Pathogenesis Of Babesiosis Research Articles

Continuous In Vitro Culture of Babesia duncani in a Serum-Free Medium.

Human babesiosis is an emerging tick-borne disease, caused by haemoprotozoa genus of Babesia. Cases of transfusion-transmitted and naturally acquired Babesia infection have been reported worldwide in recent years and causing a serious public health problem. Babesia duncani is one of the important pathogens of human babesiosis, which seriously endangers human health. The in vitro culture systems of B. duncani have been previously established, and it requires fetal bovine serum (FBS) to support long-term proliferation. However, there are no studies on serum-free in vitro culture of B. duncani. In this study, we reported that B. duncani achieved long-term serum-free culture in VP-SFM AGTTM (VP-SFM) supplemented with AlbuMaxTM I. The effect of adding different dilutions of AlbuMaxTM I to VP-SFM showed that 2 mg/mL AlbuMaxTM I had the best B. duncani growth curve with a maximum percentage of parasitized erythrocytes (PPE) of over 40%, and it can be used for long-term in vitro culture of B. duncani. However, the commonly used 20% serum-supplemented medium only achieves 20% PPE. Clearly, VP-SFM with 2 mg/mL AlbuMaxTM I (VP-SFMA) is more suitable for the in vitro proliferation of B. duncani. VP-SFM supplemented with CD lipid mixture was also tested, and the results showed it could support the parasite growth at 1:100 dilution with the highest PPE of 40%, which is similar to that of 2 mg/mL AlbuMaxTM I. However, the CD lipid mixture was only able to support the in vitro culture of B. duncani for 8 generations, while VP-SFMA could be used for long-term culture. To test the pathogenicity, the VP-SFMA cultured B. duncani was also subjected to hamster infection. Results showed that the hamster developed dyspnea and chills on day 7 with 30% PPE before treatment, which is similar to the symptoms with un-cultured B. duncani. This study develops a unique and reliable basis for further understanding of the physiological mechanisms, growth characteristics, and pathogenesis of babesiosis, and provides good laboratory material for the development of drugs or vaccines for human babesiosis and possibly other parasitic diseases.

THE ROLE AND SIGNIFICANCE OF MORPHOLOGICAL CHANGES IN INTRAORGAN VESSELS IN ANIMALS DURING PATHOGENESIS OF BABESIOSIS

The aim of this study is to investigate morphological changes in intraorgan vessels and their role in susceptible animals in the pathogenesis of babesiosis. The material of the study included the intraorgan vessels of domestic dogs with clinically and laboratory confirmed babesiosis and wild mouse-like rodents from latent foci of babesiosis in Volyn, Zhitomir, Kiev, Poltava, Sumy, Kharkov, Chernigov regions. For histological study, we used standard fixation in a 12% aqueous formalin solution in phosphate buffer (pH = 7.0-7.2). After the post-fixation and dehydration, the samples were placed into paraffin blocks; then a series of histological slices (5 μm) were prepared. The preparations were stained with hematoxylin and eosin, according to Van Gieson technique. All test animals, regardless of the species taxonomy, were divided into two groups. The control group included clinically healthy animals (∑ = 36). The group under clinical study consisted of animals with clinically and laboratory confirmed babesiosis (∑ = 91). Histological changes in intraorgan vessels in the control group corresponded to the anatomical and functional parameters in the health. The preparations taken from the group with basesiosis demonstrate that microvessels are branched, different in size, spasmodic; their walls have signs of delamination and through lesions. Delamination developed gradually, started with the detachment of a small horizontal fragment of the outer layer. Defects in the integrity of microvessels resulted in penetrations; there was an active diapedesis of erythrocytes into the periovascular space. The accumulation of erythrocytes directed to the areas of connective tissue, branching of blood vessels, and fatty fragments. Hemorrhages were local in nature, concentrated in the form of small blurred foci of irregular shape. In the pathogenesis of babesiosis, the defects in the walls of blood vessels with their further penetration and dissection, hemorrhages, microvesiculation of the endothelium, and its desquamation play a critical role. Other manifestations included the development of intravascular blood coagulation, thrombosis, stasis, microcirculation disorders followed by ischemia, destructive and degenerative changes in the walls of blood vessels.

Babesia divergens glycosylphosphatidylinositols modulate blood coagulation and induce Th2-biased cytokine profiles in antigen presenting cells

Glycosylphosphatidylinositols (GPIs) are glycolipids described as toxins of protozoan parasites due to their inflammatory properties in mammalian hosts characterized by the production of interleukin (IL)-1, IL-12 and tumor necrosis factor (TNF)-α. In the present work, we studied the cytokines produced by antigen presenting cells in response to ten different GPI species extracted from Babesia divergens, responsible for babesiosis. Interestingly, B. divergens GPIs induced the production of anti-inflammatory cytokines (IL-2, IL-5) and of the regulatory cytokine IL-10 by macrophages and dendritic cells. In contrast to all protozoan GPIs studied until now, GPIs from B. divergens did not stimulate the production of TNF-α and IL-12, leading to a unique Th1/Th2 profile. Analysis of the carbohydrate composition of the B. divergens GPIs indicated that the di-mannose structure was different from the evolutionary conserved tri-mannose structure, which might explain the particular cytokine profile they induce. Expression of major histocompatibility complex (MHC) molecules on dendritic cells and apoptosis of mouse peritoneal cells were also analysed. B. divergens GPIs did not change expression of MHC class I, but decreased expression of MHC class II at the cell surface, while GPIs slightly increased the percentages of apoptotic cells. During pathogenesis of babesiosis, the inflammation-coagulation auto-amplification loop can lead to thrombosis and the effect of GPIs on coagulation parameters was investigated. Incubation of B. divergens GPIs with rat plasma ex vivo led to increase of fibrinogen levels and to prolonged activated partial thromboplastin time, suggesting a direct modulation of the extrinsic coagulation pathway by GPIs.

