns. O Melro (Turdus merula) e o Pisco-de-peito-ruivo (Erithacus rubecula) foram as espécies mais infestadas, possivelmente devido aos seus hábitos de pesquisa de alimento a níveis mais baixos. Carraças do género Ixodes sp. infectadas com Borrelia burgdorferi s.l. foram recolhidas de Tentilhões (Fringilla coelebs), Chapins-reais (Parus major), Toutinegras-dosvalados (Sylvia melanocephala), Carriças (Troglodytes troglodytes), Tordos-ruivos (Turdus iliacus), Melros (T. merula) e Tordos-pintos (Turdus philomelos), com maior prevalência em carraças provenientes de T. philomelos (26%). Detectámos B. turdi (4,4%), B. valaisiana (3,7%), B. garinii (3,3%), B. miyamotoi (0,06%) e B. bissettii (0,06%) em Ixodes sp. recolhidas das aves. A caracterização genética das linhagens de B. turdi sugere divergência filogenética da linhagem originalmente detectada no Japão. Uma experiência de xenodiagnóstico provou a capacidade reservatório de T. merula para B. valaisiana e B. turdi. Estes resultados reforçam o papel das aves como agentes chave na manutenção de diferentes genoespécies do complexo B. burgdorferi s.l.
- The importance of wildlife health on zoonotic bacteria transmission: interactions between Borrelia burgdorferi s.l. and its avian hostsPublication . Norte, A.C.; Heylen, D.; Araújo, P.M.; Pascoal da Silva, L.; Sprong, H.; Krawczyk, A.; Costantini, D.; Eens, M.; Núncio, M.S.; Ramos, J.A.; Lopes de Carvalho, I.Borrelia burgdorferi sensu lato (s.l.) is a tick-borne zoonotic agent maintained in enzootic cycles in nature by vertebrate reservoir hosts, including mammals, lizards and birds. To understand the eco-epidemiology of Lyme borreliosis it is necessary to evaluate the relationships between Borrelia genospecies and vertebrate reservoir hosts. We surveyed Borrelia infection prevalence in avian hosts and using wild birds as models, we assessed the physiological impact of infection in reservoir hosts and how exposure to stress could affect hosts’ infectivity to vector ticks. This helps to understand how these host-parasite interactions may affect tick-borne zoonotic agents’ circulation and transmission, and, ultimately, disease risk. Thrushes (Turdus spp.) were the most important birds in the enzootic cycle of Borrelia. The diversity of Borrelia genospecies detected in ticks feeding on birds was high, and the most common genospecies was B. garinii, a pathogenic genospecies. The ubiquitous blackbird Turdus merula successfully transmitted B. turdi, B. valaisiana and B. burgdorferi s.s. to vector ticks in laboratory conditions. There was no evidence that exposure to stress increased infectivity of wild avian hosts to vector ticks in an experiment performed in captivity. However, oxidative balance (protein carbonyls and glutathione peroxidase levels) of naïve blackbirds was affected by experimental infection with Borrelia, suggesting that these bacteria may inflict non-negligible physiological harm on its natural reservoir hosts with potential impact on transmission success.