Gapless assembly of Babesia bovis NVSL348.

We are reporting a Babesia bovis genome containing four nuclear chromosomes, a mitochondrial genome, and an apicoplast from reference isolate NVSL348. This report includes a gapless assembly consisting of all six genetic molecules.

The Prevalence and Molecular Characterization of Bovine Babesia Species and the First Report of B. bovis from Kashmir Himalayas.

Background: Bovine babesiosis, a global disease, has not been studied so far in Kashmir valley, which is having temperate type of climate as compared to rest of India having tropical to sub-tropical climate, so we felt the need to investigate it. Methods: To diagnose the babesiosis in clinically suspected cattle (n=450), peripheral blood film examination and PCR tests using generic and species-specific primers targeting Babesia/Theleria genera and B. bigemina, B. bovis as well as B. divergens, respectively were conducted. Four PCR products were sequenced and subjected to BLASTn analysis. Ticks were collected from the clinically suspected animals and identified as per the standard morphological keys. Results: The prevalence of babesiosis among suspected cattle in central Kashmir by peripheral blood film examination and PCR technique was 11.11% and 33.62%, respectively. The 18S rRNA gene of Isolate B1 of Babesia spp. showed 99.0 to 100% nucleotide sequence homology with 18S rRNA gene of different isolates of B. bigemina registered in the GenBank, while as 18S rRNA gene of Isolate Z showed 98.5 to 99.2% and 93.1 to 93.9% nucleotide sequence homology with 18S rRNA gene of different isolates of Babesia spp. and B. bigemina, respectively, registered in the GenBank. Rhipicephalus spp. and Haemaphysalis spp. were the two major tick genera identified in the present study. Conclusion: Bovine Babesiosis in Kashmir is attributed to B. bovis, B. bigemina and some other Babesia spp. or strains which needs further investigation. To our knowledge, this is the first report of Babesia bovis from northern India in cattle.

Discovery of Colpodella spp. in ticks (Hyalomma dromedarii) infesting camels in southern Egypt.

In Egypt, tick-borne diseases pose a significant threat to human and animal health, and the threat to dromedaries (Camelus dromedarius), the country's dominant camelid species, is of particular concern. These animals are frequently infested with ticks, and may thus develop tick-borne diseases or become reservoirs of tick-borne pathogens. However, there is a paucity of data on tick infestation in Egyptian camels, especially in the south of the country. Accordingly, we aimed to determine the prevalence of tick infestation in southern Egyptian camel populations (in Luxor and Aswan governorates), and identify the hemoprotozoan parasites carried by camel-infesting ticks. Camels were checked for ticks during veterinary examination at quarantine and household checks, and ticks were collected from infested camels for species identification using morphological examination and PCR analyses. Tick and hemoprotozoan species were identified using Basic Local Alignment Search Tool analysis with subsequent confirmation in phylogenetic analyses. All camel-infesting ticks belonged to the species Hyalomma dromedarii, and were clustered with ticks of this species previously found in Egypt in a phylogenetic tree based on the 16S rRNA gene. Molecular analysis targeting the 18S rRNA gene revealed the presence of hitherto undetected hemoprotozoan parasites, Colpodella spp., in 30/297 (10.1 %) camel-infesting ticks. In phylogenetic analysis, these Colpodella spp. were highly homologous (94-98.6 %) with Colpodella spp. previously deposited in GenBank with accession numbers OQ540590Q, MH208621, and GQ411073, which relate to Colpodella spp. previously detected from Haemaphysalis longicornis, Rhipicephalus haemaphysaloides, and humans in China. PCR analyses with spherical body protein-4 (SBP-4) gene-specific primers revealed Babesia bovis in 16/297 (5 %) of camel-infesting ticks, however, Babesia bigemina and Theileria annulata were not detected. Here, we report the first detection of Colpodella spp. in H. dromedarii in Egypt. Further epidemiological studies are needed to assess the risk to camels and humans, and the transmission dynamics. Based on the high tick infestation rates in Egyptian camels and the identification of previously unreported protozoan hemoparasites in ticks, we consider that the dromedary should be subject to surveillance as a sentinel species for tick-borne diseases in Egypt. Our findings underline the need for surveillance and collecting data on lesser known pathogens circulating in camel-infesting ticks, as part of a public health strategy for dealing with tick-borne diseases in Egypt.

Sero epidemiological study on bovine babesiosis in cattle and buffaloes in Sharkia Governorate, Egypt.

Background: Bovine babesiosis represents a serious challenge for animal health, herd production, and profitability. Understanding the epidemiology and risk factors associated with babesiosis is critical to reduce their negative impacts. Aim: Investigation of the seroprevalence and risk factors associated with Babesia bigemina (B. bigemina) and Babesia bovis (B. bovis) in five districts in Sharkia governorate using ELISA. Methods: Across-sectional research was conducted to determine the seropositivity of babesiosis by collecting a total of 352 blood samples from 250 cattle and 102 buffaloes. A multivariate logistic regression model was implemented to evaluate the strength of the risk factors associated with both Babesia species infection. Results: The seroprevalence of B. bigemina and B. bovis was 42.6% and 17.0 %, respectively. The prevalence of babesiosis in cattle was found to be 48.8% for B. bigemina and 16.8% for B. bovis. Inclusive, in buffaloes, the prevalence was 27.5% for B. bigemina and 17.6% for B. bovis. Adult animals were more vulnerable to infection with babesia than young animals by 3-5 times, respectively. Males were more susceptible to B. bigemina and B. bovis than females by 3.7 and 3.5 times. Similarly, the odds of infection in infested animals with ticks were 2-4 times higher than in animals without ticks. Conclusion: The obtained results revealed that age, sex of the animal, and tick infestation were major risk factors for the seropositivity of both Babesia species. Inclusive, there was no evidence to support the premise that seroprevalence of babesiosis is correlated with the season and species.

