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.

A conserved protein of Babesia microti elicits partial protection against Babesia and Plasmodium infection.

BACKGROUND: The protozoan parasite Babesia microti that causes the zoonotic disease babesiosis resides in the erythrocytes of its mammalian host during its life-cycle. No effective vaccines are currently available to prevent Babesia microti infections. METHODS: We previously identified a highly seroactive antigen, named Bm8, as a B. microti conserved erythrocyte membrane-associated antigen, by high-throughput protein chip screening. Bioinformatic and phylogenetic analysis showed that this membrane-associated protein is conserved among apicomplexan hemoprotozoa, such as members of genera Babesia, Plasmodium and Theileria. We obtained the recombinant protein Bm8 (rBm8) by prokaryotic expression and purification. RESULTS: Immunofluorescence assays confirmed that Bm8 and its Plasmodium homolog were principally localized in the cytoplasm of the parasite. rBm8 protein was specifically recognized by the sera of mice infected with B. microti or P. berghei. Also, mice immunized with Bm8 polypeptide had a decreased parasite burden after B. microti or P. berghei infection. CONCLUSIONS: Passive immunization with Bm8 antisera could protect mice against B. microti or P. berghei infection to a certain extent. These results lead us to hypothesize that the B. microti conserved erythrocyte membrane-associated protein Bm8 could serve as a novel broad-spectrum parasite vaccine candidate since it elicits a protective immune response against Babesiosis and Plasmodium infection.

Chemoprophylaxis for babesiosis and anaplasmosis in cattle: case report.

Cattle tick fever (CTF) causes significant economic losses in the livestock sector. The pathogenic action of the hemoparasites is associated with anemia, weight loss, abortion and reduced productivity, which result with animal death. Programs to prevent CTF involve several procedures, including immunization, chemoprophylaxis and use of ectoparasiticides, together with the vector control in the environment. The objective of this study was to report an acute outbreak of CTF in a group of 157 Hereford cattle from a farm without presence of the vector, that were moved to a farm in the same state with a high tick infestation (Rhipicephalus microplus). On the day before the transportation, the animals received a chemoprophylaxis with imidocarb dipropionate (3 mg/kg, SC), which was repeated 21 days after the first application. After 42 days, some animals showed signs compatible with CTF, which was confirmed through clinical examination, necropsy, histopathological and hemoparasitological analyses. The morbidity rate was 37.6% and the mortality rate was 24.8%. Calves that were recently weaned were the group most affected with the tick fever, morbidity (100% and mortality (73%). Chemoprophylaxis in association with use of ectoparasiticides was not sufficient to control the outbreak of the disease.

Babesia microti Confers Macrophage-Based Cross-Protective Immunity Against Murine Malaria.

Malaria and babesiosis, the two primary intraerythrocytic protozoan diseases of humans, have been reported in multiple cases of co-infection in endemic regions. As the geographic range and incidence of arthropod-borne infectious diseases is being affected by climate change, co-infection cases with Plasmodium and Babesia are likely to increase. The two parasites have been used in experimental settings, where prior infection with Babesia microti has been shown to protect against fatal malarial infections in mice and primates. However, the immunological mechanisms behind such phenomena of cross-protection remain unknown. Here, we investigated the effect of a primary B. microti infection on the outcome of a lethal P. chabaudi challenge infection using a murine model. Simultaneous infection with both pathogens led to high mortality rates in immunocompetent BALB/c mice, similar to control mice infected with P. chabaudi alone. On the other hand, mice with various stages of B. microti primary infection were thoroughly immune to a subsequent P. chabaudi challenge. Protected mice exhibited decreased levels of serum antibodies and pro-inflammatory cytokines during early stages of challenge infection. Mice repeatedly immunized with dead B. microti quickly succumbed to P. chabaudi infection, despite induction of high antibody responses. Notably, cross-protection was observed in mice lacking functional B and T lymphocytes. When the role of other innate immune effector cells was examined, NK cell-depleted mice with chronic B. microti infection were also found to be protected against P. chabaudi. Conversely, in vivo macrophage depletion rendered the mice vulnerable to P. chabaudi. The above results show that the mechanism of cross-protection conferred by B. microti against P. chabaudi is innate immunity-based, and suggest that it relies predominantly upon the function of macrophages. Further research is needed for elucidating the malaria-suppressing effects of babesiosis, with a vision toward development of novel tools to control malaria.

