Extensive diversity of Rickettsiales bacteria in two species of ticks from China and the evolution of the Rickettsiales

Emergence of Novel Anaplasma Species in the Mediterranean Area

The emergence of new Anaplasma strains in the Mediterranean region poses a challenge for both veterinary medicine and public health, as it can lead to more complex diagnostic and treatment strategies. Species related to Anaplasma platys and A. phagocytophilum, two important tick-borne pathogens, have been reported in several Mediterranean countries. However, the data on their presence in Sardinia remain limited. This study aimed to identify theAnaplasmaspecies genetically related to zoonotic agents, such as A. phagocytophilum or A. platys, in Sardinian horses, cattle, and swine. Using various molecular approaches targeting the groEL and gltA genes, the results confirm the presence of Candidatus (Ca.) Anaplasma turritanum and reveal the emergence of Candidatus (Ca.) Anaplasma cinensis and an A. phagocytophilum-like strain, designated as A. phagocytophilum-like 2, in Sardinian horses and cattle. These findings underscore the importance of ongoing surveillance in Sardinia and similar Mediterranean regions, as well as the urgent need for enhanced diagnostic tools and preventive strategies. Given the zoonotic potential of these emerging strains, these findings emphasize the need for greater vigilance in both veterinary and human health sectors to mitigate the risks associated with tick-borne Anaplasma species transmission. Ongoing research and proactive measures are essential to reduce the public health burden and prevent the spread of these pathogens across animal and human populations.

High Diversity and Prevalence of Rickettsial Agents in Rhipicephalus microplus Ticks from Livestock in Karst Landscapes of Southwest China

Ticks and tick-borne pathogens pose a significant threat to human and animal health, yet the diversity and prevalence of tick-borne microorganisms in karst regions remains inadequately explored. In October 2023, a total of 274 Rhipicephalus microplus ticks were collected from livestock in Guizhou Province, which boasts the largest karst area in China. Pathogen identification was subsequently performed using PCR amplification, Sanger sequencing, and phylogenetic analysis. High microbial diversity was noted, with five bacterial species from the order Rickettsiales detected, including those from the genera Rickettsia (family Rickettsiaceae), Anaplasma, and Ehrlichia (family Anaplasmataceae). The overall prevalence of infection with at least one pathogen was remarkably high at 94.5%. The highest positive rate was observed for Candidatus Rickettsia jingxinensis at 90.9%. A novel Ehrlichia species, provisionally designated as Candidatus Ehrlichia carsus, was identified with a positive rate of 16.8%. In addition, Anaplasma marginale, Ehrlchia minasensis and Ehrlichia canis were detected in 15.3%, 4.7% and 1.5%, respectively. The co-infections involving two or three rickettsial species were observed in 34.3% ticks. These findings highlight the high diversity and prevalence of tick-borne rickettsial agents in the karst area, underscoring the need for enhanced surveillance and effective tick control to mitigate disease risks to both humans and livestock.

Molecular Detection and Phylogenetic Analysis of Anaplasma phagocytophilum and Related Strains in Cattle from Henan, China

Anaplasma phagocytophilum is a zoonotic pathogen transmitted by arthropod vectors. The pathogen infects various vertebrate hosts, causing mild to severe illness. Molecular studies have demonstrated that A. phagocytophilum exhibits a high level of genetic diversity, with two A. phagocytophilum-related variants identified in several countries. This study represents the first application of PCR amplification and restriction fragment length polymorphism (PCR-RFLP) in conjunction with DNA sequencing to investigate the frequency and phylogenetic relationships of A. phagocytophilum and its related strains in cattle from China. A total of 662 bovine blood samples were collected from diverse regions within Henan Province, China, and pathogen DNA was detected in 75 samples, comprising 11.33% of the total. PCR-RFLP analysis identified three strains with frequency rates of 2.87% (19/662) for A. phagocytophilum, 11.33% (75/662) for A. phagocytophilum-like 1, and 3.22% (22/662) for A. phagocytophilum-like 2. Additionally, co-infections involving A. phagocytophilum and A. phagocytophilum-like 1 were observed as well as between A. phagocytophilum-like 1 and A. phagocytophilum-like 2. Anaplasma phagocytophilum-like strains 1 and 2 should be considered when diagnosing bovine anaplasmosis. Despite recent molecular studies of A. phagocytophilum-related strains, there remains a shortage of data concerning vector capability, the epidemiology of the disease, clinical signs, and genetic diversity of the pathogens. Thus, large-scale investigations involving animals and tick vectors are necessary to obtain more detailed information concerning the etiology of anaplasmosis.

Diversity of Anaplasmataceae Transmitted by Ticks (Ixodidae) and the First Molecular Evidence of Anaplasma phagocytophilum and Candidatus Anaplasma boleense in Paraguay

Anaplasmataceae bacteria are emerging infectious agents transmitted by ticks. The aim of this study was to identify the molecular diversity of this bacterial family in ticks and hosts, both domestic and wild, as well as blood meal sources of free-living ticks in northeastern Paraguay. The bacteria were identified using PCR-HRM, a method optimized for this purpose, while the identification of ticks and their blood meal was performed using conventional PCR. All amplified products were subsequently sequenced. The bacteria detected in the blood hosts included Ehrlichia canis, Anaplasma platys, and Anaplasma phagocytophilum, Candidatus Anaplasma boleense, and Wolbachia spp., which had not been previously reported in the country. Free-living and parasitic ticks on dogs (Canis lupus familiaris) and wild armadillos (Dasypus novemcinctus) were collected and identified as Rhipicephalus sanguineus and Amblyomma spp. The species E. canis, A. platys, A. phagocytophilum, and Ca. A. boleense were detected in domestic dog ticks, and E. canis and A. platys were found for the first time in armadillos and free-living ticks. Blood feeding sources detected in free-living ticks were rodents, humans, armadillos and dogs. Results show a high diversity of tick-borne pathogens circulating among domestic and wild animals in the northeastern region of Paraguay.

Molecular detection of Anaplasma bovis, Candidatus Anaplasma boleense and Rickettsia spp. in ticks infesting small ruminants

Anaplasma spp. and Rickettsia spp. are intracellular vector-borne pathogens and harbored by a wide range of ticks and vertebrate hosts. Aim of this study was to molecularly characterize Anaplasma spp. and Rickettsia spp. in different ticks collected from livestock hosts in nine districts of Khyber Pakhtunkhwa (KP), Pakistan. In total, 862 ticks were collected from cattle, goats and sheep. Highest tick's infestation was observed on cattle 56.14% (32/57), followed by goats 45.45% (40/88), and sheep 42.05% (45/107). Rhipicephalus microplus (305/862, 35.38%) was predominant species, followed by Haemaphysalis sulcata (243/862, 28.19%), Hyalomma anatolicum (133/862, 15.42%), Haemaphysalis bispinosa (120/862, 13.92%), and Hyalomma kumari (61/862, 7.07%). A subset of 135 ticks were screened for Anaplasma spp. and Rickettsia spp. based on the amplification of partial 16 S rDNA and outer-membrane protein A (ompA) fragments, respectively. In total, 16 ticks (11.85%) were positive for Anaplasma spp. and Rickettsia spp. Obtained 16 S rDNA sequences for Anaplasma spp. detected in Ha. bispinosa and Ha. sulcata showed 99.98% identity with Anaplasma bovis, while other detected in Rh. microplus showed 99.84% identity with Candidatus Anaplasma boleense. Similarly, detected ompA sequence in Ha. sulcata showed 100% identity with Rickettsia sp. and 97.93% with Rickettsia slovaca, and another sequence detected in Rh. microplus showed 100% identity with Candidatus Rickettsia shennongii. In phylogenetic trees, these sequences clustered with corresponding species from Pakistan, China, Turkey, South Korea, South Africa, and Herzegovina. This is the first study reporting detection of A. bovis in Ha. bispinosa and Ha. sulcata, Ca. A. boleense in Rh. microplus collected from goats, and R. slovaca-like in Ha. sulcata. Our results enforce the need for regular surveillance of Rickettsiales in hard ticks infesting livestock in the region.

Current status of ruminant anaplasmosis in Algeria: a systematic review and meta-analysis

Anaplasmosis is an emerging infectious disease that is being recognised all over the world, with impact on animal health.This systematic review and meta-analysis aimed to assess the rate infection of Anaplasma spp. infection in Algerian ruminants. Three databases were searched to identify eligible studies for the final systematic review and meta-analysis. The 'meta' package in the R software was used for the meta-analysis, and the random effects model was chosen to pool the data. Meta-analysis encompasses 14 research papers spanning 19 years (2004-2023), out of an initial pool of 737 articles retrieved from various databases. The study included a total of 1515 cattle, 190 sheep, and 310 goats, and the overall Anaplasma infection rate was estimated at 28% (95% CI, 17-41%). The analysis revealed varying infection rates among species, with cattle at 20%, sheep at 30%, and goats at 61%. Five classified species and two unclassified strains belonging to Anaplasma genus were identified in ruminants, which are A. marginale, A. centrale, A. bovis, A. ovis, A. phagocytophilum, A. phagocytophilum-like strains, and A. platys-like strains. Among these, A. marginale was prevalent in ten out of eleven cattle studies. The data also revealed regional variations, with Northeastern Algeria showing a higher infection rate (26%) compared to North-central Algeria (9%). In the subgroup analysis, clinically healthy cattle had a higher infection rate (28%) compared to suspected disease cattle (16%). Molecular biology screening methods yielded a significantly higher infection rate (33%) than microscopy (12%). Gender analysis suggested slightly higher infection rates among male cattle (19%) compared to females (16%). Age analysis indicated that Anaplasma infection was more common in cattle less than 12 months (14%) compared to those over 12 months (9%). This systematic review provides valuable insights, highlighting the need for continued surveillance and potential preventive strategies in different regions and among different animal populations in Algeria.

