Context: Members of the order Chlamydiales are obligate intracellular bacteria identified within a wide host range. The Chlamydiales order currently includes nine families: Chlamydiaceae, Clavichlamydiaceae, Criblamidiaceae, Piscichlamydiaceae, Parachlamydiaceae, Rhabdochlamydiaceae, Simkaniaceae, Waddliaceae and Parilichlamydiaceae. Two recent studies suggested that ticks are vectors for Chlamydiales propagation to both people and animals. This study aimed to assess the prevalence and sequence diversity of Chlamydiales 16S rDNA in questing ticks collected in three parks in northern Italy. Main conclusion: The results confirmed the potential vector role of ticks for Chlamydiales bacteria. Approach: From April to October 2010, 2284 ticks were collected by flagging low vegetation at four different sites distributed along the hilly part of the Emilia-Romagna Apennines (northern Italy). Ticks were processed individually when adults (n=59) or in pools when larvae or nymphs, obtaining 397 samples. PCR targeting a 243 bp fragment of the 16S rRNA encoding gene of Chlamydiales was performed. Results: Chlamydiales DNA was detected in each tick life stage. Seventy-three of 397 samples (18.3 per cent) were PCR-positive: 25 sequences belonged to the Parachlamydiaceae family, five to the Chlamydiaceae family and 26 sequences exhibited the highest homology with unclassified Chlamydiales bacteria. Sequencing failed for 17 samples. Among Parachlamydiaceae, four sequences showed the highest homology with the genus Neochlamydia, one with the genus Mesochlamydia, one with the genus Parachlamydia and 19 could not be classified at genus level. Among the five sequences corresponding to the Chlamydiaceae, one showed 100 per cent identity with Chlamydia abortus and four exhibited 99 to 100 per cent homology with Chlamydia suis. Interpretation: This study suggests that Chlamydiales passage via transovarial transmission. Sequencing showed a high prevalence of Parachlamydiaceae, as previously observed. Interestingly, this study also identified C abortus and C suis DNA. To the authors’ knowledge, this is the first evidence of these Chlamydia species in ticks. C abortus is an abortigenic agent in small ruminants, which can also colonise the human placenta and lead to fetal death and miscarriage. The zoonotic potential of C suis has been recently investigated. Significance of findings: The results confirm the potential vector role of ticks for Chlamydiales bacteria and suggest a need for further investigation to better characterise Chlamydiales bacteria in arthropods.

Detection of Chlamydiales DNA in questing ticks

SALVATORE, DANIELA;GALUPPI, ROBERTA;TAMPIERI, MARIA PAOLA;DI FRANCESCO, ANTONIETTA
2016

Abstract

Context: Members of the order Chlamydiales are obligate intracellular bacteria identified within a wide host range. The Chlamydiales order currently includes nine families: Chlamydiaceae, Clavichlamydiaceae, Criblamidiaceae, Piscichlamydiaceae, Parachlamydiaceae, Rhabdochlamydiaceae, Simkaniaceae, Waddliaceae and Parilichlamydiaceae. Two recent studies suggested that ticks are vectors for Chlamydiales propagation to both people and animals. This study aimed to assess the prevalence and sequence diversity of Chlamydiales 16S rDNA in questing ticks collected in three parks in northern Italy. Main conclusion: The results confirmed the potential vector role of ticks for Chlamydiales bacteria. Approach: From April to October 2010, 2284 ticks were collected by flagging low vegetation at four different sites distributed along the hilly part of the Emilia-Romagna Apennines (northern Italy). Ticks were processed individually when adults (n=59) or in pools when larvae or nymphs, obtaining 397 samples. PCR targeting a 243 bp fragment of the 16S rRNA encoding gene of Chlamydiales was performed. Results: Chlamydiales DNA was detected in each tick life stage. Seventy-three of 397 samples (18.3 per cent) were PCR-positive: 25 sequences belonged to the Parachlamydiaceae family, five to the Chlamydiaceae family and 26 sequences exhibited the highest homology with unclassified Chlamydiales bacteria. Sequencing failed for 17 samples. Among Parachlamydiaceae, four sequences showed the highest homology with the genus Neochlamydia, one with the genus Mesochlamydia, one with the genus Parachlamydia and 19 could not be classified at genus level. Among the five sequences corresponding to the Chlamydiaceae, one showed 100 per cent identity with Chlamydia abortus and four exhibited 99 to 100 per cent homology with Chlamydia suis. Interpretation: This study suggests that Chlamydiales passage via transovarial transmission. Sequencing showed a high prevalence of Parachlamydiaceae, as previously observed. Interestingly, this study also identified C abortus and C suis DNA. To the authors’ knowledge, this is the first evidence of these Chlamydia species in ticks. C abortus is an abortigenic agent in small ruminants, which can also colonise the human placenta and lead to fetal death and miscarriage. The zoonotic potential of C suis has been recently investigated. Significance of findings: The results confirm the potential vector role of ticks for Chlamydiales bacteria and suggest a need for further investigation to better characterise Chlamydiales bacteria in arthropods.
Salvatore, D.; Galuppi, R.; Aureli, S.; Tampieri, M.P.; Di Francesco, A.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11585/567214
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