Comparison of protectiveness of recombinant Babesia ovis apical membrane antigen 1 and B. ovis-infected cell line as vaccines against ovine babesiosis.

Babesiosis is a disease complex caused by unicellular Babesia parasites and among them, malignant ovine babesiosis caused by B. ovis has a devastating economical impact on the small ruminant industry. The control of disease is mainly based on chemotherapy and preventing animals from tick infestation and to date no vaccine is available against ovine babesiosis. The requirement for vaccination against B. ovis infection in endemically unstable regions is necessary for implementation of effective disease control measures. The aim of the present study was to evaluate the effectiveness of different immunisation protocols against disease in sheep experimentally vaccinated with recombinant B. ovis apical membrane antigen-1 (rBoAMA-1) and/or live, a B. ovis-infected cell line. Sheep were divided into four experimental groups, plus a control group. Animals were immunised either with the B. ovis stabilate, or with rBoAMA-1, or with both rBoAMA-1 and the B. ovis stabilate. Western blots and ELISAs indicated that immunisation with rBoAMA-1 resulted in generation of a specific response against the recombinant protein, but the degree of antibody response did not correlate with the level of induced protection against challenge. The strongest immune response was induced in animals co-immunised with the live B. ovis stabilate plus rBoAMA-1. Both the hematological and parasitological findings indicated that this co-immunisation regimen has vaccine potential to limit losses incurred by ovine babesiosis in endemic countries.

Chemoprophylaxis for babesiosis and anaplasmosis in cattle: case report / Quimioprofilaxia para babesiose e anaplasmose em bovinos: relato de caso

Abstract Cattle tick fever (CTF) causes significant economic losses in the livestock sector. The pathogenic action of the hemoparasites is associated with anemia, weight loss, abortion and reduced productivity, which result with animal death. Programs to prevent CTF involve several procedures, including immunization, chemoprophylaxis and use of ectoparasiticides, together with the vector control in the environment. The objective of this study was to report an acute outbreak of CTF in a group of 157 Hereford cattle from a farm without presence of the vector, that were moved to a farm in the same state with a high tick infestation (Rhipicephalus microplus). On the day before the transportation, the animals received a chemoprophylaxis with imidocarb dipropionate (3 mg/kg, SC), which was repeated 21 days after the first application. After 42 days, some animals showed signs compatible with CTF, which was confirmed through clinical examination, necropsy, histopathological and hemoparasitological analyses. The morbidity rate was 37.6% and the mortality rate was 24.8%. Calves that were recently weaned were the group most affected with the tick fever, morbidity (100% and mortality (73%). Chemoprophylaxis in association with use of ectoparasiticides was not sufficient to control the outbreak of the disease.

Resumo A "tristeza parasitária bovina" (TPB) gera importantes perdas econômicas na bovinocultura mundial. A ação patogênica dos hemoparasitas resulta em anemia, perda de peso, abortos e diminuição da produtividade, culminando, muitas vezes, em óbito dos animais. Um programa de prevenção para TPB necessita de medidas integradas, como a imunização, quimioprofilaxia e utilização de ectoparasiticidas, em conjunto com ações que visem ao controle ambiental dos vetores. Este artigo tem em vista o relato de um surto de TPB em uma fazenda de produção de bovinos de corte e com alta infestação do carrapato (Rhipicephalus microplus). A fazenda adquiriu 157 animais puros de origem, da raça Hereford, proveniente de uma fazenda sem presença do vetor. No dia anterior ao transporte, os animais receberam quimioprofilaxia com dipropionato de imidocarb (3mg/Kg/SC), repetindo-se 21 dias após a primeira aplicação. Aos 42 dias, alguns bezerros manifestaram sinais clínicos compatíveis com TPB, sendo confirmado pelo exame clínico, necropsia, análises histopatológicas e hemoparasitológicas. A morbidade foi de 37,6% (59/157), e a letalidade de 24,8% (39/157). A categoria de bezerros recém desmamados foi a mais acometida, com morbidade de 100% (52/52) e letalidade de 73% (38/52). A quimioprofilaxia associada à utilização de ectoparasiticidas foram insuficientes para evitar a ocorrência do surto da enfermidade.