Metagenome diversity illuminates the origins of pathogen effectors

Recent metagenome-assembled genome (MAG) analyses have profoundly impacted Rickettsiology systematics. The discovery of basal lineages (novel families Mitibacteraceae and Athabascaceae) with predicted extracellular lifestyles exposed an evolutionary timepoint for the transition to host dependency, which seemingly occurred independent of mitochondrial evolution. Notably, these basal rickettsiae carry the Rickettsiales vir homolog (rvh) type IV secretion system and purportedly use rvh to kill congener microbes rather than parasitize host cells as described for later-evolving rickettsial pathogens. MAG analysis also substantially increased diversity for the genus Rickettsia and delineated a sister lineage (the novel genus Tisiphia) that stands to inform on the emergence of human pathogens from protist and invertebrate endosymbionts. Herein, we probed Rickettsiales MAG and genomic diversity for the distribution of Rickettsia rvh effectors to ascertain their origins. A sparse distribution of most Rickettsia rvh effectors outside of Rickettsiaceae lineages illuminates unique rvh evolution from basal extracellular species and other rickettsial families. Remarkably, nearly every effector was found in multiple divergent forms with variable architectures, indicating profound roles for gene duplication and recombination in shaping effector repertoires in Rickettsia pathogens. Lateral gene transfer plays a prominent role in shaping the rvh effector landscape, as evinced by the discovery of many effectors on plasmids and conjugative transposons, as well as pervasive effector gene exchange between Rickettsia and Legionella species. Our study exemplifies how MAGs can yield insight into pathogen effector origins, particularly how effector architectures might become tailored to the discrete host cell functions of different eukaryotic hosts.IMPORTANCEWhile rickettsioses are deadly vector-borne human diseases, factors distinguishing Rickettsia pathogens from the innumerable bevy of environmental rickettsial endosymbionts remain lacking. Recent metagenome-assembled genome (MAG) studies revealed evolutionary timepoints for rickettsial transitions to host dependency. The rvh type IV secretion system was likely repurposed from congener killing in basal extracellular species to parasitizing host cells in later-evolving pathogens. Our analysis of MAG diversity for over two dozen rvh effectors unearthed their presence in some non-pathogens. However, most effectors were found in multiple divergent forms with variable architectures, indicating gene duplication and recombination-fashioned effector repertoires of Rickettsia pathogens. Lateral gene transfer substantially shaped pathogen effector arsenals, evinced by the discovery of effectors on plasmids and conjugative transposons, as well as pervasive effector gene exchanges between Rickettsia and Legionella species. Our study exemplifies how MAGs yield insight into pathogen effector origins and evolutionary processes tailoring effectors to eukaryotic host cell biology.

Molecular investigation of Anaplasma phagocytophilum and related strains among sheep flocks from different parts of Türkiye; with a note of phylogenetic analyses of Anaplasma phagocytophilum- like 1

Anaplasma phagocytophilum is a vector-borne zoonotic pathogen and can infect various vertebrate hosts, especially cattle, sheep, goats, horses, and dogs. Molecular-based studies have revealed that the agent has a high genetic diversity and closely related strains circulate in hosts. In this study, 618 sheep blood samples obtained from different geographic regions of Türkiye were researched for A.phagocytophilum and related strains with PCR, RFLP, and DNA sequence analyses. The DNA of these pathogens was detected in 110 (17.79%) samples. RFLP assay showed that all positive samples were infected with A.phagocytophilum-like 1, whereas A.phagocytophilum-like 2 and A.phagocytophilum were not detected. Partial parts of 16 S rRNA gene of seven randomly selected positive samples were sequenced. The phylogenetic analyses of these isolates revealed that at least two A.phagocytophilum-like 1 isolates circulate among hosts in Türkiye and around the world. A.phagocytophilum-related strains have been reported in molecular-based studies over the last few years, but there is a lack of data on the vector competence, epidemiology, clinical symptoms, and genetic diversity of these pathogens. Therefore, large-scale molecular studies are still needed to obtain detailed data on the above-mentioned topics.

First screening for tick-borne pathogens in Chinese Milu deer (Elaphurus davidianus)

Ticks are primary vectors for many tick-borne pathogens (TBPs) and pose a serious threat to veterinary and public health. Information on the presence of TBPs in Chinese Milu deer (Elaphurus davidianus) is limited. In this study, a total of 102 Chinese Milu deer blood samples were examined for Anaplasma spp., Theileria spp., Babesia spp., Rickettsia spp., and Borrelia spp., and three TBPs were identified: Anaplasma phagocytophilum (48; 47.1 %), Candidatus Anaplasma boleense (47; 46.1%), and Theileria capreoli (8; 7.8 %). Genetic and phylogenetic analysis of the 16S rRNA and 18S rRNA confirmed their identity with corresponding TBPs. To our knowledge, this is the first report on Candidatus A. boleense and T. capreoli detection in Chinese Milu deer. A high prevalence of A. phagocytophilum with veterinary and medical significance was identified in endangered Chinese Milu deer, which could act as potential zoonotic reservoirs. The identification of the TBPs in Chinese Milu deer provides useful information for the prevention and control of tick-borne diseases.

Molecular detection of Candidatus Ehrlichia pampeana (Rickettsiales: Anaplasmataceae) in Haemaphysalis juxtakochi (Acari: Ixodidae) from central Argentina

The aim of this study was to report the first detection of Candidatus Ehrlichia pampeana in Haemaphysalis juxtakochi from Argentina. Free-living ticks were collected from vegetation by drag-flag method on five sample sites in Entre Ríos Province, central Argentina, belonging to the Espinal Phytogeographic Province. Molecular detection of order Rickettsiales agents was performed using gltA (Rickettsia spp.), 16 S rRNA and groEL (Anaplasmataceae) genes as targets. A total of 67 ticks of Amblyomma aureolatum (20 nymphs and 4 adults), Amblyomma dubitatum (15 nymphs) and Haemaphysalis juxtakochi (24 nymphs and 4 adults) were collected. While all tested ticks were negative for Rickettsia spp., and Anaplasmataceae agents could neither be detected in A. aureolatum nor in A. dubitatum, Candidatus Ehrlichia pampeana was detected in one male of H. juxtakochi. DNA sequences of this microorganism (16 S rDNA and groEL) are related to sequences of Ehrlichia ewingii. The findings of the current study represent the first report of this Ehrlichia strain for Argentina.

Human Tick-Borne Diseases and Advances in Anti-Tick Vaccine Approaches: A Comprehensive Review

This comprehensive review explores the field of anti-tick vaccines, addressing their significance in combating tick-borne diseases of public health concern. The main objectives are to provide a brief epidemiology of diseases affecting humans and a thorough understanding of tick biology, traditional tick control methods, the development and mechanisms of anti-tick vaccines, their efficacy in field applications, associated challenges, and future prospects. Tick-borne diseases (TBDs) pose a significant and escalating threat to global health and the livestock industries due to the widespread distribution of ticks and the multitude of pathogens they transmit. Traditional tick control methods, such as acaricides and repellents, have limitations, including environmental concerns and the emergence of tick resistance. Anti-tick vaccines offer a promising alternative by targeting specific tick proteins crucial for feeding and pathogen transmission. Developing vaccines with antigens based on these essential proteins is likely to disrupt these processes. Indeed, anti-tick vaccines have shown efficacy in laboratory and field trials successfully implemented in livestock, reducing the prevalence of TBDs. However, some challenges still remain, including vaccine efficacy on different hosts, polymorphisms in ticks of the same species, and the economic considerations of adopting large-scale vaccine strategies. Emerging technologies and approaches hold promise for improving anti-tick vaccine development and expanding their impact on public health and agriculture.

Tick-borne microorganisms in Amblyomma tigrinum (Acari: Ixodidae) from the Patagonian region of Argentina

This study presents the results of the molecular detection of tick-borne microorganisms in Amblyomma tigrinum Koch collected near the city of Viedma, Río Negro, Argentina. Ticks were collected in their non-parasitic stage, on pet dogs and on Lycalopex gymnocercus (Pampa fox). Also, six tick samples from humans were analyzed. All ticks were morphologically identified to species level and genomic DNA was extracted. The DNA samples were examined by end point PCR assays to amplified DNA of Anaplasma sp., Babesia sp., Ehrlichia sp., Rickettsia sp. and Theileria sp. Although all tested DNA samples from the collected ticks resulted negative to the detection of Piroplasmida and Rickettsia spp., 16 samples (16.5%, including all hosts) were positive in the 16S rDNA gene PCR that detects bacteria from the Anaplasmataceae family. Phylogenetic analysis of seven obtained partial sequences resulted in the identification of three bacteria: two Ehrlichia spp. (related to Ehrlichia sp. strain Iberá and strain Viedma) and Candidatus Anaplasma boleense. The latter finding represents the first detection of this novel Candidatus species in A. tigrinum. Based on the results of this study, it must be assumed that the diversity of bacteria of the Anaplasmataceae family in Argentina is greater than previously thought, and that these bacteria can infect a wide range of domestic and wild animals.

Zoonotic pathogens identified in rodents and shrews from four provinces, China, 2015-2022

Rodents and shrews are major reservoirs of various pathogens that are related to zoonotic infectious diseases. The purpose of this study was to investigate co-infections of zoonotic pathogens in rodents and shrews trapped in four provinces of China. We sampled different rodent and shrew communities within and around human settlements in four provinces of China and characterised several important zoonotic viral, bacterial, and parasitic pathogens by PCR methods and phylogenetic analysis. A total of 864 rodents and shrews belonging to 24 and 13 species from RODENTIA and EULIPOTYPHLA orders were captured, respectively. For viral pathogens, two species of hantavirus (Hantaan orthohantavirus and Caobang orthohantavirus) were identified in 3.47% of rodents and shrews. The overall prevalence of Bartonella spp., Anaplasmataceae, Babesia spp., Leptospira spp., Spotted fever group Rickettsiae, Borrelia spp., and Coxiella burnetii were 31.25%, 8.91%, 4.17%, 3.94%, 3.59%, 3.47%, and 0.58%, respectively. Furthermore, the highest co-infection status of three pathogens was observed among Bartonella spp., Leptospira spp., and Anaplasmataceae with a co-infection rate of 0.46%. Our results suggested that species distribution and co-infections of zoonotic pathogens were prevalent in rodents and shrews, highlighting the necessity of active surveillance for zoonotic pathogens in wild mammals in wider regions.