Evaluation of different supportive treatments during packed cell volume replacement in calves naturally infected with tick fever agents.

This study evaluated the effect of different supportive treatments on PCV replacement of dairy calves naturally infected with tick fever (TF) agents, and treated with diminazene and enrofloxacin. Five products were tested as supportive treatments in four experiments. In these experiments, we used Girolando female calves (Gyr × Holstein, genetic ratio of 15/16 and 31/32 Holstein) four to six months old, raised in pasture, naturally infected with TF agents, and infested with R. microplus. Supportive treatment was administered once on day 0 of the study concurrently with specific treatment targeting TF agents. The animals were observed on days 0, 3, and 7. Oral or intravenous administration of a vitamin complex and mineral salts enhanced the increase in PCV and biochemical analytes present in the serum of calves naturally infected with TF agents. No positive effect on PCV values was observed with the administration of (1) invigorating tonic: calcium, casein-peptides and vitamin B12, (2) iron-based stimulant tonic and (3) metabolic tonic: vitamin A, vitamin D, and a fraction of polyunsaturated fatty acids. Supplementation by injection with Type III iron resulted in increased hemoglobin and PCV in treated animals. However, these results did not occur with iron citrate. Therefore, more studies with Type III iron need to be performed. Supportive treatment conferred no advantage in animals with no history of reduced PCV.

Molecular detection and characterization of Theileria annulata, Babesia bovis, and Babesia bigemina infecting cattle and buffalo in southern Egypt.

Tick-borne diseases have a major adverse effect on livestock worldwide, causing enormous economic losses in meat and milk production as well threatening animal and public health. In this study, we aimed to detect and characterize piroplasms isolated from cattle and buffalo in southern Egypt, using molecular techniques. Three hundred blood samples were collected from cattle and buffalo in two governorates in southern Egypt. All 300 samples (100%) were confirmed to contain DNA, as they exhibited bands of bovine ß-actin gene at the expected 227 bp for cattle and buffalo. The samples were analyzed by PCR for the presence of piroplasms, specifically Babesia bovis, Babesia bigemina, and Theileria annulata. Samples positive for the piroplasma 18S ribosomal RNA gene were further examined for two additional genes, spherical body protein 4 gene, to provide an enhanced degree of specificity for the identification of B. bovis and B. bigemina, and the major merozoite surface antigen gene for T. annulata. The infection rate for piroplasma spp. was 60/300 (20%). The positivity rates were 10.7% (32/300) for T. annulata, 5.3% (16/300) for B. bovis, and 4% (12/300) for B. bigemina. By host species, 42/150 (28%) cattle and 18/150 (12%) buffalo were positive for piroplasms. None of the isolates sequenced for the B. bovis isolates from buffalo in this study showed 100% identity with any sequence deposited in GenBank for the small subunit ribosomal RNA gene (maximum identity value = 99.74%). Similarly, no T. annulata small subunit ribosomal RNA gene sequence identified in this study exhibited 100% identity with any sequence deposited in GenBank (maximum identity value = 99.89%). The current study provides a partial sequence of the T. annulata merozoite-piroplasm surface antigen gene, as well as the B. bovis and B. bigemina spherical body protein 4 genes, in cattle and buffalo in southern Egypt, and is the first report on these piroplasma genes in cattle and buffalo in southern Egypt.

Babesia bovis RON2 binds to bovine erythrocytes through a highly conserved epitope.

B. bovis invasion of bovine erythrocytes requires tight junction formation involving AMA-1/RON2 complex interaction. RON2 has been considered a vaccine candidate since antibodies targeting the protein can inhibit parasite invasion of target cells; however, the mechanism controlling B. bovis RON2 interaction with red blood cells is not yet fully understood. This study was thus aimed at identifying B. bovis RON2 protein regions associated with interaction with bovine erythrocytes. Natural selection analysis of the ron2 gene identified predominantly negative selection signals in the C-terminal region. Interestingly, protein-cell and competition assays highlighted the RON2-C region's role in peptide 42918-mediated erythrocyte binding, probably to a sialoglycoprotein receptor. This peptide (1218SFIMVKPPALHCVLKPVETL1237) lies within an intrinsically disordered region of the RON2 secondary structure flanked by two helical residues. The study provides, for the first time, valuable insights into RON2's role in interaction with its target cells. Future studies are required for studying the peptide's potential as an anti-B. bovis vaccine component.

Expression of sex-specific molecular markers by Babesia bovis gametes.

BACKGROUND: Bovine babesiosis caused by Babesia bovis is one of the most important tick-borne diseases of cattle in tropical and subtropical regions. Babesia bovis parasites have a complex lifecycle, including development within the mammalian host and tick vector. In the tick midgut, extracellular Babesia parasites transform into gametes that fuse to form zygotes. To date, little is known about genes and proteins expressed by male gametes. METHODS AND RESULTS: We developed a method to separate male gametes from in vitro induced B. bovis culture. Separation enabled the validation of sex-specific markers. Collected male gametocytes were observed by Giemsa-stained smear and live-cell fluorescence microscopy. Babesia male gametes were used to confirm sex-specific markers by quantitative real-time PCR. Some genes were found to be male gamete specific genes including pka, hap2, α-tubulin II and znfp2. However, α-tubulin I and ABC transporter, trap2-4 and ccp1-3 genes were found to be upregulated in culture depleted of male gametes (female-enriched). Live immunofluorescence analysis using polyclonal antibodies confirmed surface expression of HAP2 by male and TRAP2-4 by female gametes. These results revealed strong markers to distinguish between B. bovis male and female gametes. CONCLUSIONS: Herein, we describe the identification of sex-specific molecular markers essential for B. bovis sexual reproduction. These tools will enhance our understanding of the biology of sexual stages and, consequently, the development of additional strategies to control bovine babesiosis.