Evaluation of the protective effect of a prime-boost strategy with plasmid DNA followed by recombinant adenovirus expressing BmAMA1 as vaccines against Babesia microti infection in hamster.

In the present study, we have investigated the protective effect of a heterologous prime-boost strategy with priming plasmid DNA followed by recombinant adenovirus, both expressing BmAMA1, against Babesia microti infection. Four groups consisting of 3 hamsters per group were immunized with pBmAMA1/Ad5BmAMA1, pNull/Ad5BmAMA1, pBmAMA1/Ad5Null and pNull/Ad5Null, followed by challenge infection with B. microti. Our results showed that hamsters immunized with plasmid and adenovirus expressing BmAMA1 developed a robust IgG and IgG2a antibody response against BmAMA1, suggesting the DNA vaccine or viral vector vaccine tend to induce a Th1-biased response. Compared to the control hamsters, the hamsters vaccinated either with the prime-boost strategy or one of the two "vaccines" exhibited no significant protection against B. microti challenge. Although a slight difference in terms of parasitemia and hematocrit values at days 14-16 post challenge infection was observed, no other statistical difference was detected. Our results indicate that the prime-boost vaccination strategy of injection of plasmid and adenovirus expressing BmAMA1 is not efficient in protecting against B. microti infection.

Inactivation of Babesia microti in red blood cells and platelet concentrates.

BACKGROUND: With an increasing number of recognized transfusion-transmitted (TT) babesiosis cases, Babesia microti is the most frequently TT parasite in the United States. We evaluated the inactivation of B. microti in red blood cells (RBCs) prepared in Optisol (AS-5) using amustaline and glutathione (GSH) and in platelet components (PCs) in 100% plasma using amotosalen and low-energy ultraviolet A (UVA) light. STUDY DESIGN AND METHODS: Individual RBCs and apheresis PCs were spiked with B. microti-infected hamster RBCs (iRBCs) to a final concentration of 106 iRBCs/mL and treated with the respective inactivation systems according to the manufacturer's instruction. Samples were collected before (control) and after (test) each treatment. Dilutions of the control samples to 10-6 were inoculated into hamsters, while the test samples were inoculated neat or at 10-1 dilution. At 3 and 5 weeks postinoculation, hamsters were evaluated for B. microti infection by microscopic observation of blood smears and 50% infectivity titers (ID50 ) were determined. Log reduction was calculated as control log ID50 minus test log ID50 . RESULTS: Parasitemia was detected in hamsters injected with as low as 100,000-fold diluted control samples, while no parasites were detectable in the blood smears of any hamsters receiving neat test samples. Mean log reduction was more than 5 log/mL by amustaline/GSH for RBCs and more than 4.5 log/mL by amotosalen/UVA for PCs. CONCLUSION: B. microti was inactivated to the limit of detection in RBCs and PCs after the respective inactivation treatment. Complete inactivation of B. microti was achieved in this animal infectivity model, and pathogen reduction treatment inhibited transmission of infection.

Transfusion-transmitted babesiosis: is it time to screen the blood supply?

PURPOSE OF REVIEW: This review summarizes the current status of blood screening to prevent transfusion-transmitted babesiosis (TTB). RECENT FINDINGS: Babesia microti has recently been determined to be the most common transfusion-transmitted pathogen in the United States. Patients who acquire TTB often experience severe illness with an associated mortality rate of about 20%. Recent studies have demonstrated that laboratory screening using B. microti antibody and/or PCR assays can effectively identify infectious blood donors and that this approach may offer a cost- effective means of intervention. Pathogen inactivation methods may offer an alternative solution. None of these methods has yet been licensed by US Food and Drug Administration, however, and current efforts to prevent TTB rely on excluding blood donors who report having had babesiosis. SUMMARY: TTB imposes a significant health burden on the United States population. Further research is needed to better inform decisions on optimal screening strategies and reentry criteria, but given the acute need and the currently available screening tools, initiation of blood donor screening to prevent TTB should be given high priority.