Genetic diversity of vector-borne pathogens in ixodid ticks infesting dogs from Pakistan with notes on Ehrlichia canis, Rickettsia raoultii and Dirofilaria immitis detection

BACKGROUND

Vector-/tick-borne pathogens (V/TBPs) pose a potential threat to human and animal health globally. Information regarding canine V/TBPs is scarce and no specific study has been conducted so far to explore the microbial diversity within ticks infesting dogs from Pakistan. Herein, this knowledge gap is addressed by assessing the genetic diversity and prevalence pattern of V/TBPs in ixodid ticks with special implications for public and canine health.

METHODS

A total of 1150 hard ticks were collected from 300 dogs across central Khyber Pakhtunkhwa (KP), Pakistan. After morpho-molecular identification, 120 tick samples were screened for the presence of V/TBPs by amplifying 16S rRNA/gltA (Rickettsia/Ehrlichia and Wolbachia sp.), 18S rRNA (Theileria sp.) and cox1 (Dirofilaria sp.) genes through PCR followed by sequencing and phylogenetic study.

RESULTS

In toto, 50 ixodid ticks (50/120, 41.7%) were found positive for V/TBPs DNA. The detected V/TBPs were categorized into five genera and eight species, viz. Ehrlichia (E. canis and Ehrlichia sp.), Rickettsia (R. massiliae, R. raoultii and Rickettsia sp.), Theileria (T. annulata), Dirofilaria (D. immitis) and Wolbachia (Wolbachia sp.). The pathogen prevalence patterns showed that R. massiliae was the most prevalent zoonotic V/TBP (19.5%), followed by E. canis (10.8%), Rickettsia sp. (7.5%), R. raoultii (6.7%), T. annulata (5.8%), D. immitis (5.8%), Wolbachia sp. (4.2%) and Ehrlichia sp. (3.3%), respectively. Among the screened tick species, most Rhipicephalus sanguineus sensu lato samples were found positive for V/TBP DNA (20/20,100%) followed by Rh. turanicus sensu stricto (13/20, 65%), Hyalomma dromedarii (8/20, 40%), Rh. haemaphysaloides (6/20, 30%), Hy. excavatum (2/20, 10%) and Rh. microplus (1/20, 5%). Co-occurrence of V/TBP was also detected in tick specimens (single V/TBP infection: 32 ticks; double and triple: 13 and 5 tick samples). The detected pathogens shared a phylogenetic relationship with similar isolates published in NCBI GenBank from Old and New World countries.

CONCLUSION

Ixodid ticks infesting dogs harbor a diverse array of V/TBPs including zoonotic agents from Pakistan. Furthermore, the presence of D. immitis in ticks that infest dogs raises the possibility that this parasite has either attained its dead-end host (i.e. the tick) while feeding on dogs or has expanded its range of intermediate/paratenic hosts. Further research work is needed to investigate the epidemiology and confirm the vector competence of screened tick species for these pathogens from Pakistan.

Molecular survey of Anaplasma phagocytophilum and related variants in water buffaloes: The first detection of Anaplasma phagocytophilum-like 1

Anaplasma phagocytophilum infects various hosts and lead to mild to severe infection. Currently, two A.phagocytophilum-related variants have been documented in different countries. Although limited, there are studies revealing the presence of A.phagocytophilum in water buffaloes, but no study investigating A.phagocytophilum-like 1 and -like 2. A.phagocytophilum and related variants were investigated using PCR, PCR-RFLP, and DNA sequence analysis in water buffaloes in Türkiye. 364 buffalo blood samples were examined for A.phagocytophilum and related strains. Seven buffaloes were determined to be positive with PCR and PCR-RFLP revealed that all samples were A.phagocytophilum-like 1. According to the partial sequence of 16 S rRNA gene, A.phagocytophilum like-1 may split into two different variants. This work supplies the first molecular report of A.phagocytophilum-like 1 in water buffaloes. However, a lack of information is present on the pathogen's clinical manifestations and vector species. There is still a need to investigate vectors and clinical signs of the pathogen.

Molecular detection and phylogenetic analysis of Anaplasma platys-like and Candidatus Anaplasma boleense strains from Argentina

The present study aimed at the molecular detection of Anaplasma spp. in different samples obtained from cattle, goats and free-living Rhipicephalus microplus ticks from Argentina. DNA of members of the Anaplasmataceae family was detected by different PCR assays. The phylogenetic analyses of the obtained partial DNA sequences of the 16 S rDNA gene resulted in the identification of two different Anaplasma spp.: (I) Anaplasma platys-like bacteria (in blood sample from cattle and pools of R. microplus larvae and (II) Candidatus Anaplasma boleense (in blood samples from goats and one pool of R. microplus larvae of R. microplus). Candidatus A. boleense was found in two provinces that belong to different biogeographic regions, which leads to the conclusion that this bacterium may be widely distributed in Argentina. Interestingly, both Anaplasma spp. were found in the same R. microplus population in Chaco province, indicating that these two strains of Anaplasma are circulating in the same tick population. The results of this work represent the first report of the circulation of A. platys-like bacteria and Ca. A. boleense in domestic ruminants and free-living R. microplus ticks in Argentina. Further studies to determine the prevalence of infection, dispersion, clinical impact, transmission routes and cross-reactivity in serological tests of both Anaplasma species are needed.

Metagenome diversity illuminates origins of pathogen effectors

Recent metagenome assembled genome (MAG) analyses have profoundly impacted Rickettsiology systematics. Discovery of basal lineages (Mitibacteraceae and Athabascaceae) with predicted extracellular lifestyles reveals an evolutionary timepoint for the transition to host dependency, which occurred independent of mitochondrial evolution. Notably, these basal rickettsiae carry the Rickettsiales vir homolog (rvh) type IV secretion system (T4SS) and purportedly use rvh to kill congener microbes rather than parasitize host cells as described for derived rickettsial pathogens. MAG analysis also substantially increased diversity for genus Rickettsia and delineated a basal lineage (Tisiphia) that stands to inform on the rise of human pathogens from protist and invertebrate endosymbionts. Herein, we probed Rickettsiales MAG and genomic diversity for the distribution of Rickettsia rvh effectors to ascertain their origins. A sparse distribution of most Rickettsia rvh effectors outside of Rickettsiaceae lineages indicates unique rvh evolution from basal extracellular species and other rickettsial families. Remarkably, nearly every effector was found in multiple divergent forms with variable architectures, illuminating profound roles for gene duplication and recombination in shaping effector repertoires in Rickettsia pathogens. Lateral gene transfer plays a prominent role shaping the rvh effector landscape, as evinced by the discover of many effectors on plasmids and conjugative transposons, as well as pervasive effector gene exchange between Rickettsia and Legionella species. Our study exemplifies how MAGs can provide incredible insight on the origins of pathogen effectors and how their architectural modifications become tailored to eukaryotic host cell biology.

Population dynamics of Brachionus calyciflorus driven by the associated natural bacterioplankton

Zooplankton provides bacteria with a complex microhabitat richen in organic and inorganic nutrients, and the bacteria community also changes the physiochemical conditions for zooplankton, where the symbiotic relationship between them plays an important role in the nutrient cycle. However, there are few studies on the effect of associated bacteria on the population dynamics of rotifers. In order to make clear their relationships, we reconstructed the associated bacterial community in Brachionus calyciflorus culture, and examined the life history and population growth parameters, and analyzed the diversity and community composition of the associated bacteria at different growth stages of B. calyciflorus. The results showed that the addition of bacteria from natural water can promote the population growth and asexual reproduction of B. calyciflorus, but has no significant effect on sexual reproduction, exhibited by the improvement of its life expectancy at hatching, net reproduction rates and intrinsic growth rate, no significant effects on the generation time and mixis ratio of offspring. It was found that the B. calyciflorus-associated bacterial community was mainly composed of Proteobacteria, Bacteroidota, Actinobacteriota, Cyanobacteria and Firmicutes. Through correlation network analysis, the members of Burkholderiales, Pseudomonadales, Micrococcales, Caulobacterales and Bifidobacteriales were the keystone taxa of B. calyciflorus-associated bacteria. In addition, the relative abundance of some specific bacteria strains increased as the population density of B. calyciflorus increased, such as Hydrogenophaga, Acidovorax, Flavobacterium, Rheinheimera, Novosphingobium and Limnobacter, and their relative abundance increased obviously during the slow and exponential phases of population growth. Meanwhile, the relative abundance of adverse taxa (such as Elizabethkingia and Rickettsiales) decreased significantly with the increase in rotifer population density. In conclusion, the closely associated bacteria are not sufficient for the best growth of B. calyciflorus, and external bacterioplankton is necessary. Furthermore, the function of keystone and rare taxa is necessary for further exploration. The investigation of the symbiotic relationship between zooplankton-associated bacterial and bacterioplankton communities will contribute to monitoring their roles in freshwater ecosystems, and regulate the population dynamics of the micro-food web.

