Low genetic diversity associated with low prevalence of Anaplasma marginale in water buffaloes in Marajó Island, Brazil

Artificial Feeding of Ornithodoros fonsecai and O. brasiliensis (Acari: Argasidae) and Investigation of the Transstadial Perpetuation of Anaplasma marginale

Anaplasma marginale is a Gram-negative, obligate intraerythrocytic bacterium that causes bovine anaplasmosis. While hard ticks of the genera Dermacentor and Rhipicephalus can be biological vectors, transmitting this pathogen via saliva during blood meals, blood-sucking insects, and fomites play a role as mechanical vectors. Little is known about the interaction between Anaplasma marginale and Argasidae ticks. Among soft ticks, Ornithodoros fonsecai (Labruna and Venzal) and Ornithodoros brasiliensis Aragão inhabit environments surrounding localities where many cases of bovine anaplasmosis have been reported. Ticks of the species O. fonsecai parasitize bats, while O. brasiliensis can parasitize different vertebrate species. Therefore, the present study aimed to feed third-instar nymphs artificially (N3) of O. fonsecai and O. brasiliensis using blood samples obtained from a calf naturally infected with A. marginale and rabbit blood added to A. marginale-containing bovine erythrocytes, to investigate the ability of these nymphs to acquire, infect and transstadially perpetuate this agent. For the artificial feeding system, adapted chambers and parafilm membranes were used. Nymphs of both tick species were submitted to different replications weighed before and after each feeding. Blood samples and molted ticks were submitted to DNA extraction, quantitative real-time PCR for the msp1β gene to detect A. marginale DNA, while a semi-nested polymerase chain reaction for the msp1α gene was performed for genotyping. Using calf blood naturally infected with A. marginale, among the three artificial feeding replications performed with O. fonsecai and O. brasiliensis nymphs, the DNA of A. marginale was detected in both nymphs after 30-50 days of molting. For artificial feeding with rabbit blood added to bovine erythrocytes containing A. marginale, the DNA of this pathogen was also detected in both nymph species. As for the assay for the msp1α gene, strains were found Is9; 78 24-2; 25; 23; α; and β. It was concluded that nymphs (N3) of O. fonsecai and O. brasiliensis could feed artificially through a parafilm membrane using blood from calves and rabbits infected by A. marginale. The DNA of A. marginale was detected in nymphs fed artificially of both tick species studied after molt. However, further studies are needed to confirm transstadial perpetuation in other instars and their host transmission capacity.

Global prevalence and species diversity of tick-borne pathogens in buffaloes worldwide: a systematic review and meta-analysis

BACKGROUND

Buffaloes are important contributors to the livestock economy in many countries, particularly in Asia, and tick-borne pathogens (TBPs) commonly infect buffaloes, giving rise to serious pathologies other than their zoonotic potential.

METHODS

The present investigation focuses on the prevalence of TBPs infecting buffaloes worldwide. All published global data on TBPs in buffaloes were collected from different databases (e.g., PubMed, Scopus, ScienceDirect, and Google Scholar) and subjected to various meta-analyses using OpenMeta[Analyst] software, and all analyses were conducted based on a 95% confidence interval.

RESULTS

Over 100 articles discussing the prevalence and species diversity of TBPs in buffaloes were retrieved. Most of these reports focused on water buffaloes (Bubalus bubalis), whereas a few reports on TBPs in African buffaloes (Syncerus caffer) had been published. The pooled global prevalence of the apicomplexan parasites Babesia and Theileria, as well as the bacterial pathogens Anaplasma, Coxiella burnetii, Borrelia, Bartonella, and Ehrlichia in addition to Crimean-Congo hemorrhagic fever virus, were all evaluated based on the detection methods and 95% confidence intervals. Interestingly, no Rickettsia spp. were detected in buffaloes with scarce data. TBPs of buffaloes displayed a fairly high species diversity, which underlines the high infection risk to other animals, especially cattle. Babesia bovis, B. bigemina, B. orientalis, B. occultans and B. naoakii, Theileria annulata, T. orientalis complex (orientalis/sergenti/buffeli), T. parva, T. mutans, T. sinensis, T. velifera, T. lestoquardi-like, T. taurotragi, T. sp. (buffalo) and T. ovis, and Anaplasma marginale, A. centrale, A. platys, A. platys-like and "Candidatus Anaplasma boleense" were all were identified from naturally infected buffaloes.