Evaluation of different heterologous prime-boost immunization strategies against Babesia bovis using viral vectored and protein-adjuvant vaccines based on a chimeric multi-antigen.

Protection against the intraerythrocytic bovine parasite Babesia bovis requires both humoral and cellular immune responses. Therefore, tailored combinations of immunogens targeted at both arms of the immune system are strategies of choice to pursue sterilizing immunity. In this study, different heterologous prime-boost vaccination schemes were evaluated in mice to compare the immunogenicity induced by a recombinant adenovirus, a modified vaccinia Ankara vector or a subunit vaccine all expressing a chimeric multi-antigen. This multi-antigen includes the immunodominant B and T cell epitopes of three B. bovis proteins: Merozoite Surface Antigen - 2c (MSA-2c), Rhoptry Associated Protein - 1 (RAP-1) and Heat Shock Protein 20 (HSP20). Both priming with the adenovirus or recombinant multi-antigen and boosting with the modified vaccinia Ankara vector achieved a high degree of activation of TNFα and IFNγ-secreting CD4(+) and CD8(+) specific T cells 60days after the first immunization. High titers of specific IgG antibodies were also detected at the same time point and lasted up to day 120 of the first immunization. Only the adenovirus - MVA combination triggered a marked isotype skew for the IgG2a antibody subclass meanwhile for the other immune traits analyzed here, both vaccination schemes showed similar performances. The immunological characterization in the murine model of these rationally designed immunogens led us to propose that adenoviruses as well as the bacterially expressed multi-antigen are highly reliable primer candidates to be considered in future experiments in cattle to test protection against bovine babesiosis.

Diagnosis, Treatment, and Prevention of Lyme Disease, Human Granulocytic Anaplasmosis, and Babesiosis: A Review.

IMPORTANCE: Lyme disease, human granulocytic anaplasmosis (HGA), and babesiosis are emerging tick-borne infections. OBJECTIVE: To provide an update on diagnosis, treatment, and prevention of tick-borne infections. EVIDENCE REVIEW: Search of PubMed and Scopus for articles on diagnosis, treatment, and prevention of tick-borne infections published in English from January 2005 through December 2015. FINDINGS: The search yielded 3550 articles for diagnosis and treatment and 752 articles for prevention. Of these articles, 361 were reviewed in depth. Evidence supports the use of US Food and Drug Administration-approved serologic tests, such as an enzyme immunoassay (EIA), followed by Western blot testing, to diagnose extracutaneous manifestations of Lyme disease. Microscopy and polymerase chain reaction assay of blood specimens are used to diagnose active HGA and babesiosis. The efficacy of oral doxycycline, amoxicillin, and cefuroxime axetil for treating Lyme disease has been established in multiple trials. Ceftriaxone is recommended when parenteral antibiotic therapy is recommended. Multiple trials have shown efficacy for a 10-day course of oral doxycycline for treatment of erythema migrans and for a 14-day course for treatment of early neurologic Lyme disease in ambulatory patients. Evidence indicates that a 10-day course of oral doxycycline is effective for HGA and that a 7- to 10-day course of azithromycin plus atovaquone is effective for mild babesiosis. Based on multiple case reports, a 7- to 10-day course of clindamycin plus quinine is often used to treat severe babesiosis. A recent study supports a minimum of 6 weeks of antibiotics for highly immunocompromised patients with babesiosis, with no parasites detected on blood smear for at least the final 2 weeks of treatment. CONCLUSIONS AND RELEVANCE: Evidence is evolving regarding the diagnosis, treatment, and prevention of Lyme disease, HGA, and babesiosis. Recent evidence supports treating patients with erythema migrans for no longer than 10 days when doxycycline is used and prescription of a 14-day course of oral doxycycline for early neurologic Lyme disease in ambulatory patients. The duration of antimicrobial therapy for babesiosis in severely immunocompromised patients should be extended to 6 weeks or longer.