Genetic diversity of tick (Acari: Ixodidae) populations and molecular detection of Anaplasma and Ehrlichia infesting beef cattle from upper-northeastern Thailand

Genetic diversity, genetic structure and demographic history of the ticks infesting beef cattle in Thailand were examined based on mitochondrial cytochrome c oxidase I (cox1) sequences. Tick samples were collected in 12 provinces in upper-northeastern Thailand. Three species were found; Rhipicephalus microplus, R. sanguineus, and Haemaphysalis bispinosa. Of these, R. microplus was by far the most abundant species in beef cattle and was widely distributed throughout the area. No cox1 sequence variation was found in the R. sanguineus or H. bispinosa specimens collected. Low nucleotide diversity but high haplotype diversity was observed in R. microplus. All collected R. microplus specimens belonged to lineage A. Mismatch-distribution analysis, as well as Tajima's D and Fu's Fs tests, provided evidence of recent demographic expansion. A subsample of tick specimens was investigated for presence of Anaplasma and Ehrlichia using a fragment of the 16S rRNA gene. Three species of Anaplasma were detected from R. microplus; Anaplasma marginale (19.08%), Anaplasma platys (1.97%) and unidentified Anaplasma strain (0.66%). The infection rate of Ehrlichia was 7.24% (two ticks were infected with E. minasensis (1.97%) and eight with an unidentified Ehrlichia strain (5.26%). No infections were found in R. sanguineus or H. bispinosa. This is the first report of A. platys and E. minasensis in cattle ticks in Thailand, providing information for future epidemiological surveys and control strategies in this region.

The life cycle of Dermacentor nuttalli from the Qinghai-Tibetan Plateau under laboratory conditions and detection of spotted fever group Rickettsia spp

Dermacentor nuttalli has been a focus of study because tick-borne pathogens have been widely identified in this tick from northern and southwestern China. The aim of this study was to characterize the life cycle of D. nuttalli under laboratory conditions and to detect spotted fever group (SFG) Rickettsia in the midgut and salivary glands of both field-collected and first laboratory generation adults. D. nuttalli ticks were collected in the field on the Qinghai-Tibetan Plateau from March to April 2021 and their life cycle was studied under laboratory conditions. Tick identify was molecularly confirmed, and SFG Rickettsia were detected in the midgut and salivary glands of males and females by PCR targeting different rickettsial genes. The results showed that the life cycle of D. nuttalli under laboratory conditions was completed in an average of 86.1 days. High positivity of Rickettsia spp. was detected in the midgut and salivary glands of both males (92.0%) and females (93.0%) of field-collected D. nuttalli ticks. However, a relatively lower positivity (4.0-6.0%) was detected in first laboratory generation adults. Furthermore, sequencing analysis showed that the Rickettsia sequences obtained in this study shared 98.6 to 100% nucleotide identity with Rickettsia slovaca and Rickettsia raoultii isolated from Dermacentor spp. in China. Phylogenetic analysis of Rickettsia spp. based on the gltA, ompA, ompB and sca4 genes revealed that the Rickettsia sequences obtained could be classified as belonging to R. slovaca and R. raoultii clades. This study described for the first time the life cycle of D. nuttalli from the Qinghai-Tibetan Plateau under laboratory conditions. Two species of SFG Rickettsia were detected in the midgut and salivary glands of males and females in both field-collected and first laboratory-generation adults of D. nuttalli. Our study provides new insights into pathogen detection in ticks in the Qinghai-Tibet Plateau, and the relationships among hosts, ticks, and pathogens.

Emergence of Anaplasma Species Related to A. phagocytophilum and A. platys in Senegal

The genus Anaplasma (Anaplasmataceae, Rickettsiales) includes tick-transmitted bacterial species of importance to both veterinary and human medicine. Apart from the traditionally recognized six Anaplasma species (A. phagocytophilum, A. platys, A. bovis, A. ovis, A. centrale, A. marginale), novel strains and candidate species, also of relevance to veterinary and human medicine, are emerging worldwide. Although species related to the zoonotic A. platys and A. phagocytophilum have been reported in several African and European Mediterranean countries, data on the presence of these species in sub-Saharan countries are still lacking. This manuscript reports the investigation of Anaplasma strains related to zoonotic species in ruminants in Senegal by combining different molecular tests and phylogenetic approaches. The results demonstrated a recent introduction of Candidatus (Ca) Anaplasma turritanum, a species related to the pathogenic A. platys, possibly originating by founder effect. Further, novel undetected strains related to Candidatus (Ca) Anaplasma cinensis were detected in cattle. Based on groEL and gltA molecular comparisons, we propose including these latter strains into the Candidatus (Ca) Anaplasma africanum species. Finally, we also report the emergence of Candidatus (Ca) A. boleense in Senegal. Collectively, results confirm that Anaplasma species diversity is greater than expected and should be further investigated, and that Anaplasma routine diagnostic procedures and epidemiological surveillance should take into account specificity issues raised by the presence of these novel strains, suggesting the use of a One Health approach for the management of Anaplasmataceae in sub-Saharan Africa.

Molecular detection of Ehrlichia spp. in ticks parasitizing wild lagomorphs from Spain: characterization of a novel Ehrlichia species

Background

Several species belonging to the genus Ehrlichia are considered pathogenic for animals and humans. Although wildlife are known to play an important role in the epidemiology of these bacteria, information on the role of wild lagomorphs in their sylvatic cycle is limited. Thus, the objective of the present study was to assess the occurrence of Ehrlichia spp. in ticks collected from wild lagomorphs in Spanish Mediterranean ecosystems.

Methods

A total of 1122 pooled ticks (254 pools) collected from 506 wild rabbits (Oryctolagus cuniculus) and 29 Iberian hares (Lepus granatensis) were analysed using a nested PCR assay targeting the partial groEL gene. Ehrlichia spp.-positive samples were further subjected to a second PCR assay targeting 16S rRNA.

Results

Three (1.2%) tick pools comprising Rhipicephalus pusillus collected from nine wild rabbits were positive for Ehrlichia spp. All the Ehrlichia DNA sequences were identical, and use of sequence and phylogenetic analyses allowed us to identify a novel Ehrlichia species.

Conclusions

We provide evidence that a novel Ehrlichia species, named herein as ‘Candidatus Ehrlichia andalusi’, which may be of concern for animal and public health, is circulating in R. pusillus in Spanish Mediterranean ecosystems. Further studies are warranted to assess the epidemiology, pathogenicity and zoonotic potential of this Ehrlichia species.

Graphical Abstract

The Relationship between Brachionus calyciflorus-Associated Bacterial and Bacterioplankton Communities in a Subtropical Freshwater Lake

Zooplankton bodies are organic-rich micro-environments that support fast bacterial growth. Therefore, the abundance of zooplankton-associated bacteria is much higher than that of free-living bacteria, which has profound effects on the nutrient cycling of freshwater ecosystems. However, a detailed analysis of associated bacteria is still less known, especially the relationship between those bacteria and bacterioplankton. In this study, we analyzed the relationships between Brachionus calyciflorus-associated bacterial and bacterioplankton communities in freshwater using high-throughput sequencing. The results indicated that there were significant differences between the two bacterial communities, with only 29.47% sharing OTUs. The alpha diversity of the bacterioplankton community was significantly higher than that of B. calyciflorus-associated bacteria. PCoA analysis showed that the bacterioplankton community gathered deeply, while the B. calyciflorus-associated bacterial community was far away from the whole bacterioplankton community, and the distribution was relatively discrete. CCA analysis suggested that many environmental factors (T, DO, pH, TP, PO₄^3-, NH₄⁺, and NO₃^-) regulated the community composition of B. calyciflorus-associated bacteria, but the explanatory degree of variability was only 37.80%. High-throughput sequencing revealed that Raoultella and Delftia in Proteobacteria were the dominant genus in the B. calyciflorus-associated bacterial community, and closely related to the biodegradation function. Moreover, several abundant bacterial members participating in carbon and nitrogen cycles were found in the associated bacterial community by network analysis. Predictive results from FAPROTAX showed that the predominant biogeochemical cycle functions of the B. calyciflorus-associated bacterial community were plastic degradation, chemoheterotrophy, and aerobic chemoheterotrophy. Overall, our study expands the current understanding of zooplankton-bacteria interaction and promotes the combination of two different research fields.

Comprehensive screening of tick-borne microorganisms indicates that a great variety of pathogens are circulating between hard ticks (Ixodoidea: Ixodidae) and domestic ruminants in natural foci of Anatolia

Grazing domestic ruminants serve as important reservoirs and/or amplificatory hosts in the ecology of tick-borne pathogens (TBPs) and tick vectors in the natural foci; however, many enzootic life cycles including ruminants and ticks are still unknown. This study investigated a wide range of TBPs circulating among ticks and grazing ruminants in the natural foci of Anatolia, Turkey. Tick specimens (n = 1815) were collected from cattle, sheep, and goats in three ecologically distinct areas (wooded, transitional, and semi-arid zones) of Anatolia and identified by species: Dermacentor marginatus, Dermacentor reticulatus, Hyalomma anatolicum, Hyalomma excavatum, Hyalomma marginatum, Hyalomma scupense, Haemaphysalis inermis, Haemaphysalis parva, Haemaphysalis punctata, Haemaphysalis sulcata, Ixodes ricinus, Rhipicephalus bursa, and Rhipicephalus turanicus. PCR-sequencing analyses revealed TBPs of great diversity, with 32 different agents identified in the ticks: six Babesia spp. (Babesia occultans, Babesia crassa, Babesia microti, Babesia rossi, Babesia sp. tavsan1, and Babesia sp. Ucbas); four Theileria spp., including one putative novel species (Theileria annulata, Theileria orientalis, Theileria ovis, and Theileria sp.); one Hepatozoon sp.; four Anaplasma spp., including one novel genotype (Anaplasma phagocytophilum, Anaplasma marginale, Anaplasma ovis, and Anaplasma sp.); six unnamed Ehrlichia spp. genotypes; Neoehrlichia mikurensis; nine spotted fever group rickettsiae, including one putative novel species (Rickettsia aeschlimannii, Rickettsia slovaca, Rickettsia hoogstraalii, Rickettsia monacensis with strain IRS3, Rickettsia mongolitimonae, Rickettsia raoultii, Candidatus Rickettsia goldwasserii, Candidatus Rickettsia barbariae, and Rickettsia sp.); and Borrelia valaisiana. Detailed phylogenetic analyses showed that some of the detected pathogens represent more than one haplotype, potentially relating to the tick species or the host. Additionally, the presence of Neoehrlichia mikurensis, an emerging pathogen for humans, was reported for the first time in Turkey, expanding its geographical distribution. Consequently, this study describes some previously unknown tick-borne protozoan and bacterial species/genotypes and provides informative epidemiological data on TBPs, which are related to animal and human health, serving the one health concept.