Comparative efficacy of buparvaquone and imidocarb in inhibiting the in vitro growth of Babesia bovis.

Introduction: B. bovis is an apicomplexan parasite responsible for bovine babesiosis, a tick-borne disease with a worldwide impact. The disease remains inefficiently controlled, and few effective drugs, including imidocarb dipropionate (ID), are currently available in endemic areas. The objective of this study was to evaluate whether buparvaquone (BPQ), a drug currently used to treat cattle infected with the Babesia-related Theileria spp. parasites, could be active against Babesia parasites. Herein, we compared the effect of ID and BPQ on B. bovis growth in vitro erythrocyte culture. Methods: We compared the effect of ID and BPQ on the culture-adapted Texas T2Bo strain of B. bovis. In vitro cultured parasites were incubated with ID and BPQ at two starting parasitemia levels (PPE), 0.2% and 1%. In vitro cultured parasites were treated with ID or BPQ at concentrations ranging from 10 to 300 nM, during 4 consecutive days. Parasitemia levels were daily evaluated using microscopic examination. Data was compared using the independent Student's t-test. Results and discussion: Both ID and BPQ significantly inhibited (p < 0.05) the growth of B. bovis, regardless of the initial parasitemia used. At 1% parasitemia, BPQ had lower calculated inhibitory concentration 50 (IC50: 50.01) values than ID (IC50: 117.3). No parasites were found in wells with 0.2% starting parasitemia, treated previously with 50 nM of BPQ or ID, after 2 days of culture without drugs. At 1% parasitemia, no parasite survival was detected at 150 nM of BPQ or 300 nM of ID, suggesting that both drugs acted as babesiacidals. Conclusion: Overall, the data suggests that BPQ is effective against B. bovis and shows a residual effect that seems superior to ID, which is currently the first-line drug for treating bovine babesiosis globally.

Nilgai antelope display no signs of infection upon experimental challenge with a virulent Babesia bovis strain.

BACKGROUND: Bovine babesiosis is caused by infection with the protozoal parasite Babesia bovis, which is transmitted by Rhipicephalus (Boophilus) spp. It can cause mortality rates up to 90% in immunologically naive Bos taurus cattle. In south Texas, R. (B.) microplus is known to infest nilgai antelope (Boselaphus tragocamelus); however, their susceptibility to infection with B. bovis and their role in the transmission of the parasite remain unknown. In this study, we challenged nilgai antelope with B. bovis and evaluated their susceptibility to infection. METHODS: Nilgai were needle inoculated with ≈108 B. bovis-parasitized erythrocytes (merozoites) or a homogenate of B. bovis-infected larval ticks (sporozoite) delivered intravenously. Bos taurus beef calves were inoculated in parallel, as this strain of B. bovis is lethal to cattle. Temperature and hematocrit were monitored daily over the course of each study, and whole blood was collected for molecular [polymerase chain reaction (PCR)] and serological [indirect enzyme-linked immunosorbent assay (ELISA)] diagnostic evaluation. Histological sections of nilgai cerebral tissue were examined for evidence of infection. Recipient bovine calves were sub-inoculated with blood from nilgai challenged with either stage of the parasite, and they were monitored for clinical signs of infection and evaluated by a PCR diagnostic assay. Red blood cells (RBCs) from prechallenged nilgai and B. taurus beef cattle were cultured with an in vitro B. bovis merozoite culture to examine colonization of the RBCs by the parasite. RESULTS: Nilgai did not display clinical signs of infection upon inoculation with either the merozoite or sporozoite stage of B. bovis. All nilgai were PCR-negative for the parasite, and they did not develop antibodies to B. bovis. No evidence of infection was detected in histological sections of nilgai tissues, and in vitro culture analysis indicated that the nilgai RBCs were not colonized by B. bovis merozoites. Cattle subinoculated with blood from challenged nilgai did not display clinical signs of infection, and they were PCR-negative up to 45 days after transfer. CONCLUSIONS: Nilgai do not appear to be susceptible to infection with a strain of B. bovis that is lethal to cattle. Tick control on these alternative hosts remains a critical priority, especially given their potential to disseminate ticks over long distances.

Haemaphysalis longicornis (Acari: Ixodidae) does not transmit Babesia bovis, a causative agent of cattle fever.

The Asian longhorned tick (Haemaphysalis longicornis) was first reported in the United States in 2017 and has since been detected in at least 17 states. This tick infests cattle and can produce large populations quickly due to its parthenogenetic nature, leading to significant livestock mortalities and economic losses. While H. longicornis has not been detected in Texas, species distribution models have identified southern Texas as a possible hospitable region for this tick. Southern Texas is currently home to the southern cattle tick (Rhipicephalus microplus), which can transmit the causative agent of cattle fever (Babesia bovis). With the potential for H. longicornis and B. bovis to overlap in southern Texas and their potential to negatively impact the national and global livestock industry, it is imperative to identify the role H. longicornis may play in the cattle fever disease system. A controlled acquisition and transmission experiment tested whether H. longicornis is a vector for B. bovis, with the R. microplus-B. bovis system used as a positive control. Transstadial (nymphs to adults) and transovarial (adults to larvae) transmission and subsequent transstadial maintenance (nymphs and adults) routes were tested in this study. Acquisition-fed, splenectomized animals were used to increase the probability of tick infection. Acquisition nymphs were macerated whole and acquisition adults were dissected to remove midguts and ovaries at five time points (4, 6, 8, 10, and 12 days post-repletion), with 40 ticks processed per time point and life stage. The greatest percentage of nymphs with detectable B. bovis DNA occurred six days post-repletion (20.0 %). For adults, the percentage of positive midguts and ovaries increased as days post-repletion progressed, with day 12 having the highest percentage of positive samples (67.5 % and 60.0 %, respectively). When egg batches were tested in triplicate, all H. longicornis egg batches were negative for B. bovis, while all R. microplus egg batches were positive for B. bovis. During the transmission phase, the subsequent life stages for transstadial (adults) and transovarial transmission/transstadial maintenance (larvae, nymphs, and adults) were fed on naïve, splenectomized calves. All life stages of H. longicornis ticks tested during transmission were negative for B. bovis. Furthermore, the transmission fed animals were also negative for B. bovis and did not show signs of bovine babesiosis during the 45-day post tick transmission period. Given the lack of successful transstadial or transovarial transmission, it is unlikely that H. longicornis is a vector for B. bovis.