CONCLUSIONS

Several important aspects were highlighted for the status of TBPs, which have serious economic implications for the buffalo as well as cattle industries, particularly in Asian and African countries, which should aid in the development and implementation of prevention and control methods for veterinary care practitioners, and animal owners.

High genetic diversity of Anaplasma marginale infecting dairy cattle in northeastern Brazil

Anaplasma marginale is an obligate intracellular Gram-negative bacterium found in ruminants' erythrocytes and is the etiological agent of bovine anaplasmosis. The bacterium's genetic diversity has been characterized based on sequences of major surface proteins (MSPs), such as MSP1α. The aim of the present study was to investigate the genetic diversity of A. marginale in cattle in the state of Maranhão, northeastern Brazil. To this end, 343 blood samples were harvested and subjected to iELISA assays using the recombinant surface protein MSP5. Out of 343 blood samples, 235 (68.5%) were randomly chosen and submitted to DNA extraction, qPCR and conventional PCR targeting the msp1α gene to determine amino acid sequences and classify the genotypes. The iELISA results showed 81.34% seropositivity (279/343), whereas qPCR revealed 224 positive samples (95.32%). Among these qPCR-positive samples, 67.4% (151/224) were also positive in the cPCR. Among the 50 obtained sequences, 21 strains had not been previously reported. Regarding the genotypes, H (26/50) and E (18/50) were identified most often, while genotypes F and C were only identified twice each and B and G once each. In conclusion, high prevalence and genetic diversity for A. marginale were observed in dairy cattle herds in the state of Maranhão.

High genetic diversity and superinfection by Anaplasma marginale strains in naturally infected Angus beef cattle during a clinical anaplasmosis outbreak in southeastern Brazil

Anaplasma marginale is an obligate intracellular Gram-negative bacterium that is parasitic to erythrocytes and is the main agent of bovine anaplasmosis. This disease causes severe anemia and reduces weight gain and milk production, thus giving rise to major economic losses relating to livestock worldwide. The genetic diversity of this bacterium has been characterized based on sequences of major surface proteins (MSPs), especially MSP1α. This has enabled identification of several geographical strains, according to different amino acid sequences. The aim of this study was to investigate the genetic diversity of A. marginale in naturally infected Angus beef cattle during a disease outbreak in southeastern Brazil. Four blood samples were collected over a four-month period from each of 20 animals on a cattle farm in Itú, São Paulo, Brazil. Serum samples were subjected to indirect ELISA to detect anti-A. marginale IgG antibodies. The 80 whole-blood samples obtained were subjected to DNA extraction, quantitative real-time PCR (qPCR) for the msp1β gene, semi-nested PCR (snPCR) for the msp1α gene, cloning of the target fragment and sequencing using the Sanger method. The sequences obtained were analyzed for genetic diversity using the RepeatAnalyzer software. Both iELISA tests, using recombinant MSP5 and the Anaplasma antibody test kit (VMRD), revealed high seroprevalence: 91.25% and 97.5%, respectively. In qPCR, 100% of the samples were positive, with between 10³ and 10⁷ DNA copies/μL. In the snPCR based on the msp1α gene, 57.5% (46/80) of the samples were positive. Microsatellite analysis on the 36 sequences obtained showed the presence of genotypes H (58.3%), F (25%), E (19.4%), C (2.7%) and G (2.7%). The RepeatAnalyzer software identified 36 strains in the study region, among which some had not previously been described in the literature (13 27 13 27 13 F; 16 FF; τ 27; 63 29 104 29; LJ1 13 LJ1 13; 16 F 17; 16 F 91). High genetic diversity of A. marginale bacteria was found on this farm in Itú, São Paulo.