High diversity of Rickettsia spp., Anaplasma spp., and Ehrlichia spp. in ticks from Yunnan Province, Southwest China

Rickettsia, Anaplasma, and Ehrlichia belonging to the order Rickettsiales are causative agents of tick-borne diseases in humans. During 2021, 434 ticks including Rhipicephalus microplus and R. haemaphysaloides were collected from three sampling sites in Yunnan Province, Southwest China, and analyzed for the presence of these bacteria. Nine bacterial species were identified, including two Rickettsia spp., three Anaplasma spp., and four Ehrlichia spp., some of which are potential human pathogens. Genetic and phylogenetic analysis on 16S rRNA, gltA, groEL, ompA, ompB, and sca4 genes indicated the presence of a novel spotted fever group Rickettsia (SFGR) named “Candidatus Rickettsia shennongii” in six of the 38 R. haemaphysaloides ticks from two locations, Dehong Autonomous Prefecture and Honghe City. Another SFGR species, Candidatus Rickettsia jingxinensis was detected in ticks from all three sites, with an overall positive rate of 62.67%. Three other human pathogenic species, Anaplasma ovis (1.38%, 6/434), Ehrlichia canis (16.36%, 71/434), and E. chaffeensis (0.23%, 1/434) were detected in these ticks and characterized. Moreover, Ehrlichia sp. (4.84%, 21/434), E. minasensis (7.37%, 32/434), A. marginale (6.91%, 30/434), and Cadidatus Anaplasma boleense (1.15%, 5/434) were detected in R. microplus ticks, for which pathogenicity to humans remains to be determined. The results reveal the remarkable diversity of Rickettsiales bacteria in ticks from Yunnan Province, Southwest China. The high infection rate of some human pathogenic bacteria in ticks may indicate potential infection risk in humans, and it highlights the need for surveillance in local populations.

The diversity and evolutionary relationships of ticks and tick-borne bacteria collected in China

Background

Ticks (order Ixodida) are ectoparasites, vectors and reservoirs of many infectious agents affecting humans and domestic animals. However, the lack of information on tick genomic diversity leaves significant gaps in the understanding of the evolution of ticks and associated bacteria.

Results

We collected > 20,000 contemporary and historical (up to 60 years of preservation) tick samples representing a wide range of tick biodiversity across diverse geographic regions in China. Metagenomic sequencing was performed on individual ticks to obtain the complete or near-complete mitochondrial (mt) genome sequences from 46 tick species, among which mitochondrial genomes of 23 species were recovered for the first time. These new mt genomes data greatly expanded the diversity of many tick groups and revealed five cryptic species. Utilizing the same metagenomic sequence data we identified divergent and abundant bacteria in Haemaphysalis, Ixodes, Dermacentor and Carios ticks, including nine species of pathogenetic bacteria and potentially new species within the genus Borrelia. We also used these data to explore the evolutionary relationship between ticks and their associated bacteria, revealing a pattern of long-term co-divergence relationship between ticks and Rickettsia and Coxiella bacteria.

Conclusions

In sum, our study provides important new information on the genetic diversity of ticks based on an analysis of mitochondrial DNA as well as on the prevalence of tick-borne pathogens in China. It also sheds new light on the long-term evolutionary and ecological relationships between ticks and their associated bacteria.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05485-3.

The detection and phylogenetic analysis of Anaplasma phagocytophilum-like 1, A. ovis and A. capra in sheep: A. capra divides into two genogroups

In this study, the presence, prevalence, and genotypes of Anaplasma phagocytophilum, A. ovis, and A. capra in sheep were investigated based on 16 S SSU rRNA, groEL, and gtlA gene-specific polymerase chain reaction (PCR), respectively. The sequences of the genes were used for detection of the phylogenetic position of the species. Additionally, a restriction fragment length polymorphism (RFLP) were carried out for discrimination of A. phagocytophilum and related variants (A. phagocytophilum-like 1 and 2). The prevalence of Anaplasma spp. was found as 25.8% (101/391), while it was found that A. ovis, A. phagocytophilum-like 1, and A. capra are circulating in the sheep herds in Kyrgyzstan, according to the PCRs, RFLP and the partial DNA sequencing results. The positivity rates of A. phagocytophilum-like 1, A. ovis, and A. capra genotype-1 were 6.9, 22.5, and 5.3%, respectively. A total of 32 (8.2%) sheep were found to be mix infected. Moreover, phylogenetic analyses and sequence comparison with those available in the GenBank showed that A. capra formed two distinct genetic groups (A. capra genotype-1 and A. capra genotype-2). Considering the zoonotic potential of these species, it may be necessary to make changes in the interpretation of anaplasmosis cases in animals and there is a need for further studies to determine the pathogenicity of the species/genotypes circulating in animals.

Molecular detection and phylogeny of Anaplasma spp. closely related to Anaplasma phagocytophilum in small ruminants from China

The genus Anaplasma comprises eight bacterial species that are obligate intracellular pathogens that affect human and animal health. The zoonotic species A. phagocytophilum is the causative agent of tick-borne fever in ruminants, and of granulocytic anaplasmosis in horses, dogs, and humans. Recently, novel strains related to A. phagocytophilum (A. phagocytophilum-like 1/Japanese variant and A. phagocytophilum-like 2/Chinese variant) have been identified. The aim of this study was to reveal the prevalence and phylogeny of A. phagocytophilum and related stains in small ruminants and ticks in China based on sequences of the 16S rRNA combined restriction fragment length polymorphism (RFLP) and groEL genes. PCR-RFLP and phylogenetic analyses based on the 16S rRNA gene showed the presence of A. phagocytophilum-like 1 and 2 variants in sampled animals from China, with prevalence rates of 22.6% (303/1338) and 0.7% (10/1338), respectively. Only A. phagocytophilum-like 1 DNA was found in Haemaphysalis longicornis. The phylogeny based on the groEL gene showed inclusion of A. phagocytophilum-like 1 and some A. phagocytophilum-like 2 strains in two unique clades distinct from, but related to, Japanese and Chinese strains of related A. phagocytophilum, respectively. One noteworthy result was that the SSAP2f/SSAP2r primers detected Ehrlichia spp. strains. Moreover, the A. phagocytophilum-like 1 and 2 strains should be considered in the differential diagnosis of caprine and ovine anaplasmosis. Further investigations should be conducted to provide additional epidemiological information about A. phagocytophilum and A. phagocytophilum-like variants in animals and ticks.

Genomic diversity across the Rickettsia and 'Candidatus Megaira' genera and proposal of genus status for the Torix group

Members of the bacterial genus Rickettsia were originally identified as causative agents of vector-borne diseases in mammals. However, many Rickettsia species are arthropod symbionts and close relatives of 'Candidatus Megaira', which are symbiotic associates of microeukaryotes. Here, we clarify the evolutionary relationships between these organisms by assembling 26 genomes of Rickettsia species from understudied groups, including the Torix group, and two genomes of 'Ca. Megaira' from various insects and microeukaryotes. Our analyses of the new genomes, in comparison with previously described ones, indicate that the accessory genome diversity and broad host range of Torix Rickettsia are comparable to those of all other Rickettsia combined. Therefore, the Torix clade may play unrecognized roles in invertebrate biology and physiology. We argue this clade should be given its own genus status, for which we propose the name 'Candidatus Tisiphia'.

Systematic evaluation of TaqMan real-time polymerase chain reaction assays targeting the dsb and gltA loci of Ehrlichia canis in recombinant plasmids and naturally infected dogs

Background and Aim: Because of the diversity of local genotypes of Ehrlichia canis, genes targeted by TaqMan real-time polymerase chain reaction (RT-PCR) assays should be systematically evaluated. This study evaluated the amplification efficiency, linearity, precision, and sensitivity of two TaqMan RT-PCR assays targeting the dsb and gltA loci of E. canis in recombinant plasmids and naturally infected dogs. Materials and Methods: Thirty blood samples were collected from dogs showing clinical signs of canine monocytic ehrlichiosis at the Kasetsart University Veterinary Teaching Hospital, Bangkok, Thailand. The dsb and gltA genes were amplified by conventional PCRs (cPCRs) on the blood samples and were then sequenced. Meanwhile, RT-PCR was used to detect dsb and gltA genes in 10-fold dilutions of the recombinant plasmids. Results: Both dsb and gltA were amplified with a high degree of linearity (R2≥0.975 and 0.993, respectively) in all dilutions, although the mean percentage of relative standard deviation of gltA was lower, but the difference was non-significant. The detection limits of RT-PCR and cPCR were 10–7 and 10–6, respectively, for both loci. RT-PCR targeting dsb (22/30; 73.3%) and gltA (15/30; 50%) yielded a number of positive results that did not differ significantly (p=0.06). The RT-PCR positive results of the dsb gene (22/30) differed significantly from that of cPCR (11/30) (p=0.004). In contrast, the RT-PCR positive results of the gltA gene (15/30) did not differ significantly from that of cPCR (12/30) (p=0.43). The mean Ct value (30.2) based on dsb RT-PCR of 22 positive cases was higher than that of gltA RT-PCR (Ct=27.4) on 15 positive cases. The Ct values from dsb RT-PCR were >30 in all seven discordant samples that were not detected by the gltA RT-PCR. Conclusion: RT-PCR targeting the dsb gene was more sensitive for detecting E. canis in naturally infected dogs. This study suggested that TaqMan RT-PCR of the dsb gene should be selected for E. canis research in this region.