A conserved motif in the immune-subdominant RAP-1 related antigen of Babesia bovis contains a B-cell epitope recognized by antibodies from protected cattle.

Introduction: Babesia bovis, a tick-borne apicomplexan parasite causing bovine babesiosis, remains a significant threat worldwide, and improved and practical vaccines are needed. Previous studies defined the members of the rhoptry associated protein-1 (RAP-1), and the neutralization-sensitive rhoptry associated protein-1 related antigen (RRA) superfamily in B. bovis, as strong candidates for the development of subunit vaccines. Both RAP-1 and RRA share conservation of a group of 4 cysteines and amino acids motifs at the amino terminal end (NT) of these proteins. Methods and results: Sequence comparisons among the RRA sequences of several B. bovis strains and other Babesia spp parasites indicate a high level of conservation of a 15-amino acid (15-mer) motif located at the NT of the protein. BlastP searches indicate that the 15-mer motif is also present in adenylate cyclase, dynein, and other ATP binding proteins. AlphaFold2 structure predictions suggest partial exposure of the 15-mer on the surface of RRA of three distinct Babesia species. Antibodies in protected cattle recognize a synthetic peptide representing the 15-mer motif sequence in iELISA, and rabbit antibodies against the 15-mer react with the surface of free merozoites in immunofluorescence. Discussion and conclusion: The presence of the 15-mer-like regions in dynein and ATP-binding proteins provides a rationale for investigating possible functional roles for RRA. The demonstrated presence of a surface exposed B-cell epitope in the 15-mer motif of the B. bovis RRA, which is recognized by sera from protected bovines, supports its inclusion in future subunit epitope-based vaccines against B. bovis.

Analysis of serum proteomic profiles of endangered Siamese and Burmese Eld's deer infected with subclinical Babesia bovis in Thailand.

The endangered Eld's deer is a conserved species in Thailand, where tropical parasitic infections are endemic. Although Eld's deer with babesiosis are generally asymptomatic, they can still harbor the parasite and serve as reservoirs for ticks, spreading the infection to healthy animals within the herd. The present study aimed to investigate potential serum proteome biomarkers of Eld's deer with subclinical Babesia bovis infection. A total of 67 blood samples were collected from captive Siamese and Burmese Eld's deer showing no signs of parasitic infection. The nested polymerase chain reaction (nPCR) of a conserved spherical body protein 2 (sbp-2) gene of B. bovis was utilized to classify Eld's deer groups, with 25.37 % (17/67) testing positive for B. bovis. Additionally, the application of proteomic studies showed that six B. bovis proteins, such as Obg-like ATPase 1 (OLA1) and heat shock protein 90 (HSP90), were significantly upregulated by more than a two-fold change compared with the PCR-negative samples. Of the 55 overexpressed serum proteins in the PCR-positives, alpha 2-HS glycoprotein (AHSG) and immunoglobulin lambda variable 2-8 (IGLV2-8) were notably among the top 10 proteins with the highest area under curve (AUC) values. Hence, they were proposed as potential biomarkers for subclinical B. bovis infection in Eld's deer. Analysis of the protein interaction network revealed interactions between Eld's deer AHSG and B. bovis OLA1 and HSP90, alongside associations with other proteins such as erb-b2 receptor tyrosine kinase 2 (ERBB2) and epidermal growth factor receptor (EGFR). These interactions were involved in the immune system pathway and inflammatory responses. Our findings shed light on subclinical infection of B. bovis in Eld's deer and identify potential biomarkers, contributing to the further effective detection and monitoring of B. bovis infection in this endangered species.

Proteínas importantes para la invasión de Babesia bovis a las células huésped / Important Proteins for Babesia bovis Invasion to Host Cells / Proteínas importantes para a invasão das células hospedeiras por Babesia bovis

Introducción: La babesiosis bovina es causada por parásitos Apicomplexa del género Babesia, siendo la Babesia bovis la especie asociada con cuadros clínicos más graves de la enfermedad. La invasión de B. bovis a los eritro-citos bovinos implica la interacción entre moléculas de los merozoítos del parásito con receptores de las células huésped. Por ende, conocer las proteínas involucradas en este proceso supone un importante paso para entender la biología del parásito. Objetivo: Describir las principales moléculas implicadas en el proceso de invasión de B. bovis a eritrocitos bovinos. Metodología: Se realizó una búsqueda en NCBI, Medline, LILACS y SciELO usando los términos: "Babesia bovis AND invasion process", "MSA-1", "RON2", "AMA-1", "moving junction", "B. bovis AND Vaccine candidates". Con corte en mayo de 2020, había 61 publicaciones disponibles en inglés que describen el estudio de las anteriores proteínas y su participación en la invasión.Resultados: Por ser clave el proceso de invasión a eritrocitos bovinos para la patogénesis de la babesiosis bovina, la revisión encontró 3 proteínas de B. bovis que participan en el reconocimiento e invasión a las células diana: MSA-1, AMA-1 y RON2. Sin embargo, los detalles a nivel molecular para las interacciones inter e intramoleculares aún no se han dilucidado por completo. Conclusiones: Conocer las moléculas involucradas en las interacciones parásito-hospedero permitirá entender cómo ocurre el proceso de invasión de B. bovis a los eritrocitos y, así, evaluar su futura utilidad como componente de una estrategia de control efectiva contra esta parasitosis