Genomic analysis on Brazilian strains of Anaplasma marginale

Anaplasma marginale is a vector-borne pathogen that causes a disease known as anaplasmosis. No sequenced genomes of Brazilian strains are yet available. The aim of this work was to compare whole genomes of Brazilian strains of A. marginale (Palmeira and Jaboticabal) with genomes of strains from other regions (USA and Australia strains). Genome sequencing of Brazilian strains was performed by means of next-generation sequencing. Reads were mapped using the genome of the Florida strain of A. marginale as a reference sequence. Single nucleotide polymorphisms (SNPs) and insertions/deletions (INDELs) were identified. The data showed that two Brazilian strains grouped together in one particular clade, which grouped in a larger American group together with North American strains. Moreover, some important differences in surface proteins between the two Brazilian isolates can be discerned. These results shed light on the evolutionary history of A. marginale and provide the first genome information on South American isolates. Assessing the genome sequences of strains from different regions is essential for increasing knowledge of the pan-genome of this bacteria.

Genetic diversity of major surface protein 1a of Anaplasma marginale in dairy cattle

Major surface protein 1 alpha (Msp1α) is a stable genetic marker for identifying Anaplasma marginale. Our aims were to investigate the genetic diversity of A. marginale based on microsatellites and tandem repeats of the msp1α gene and to determine the phylogenetic relationships among six isolates obtained from 63 dairy cows positive for the pathogen from Turkey and from strains worldwide. Msp1α microsatellite analysis revealed infection with three genotypes (B, C, G). Genotype B was found in cows held in an intensive management system, while genotypes C and G were found in grazing cows. Microsatellite sequences produced SD-ATG distances of 19 and 23 nucleotides, with 23 nucleotides predominating, showing high infection potential. Fourteen different tandem repeats of A. marginale were found in the samples, and four msp1α gene repeats designated Tr4, Tr5, Tr6 and Tr7 were newly described. The majority of A. marginale isolates exhibited more than three Msp1a tandem repeats, with a maximum of seven. The Msp1a tandem repeats α-73-73-73-73-73-73 were commonly observed in intensively managed cows. The phylogenetic analysis revealed A. marginale strains from Turkey clustering with those of the Americas, Africa, Asia and Europe, suggesting a history of cattle trade and transport.

Epidemiology and genetic diversity of Anaplasma marginale in Zamora-Chinchipe, Ecuador

Bovine anaplasmosis, caused by the tick-borne pathogen Anaplasma marginale, is a hemolytic disease that constitutes a major constraint to cattle production in tropical and subtropical regions including Ecuador. However, the epidemiological situation of this hemoparasitosis in Ecuador is poorly characterized. The present study was aimed to determine the prevalence and genetic diversity of A. marginale in cattle of Ecuador. A cross-sectional study was carried out covering several farms from six out nine cantons of the Zamora-Chinchipe province. A total of 185 cattle were randomly selected and blood samples were collected from the animals. The studied group of animals included six breeds, three age groups, and both sexes. The molecular diagnostic was performed based on a nPCR assay targeting the A. marginale msp5 gene. Anaplasma marginale prevalence was 63.8 % and the bacteria were detected in all the cantons studied. Thirteen representative strains were selected and genetically characterized based on the msp1α gene. Genetic diversity analysis revealed that different strains circulate in the bovine herds studied. The results suggest that cattle movement may contribute to the circulation of common strains in the area. The results demonstrate a high prevalence of A. marginale in the region which should be considered by the sanitary authorities. The epidemiological surveillance for this disease should increase to anticipate acute disease outbreaks with high mortality. Bovine anaplasmosis outbreaks can cause economic losses and the death of several animals; therefore, measures for the prevention and control of this disease are required.

Development and application of a multiplex TaqMan® real-time qPCR assay for the simultaneous detection of Anaplasma marginale and Theileria annulata and molecular characterization of Anaplasma marginale from cattle in Western Cuba

Anaplasmosis and theileriosis are considered the most important tick-borne diseases for livestock production worldwide, causing significant economic losses in tropical and subtropical regions. The present study was aimed to develop a multiplex TaqMan® qPCR assay to simultaneously detect Anaplasma marginale and Theileria annulata and to applied it to investigate naturally infected cattle in Cuba. The assay was highly specific, sensible, and efficient; it was more sensitive than a well-established nested PCR and detected 1 DNA copy of each target. Consistent repeatability and reproducibility within and between multiplex qPCR runs was shown. A total of 223 blood samples collected in western Cuba were analyzed for haemoparasites infection in cattle. The multiplex qPCR assay detected A. marginale in 213 samples (95.5%; CI: 95%; 91.9%-97.5%), but all samples were negative for T. annulata. Additionally, the genetic diversity of A. marginale was assessed using 16S rRNA, MSP1a and MSP4 nucleotide and protein sequences. The MSP1a tandem repeats ranged from three to five, and twelve different MSP1a tandem repeats of A. marginale were found, which presented genotypes C, E, and G in the 5'UTR microsatellite region. Phylogenetic analysis using the msp4 gene showed that Cuban strains were closely related to others previously reported in Mexico, Brazil and Asian countries. The multiplex qPCR described here proved to be a rapid, specific and cost-effective mean for the simultaneous detection of A. marginale and T. annulata. Further epidemiological studies using this assay will improve the surveillance of the associated diseases in regions where they are endemic.