Identification of Rickettsia spp., Anaplasma spp., and an Ehrlichia canis-like agent in Rhipicephalus microplus from Southwest and South-Central China

Rhipicephalus microplus is considered to be the most important tick infesting cattle, buffalo, horse, goats as well as other animals. They transmit diseases between domestic animals and act as vectors of a variety of zoonotic pathogens. Although pathogens harbored by R. microplus have been extensively studied, the Rickettsiales pathogens vectored by R. microplus in some areas of China remained largely unexplored. From August to October 2020, a total of 291 R. microplus ticks were collected from goats and cattle in three Southern China provinces, Guangxi (n = 138), Sichuan (n = 120) and Hubei (n = 33) provinces. Phylogenetic analysis based on COI gene sequences shows that these ticks are divided into three distinct clades, indicating the remarkable genetic diversity of R. microplus ticks in China. These samples were subsequently screened for the presence of Rickettsia, Anaplasma and Ehrlichia using conventional PCR and sequencing. Subsequently, five bacterial species were identified. Out of the 120 tick DNA samples from Sichuan province, 35.83% (43/120) were positive for Rickettsia sp. belonging to spotted fever group (SFG), 12.50% (15/120) were positive for Anaplasma marginale and 0.83% (1/120) was identified as A. platys. From the 138 DNA samples from Guangxi province, an Ehrlichia canis-like and Rickettsia sp. were detected, with a positive rate of 11.59% (16/138) and 2.17% (3/138), respectively. A. capra DNA was detected in 4 out of 33 (12.12%) samples from Hubei province. Notably, the 16S, gltA and groEL sequences of the E. canis-like are closely related to the E. canis strain previously identified from China, and form a distinct cluster in the phylogenetic trees. Collectively, our results expand the knowledge on tick-borne Rickettsiales pathogens in China. Because the state of engorgement of ticks was not recorded, it is not clear at this stage whether these pathogens are infecting the ticks or are simply present in the blood meal. Given the public health significance of SFG Rickettsia, A. capra, A. platys and E. canis, a thorough investigation of the diversity and presence of pathogens in R. microplus in areas with tick-associated diseases are needed.

First molecular detection of Anaplasma species in cattle from Kyrgyzstan; molecular identification of human pathogenic novel genotype Anaplasma capra and Anaplasma phagocytophilum related strain

Anaplasmosis is a rickettsial infection with significant effects on human and animal health, and the discovery of new species or genotypes with zoonotic potential in recent years has increased this importance. The aim of this study was to provide the first assessment of the molecular etiology and prevalence of bovine anaplasmosis in Kyrgyzstan (specifically in the Chuy, Talas, Djalal-Abad, Naryn, and Issyk-Kul regions). The prevalence of bovine anaplasmosis was determined as 1.7% (6/358). PCR and partial DNA sequencing results of the 16S ribosomal RNA (rRNA) gene revealed that Anaplasma centrale, A. phagocytophilum like-1, and the human pathogenic novel genotype A. capra are circulating in cattle herds in Kyrgyzstan. Six DNA nucleotide sequences obtained in this study were deposited in GenBank under the following accession numbers: A. centrale (MW672117, MW672118, MW672119, MW672120), A. phagocytophilum (MW672121), and A. capra (MW672115).

Characterization of "Candidatus Ehrlichia Pampeana" in Haemaphysalis juxtakochi Ticks and Gray Brocket Deer (Mazama gouazoubira) from Uruguay

Human ehrlichiosis are scantily documented in Uruguay. The aim of this study was to investigate the presence of Ehrlichia spp. in Haemaphysalis juxtakochi and in a gray brocket deer (Mazama gouazoubira) from Uruguay. The presence of Ehrlichia DNA was investigated in free-living H. juxtakochi in five localities of southeast and northeast Uruguay, as well as blood, spleen, and ticks retrieved from a M. gouazoubira. Ehrlichia spp. DNA was detected in six out of 99 tick pools from vegetation, in the spleen of M. gouazoubira, and in one out of five pools of ticks feeding on this cervid. Bayesian inference analyses for three loci (16S rRNA, dsb, and groEL) revealed the presence of a new rickettsial organism, named herein as "Candidatus Ehrlichia pampeana". This new detected Ehrlichia is phylogenetically related to those found in ticks from Asia, as well as Ehrlichia ewingii from USA and Cameroon. Although the potential pathogenicity of "Ca. E. pampeana" for humans is currently unknown, some eco-epidemiological factors may be relevant to its possible pathogenic role, namely: (i) the phylogenetic closeness with the zoonotic agent E. ewingii, (ii) the evidence of H. juxtakochi parasitizing humans, and (iii) the importance of cervids as reservoirs for zoonotic Ehrlichia spp. The molecular detection of "Ca. E. pampeana" represents the third Ehrlichia genotype described in Uruguay.

gltA typing of Anaplasma strains related to A. platys: Taxonomical and one health implications

Species belonging to the genus Anaplasma (Rickettsiales) include bacteria of veterinary and public health importance. Beside the zoonotic Anaplasma phagocytophilum, A. platys, the etiological agent of canine cyclic thrombocytopenia, has been sporadically reported in clinically ill human patients. The ongoing emergence of novel strains related to this species in vertebrate hosts emphasises the need for genetic comparisons among strains identified in different regions of the world. In this paper we developed a PCR test suitable for amplification of the still undescribed gltA gene of Anaplasma strains related to A. platys from Mediterranean ruminants and applied on a panel of 248 samples. gltA sequencing allowed phylogenetic comparison with strains related to A. platys recently identified in China, and strains representative of the Anaplasmataceae family. Results suggest the designation of Candidatus A. turritanum, including Mediterranean A. platys - like strains, and Candidatus A. cinensis, including strains isolated in China. Data generated in this study are a solid reference for future epidemiological studies of novel unclassified strains related to A. platys and for their diagnosis and raise concern on their potential veterinary and public health implications encouraging investigating the suspected unexplored diversity within the genus Anaplasma in animals and human.

Atelerix algirus, the North African Hedgehog: Suitable Wild Host for Infected Ticks and Fleas and Reservoir of Vector-Borne Pathogens in Tunisia

Small wild mammals are an important element in the emergence and transmission of vector-borne pathogens (VBPs). Among these species, hedgehogs have been found to be a reservoir of VBPs and host of arthropod vectors. Surveillance of VBPs in wildlife and their arthropods are crucial in a one health context. We conducted an exploratory study to screen Atelerix algirus hedgehogs and their infesting ticks and fleas for VBPs using a high throughput microfluidic real-time PCR system. Tested biopsies from hedgehogs were found to be naturally infected by Theileria youngi, Hepatozoon sp., Ehrlichia ewingii, Coxiella burnetii, and Candidatus Ehrlichia shimanensis. Similarly, Haemaphysalis erinacei and Rhipicephalus sanguineus tick species were infected by Ehrlichia ewingii, Rickettsia spp., Rickettsia massiliae, Borrelia sp., Coxiella burnetii, Rickettsia lusitaniae and Anaplasma sp. Archaeopsylla erinacei fleas were infected by Rickettsia asembonensis, Coxiella burnetii, and Rickettsia massiliae. Co-infections by two and three pathogens were detected in hedgehogs and infesting ticks and fleas. The microfluidic real-time PCR system enabled us not only to detect new and unexpected pathogens, but also to identify co-infections in hedgehogs, ticks, and fleas. We suggest that hedgehogs may play a reservoir role for VBPs in Tunisia and contribute to maintaining enzootic pathogen cycles via arthropod vectors.

Molecular detection and phylogenetic analyses of Anaplasma spp. in Haemaphysalis longicornis from goats in four provinces of China

Anaplasma species, which are distributed worldwide, are gram-negative obligate intracellular tick-borne bacteria that pose a threat to human and animal health. Haemaphysalis longicornis ticks play a vital role as vectors in the transmission of Anaplasma pathogens. However, the Anaplasma species carried by H. longicornis in China are yet to be characterized. In this study, 1074 H. longicornis specimens were collected from goats in four provinces of China from 2018 to 2019 and divided into 371 sample pools. All tick sample pools were examined for the presence of Anaplasma species via nested PCR amplification of 16S ribosomal RNA, major surface protein 4 (msp4), or citric acid synthase (gltA) genes, which were sequenced to determine the molecular and phylogenetic characteristics of the isolates. The overall Anaplasma spp-positive rate of H. longicornis was determined to be 26.68% (99/371). The percentage prevalence of A. phagocytophilum-like1, A. bovis, A. ovis, A. marginale, and A. capra were 1.08% (4/371), 13.21% (49/371), 13.21% (49/371), 1.35% (5/371), and 10.24% (38/371), respectively, and the co-infection rate of two or more types of Anaplasma was 6.47% (24/371). Phylogenetic analyses led to the classification of A. phagocytophilum into an A. phagocytophilum-like1 (Anaplasma sp. Japan) group. Anaplasma bovis sequences obtained in this study were 99.8–100% identical to those of an earlier strain isolated from a Chinese tick (GenBank accession no. KP314251). Anaplasma ovis sequences showed 99.3–99.6% identity to an A. ovis human strain identified from a Cypriot patient (GenBank accession no. FJ460443). Only one msp4 sequence of A. marginale was detected and was grouped with those of other A. marginale isolates, and these A. capra isolates obtained in this present study may be zoonotic. The detection and characterization of four Anaplasma species in H. longicornis in this study have added to the current knowledge of the parasite and provided data on multiple Anaplasma species with veterinary and medical significance from four provinces of China.

