Infections of humans with intraerythrocytic parasites of the genus Babesia can be locally prevalent in diverse regions of the United States. Transfusion of blood and blood products collected from donors infected with Babesia may result in a serious illness that can be fatal. In September 2008, the Food and Drug Administration organized a public workshop to discuss the various aspects of transfusion-transmitted babesiosis in the United States including the possible strategies to identify and defer blood donors who may have been infected with Babesia. Discussions were also held on the biology, pathogenesis, and epidemiology of Babesia species. In this article, we summarize the scientific presentations and panel discussions that took place during the workshop.
"The bite by an infected hard tick, Ixodes scapularis, is considered to be the primary mode of transmission. However, many transfusion-acquired infections have been documented, and such cases appear to be persistently increasing (Leiby, 2006; Gubernot et al., 2009). Therefore, it is important to establish a reliable diagnosis and vaccine to control and eliminate this disease. "
[Show abstract][Hide abstract] ABSTRACT: In this report, a novel gene encoding an interspersed repeat antigen from Babesia microti (BmIRA) was identified and described. The full-length cDNA containing an open reading frame of 1,947 bp was obtained by immunoscreening a B. microti cDNA expression library. The full-length of BmIRA gene was expressed as a GST fusion recombinant BmIRA (rBmIRA) in E. coli. Sera of mice immunized with the rBmIRA detected a native parasite protein with a molecular mass of 76 kDa on Western blot analysis. The same protein was detected in the parasites by immunofluorescent antibody tests (IFAT). An enzyme-linked immunosorbent assay (ELISA) using rBmIRA detected specific antibodies as early as 11 days post-infection in sera from a hamster experimentally infected with B. microti Gray stain (US type). Furthermore, a rapid immunochromatographic test (ICT) using rBmIRA detected specific antibodies in a hamster experimentally infected with B. microti from day 11 to at least day 180 post-infection. The results indicate the antibody response against the rBmIRA was maintained during the chronic stage of infection. On the other hand, an immunoprotective property of rBmIRA as a subunit vaccine was evaluated in hamsters against B. microti challenge, but no significant protection was observed. Our data suggest that the immunodominant antigen BmIRA could be a useful serodiagnostic antigen for screening of B. microti infection.
"Babesia microti, an intraerythrocytic protozoan of the genus Babesia, is a common parasite of wild rodents and a major cause of the emerging human disease babesiosis, an asymptomatic malaria-like disease , , . Human infection by B. microti often occurs in diverse regions of North America and Europe, and is increasingly recognized as a health problem . Babesiosis is often lethal in immunocompromised humans. "
[Show abstract][Hide abstract] ABSTRACT: Understanding the induction of immune regulatory cells upon helminth infection is important for understanding the control of autoimmunity and allergic inflammation in helminth infection. Babesia microti, an intraerythrocytic protozoan of the genus Babesia, is a major cause of the emerging human disease babesiosis, an asymptomatic malaria-like disease. We examined the influence of acute B. microti infection on the development of regulatory B cells together with regulatory T cells.
Our data demonstrate that B cells stimulated in vitro with B. microti produce interleukin (IL)-10. This cytokine is also secreted by B cells isolated from B. microti-infected mice in response to lipopolysaccharide stimulation. In addition, high levels of IL-10 were detected in the serum of mice after infection with B. microti. The frequency of IL-10-producing CD1d(high)CD5(+) regulatory B cells (Bregs) and CD4(+)CD25(+)FoxP3(+) T cells increased during the course of B. microti infection. Furthermore, adoptive transfer of IL-10-producing B cells induced by B. microti infection led to increased susceptibility of recipient mice to infection with B. microti. In contrast, experiments with B cell-deficient (µMT) mice demonstrated that lack of B cells enhances susceptibility to B. microti infection.
This study is the first demonstration of the expansion of Bregs following infection by an intraerythrocytic protozoan parasite. These data suggest that B. microti infection in mice provides an excellent model for studying Breg-mediated immune responses and begins to elucidate the mechanism by which helminth infection regulates autoimmunity and allergic inflammation.
PLoS ONE 10/2012; 7(10):e46553. DOI:10.1371/journal.pone.0046553 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Babesiosis is a zoonosis caused by tick-transmitted intraerythrocytic protozoa of the Phylum Apicomplexa. The disease mostly occurs in the USA, but cases have also been reported in several European countries, in Egypt, India, Japan, Korea, Taiwan, and South Africa. The main pathological event is lysis of erythrocytes resulting in haemolytic anaemia, which in severe cases may lead to organ failure and death, particularly in immunocompromised patients. The 2 groups of parasites involved, Babesia microti-like and Babesia sensu stricto (s.s.) species, differ in their life cycle characteristics and susceptibility to antibabesial drugs. Molecular taxonomy is now making a major contribution to the identification of novel pathogens within both groups. Effective treatment of severe cases was initially hampered by the lack of specific antibabesial drugs for human use, but increased use of supportive measures and of the recently developed antimalarial, atovaquone, particularly in combination with azithromycin, has improved the prospects for management of acute disease especially when caused by Babesia s.s. species. Prevention should be based primarily on increasing the awareness of physicians and the public to the risks, but infection from blood transfusions is particularly difficult to prevent. Expanding deer populations, resulting in wider distribution and greater abundance of ticks, heightened medical awareness, and growing numbers of immunocompromised patients are likely to result in a continuing rise of reported cases.
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