Genetic diversity of Anaplasma marginale in beef cattle in the Brazilian Pantanal

There are few studies on the genetic diversity of Anaplasma marginale in Brazilian cattle herds, especially about beef cattle. The objective of this study was to evaluate the genetic diversity of A. marginale, based on the msp1α gene in Bos taurus indicus sampled from the Brazilian Pantanal. Aliquots of blood with and without EDTA were taken from 400 cattle (200 cows and 200 calves) across five extensive farms. The samples were submitted to the indirect immunoenzymatic assay (iELISA), quantitative real-time PCR (qPCR) for the msp1β gene and to the semi-nested (sn) PCR for the msp1α gene. Positive samples were sequenced by the Sanger method and subjected to diversity analysis using the RepeatAnalyser software. The percentage of positive animals by iELISA, qPCR and (sn) PCR was 72.2% (289/400), 56.7% (227/400) and 23% (52/227), respectively. Cows (154/200) showed to be significantly more seropositive than calves (135/200). In qPCR, the number of calves and average quantification value (138/200; 1.3 × 10⁶) A. marginale msp1α copies per μL proved to be higher when compared to that found for the cows (89/200; 3.9 × 10⁴). The microsatellite analysis of the 26 sequences obtained from the msp1α gene revealed the presence of E (77%), C (15.4%) and B (7.7%) genotypes. Fourteen A. marginale strains were identified in the studied region, with eight that have never before been described in the literature (τ-10-13-13-18; τ-27-18; EV8-EV8-17; α-β-β-β-100; EV7-11-10-15; τ-11-11-27-18; τ-11-10-15; τ-27-13-18). Beef cattle are highly exposed to A. marginale in the Brazilian Pantanal. Moreover, a high genetic diversity of A. marginale, with eight new strains, was found in the studied region. While cows may act as chronic carriers, perpetuating the pathogen within the herd, male beef calves sold to other regions may disperse these strains.

Theileria sp. in water buffaloes from Maranhão State, northeastern Brazil

Anaplasma marginale and piroplasm species are widespread among Brazilian cattle herds. Both of these tick-borne pathogens hamper livestock production and cause a significant economic impact. Although buffaloes have demonstrated a high level of adaptability, data on tick-borne pathogens are scarcely reported in Brazil. Thus, the aim of this study was to screen water buffaloes from the state of Maranhão for piroplasm and A. marginale occurrence using PCR assays. All samples were negative for A. marginale. One of the 287 (0.35%) water buffaloes tested was positive for Theileria sp. Sequencing of the 18S rDNA fragment (356 bp) showed that the Theileria sp. identified was closely related to the T. buffeli /orientalis group. Future studies on the clinical signs of infection and the main vector in this country are needed.

Molecular evidence of the reservoir competence of water buffalo (Bubalus bubalis) for Anaplasma marginale in Cuba

Water buffalo (Bubalus bubalis) is a potential reservoir for Anaplasma marginale in livestock ecosystems of tropical countries. However, their participation in the epidemiological process of bovine anaplasmosis in endemic areas remains unclear. In the present study, the reservoir competence of water buffalo for A. marginale was explored by focusing on the analysis of rickettsemia levels in carrier animals, and the genetic characterization of A. marginale strains from cattle and buffalo. Eight groups of cattle and water buffaloes were randomly selected from cohabiting herds in four livestock ecosystems of Cuba, together with two control groups from unrelated cattle and buffalo herds. A total of 180 adult animals (88 water buffalo and 92 cattle) were sampled. Rickettsemia in carrier animals was determined by quantitative real-time PCR. The rickettsemia (parasitemia) levels in cattle were higher than in buffaloes, however the rickettsemia in buffalo may be enough to infect R. microplus ticks. The genetic diversity of A. marginale was assessed by strain characterization and phylogenetic analysis of 27 msp1α gene sequences. The results showed genetic similarity among strains from cattle and water buffalo, suggesting the occurrence of cross-species transmission.