Dating Alphaproteobacteria evolution with eukaryotic fossils

Elucidating the timescale of the evolution of Alphaproteobacteria, one of the most prevalent microbial lineages in marine and terrestrial ecosystems, is key to testing hypotheses on their co-evolution with eukaryotic hosts and Earth's systems, which, however, is largely limited by the scarcity of bacterial fossils. Here, we incorporate eukaryotic fossils to date the divergence times of Alphaproteobacteria, based on the mitochondrial endosymbiosis that mitochondria evolved from an alphaproteobacterial lineage. We estimate that Alphaproteobacteria arose ~1900 million years (Ma) ago, followed by rapid divergence of their major clades. We show that the origin of Rickettsiales, an order of obligate intracellular bacteria whose hosts are mostly animals, predates the emergence of animals for ~700 Ma but coincides with that of eukaryotes. This, together with reconstruction of ancestral hosts, strongly suggests that early Rickettsiales lineages had established previously underappreciated interactions with unicellular eukaryotes. Moreover, the mitochondria-based approach displays higher robustness to uncertainties in calibrations compared with the traditional strategy using cyanobacterial fossils. Further, our analyses imply the potential of dating the (bacterial) tree of life based on endosymbiosis events, and suggest that previous applications using divergence times of the modern hosts of symbiotic bacteria to date bacterial evolution might need to be revisited.

Epizootic Situation on Anaplasmosis of Small Ruminants in the Irkutsk Region

Anaplasmosis of ruminants is a group of natural focal infections caused by bacteria from the genus Anaplasma of the Anaplasmataceae family. The main etiological agent of anaplasmosis in sheep, goats, and wild ruminants is Anaplasma ovis, which parasitizes in the erythrocytes of these animals. The purpose of this study was the finding and identification of Anaplasma spp. in the blood of small ruminants using genetic methods and obtaining data on the distribution of anaplasmosis in the Irkutsk region. 20 goat blood samples, 611 sheep blood samples and 209 Dermacentor nuttalli ticks from 12 districts of the Irkutsk region were examined for the presence of Anaplasma spp. Only one type of anaplasma, A. ovis, was found among the genotyped samples. A. ovis was found in the blood of sheep and goats in all of the studied districts of the Irkutsk region. The proportion of sheep blood samples containing anaplasma DNA varied from 30 % to 85 %, in goats – from 10 % to 100 % in different districts, and averaged 57.8 % in sheep and 55,0 % in goats. Frequency of infection of D. nuttalli ticks with A. ovis was 5.7 %. The nucleotide sequences of the samples detected in the blood of small ruminants on the territory of the Irkutsk region differed from each other by a single nucleotide substitution and were identical to the sequences of the type strain Haibei, as well as the sequences of A. ovis previously found in the blood of sheep from Mongolia, deer from China, and Dermacentor niveus and Dermacentor nuttalli ticks from China. These sequences were also identical to the sequences previously found in the blood of sheep from Altai and in Dermacentor nuttalli ticks from Tuva, which indicates the wide distribution of these A. ovis genovariants in Siberia and the probable role of D. nuttalli as a carrier of the agent of anaplasmosis of small ruminants in the Irkutsk region.

Genetic diversity of Anaplasma bacteria: Twenty years later

The genus Anaplasma (family Anaplasmataceae, order Rickettsiales) includes obligate intracellular alphaproteobacteria that multiply within membrane-bound vacuoles and are transmitted by Ixodidae ticks to vertebrate hosts. Since the last reclassification of Anaplasmataceae twenty years ago, two new Anaplasma species have been identified. To date, the genus includes eight Anaplasma species (A. phagocytophilum, A. marginale, A. centrale, A. ovis, A. bovis, A. platys, A. odocoilei, and A. capra) and a large number of unclassified genovariants that cannot be assigned to known species. Members of the genus can cause infection in humans and a wide range of domestic animals with different degrees of severity. Long-term persistence which, in some cases, is manifested as cyclic bacteremia has been demonstrated for several Anaplasma species. Zoonotic potential has been shown for A. phagocytophilum, the agent of human granulocytic anaplasmosis, and for some other Anaplasma spp. that suggests a broader medical relevance of this genus. Genetic diversity of Anaplasma spp. has been intensively studied in recent years, and it has been shown that some Anaplasma spp. can be considered as a complex of genetically distinct lineages differing by geography, vectors, and host tropism. The aim of this review was to summarize the current knowledge concerning the natural history, pathogenic properties, and genetic diversity of Anaplasma spp. and some unclassified genovariants with particular attention to their genetic characteristics. The high genetic variability of Anaplasma spp. prompted us to conduct a detailed phylogenetic analysis for different Anaplasma species and unclassified genovariants, which were included in this review. The genotyping of unclassified genovariants has led to the identification of at least four distinct clades that might be considered in future as new candidate species.

Molecular Detection and Phylogeny of Anaplasma phagocytophilum and Related Variants in Small Ruminants from Turkey

Simple Summary

We explored the existence of Anaplasma phagocytophilum and related variant in samples of goats and sheep obtained from Antalya and Mersin provinces, representative of Mediterranean region of Turkey. Based on 16S rRNA and groEL genes of A. phagocytophilum and related variants, we examined blood samples by polymerase chain reaction (PCR) followed by sequencing. The results showed that the prevalence of A. phagocytophilum and A. phagocytophilum-like 1 infection was 1.4% and 26.5%, respectively. Sequencing confirmed molecular data and showed the presence of A. phagocytophilum and A. phagocytophilum-like-1 variant in the sampled animals.

Abstract

Anaplasma phagocytophilum causes tick-borne fever in small ruminants. Recently, novel Anaplasma variants related to A. phagocytophilum have been reported in ruminants from Tunisia, Italy, South Korea, Japan, and China. Based on 16S rRNA and groEL genes and sequencing, we screened the frequency of A. phagocytophilum and related variants in 433 apparently healthy small ruminants in Turkey. Anaplasma spp. overall infection rates were 27.9% (121/433 analyzed samples). The frequency of A. phagocytophilum and A. phagocytophilum-like 1 infections was 1.4% and 26.5%, respectively. No A. phagocytophilum-like 2 was detected in the tested animals. The prevalence of Anaplasma spp. was comparable in species, and no significant difference was detected between sheep and goats, whereas the prevalence significantly increased with tick infestation. Sequencing confirmed PCR-RFLP data and showed the presence of A. phagocytophilum and A. phagocytophilum-like-1 variant in the sampled animals. Phylogeny-based on 16S rRNA gene revealed the A. phagocytophilum-like 1 in a separate clade together with the previous isolates detected in small ruminants and ticks. In this work, A. phagocytophilum-like 1 has been detected for the first time in sheep and goats from Turkey. This finding revealed that the variant should be considered in the diagnosis of caprine and ovine anaplasmosis.

'Candidatus Sarmatiella mevalonica' endosymbiont of the ciliate Paramecium provides insights on evolutionary plasticity among Rickettsiales

Members of the bacterial order Rickettsiales are obligatorily associated with a wide range of eukaryotic hosts. Their evolutionary trajectories, in particular concerning the origin of shared or differential traits among distant sub-lineages, are still poorly understood. Here, we characterized a novel Rickettsiales bacterium associated with the ciliate Paramecium tredecaurelia and phylogenetically related to the Rickettsia genus. Its genome encodes significant lineage-specific features, chiefly the mevalonate pathway gene repertoire, involved in isoprenoid precursor biosynthesis. Not only this pathway has never been described in Rickettsiales, it also is very rare among bacteria, though typical in eukaryotes, thus likely representing a horizontally acquired trait. The presence of these genes could enable an efficient exploitation of host-derived intermediates for isoprenoid synthesis. Moreover, we hypothesize the reversed reactions could have replaced canonical pathways for producing acetyl-CoA, essential for phospholipid biosynthesis. Additionally, we detected phylogenetically unrelated mevalonate pathway genes in metagenome-derived Rickettsiales sequences, likely indicating evolutionary convergent effects of independent horizontal gene transfer events. Accordingly, convergence, involving both gene acquisitions and losses, is highlighted as a relevant evolutionary phenomenon in Rickettsiales, possibly favoured by plasticity and comparable lifestyles, representing a potentially hidden origin of other more nuanced similarities among sub-lineages.

Wentzel J, Wills-Berriman S, Boni LD, Weyer J, Rossouw J, Oosthuizen MC. Anaplasma phagocytophilum and Other Anaplasma spp. in Various Hosts in the Mnisi Community, Mpumalanga Province, South Africa

DNA samples from 74 patients with non-malarial acute febrile illness (AFI), 282 rodents, 100 cattle, 56 dogs and 160 Rhipicephalus sanguineus ticks were screened for the presence of Anaplasma phagocytophilum DNA using a quantitative PCR (qPCR) assay targeting the msp2 gene. The test detected both A. phagocytophilum and Anaplasma sp. SA/ZAM dog DNA. Microbiome sequencing confirmed the presence of low levels of A. phagocytophilum DNA in the blood of rodents, dogs and cattle, while high levels of A. platys and Anaplasma sp. SA/ZAM dog were detected in dogs. Directed sequencing of the 16S rRNA and gltA genes in selected samples revealed the presence of A. phagocytophilum DNA in humans, dogs and rodents and highlighted its importance as a possible contributing cause of AFI in South Africa. A number of recently described Anaplasma species and A. platys were also detected in the study. Phylogenetic analyses grouped Anaplasma sp. SA/ZAM dog into a distinct clade, with sufficient divergence from other Anaplasma species to warrant classification as a separate species. Until appropriate type-material can be deposited and the species is formally described, we will refer to this novel organism as Anaplasma sp. SA dog.