Babesia canis vogeli infection in dogs and ticks in the semiarid region of Pernambuco, Brazil / Infecção por Babesia canis vogeli em cães e carrapatos de uma região semiárida de Pernambuco

This study aimed to report the prevalence of Babesia canis vogeli in dogs and ticks in the urban and rural areas of Petrolina, Pernambuco. Serum and peripheral blood samples of 404 dogs were tested by indirect immunofluorescence assay (IFA) and by blood smears, respectively. The presence of tick infestation was evaluated, and some specimens were submitted to DNA amplification by polymerase chain reaction (PCR). The presence of antibodies anti-B. canis vogeli was determinate in 57.9% (234/404) of dogs. The direct detection of Babesia spp was obtained in 0.5% (2/404) dogs by visualization of intraerythrocytic forms. Infestation by Rhipicephalus sanguineus sensu lato was observed in 54.5% (220/404) of dogs in both urban and rural areas. DNA of Babesia canis vogeli were obtained by PCR in 6% individual (3/50) and 8.7% of pool of ticks (7/80). The risk factors for the presence of anti-B. canis vogeli antibodies, as determined through the application of logistic regression models (P<0.05), were the following: medium breed size variables (P<0.001); contact with areas of forest (P=0.021); and access on the street (P=0.046). This study describes, for the first time, the confirmation of infection of B. canis vogeli in dogs and ticks in the semiarid region of Pernambuco, Brazil.

Este trabalho objetivou avaliar a prevalência de Babesia canis vogeli em cães e carrapatos de áreas urbanas e rurais do município de Petrolina, Pernambuco, Nordeste do Brasil. Amostras de soro e sangue periférico de 404 cães foram testadas pela Reação de Imunoflorescência Indireta (RIFI), e por esfregaço sanguíneo. A presença de infestação por carrapatos foi avaliada, e alguns espécimes foram submetidos à amplificação do DNA pela Reação em Cadeia pela Polimerase (PCR). A presença de anticorpos anti-B. canis vogeli foi determinada em 57,9% (234/404) dos cães. A soroprevalência em áreas urbanas e rurais foi 48,5% e 67,3%, respectivamente. A detecção direta de Babesia spp foi obtida em 0,5% dos cães pela visualização de formas intraeritrocitárias. A infestação pelo carrapato Rhipicephalus sanguineus foi observada em 54,5% (220/404) dos cães. DNA de Babesia canis vogeli obtido pela PCR foi 6% (3/50) em carrapatos processados individualmente e 8,7% (7/80) em pools. Os fatores de risco para presença de anticorpos anti- B. canis vogeli utilizando modelo de regressão logística (P < 0,05) foram porte médio (P <0,001), contato com áreas de floresta (P = 0,021), e acesso dos cães à rua (P = 0,046). Este estudo descreve pela primeira vez a confirmação da infecção de Babesia canis infectando cães e carrapatos em uma região semiárida de Pernambuco, Brasil.

Babesiosis in cats: ABCD guidelines on prevention and management.

OVERVIEW: Babesiosis is a tick-borne protozoan disease caused by parasites of the genus Babesia that belong to the Piroplasmida. The disease is named after the Romanian bacteriologist Victor Babes. Babesiosis is also known as piroplasmosis (from Latin pirum, meaning 'pear', and plasma, 'image, formation'). INFECTION: Babesiosis affects domestic and wild animals and humans worldwide. While the disease is recognised in dogs around the world, it is found only rarely in cats. HUMAN DISEASE: Babesia species are common blood parasites of mammals. Human babesiosis is uncommon, but more cases in people have been reported recently, most likely because of rising awareness.

Riboflavin and ultraviolet light reduce the infectivity of Babesia microti in whole blood.