Introduction: Bovine babesiosis is caused by Apicomplexas parasites of the genus Babesia, Babesia bovis being the species associated with the most serious clinical conditions of the disease. B. bovisinvasion into the bovine erythrocytes involves the interaction between the parasites merozoites mo-lecules with host cell receptors. Therefore, knowing the proteins involved in the invasion process will enable understanding the parasite biology. Objective: To describe the important molecules involved in the B. bovis invasion process to bovine erythrocytes.Methodology: A search was made on NCBI, Medline, LILACS and SciELO databases using keywords as "Babesia bovis AND invasion process", "MSA-1", "RON2", "AMA-1", "moving junction", "B. bovis AND Vaccine candidates". 61 studies written in English describing the study for proteins that take place during invasion process which have been published until mayo were completely revised. Results: Given that the bovine erythrocyte invasion process is key for the pathogenesis of bovine babesiosis, a review was made where 3 proteins were found to be associated to the recognition and invasion processes of target cells: MSA-1, AMA-1 and RON2. However, the details at molecular level for the inter an intramolecular interaction have not yet been fully elucidated. Conclusions: Study the molecules involved in host-parasite interactions will allow understanding how the B. bovis invasion process to erythrocytes occurs and evaluating their future utility as a component of an effective control strategy for this parasitosis

Introdução: A babesiose bovina é causada por parasitas Apicomplexa do gênero Babesia, sendo a Babesia bovis a espécie associada com os sinais clínicos mais graves da doença. A invasão de B. bovis em eritrócitos bovinos envolve a interação entre moléculas dos merozoítos parasitas com receptores nas células hospedeiras. Por conseguinte, o conhecimento das proteínas envolvidas neste processo é um passo importante para a compreensão da biologia do parasita. Objetivo: Descrever as principais moléculas envolvidas no processo de invasão de B. bovis em eritró-citos bovinos. Metodologia: Foi realizada uma pesquisa no NCBI, Medline, LILACS e SciELO utilizando os termos: "Babesia bovis AND invasion process", "MSA-1", "RON2", "AMA-1", "moving junction", "B. bovis AND Vaccine candidates". Até maio de 2020 estavam disponíveis 61 publicações em inglês, que descreviam o estudo das proteínas acima referidas e o seu envolvimento na invasão. Resultados: Como o processo de invasão de eritrócitos bovinos é fundamental para á patogênese da babesiose bovina, a revisão encontrou 3 proteínas de B. bovis envolvidas no reconhecimento e invasão de células alvo: MSA-1, AMA-1 e RON2. No entanto, os detalhes a nível molecular para as interações Inter e intramoleculares ainda não foram completamente elucidados. Conclusões: A compreensão das moléculas envolvidas nas interações parasita-hospedeiro permitirá entender como ocorre o processo da invasão de B. bovis em eritrócitos e, assim, avaliar sua utilidade futura como componente de uma estratégia efetiva de controle contra esta parasitose

Descripción de dos casos de babesiosis cerebral en terneros de hasta 15 días de edad / Description of two cases of cerebral babesiosis in calves up to 15 days of age

Resumen La babesiosis es una enfermedad causada por Babesia bovis y Babesia bigemina, integrante del complejo conocido como "Tristeza bovina" y relevante en el Noroeste argentino (NOA). La presentación clínica de esta enfermedad es infrecuente en bovinos jóvenes, a los que se considera parcialmente resistentes a la babesiosis. Este trabajo describe dos casos de babesiosis cerebral en terneros de dos rodeos de cría diferentes, que a la necropsia mostraron ictericia, esplenomegalia y severa congestión cerebral y hemoglobinuria. Estructuras intraeritrocitarias compatibles morfológicamente con B. bovis fueron identificadas en extendidos de sistema nervioso central y sangre periférica teñidos con Giemsa y se confirmó luego la infección por medio de técnicas moleculares. La evaluación del estatus epidemiológico en los rodeos de origen determinó diferentes contextos: uno de los casos fue aislado en un rodeo con estabilidad enzoótica para babesiosis, donde la enfermedad clínica era escasa a pesar de altas tasas de transmisión de B. bovis; el segundo caso ocurrió en un rodeo en situación de brote con niveles significativos de mortandad. La ocurrencia de babesiosis (B. bovis) no había sido descripta todavía en terneros de la Argentina, sumándose ahora al diagnóstico diferencial para esta categoría de bovinos en zonas donde la enfermedad es enzoótica.

Abstract Bovine babesiosis is a disease caused by Babesia bovis and Babesia bigemina, as part of the tick fever complex and relevant in the Northwest of Argentina. Clinical occurrence of this illness is uncommon in young cattle, considered resistant to babesiosis. This work described two cases of cerebral babesiosis in calves of different beef herds. Jaundice, splenomegaly, severe cerebral congestion and hemoglobinuria was observed at necropsy. Babesia bovis-like structures were identified in cerebral and blood smears Giemsa stained and confirmed by molecular techniques. Different situations were recognized following the evaluation of the epidemiological status of both herds: the first one was a single case in a herd with enzootic stability for babesiosis, with scarce clinical cases despite high rates of B. bovis transmission; the other case was in a context of outbreak with high level of mortality within a herd susceptible to babesiosis. Clinical babesiosis was not previously described in calves from Argentina. Babesiosis must be taken into account for the differential diagnosis in calves from endemic areas of the disease.