Molecular detection and phylogeny of Anaplasma spp. in cattle reveals the presence of novel strains closely related to A. phagocytophilum in Turkey

Anaplasma species are obligate intracellular rickettsial pathogens that affect the health of humans and animals. In this study, we investigated the presence and frequency of Anaplasma species by 16S rRNA PCR-RLB, RFLP, and DNA sequencing in 200 apparently healthy cattle. Anaplasma spp. overall infection rate was 38.5 % (77/200) by RLB. The frequency of single and mixed infections was 31.5 % (63/200) and 7% (14/200), respectively. The most common species was A. marginale (32.5 %), followed by A. centrale (5.5 %), Anaplasma/Ehrlichia catc-all (5.5 %) and Anaplasma sp. Omatjenne (2.5 %). No A. phagocytophilum and A. bovis were detected in the tested animals. Eleven of 77 PCR-positive amplicons gave positive reactions to the catch-all probes but did not show any signals to the species-specific probes, but PCR-RFLP results showed that these amplicons were A. phagocytophilum-like 1 and A. phagocytophilum-like 2 strains. Sequencing and phylogenetic analyses based on 16S rRNA gene validated RFLP findings and provided evidence for the circulation of A. phagocytophilum-like-1 and 2 strains in Turkish cattle. This is the first report of the presence of A. phagocytophilum-like strains in the country. These findings indicate that A. phagocytophilum-like 1 and 2 strains should be taken into account in the differential diagnosis with bovine anaplasmosis.

The Prevalence of Different Human Pathogenic Microorganisms Transmitted by Ixodes Tick Vectors in Belarus

Pathogens transmitted by ticks cause several important diseases in humans, including Lyme disease, the incidence of which has been increasing in Belarus. Between April and October 2017, a total of 504 questing Ixodid ticks (77% Ixodes ricinus and 23% Dermacentor reticulatus) were collected from six regions and city of Minsk, in Belarus. All ticks were analyzed by RT-PCR amplification for the presence of Borrelia burgdorferi sensu lato, tick-borne encephalitis virus (TBEV), Anaplasma phagocytophillum, Ehrlihia muris, and Borrelia miyamotoi. B. burgdorferi s.l. and Rickettsia spp. were the most commonly detected tick-borne pathogens, with prevalence rates of 31.08% and 33.7%, respectively. A. phagocytophillum was found in 104 (20.63%), and 107 (21.2%) ticks were positive for E. muris. TBEV was detected in 83 (16.47%). Circulation of Borrelia miyamotoi spirochete in I. ricinus ticks in Brest, Gomel, and Minsk region was detected for the first time. Our data provide a basis for further studies to determine the distribution and abundance of different tick species in Belarus and therefore a capacity to predict where cases of important tick-borne diseases may occur.

Molecular epidemiology of Rickettsia sp. and Coxiella burnetii collected from Hyalomma asiaticum in Bactrian camels (Camelus bactrianus) in inner Mongolia of China

The purpose of the present study was to determine the presence of Rickettsia sp. and Coxiella burnetii in Hyalomma asiaticum collected from Bactrian camels (Camelus bactrianus) in Inner Mongolia of China. A total of 385 H. asiaticum adults collected from Bactrian camels from Alxa in Inner Mongolia from 2017 to 2018 were examined using PCR combined with sequencing. The results indicated that 18 (4.7 %) and 5 (1.3 %) samples tested positive for Rickettsia and C. burnetii, respectively. The corresponding nucleotide identities among detected genes ranged between 99.7 % and 100 % for the sequences of 17 kD and ompB from Rickettsia and 16S rRNA and FtsX from C. burnetii. Two representative strains-Rickettsia IMA-1 strain and C. burnetii IMA-1 strain-were used for subsequent analysis. NCBI BLAST and phylogenetic analyses demonstrated that the detected strain Rickettsia IMA-1 may represent a novel species of spotted fever group (SFG) rickettsiae. The C. burnetii IMA-1 strain was grouped with Coxiella burnetii str. RSA439 (GenBank: CP040059.1). In addition, the Rickettsia sp. was successfully isolated from the ticks in Vero cells incubated at 28 °C. These findings indicate that the H. asiaticum collected off Bactrian camels in Inner Mongolia carried SFG Rickettsia species and C. burnetii and could contribute to the etiology of febrile illness in animals and humans.

Extensive genetic diversity of Anaplasma bovis in ruminants in Xi'an, China

Anaplasma bovis is an organism significant to cattle and buffalo since it is one of the causative agents of bovine anaplasmosis. Previous studies have shown the worldwide distribution of A. bovis. However, most of these studies about its genetic diversity only focused on the rrs gene. In this study, DNA of A. bovis was detected in blood samples of cattle and goats in Xi'an city, China by nested-PCR. Near full-length rrs, groEL, and gltA genes were amplified successfully from the positive samples. Genetic analysis showed that specific genetic marker (an insertion and a deletion) was found in the rrs sequences in some strains, as well as clone 88 from monkeys in previous study. Phylogenetic analysis based on the rrs, groEL, and gltA genes revealed that A. bovis circulating in Xi'an exhibited great genetic diversity. Our results also indicated that variants outside China presented geographic clustering, and all A. bovis isolates based on the groEL or gltA gene also showed a host origin clustering. Also of note was that the phylogenetic analyses of the groEL and gltA genes suggested that both frequent dispersals over long distances in recent years and local adaptation over long evolutionary timescales played important roles in the distribution and evolution of A. bovis in China. Finally, a potential recombination event in the genome of Zhouzhi-cattle-10 based on inconsistent positions in the groEL and gltA trees was also observed. These results also reinforce the need for assessing the pathogenicity to humans of A. bovis variants with specific marker in the rrs gene.

Genotypic Analysis of Piroplasms and Associated Pathogens from Ticks Infesting Cattle in Korea

Tick-borne pathogens (TBPs) impose an important limitation to livestock production worldwide, especially in subtropical and tropical areas. Earlier studies in Korea have examined TBPs residing in ticks and animals; however, information on multiple TBPs in ticks infesting cattle is lacking. This study assessed the prevalence of TBPs in ticks parasitizing cattle. A total of 576 ticks, including 340 adults and 236 nymphs, were collected from cattle in Korea between 2014 and 2018. All ticks collected were identified as Haemaphysalis longicornis based on their morphological and molecular characteristics. Among piroplasms and other tick-associated pathogens, seven TBP genes, namely Theileria orientalis (5.0%), Anaplasma bovis (2.3%), Anaplasma capra (4.7%), Anaplasma phagocytophilum-like Anaplasma spp. (APL) clades A (1.9%) and B (0.5%), Ehrlichia canis (1.6%), and Candidatus Rickettsia longicornii (17.5%), were detected. Bartonella spp. and severe fever with thrombocytopenia syndrome virus were not found. To our knowledge, this is the first study to report the presence of the pathogens T. orientalis major piroplasm surface protein genotypes 3 and 7, A. capra, and APL in ticks from Korea. Cattle ticks may be maintenance hosts for many TBPs, and veterinary and medical clinicians should be aware of their high probability of infection and clinical complexity in humans.

Molecular phylogeny and genetic diversity based on msp1a, groEL and gltA genes of Anaplasma ovis Tunisian isolates compared to available worldwide isolates and strains

Anaplasma ovis, the causative agent of ovine anaplasmosis in tropical and subtropical countries, is a tick-borne obligatory intraerythrocytic bacterium of sheep, goats and wild ruminants. In Tunisia, data about the molecular phylogeny and the genetic diversity of A. ovis isolates are limited to the analysis of msp4 and groEL genes. The aim of this study was to genetic characterize 40 A. ovis isolates infecting 28 goats, 10 sheep, one camel and one Rhipicephalus turanicus tick located in different geographic regions of Tunisia on the basis of 3 partial genes (gltA, groEL and msp1a). Sequence analysis revealed 6 and 17 different genotypes in the partial gltA and groEL genes, respectively. Phylogenetic analysis revealed, as expected for the groEL gene, that sequences from small ruminants and their infesting ticks clustered separately from those isolated from camels. The analysis of amino-acid Msp1a sequences identified 18 novel genotypes of Msp1a repeats from 20 A. ovis isolates. These Msp1a repeats were highly variable with 33-47 amino-acids, and the number of repeats is one for 19 isolates infecting 18 goats and one R. turanicus tick, and 4 for a single isolate found in one sheep. Phylogenetic trees based on Msp1a partial sequences revealed that the N-terminal region of Msp1a protein appear to be relatively more informative phylogeographically compared to other markers especially according to countries. The presented data give a more detailed knowledge regarding the molecular phylogeny and the genetic diversity of A. ovis isolates occurring in different animal species and their associated ticks in Tunisia.

Molecular detection of Anaplasma spp. in dairy cattle in southern Xinjiang, China

Bovine anaplasmosis is caused by a group of obligate intracellular bacteria belonging to the genus Anaplasma, which are transmitted by ticks. This study was conducted to determine the prevalences and molecular characterization of Anaplasma spp. in dairy cattle in the upper reaches of the Tarim River in Xinjiang, China. Using polymerase chain reaction (PCR) and sequencing approaches, DNA of Anaplasma spp. was detected in 16 of 493 (3.2%) blood samples from dairy cattle. Positive rates were 0.2% (1/493), 0.4% (2/493), 0.2% (1/493), 2.4% (12/493) and 2.4% (12/493) for A. bovis, A. ovis, A. phagocytophilum like strain, A. phagocytophilum and A. platys like strain, respectively. Anaplasma phagocytophilum and A. platys like strain co-infection was detected in 12 samples. To our knowledge, this is the first report of A. ovis infection in dairy cattle in Xinjiang. This study provides new data on the prevalences of Anaplasma spp. in cattle in Xinjiang, which will help to formulate appropriate control strategies for these pathogens in this area.