BACKGROUND: Babesia microti is the parasite most frequently transmitted by blood transfusion in the United States. Previous work demonstrated the efficacy of riboflavin (RB) and ultraviolet (UV) light to inactivate B.microti in apheresis plasma and platelet units. In this study we investigated the effectiveness of RB and UV light to reduce the levels of B.microti in whole blood (WB). STUDY DESIGN AND METHODS: WB units were spiked with B. microti-infected hamster blood. Spearman-Karber methods were used to calculate infectivity of each sample in terms of hamster infectious dose 50% (HID50 ) value. After RB addition, the units were illuminated with 80 J/mLRBC UV light. Two samples were collected: one before illumination and one after illumination. The samples were serially diluted and dilutions injected into a group of five naive hamsters. Four weeks postinoculation (PI), blood was collected from the animals and evaluated by microscopic observation. RESULTS: One pilot study showed a good dose response in the animals and demonstrated that sample infectivity could be calculated in terms of an HID50 . Three additional replicates were performed in the same manner as the pilot study, but with fewer dilutions. Infectivity values were consistent between the experiments and were used to calculate log reduction. The posttreatment reduction of B. microti for all the experiments was more than 5 log. CONCLUSIONS: The data collected indicate that use of RB and UV is able to decrease the parasite load in WB units thus reducing the risk of transfusion-transmitted B. microti from blood components containing B. microti-infected RBCs.

Macrophages are critical for cross-protective immunity conferred by Babesia microti against Babesia rodhaini infection in mice.

Although primary infection of mice with Babesia microti has been shown to protect mice against subsequent lethal infection by Babesia rodhaini, the mechanism behind the cross-protection is unknown. To unravel this mechanism, we investigated the influence of primary infection of mice with nonlethal B. microti using different time courses on the outcome of subsequent lethal B. rodhaini infection. Simultaneous infections of mice with these parasites resulted in rapid increases in parasitemia, with 100% mortality in BALB/c mice, as observed with control mice infected with B. rodhaini alone. In contrast, mice with acute, resolving, and chronic-phase B. microti infections were completely protected against B. rodhaini, resulting in low parasitemia and no mortalities. Mice immunized with dead B. microti were not protected from B. rodhaini infection, although high antibody responses were induced. Interestingly, the protected mice had significantly decreased levels of antibody response, cytokines (including gamma interferon [IFN-γ], interleukin-2 [IL-2], IL-8, IL-10, and IL-12), and nitric oxide levels after infection with B. rodhaini. SCID mice and IFN-γ-deficient mice with chronic B. microti infections demonstrated protective responses comparable to those of immunocompetent mice. Likewise, in vivo NK cell depletion did not significantly impair the protective responses. Conversely, macrophage depletion resulted in increased susceptibility to B. rodhaini infection associated with changes in their antibody and cytokines profiles, indicating that macrophages contribute to the protection against this challenge infection. We conclude that future development of vaccines against Babesia should include a strategy that enhances the appropriate activation of macrophages.

Evaluation of the Mirasol pathogen [corrected] reduction technology system against Babesia microti in apheresis platelets and plasma.

BACKGROUND: Babesia microti is an intraerythrocytic parasite, transmitted naturally to humans by infected ixodid ticks, that causes babesiosis. In recent years, B. microti has been identified as a growing public health concern that has also emerged as a critical blood safety issue in the absence of appropriate interventions to reduce transmission by blood transfusion. Thus, we evaluated the ability of the Mirasol pathogen reduction technology (PRT; CaridianBCT), which uses riboflavin (RB) and ultraviolet (UV) light, to diminish the presence of B. microti in apheresis plasma and platelets (PLTs). STUDY DESIGN AND METHODS: Apheresis plasma and PLT units were spiked with B. microti-infected hamster blood and subsequently treated using the Mirasol PRT system. Control and experimental samples were collected at different stages during the treatment process and injected into hamsters to detect the presence of viable parasites. Four weeks postinoculation, hamster blood was tested for B. microti infection by blood smear and real-time polymerase chain reaction analysis. RESULTS: None of the blood smears from animals injected with samples from PRT-treated plasma or PLT units were positive by microscopy, while all the non-PRT-treated plasma and PLT units were demonstrably parasitemic. Parasite load reduction in hamsters ranged between 4 and 5 log in all PRT-treated units compared to untreated controls. CONCLUSION: The data indicate that the use of RB and UV light efficiently reduces the presence of viable B. microti in apheresis plasma and PLT products, thereby reducing the risk of transfusion-transmitted Babesia potentially associated with these products. Based on this observed "proof of principle," future studies will determine the efficacy of the Mirasol PRT in whole blood.

