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Transmission of Rickettsia sp. DmS1 in the tick, Dermacentor marginatus
10.1111/j.1469-0691.2008.02258.x
Transmission of Rickettsia sp. DmS1 in the tick, Dermacentor marginatus C. Socolovschi1, K. Matsumoto3, T. Phong Huynh1, B. Davoust2, D. Raoult1 and P. Parola1 1
Unite´ de Recherche en Maladies Infectieuses et Tropicales Emergentes (URMITE), UMR CNRS-IRD 6236, WHO Collaborative Center for Rickettsial Diseases and Other Arthropod-borne Bacterial Diseases, Faculte´ de Me´decine, Marseille, France, 2Direction Re´gionale du Service de Sante´ des Arme´es de Toulon, Toulon Arme´es, Toulon, France and 3Obihiro University of Agriculture and Veterinary Medicine, Hokkaido, Japan Tick-borne rickettsioses are caused by obligate intracellular Gram-negative bacteria belonging to the spotted fever group of the genus Rickettsia within the order Rickettsiales. These zoonoses are now recognised as important emerging vectorborne infections of humans world-wide. Many Rickettsia spp. have also been detected in ticks only and their pathogenicity for humans is as yet unknown [1]. In 2000, a rickettsial genotype, Rickettsia sp. DmSl, was detected in one out of 70 Dermacentor marginatus ticks collected from game pigs Sus scrofa in southern France (1.4%) [2]. On the basis of preliminary phylogenetic studies of partial fragments of the citrate synthase gene (gltA), this genotype appeared to be included within the Rickettsia massiliae group. Furthermore, according to the recently published criteria to define and characterise a new species, this genotype is supposed to originate from a new, yet incompletely described Rickettsia sp. [3]. Here, we study the transmission of Rickettsia sp. DmSl in D. marginatus ticks. In 2006, this Rickettsia was also detected in Spain in four D. marginatus ticks [4]. MATERIAL AND METHODS Three engorged D. marginatus females collected in Canjuers, southern France, in September 2006 from Game Pigs (Sus scrofa) were kept in glass jars at 22C and 90% RH until laying eggs. After laying eggs, ticks were tested by PCR for rickettsial gltA and ompA genes using primer pairs Rp CS.409p and Rp CS.1258n, and Rr. 190.70 and Rr. 190.701, respectively. Amplified products were sequenced as described [2]. DNA obtained from Rickettsia-free Rhipicephalus sanguineus specimens of
Corresponding author and reprint requests: P. Parola, Unite´ de Recherche en Maladies Infectieuses et Tropicales Emergentes (URMITE), UMR CNRS-IRD 6236, WHO Collaborative Center for Rickettsial Diseases and Other Arthropod-borne Bacterial Diseases, Faculte´ de Me´decine, 27 Bd Jean Moulin, 13385 Marseille Cedex 5, France E-mail: [email protected] No conflicts of interest declared.
colonies from our laboratory was used as negative control. One sample of DNA from R. montanensis was included in each PCR as positive control. All of the three ticks tested positive by the two PCRs. The ompA and gltA sequences obtained from all samples were respectively identical. The sequences of gltA were 100% (338 ⁄ 338) similar to those of Rickettsia sp. DmS1 (AY129300). The sequences of ompA gene fragment had 99.8% similarity (470 ⁄ 471) with an incompletely described rickettsia for which a Candidatus status has been proposed (‘Candidatus Rickettsia La Rioja’) (EF028201). No sequence of Rickettsia sp. DmS1 was available in GenBank. Positive and negative controls were positive and negative in each PCR, respectively. The obtained sequences were aligned with other rickettsiae registered in GenBank using CLUSTAL program (ClustalW, DDBJ, http://www.ddbj.nig.ac.jp/search/clustalw-e.html). The closest confirmed species related to the Rickettsia sp. DmS1 was found to be R. raoultii. The sequence of gltA and ompA has 98.24% (335 ⁄ 341) and 98.44% (506 ⁄ 514) similarity to those of R. raoultii.
RESULTS A New Zealand white rabbit (Oryctolagus cuniculus) was used as a host for tick blood meals for larvae, nymphs and adults of subsequent generations obtained from the three infected females. The duration of feeding, moulting, preoviposition, and periods of postmoulting development were recorded: preoviposition, 9–12 days; oviposition to hatching, 16–18 days; larval feeding, 3– 5 days; nymphal premoult, 5–16 days; nymphal feeding, 4–6 days; adults premoult, 12–23 days; females feeding, 9–5 days. Oedema and erythema were noted at the tick attachment sites, but there were no other signs of infection. Transovarial and transtadial transmission for five continuous generations and environmental shedding of Rickettsia sp. DmS1 were demonstrated by PCR. For the second generation, three pools of 10 larvae and three pools of 10 nymphs obtained from three ticks tested positive by PCR. A total of 18 larvae out of 23 (78.3%) of the fourth generation also tested positive. Finally, at the fifth generation, 80% (16 ⁄ 20) of D. marginatus adults were positive for Rickettsia sp. DmS1.