Insight into the genetic diversity of Anaplasma marginale in cattle from ten provinces of China

BACKGROUND

Anaplasma marginale is an important tick-transmitted rickettsial pathogen of cattle, with worldwide distribution and an important economic impact. The genetic diversity of A. marginale strains has been extensively characterized in different geographical regions throughout the world, while information is limited on studies in China. This study was carried out to determine the prevalence and genetic diversity of A. marginale strains in cattle from ten provinces of China.

METHODS

A total of 557 blood samples from cattle were collected and screened for the occurrence of A. marginale by PCR based on the msp4 gene. The partial msp1a gene containing tandem repeat sequences was further amplified from msp4 positive samples. The Msp1a amino acid repeats were identified, and genetic variation of A. marginale strains was characterized based on the variation in the repeated portion of Msp1a.

RESULTS

Our results showed that 31.6% of 557 cattle were positive for A. marginale. The infection rates of A. marginale varied considerably from 0 to 96.9% in different sampling regions. Sequence analysis revealed that two msp4 sequence variants of A. marginale exist in cattle. One hundred and three msp1a sequences were obtained and permitted to identify 42 Msp1a tandem repeats, 21 of which were not previously published for A. marginale. Moreover, 61 A. marginale genotypes were identified based on the structure of Msp1a tandem repeats.

CONCLUSIONS

Anaplasma marginale is widely distributed in China and a high prevalence of infection was observed in cattle. The geographical strains of A. marginale were molecularly characterized based on the structure of Msp1a tandem repeats. Forty-two Msp1a tandem repeats and 61 genotypes of A. marginale were identified. This study, for the first time, revealed the genetic diversity of A. marginale strains in cattle in China.

RepeatAnalyzer: a tool for analysing and managing short-sequence repeat data

Background

Short-sequence repeats (SSRs) occur in both prokaryotic and eukaryotic DNA, inter- and intragenically, and may be exact or inexact copies. When heterogeneous SSRs are present in a given locus, we can take advantage of the pattern of different repeats to genotype strains based on the SSRs. Cataloguing and tracking these repeats can be difficult as diverse groups of researchers are involved in the identification of the repeats. Additionally, the task is error-prone when done manually.

Results

We developed RepeatAnalyzer, a new software tool capable of tracking, managing, analysing and cataloguing SSRs and genotypes using Anaplasma marginale as a model species. RepeatAnalyzer’s analysis capability includes novel metrics for measuring regional genetic diversity (corresponding to variety and regularity of SSR occurrence). As a part of its visualization capabilities, RepeatAnalyzer produces high quality maps of the geographic distribution of genotypes or SSRs over a region of interest. RepeatAnalyzer’s repeat identification functionality was validated for all SSRs and genotypes reported in 21 publications, using 380 A. marginale isolates gathered from the five publications within that list that provided access to their isolates. The tool produced accurate genotyping results in every case. In addition, it uncovered a number of errors in the published literature: 11 cases where SSRs were misreported, 5 cases where two different SSRs had been given the same name, and 16 cases where two or more names had been given to a single SSR. The analysis and visualization functionalities of the tool are demonstrated using several examples.

Conclusions

RepeatAnalyzer is a robust software tool that can be used for storing, managing, and analysing short-sequence repeats for the purpose of strain identification. The tool can be used for any set of SSRs regardless of species. When applied to A. marginale, our test case, we show that genotype lengths for a given region follow a normal distribution, while SSR frequencies follow a power-law-like distribution. Further, we find that over 90 % of repeats are 28 to 29 amino acids long, which is in agreement with conventional wisdom. Lastly, our analysis reveals that the most common edit distance is five or six, which is counter-intuitive since we expected that result to be closer to one, resulting from the simplest change from one repeat to another.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-016-2686-2) contains supplementary material, which is available to authorized users.