Genetic diversity of Babesia bovis studied longitudinally under natural transmission conditions in calves in the state of Rio de Janeiro, Brazil / Diversidade genética de Babesia bovis estudada longitudinalmente em condições de transmissão natural entre bezerros no estado do Rio de Janeiro, Brasil

Abstract Serum and DNA samples from 15 naturally infected calves in Seropédica, Brazil, were obtained quarterly from birth to 12 months of age, in order to longitudinally evaluate their humoral immune response against Babesia bovis and the merozoite surface antigen diversity of B. bovis. Anti-B. bovis IgG antibodies were detected by an indirect fluorescent antibody test (IFAT) and enzyme-linked immunosorbent assay (ELISA). Using DNA amplification, sequencing and phylogenetic analysis, the genetic diversity of B. bovis was assessed based on the genes that encode merozoite surface antigens (MSA-1, MSA-2b and MSA-2c). The serological results demonstrated that up to six months of age, all the calves developed active immunity against B. bovis. Among the 75 DNA samples evaluated, 0, 3 and 5 sequences of the msa-1, msa-2b and msa-2c genes were obtained, respectively. The present study demonstrated that the msa-2b and msa-2c gene sequences amplified from blood DNA of B. bovis-positive calves were genetically diversified. These data emphasize the importance of conducting deeper studies on the genetic diversity of B. bovis in Brazil, in order to design diagnostic antigens and vaccines in the future.

Resumo Para avaliar longitudinalmente a resposta imune humoral anti-B. bovis e a diversidade genética de antígenos de superfície de merozoítos de B. bovis, entre bezerros naturalmente infectados em Seropédica, Brasil, amostras de soro e DNA de 15 bezerros foram obtidas trimestralmente, desde o nascimento até 12 meses de idade. Anticorpos IgG para B. bovis foram detectados pelos testes de Imunofluorescência Indireta e Ensaio de Imunoadsorção Enzimático Indireto. Usando-se amplificação de DNA, sequenciamento e análises filogenéticas, a diversidade genética de B. bovis, com base nos genes que codificam antígenos de superfície de merozoítos (MSA-1, MSA-2b e MSA-2c) foi investigada. Os resultados da sorologia demonstraram que, até os seis meses de idade, todos os bezerros desenvolveram imunidade ativa contra B. bovis. Entre as 75 amostras de DNA avaliadas, foram obtidas 0, 3 e 5 sequências dos genes msa-1, msa-2b e msa-2c. O presente estudo demonstrou que sequências dos genes msa-2b e msa-2c amplificadas a partir de amostras de sangue positivas para B. bovis de bezerros de Seropédica, foram geneticamente distintas. O presente trabalho realça a importância de se realizar estudos aprofundados sobre a diversidade genética de B. bovis no Brasil, objetivando o desenvolvimento de antígenos para o diagnóstico e vacinas no futuro.

Babesia bovis: Actualidad del desarrollo de una vacuna / Babesia bovis: An Update on vaccine development / Babesia bovis: Atualidade do desenvolvimento de uma vacina

Introducción. Babesia bovis es el principal agente causal de la babesiosis bovina, una importante enfermedad veterinaria transmitida por garrapatas a nivel mundial. Las estrategias convencionales para controlar esta parasitosis han presentado múltiples limitaciones por lo que el desarrollo de una vacuna basada en antígenos representa una estrategia apropiada para la prevención y el tratamiento. Objetivo. Describir los aspectos relevantes del ciclo de vida del parásito B. bovis, la epidemiología, diagnóstico y la aplicación de diferentes estrategias usadas para controlar esta parasitosis. Además, se discuten potenciales puntos de intervención para desarrollar una vacuna contra este parásito. Metodología. Se realizó una búsqueda en las bases de datos usando los términos: "Babesia bovis AND lyfe cycle", "B. bovis vaccine and Vaccine candidates", entre otras. Los estudios con mayor pertinencia publicados hasta la actualidad se revisaron completamente. Resultados. Los detalles de la biología de parásito B. bovis y el proceso molecular usado para ocasionar la enfermedad en el hospedador son poco conocidos, lo que explica que el desarrollado de estrategias para el control de esta parasitosis no hayan sido del todo eficientes. Por lo tanto, se requiere diseñar nuevas medidas, por ejemplo, desarrollar vacunas de nueva generación basadas en un enfoque funcional que permitan mejorar las condiciones de sanidad animal. Conclusiones. Comprender el complejo ciclo de vida de B. bovis permitirá estudiar las interacciones huésped-parásito-garrapata e identificar moléculas implicadas en la adhesión/invasión celular para evaluar su utilidad como componente de una vacuna que controle esta parasitosis.

Introduction. Babesia bovis is the main causal agent of babesiosis bovine, one important veterinary diseases transmitted by ticks worldwide. Conventional strategies to control this parasitosis have shown several limitations and therefore the development of a vaccine will be an appropriate strategy for prevention and treatment. Objective. To describe relevant aspects of B. bovis parasite's life cycle, the epidemiology, diagnosis, the application of different strategies used to control this parasitosis. In addition, potential points of intervention to develop a vaccine against this parasite has been discussed. Methodology. A search was made using keywords as "Babesia bovis AND lyfe cycle", "B. bovis vaccine and Vaccine candidates" and others. The most relevant studies published to date were completely revised. Results. The details of the B.bovis parasite biology and the molecular process used to cause disease in the host had not been describe in deep; explaining that the development of strategies for the control of this parasitosis have not been entirely efficient. Therefore, it is necessary to design new procedures, for example, to develop new generation vaccines based on a functional approach which improve the animal health conditions. Conclusions. Understand the B. bovise's life cycle complex will allow the host-parasite-tick interactions study and the identification of molecules involved in cell adhesion / invasion to evaluate its usefulness as a vaccine component that controls this parasitosis.