2009 The Authors Journal Compilation 2009 European Society of Clinical Microbiology and Infectious Diseases, CMI, 15 (Suppl. 2), 322–323
Socolovschi et al. Transmission of Rickettsia sp. DmS1 323
DISCUSSION Although we cannot precisely establish the transovarial infection rate (the proportion of infected females giving rise to at least one positive egg or larvae), or the filial infection rate (proportion of infected eggs or larvae obtained from an infected female), our results suggests that Rickettsia sp. DmS1 are maintained in D. marginatus ticks, which may act as vectors but also as reservoirs for Rickettsia sp. DmS1. As an illustration, in 2006, this rickettsia has been detected in Spain in four D. marginatus ticks [4]. Finally, Rickettsia sp. DmS1. is closely related to R. raoultii, a recently described rickettsia, previously known as Rickettsia RpA4, or DnS28, and recently found as an agent of DEBONEL ⁄ TIBOLA, that is defined as the association of a tick-bite (Dermacentor species typically biting on the scalp in Europe), and inoculation eschar on the scalp and cervical adenopathies [5]. Nevertheless, further investigations are required for a definitive characterisation
of Rickettsia sp. DmS1 and its implication for human public health. REFERENCES 1. Parola P, Paddock C, Raoult D. Tick-borne rickettsioses around the world: emerging diseases challenging old concepts. Clin Microbiol Rev 2005; 18: 719–756. 2. Sanogo YO, Davoust B, Parola P, Camicas JL, Brouqui P, Raoult D. Prevalence of Rickettsia spp. in Dermacentor marginatus ticks removed from game pigs (Sus scrofa) in southern France. Rickettsiol: Ann NY Acad Sc 2003; 990: 191– 195. 3. Raoult D, Fournier PE, Eremeeva M et al. Naming of rickettsiae and rickettsial diseases. Ann N Y Acad Sci 2005; 1063: 1–12. 4. Fernandez-Soto P, Perez-Sanchez R, amo-Sanz R, EncinasGrandes A. Spotted fever group rickettsiae in ticks feeding on humans in northwestern Spain: is Rickettsia conorii vanishing? Ann N Y Acad Sci 2006; 1078: 331–333. 5. Mediannikov O, Matsumoto K, Samoilenko I et al. Rickettsia raoultii sp. nov., a new spotted fever group rickettsia associated with Dermacentor ticks in Europe and Russia. Int J Syst Evol Microbiol 2008; 58: 1635–1639.
2009 The Authors Journal Compilation 2009 European Society of Clinical Microbiology and Infectious Diseases, CMI, 15 (Suppl. 2), 322–323
Transmission of Rickettsia sp. DmS1 in the tick, Dermacentor marginatus C. Socolovschi1, K. Matsumoto3, T. Phong Huynh1, B. Davoust2, D. Raoult1 and P. Parola1 1
Unite´ de Recherche en Maladies Infectieuses et Tropicales Emergentes (URMITE), UMR CNRS-IRD 6236, WHO Collaborative Center for Rickettsial Diseases and Other Arthropod-borne Bacterial Diseases, Faculte´ de Me´decine, Marseille, France, 2Direction Re´gionale du Service de Sante´ des Arme´es de Toulon, Toulon Arme´es, Toulon, France and 3Obihiro University of Agriculture and Veterinary Medicine, Hokkaido, Japan Tick-borne rickettsioses are caused by obligate intracellular Gram-negative bacteria belonging to the spotted fever group of the genus Rickettsia within the order Rickettsiales. These zoonoses are now recognised as important emerging vectorborne infections of humans world-wide. Many Rickettsia spp. have also been detected in ticks only and their pathogenicity for humans is as yet unknown [1]. In 2000, a rickettsial genotype, Rickettsia sp. DmSl, was detected in one out of 70 Dermacentor marginatus ticks collected from game pigs Sus scrofa in southern France (1.4%) [2]. On the basis of preliminary phylogenetic studies of partial fragments of the citrate synthase gene (gltA), this genotype appeared to be included within the Rickettsia massiliae group. Furthermore, according to the recently published criteria to define and characterise a new species, this genotype is supposed to originate from a new, yet incompletely described Rickettsia sp. [3]. Here, we study the transmission of Rickettsia sp. DmSl in D. marginatus ticks. In 2006, this Rickettsia was also detected in Spain in four D. marginatus ticks [4]. MATERIAL AND METHODS Three engorged D. marginatus females collected in Canjuers, southern France, in September 2006 from Game Pigs (Sus scrofa) were kept in glass jars at 22C and 90% RH until laying eggs. After laying eggs, ticks were tested by PCR for rickettsial gltA and ompA genes using primer pairs Rp CS.409p and Rp CS.1258n, and Rr. 190.70 and Rr. 190.701, respectively. Amplified products were sequenced as described [2]. DNA obtained from Rickettsia-free Rhipicephalus sanguineus specimens of
Corresponding author and reprint requests: P. Parola, Unite´ de Recherche en Maladies Infectieuses et Tropicales Emergentes (URMITE), UMR CNRS-IRD 6236, WHO Collaborative Center for Rickettsial Diseases and Other Arthropod-borne Bacterial Diseases, Faculte´ de Me´decine, 27 Bd Jean Moulin, 13385 Marseille Cedex 5, France E-mail: [email protected] No conflicts of interest declared.