Photochemical inactivation with amotosalen and long-wavelength ultraviolet light of Plasmodium and Babesia in platelet and plasma components.

BACKGROUND: Transfusion-transmitted cases of malaria and babesiosis have been well documented. Current efforts to screen out contaminated blood products result in component wastage due to the lack of specific detection methods while donor deferral does not always guarantee safe blood products. This study evaluated the efficacy of a photochemical treatment (PCT) method with amotosalen and long-wavelength ultraviolet light (UVA) to inactivate these agents in red blood cells (RBCs) contaminating platelet (PLT) and plasma components. STUDY DESIGN AND METHODS: Plasmodium falciparum- and Babesia microti-contaminated RBCs seeded into PLT and plasma components were treated with 150 micromol per L amotosalen and 3 J per cm2 UVA. The viability of both pathogens before and after treatment was measured with infectivity assays. Treatment with 150 micromol per L amotosalen and 1 J per cm2 UVA was used to assess the robustness of the PCT system. RESULTS: No viable B. microti was detected in PLTs or plasma after treatment with 150 mol per L amotosalen and 3 J per cm2 UVA, demonstrating a mean inactivation of greater than 5.3 log in PLTs and greater than 5.3 log in plasma. After the same treatment, viable P. falciparum was either absent or below the limit of quantification in three of four replicate experiments both in PLTs and in plasma demonstrating a mean inactivation of at least 6.0 log in PLTs and at least 6.9 log in plasma. Reducing UVA dose to 1 J per cm2 did not significantly affect the level of inactivation. CONCLUSION: P. falciparum and B. microti were highly sensitive to inactivation by PCT. Pathogen inactivation approaches could reduce the risk of transfusion-transmitted parasitic infections and avoid unnecessary donor exclusions.

Babesia: the protective effects of killed Propionibacterium acnes on the infections of two rodent Babesia parasites in mice.

In the present study, we investigated the protective effects of killed Propionibacterium acnes on the infections of two rodent Babesia parasites in mice. Pre-treatment with "EqStim" (a commercially available immunostimulant containing killed P. acnes) showed significant resistance to both infections. To elucidate the immunological status in the mice, the concentrations of multiple cytokines were measured in serum collected from infected mice. After B. microti infection, the levels of interleukin (IL)-2, IL-4, IL-5, IL-10, IL-12p70, and tumor necrosis factor (TNF)-alpha in the treated group were significantly lower than in the control group. In contrast, after B. rodhaini infection, only IL-12p70 and TNF-alpha were detectable at significantly higher levels in the treated group than in the control group. The present findings indicated the protective effects of killed P. acnes on rodent babesiosis even with different immune responses between the B. microti and B. rodhaini infections. Killed P. acnes might be a powerful tool for the control of serious livestock babesiosis.

[Natural infection by hemoparasites in calves submitted to chemoprophylaxis at 30 days of age]. / Infecção natural por hemoparasitos em bezerros submetidos à químioprofilaxia aos 30 dias de idade.

The tick-borne disease (TBD) brings great damages to cattle breeding. The most important etiologic agents are Babesia bigemina, B. bovis and Anaplasma marginale, being the tick Boophilus microplus the main vector. This work reports the occurrence of natural infection by hemoparasites of TBD in 36 calves with high ticks natural infestation submitted to chemoprophylaxis with 30 days year-old. The blood smears from animals of different ages were analized and were found B. bigemina (33.3%), B. bovis (11.1%) and A. marginale (13.9%). Six animals had clinical symptoms (16.7%) and one dead (2.8%). The number of clinical cases ocurred in consequence of an association of factors as high infestation of ticks and low passive immunity in period that calves had not developed enough active immunity.