Introdução. Babesia bovis é o principal agente causador da babesiose bovina, uma importante doença veterinária transmitida por carrapatos a nível mundial. As estratégias convencionais para o controle das parasitoses têm presentado múltiplas limitações pelo que o desenvolvimento de uma vacina baseada em antígenos representa uma estratégia apropriada para a prevenção e o tratamento. Objetivo. Descrever os aspectos relevantes do ciclo de vida do parasita B. bovis, a epidemiologia, diagnostico e aplicação de diferentes estratégias usadas para o controle desta parasitose. Além disso, são discutidos possíveis pontos de intervenção para o desenvolvimento de uma vacina contra o parasita. Metodologia. Uma pesquisa foi realizada nas bases de dados usando os termos: "Babesia bovis AND lyfe cycle", "B. bovis vaccine and Vaccine candidates", entre outras. Os estudos mais relevantes publicados até o momento foram completamente revisados. Resultados. Os detalhes da biologia do parasita B. bovis e o processo molecular usado para causar doenças no hospedeiro é pouco conhecido, o que explica que o desenvolvimento de estratégias para o controle desta parasitose não foram completamente eficientes. Portanto, é necessário projetar novas medidas, por exemplo, desenvolver vacinas de nova geração com base em uma abordagem funcional que permita melhorar as condições de saúde animal. Conclusões. Compreender o complexo ciclo de vida de B. bovis permitirá estudar as interações hospede­parasita­carrapatos e identificar moléculas envolvidas na adesão/invasão celular para avaliar sua utilidade como componente de uma vacina que controla essa parasitose.

Babesiose cerebral em bezerros / Cerebral babesiosis in calves

Babesiose cerebral é uma enfermidade causada pelo protozoário Babesia bovis. O agente faz parte do complexo Tristeza Parasitária Bovina, uma das mais importantes doenças parasitárias em bovinos. O presente estudo relata um surto causado por B. bovis em vinte bezerros de aproximadamente 7 a 25 dias de idade. O surto ocorreu entre março e junho de 2015, na região sul do Brasil, área de instabilidade enzoótica para a Tristeza Parasitária Bovina. O diagnóstico foi realizado pela epidemiologia, lesões macroscópicas e pela presença de numerosas formas parasitárias de Babesia bovis em capilares encefálicos, observados em imprints corados por Giemsa. Surtos de babesiose por B. bovis cerebral nos primeiros dias de vida de bezerros é incomum, porém não pode ser desconsiderada em surtos com alta letalidade em áreas de instabilidade enzoótica.(AU)

Cerebral babesiosis is a protozoan disease caused by Babesia bovis. This parasite belongs to the bovine parasitic complex of tick-borne diseases that affect livestock worldwide. The present study reports an outbreak caused by B. bovis affected twenty 7-25 day-old calves. Outbreak occurred from May to July 2015 in the south of Brazil, where there is an area of enzootic instability for cattle tick fever. The macroscopic lesions were anemia, hemoglobinuria, splenomegaly, hepatomegaly, yellow liver and cherry-pink discoloration of cerebral and cerebellar cortex. The diagnosis was based on epidemiology, necropsy and microscopic findings in the brain that showed B. bovis in the capillary vessels of the brain in imprints stained by Giemsa. Cases of cerebral babesiosis by Babesia bovis in such young calves are uncommon but should be considered as a diagnosis possibility when there is high mortality rate in areas ofen zootic instability.(AU)

Caracterização histoquímica no diagnóstico da babesiose bovina por Babesia bovis / Histochemical characterization in the diagnosis of bovine babesiosis by Babesia bovis

A babesiose é uma doença hemolítica transmitida por carrapatos e causada por protozoários intraeritrocitários do gênero Babesia. Esta é uma doença de incidência elevada na Região Sul do Brasil e responsável por perdas econômicas consideráveis. O diagnóstico clínico-patológico pode ser feito através da demonstração do parasito pelo exame de esfregaços sanguíneos ou de tecidos frescos. Entretanto, com frequência, somente órgãos fixados em formol são remetidos para laboratórios de patologia, o que impossibilita a realização do esfregaço. O principal objetivo deste estudo foi encontrar técnicas histoquímicas alternativas e capazes de aprimorar a evidenciação de Babesia bovis intraeritrocitária em tecidos fixados em formol. Para este estudo, foram analisadas retrospectivamente amostras de tecidos de 50 casos de necropsias de bovinos, as quais haviam sido fixadas em formol e processadas rotineiramente para histopatologia. Os casos foram divididos em um grupo controle, constituído por 12 casos de babesiose cerebral com substância cinzenta encefálica róseo-cereja característica (grupo A), e 38 casos sugestivos de tristeza parasitária bovina (grupo B), conforme os protocolos de necropsias. Foram testadas as técnicas histoquímicas de Azul Alciano, Azul de Metileno, Azul de Toluidina, Giemsa, Gram (método de McCallum-Goodpasture), Grocott, Ácido Periódico de Schiff e Ziehl-Neelsen. Dentre estas, observou-se que as técnicas de Azul de Metileno e Azul de Toluidina permitiram observar características morfológicas e tintoriais de maneira mais nítida, auxiliando na identificação de B. bovis. Adicionalmente, foram estabelecidos vários parâmetros clínico-epidemiológicos e anatomopatológicos da babesiose por B. bovis.(AU)