colonies from our laboratory was used as negative control. One sample of DNA from R. montanensis was included in each PCR as positive control. All of the three ticks tested positive by the two PCRs. The ompA and gltA sequences obtained from all samples were respectively identical. The sequences of gltA were 100% (338 ⁄ 338) similar to those of Rickettsia sp. DmS1 (AY129300). The sequences of ompA gene fragment had 99.8% similarity (470 ⁄ 471) with an incompletely described rickettsia for which a Candidatus status has been proposed (‘Candidatus Rickettsia La Rioja’) (EF028201). No sequence of Rickettsia sp. DmS1 was available in GenBank. Positive and negative controls were positive and negative in each PCR, respectively. The obtained sequences were aligned with other rickettsiae registered in GenBank using CLUSTAL program (ClustalW, DDBJ, http://www.ddbj.nig.ac.jp/search/clustalw-e.html). The closest confirmed species related to the Rickettsia sp. DmS1 was found to be R. raoultii. The sequence of gltA and ompA has 98.24% (335 ⁄ 341) and 98.44% (506 ⁄ 514) similarity to those of R. raoultii.
RESULTS A New Zealand white rabbit (Oryctolagus cuniculus) was used as a host for tick blood meals for larvae, nymphs and adults of subsequent generations obtained from the three infected females. The duration of feeding, moulting, preoviposition, and periods of postmoulting development were recorded: preoviposition, 9–12 days; oviposition to hatching, 16–18 days; larval feeding, 3– 5 days; nymphal premoult, 5–16 days; nymphal feeding, 4–6 days; adults premoult, 12–23 days; females feeding, 9–5 days. Oedema and erythema were noted at the tick attachment sites, but there were no other signs of infection. Transovarial and transtadial transmission for five continuous generations and environmental shedding of Rickettsia sp. DmS1 were demonstrated by PCR. For the second generation, three pools of 10 larvae and three pools of 10 nymphs obtained from three ticks tested positive by PCR. A total of 18 larvae out of 23 (78.3%) of the fourth generation also tested positive. Finally, at the fifth generation, 80% (16 ⁄ 20) of D. marginatus adults were positive for Rickettsia sp. DmS1.
2009 The Authors Journal Compilation 2009 European Society of Clinical Microbiology and Infectious Diseases, CMI, 15 (Suppl. 2), 322–323
Socolovschi et al. Transmission of Rickettsia sp. DmS1 323
DISCUSSION Although we cannot precisely establish the transovarial infection rate (the proportion of infected females giving rise to at least one positive egg or larvae), or the filial infection rate (proportion of infected eggs or larvae obtained from an infected female), our results suggests that Rickettsia sp. DmS1 are maintained in D. marginatus ticks, which may act as vectors but also as reservoirs for Rickettsia sp. DmS1. As an illustration, in 2006, this rickettsia has been detected in Spain in four D. marginatus ticks [4]. Finally, Rickettsia sp. DmS1. is closely related to R. raoultii, a recently described rickettsia, previously known as Rickettsia RpA4, or DnS28, and recently found as an agent of DEBONEL ⁄ TIBOLA, that is defined as the association of a tick-bite (Dermacentor species typically biting on the scalp in Europe), and inoculation eschar on the scalp and cervical adenopathies [5]. Nevertheless, further investigations are required for a definitive characterisation
of Rickettsia sp. DmS1 and its implication for human public health. REFERENCES 1. Parola P, Paddock C, Raoult D. Tick-borne rickettsioses around the world: emerging diseases challenging old concepts. Clin Microbiol Rev 2005; 18: 719–756. 2. Sanogo YO, Davoust B, Parola P, Camicas JL, Brouqui P, Raoult D. Prevalence of Rickettsia spp. in Dermacentor marginatus ticks removed from game pigs (Sus scrofa) in southern France. Rickettsiol: Ann NY Acad Sc 2003; 990: 191– 195. 3. Raoult D, Fournier PE, Eremeeva M et al. Naming of rickettsiae and rickettsial diseases. Ann N Y Acad Sci 2005; 1063: 1–12. 4. Fernandez-Soto P, Perez-Sanchez R, amo-Sanz R, EncinasGrandes A. Spotted fever group rickettsiae in ticks feeding on humans in northwestern Spain: is Rickettsia conorii vanishing? Ann N Y Acad Sci 2006; 1078: 331–333. 5. Mediannikov O, Matsumoto K, Samoilenko I et al. Rickettsia raoultii sp. nov., a new spotted fever group rickettsia associated with Dermacentor ticks in Europe and Russia. Int J Syst Evol Microbiol 2008; 58: 1635–1639.
2009 The Authors Journal Compilation 2009 European Society of Clinical Microbiology and Infectious Diseases, CMI, 15 (Suppl. 2), 322–323