Laboratory diagnostic of human babesiosis.

Human babesiosis caused by parasitic protozoan Babesia spp. is sporadic zoonotic vector-borne infection. The course of babesiosis and prognosis depend on the type of pathogen and on the patient's immunological status. Significance this disease is a severe, often fatal course with immunocompromissed patients resembling complicated falciparum malaria. In Europe to date, more than 50 cases of confirmed human babesiosis have been reported in most cases caused by Babesia divergens. Possible there are unrecognized cases. Pathogen is an obligate intraerythrocyte parasite of vertebrate animals. The organism is transmitted from animal to man through bite of Ixodidae tick. Asexual reproduction of the parasite occurs in a vertebrate host. The pathogenesis of babesiosis is caused by the destruction of host cells. Intensive haemolysis of red blood cells leads to the development of haemolytic anemia, haematuria, jaundice, and polyorgan failure may develop. The clinical manifestations of the disease are nonspecific. Detection of intraerythrocyte parasites in blood smears stained Gimsa-Romanovsky confirms the proposed diagnosis. Blood smears and some laboratory signs from fatal cases were analyzed in the Reference-centre of E. I. Martsinovskiĭ Institute. Original microphotographs B. divergens are shown. The main morphological forms of the parasite are shown. In addition to the well-known tetrades of parasites «Maltese Cross», for the first time, the parasites dividing into 6 interconnected trophozoites - "sextet" - were found. Originally, the invasion of Babesia in a normoblast is shown. An unusually high multiple invasion (14 parasites) of erythrocytes is noted. Because the patients, initially, were incorrectly diagnosed with malaria, the differential diagnosis of Babesia with Plasmodium is described step-by-step. It is important, since the treatment with antimalarial drugs is ineffective. Deviation laboratory signs are discussed. Complex morphological characteristics allowed us to speciated the parasites as B. divergens. DNA was detected in the sample with specific primers Bab di hsp70F/Bab di hsp70R and the probe Bab di hsp70P. The sequence demonstrated 99-100% and 98% similarity to the 18S rRNA gene fragment of B. divergence and Babesia venatorum, respectively. Molecular biological and serological methods of laboratory diagnosis of babesiosis are considered.

Canine Babesiosis: Where Do We Stand?

Abstract Canine babesiosis is a tick-borne disease caused by protozoal haemoparasites of different Babesia species. Babesiosis is one of the most important globally extended and quickly spreading tick-borne infections of dogs. This comprehensive review gives an in-depth overview of Babesia species currently identified in dogs together with relevant vector tick species and their geographical distribution, life cycle and transmission of parasite. The main mechanisms in the pathogenesis of babesiosis are described and elucidated by recent literature overview. As Babesia infection causes a disease with very variable clinical manifestations, special attention is given to clinical signs, laboratory features and clinicopathological findings. The diagnosis of canine babesiosis by microscopy, serological and molecular methods is reviewed, together with recent advances in mass spectrometry based assays. Accurate detection and species recognition are important for the selection of the appropriate therapy, monitoring and prediction of the outcome of the disease. Finally, guidelines for the treatment and prevention of canine babesiosis are given.

Soluble parasite antigens from Babesia canis do not directly activate the kallikrein system in dogs infected with Babesia canis

Soluble parasite antigens (SPA) from Babesia canis have been shown to induce protective immunity when used as vaccine. In order to explain the immune mechanisms of vaccination, the precise role of SPA in the pathogenesis of canine babesiosis is under investigation. Earlier studies suggested that the plasma kallikrein system is central in the pathogenesis of babesiosis, malaria and trypanosomosis, and significant plasma kallikrein activation during acute B. bovis and P. knowlesi infections has been described. In the studies presented here dogs were experimentally infected with B. canis to investigate whether the plasma kallikrein system is activated during babesiosis infection. Results showed that prekallikrein levels decreased during episodes of peak parasitaemia. No effect was found on the kallikrein levels. In order to determine whether B. canis SPA could activate plasma kallikrein, dogs were infused with variable amounts of B. canis SPA and plasma samples were taken for (pre-) kallikrein determination. The results indicated that B. canis SPA did not affect plasma (pre-) kallikrein levels. In addition, the effect of B. canis SPA on (pre-) kallikrein levels in normal dog plasma was determined in vitro. Again, no effect on (pre-) kallikrein levels was found. The results suggest that, although the kallikrein pathway may be involved in B. canis-associated pathology, the system is not directly activated by B. canis SPA. Furthermore, infusion of B. canis SPA as well as stroma of normal dog erythrocytes triggered the production of the acute phase reactant, C-reactive protein. This suggests that the inflammatory response that is triggered during B. canis infection could be in part due to the release and exposure of self molecules. The implications of these findings are discussed.

Shared features in the pathobiology of babesiosis and malaria

The pathobiology of malaria has been extensively studied in humans but many questions remain, especially regarding fulminant disease associated with Plasmodium falciparum infection. Babesiosis, recognized since biblical times as an important disease of livestock and more recently as an emerging health problem in humans, is caused by related intraerythrocytic protozoa with a similar pathogenesis and clinical course. Recent studies of cytokine activation and erythrocyte cytoadherence in babesiosis and malaria have exploited these similarities to provide new insights into malaria pathobiology. Continued investigation of similarities and differences in the pathogenesis of babesiosis and malaria should lead to additional fundamental insights for both conditions.