Babesiosis is a hemolytic tick-borne disease caused by intraerythrocytic protozoal parasites of the genus Babesia. This is a disease of high incidence in the southern Brazil and responsible for considerable economic losses. Clinical-pathological diagnosis can be made by demonstrating the parasite by examining blood smears or fresh tissues. However, frequently, only formalin-fixed organs are sent to pathology laboratories, which makes it impossible to perform the smears. The main objective of this study was to find alternative histochemical techniques capable to improve the identification of intraerythrocytic Babesia bovis in histological sections. For this study, tissue samples from 50 bovine necropsy cases were retrospectively analyzed, which had been fixed in formalin and routinely processed for histopathology. The cases were divided into a control group, consisting of 12 cases of cerebral babesiosis with characteristic pink-cherry gray matter (group A), and 38 cases suggestive of cattle tick fever (group B), according to necropsy protocols. Histochemical techniques of Alcian Blue, Methylene Blue, Toluidine Blue, Giemsa, Gram (McCallum-Goodpasture method), Grocott, Periodic Acid of Schiff and Ziehl-Neelsen were tested. Among these, it was observed that the techniques of Methylene Blue and Toluidine Blue allowed to observe morphological and dye characteristics in a clearer way, aiding in the identification of B. bovis. In addition, several clinical-epidemiological and anatomopathological parameters of babesiosis caused by B. bovis were established.(AU)

Incidência de Anaplasma marginale, Babesia bigemina e Babesia bovis em bezerros no semiárido paraibano / Incidence of Anaplasma marginale, Babesia bigemina and Babesia bovis among calves in the semiarid region of Paraiba, Brazil

Este estudo avaliou a incidência de infecções naturais pelos agentes da tristeza parasitária bovina (TPB), Anaplasma marginale, Babesia bovis e Babesia bigemina, em bezerros nascidos em cinco fazendas do semiárido paraibano. Em cada fazenda, foram coletadas amostras de sangue de 6 a 14 bezerros a cada 14 dias durante os primeiros 12 meses de vida de cada animal. As amostras de sangue foram processadas por microhematócrito e testadas por PCR para detecção de DNA de A. marginale, B. bovis e B. bigemina. Em paralelo, foram quantificadas as infestações por carrapatos nos bovinos nas cinco fazendas, assim como as populações de tabanídeos em três fazendas. De 41 bezerros monitorados durante o primeiro ano de vida, 25 (61,0%) apresentaram PCR positivo para A. marginale, 7 (17,1%) para B. bigemina e 3 (7,3%) para B. bovis. Os valores de incidência da infecção por A. marginale variaram de 83,3% a 100% em quatro fazendas. A infecção por B. bigemina ocorreu em bezerros de apenas duas fazendas (incidências de 12,5% e 85,7%) e a por B. bovis em apenas uma (incidência de 42,8%). Em uma fazenda os 14 bezerros permaneceram negativos para A. marginale, B. bigemina e B. bovis durante os 12 meses de acompanhamento. Os resultados de PCR foram confirmados por sequenciamento de DNA de produtos amplificados. A presença de carrapatos Rhipicephalus (Boophilus) microplus foi verificada somente em duas propriedades, nas quais houve infecção por A. marginale, B. bigemina e B. bovis (este último agente em apenas uma delas). Foram capturados 930 tabanídeos no estudo, a maioria durante os períodos de chuvas na região; 70,7% dos tabanídeos corresponderam a Tabanus claripennis. Houve associação significativa entre PCR positivo para A. marginale ou B. bigemina e menores valores de hematócrito. Este estudo demonstra que, mesmo avaliando apenas cinco propriedades rurais, a incidência dos agentes da TPB ocorreu de forma heterogênea na região, corroborando o status de área de instabilidade enzoótica para TPB previamente relatado para o semiárido paraibano.(AU)

This study evaluated the incidence of natural infection by agents of cattle tick fever (CTF), Anaplasma marginale, Babesia bovis and Babesia bigemina in calves born in five farms within the semiarid region of Paraíba state, Brazil. In each farm, blood samples were collected from 6 to 14 calves every 14 days during the first 12 months of life of each animal. Blood samples were processed by microhematocrit and tested by PCR for detection of DNA of A. marginale, B. bovis and B. bigemina. In parallel, the tick infestations on animals were quantified in the five farms, as well as populations in horseflies in three farms. From a total of 41 calves monitored during the first year of life, 25 (61.0%) had positive PCR for A. marginale, 7 (17.1%) for B. bigemina and 3 (7.3%) to B. bovis. Incidence values for A. marginale infection ranged from 83.3% to 100% in four farms. Infection with B. bigemina in calves was detected at only two farms (incidence of 12.5% and 85.7%) and by B. bovis in just one (42.8% incidence). On one farm 14 calves remained negative for A. marginale, B. bigemina and B. bovis during the 12 month follow-up. PCR results were confirmed by DNA sequencing of amplified products. The presence of Rhipicephalus (Boophilus) microplus was found only in two farms in which there was infection by A. marginale, B. bigemina and B. bovis (the latter agent in only one of them). A total of 930 horseflies were captured in the study, most during periods of rain in the region; 70.7% of horseflies corresponded to Tabanus claripennis. There was significant association between a positive PCR for A. marginale and B. bigemina and lower hematocrit values. This study demonstrates that even evaluating only five rural properties, the incidence of CTF occurred heterogeneously in the region, confirming the status of enzootic instability area for CTF, previously reported for the semiarid region of Paraiba.(AU)