In vitro evaluation of the growth inhibitory activities of 15 drugs against Babesia gibsoni (Aomori strain)

The in vitro growth inhibitory activities of 15 drugs against Babesia gibsoni were evaluated following establishment of a continuous culture isolate (Aomori isolate). The culture was successfully continued in an RPMI-1640 medium supplemented with 20% normal canine serum or fetal bovine serum in a humidified atmosphere containing 5% CO(2) and 5% O(2) at 37 degrees C. We used this isolate to evaluate the growth inhibitory effect of naphthoquinone (atovaquone), aromatic diamidine (diminazene and pentamidine), artemisinin compounds (artesunate and dihydroartemisinin), an iron chelator (deferoxamine), quinoline-containing compounds (quinine and chloroquine), macrolide antibiotics (azithromycin), lyncomycin antibiotics (clindamycin), tetracycline antibiotics (doxycycline and minocycline), imidazole antifungals (clotrimazole and ketoconazole), and a nitroimidazole antiprotozoal (metronidazole). Atovaquone and aromatic diamidine showed the highest activity; they were followed by artesunate compounds with nanomole levels of IC(50). Metronidazole did not exhibit activity against the parasite. Other drugs exhibited intermediate in vitro activities with micromole levels of IC(50). This is the first report to screen drug activities against B. gibsoni in vitro. The results of our study may support further in vitro drug evaluation for the establishment of therapeutic strategies against canine B. gibsoni infections.     

吉氏巴贝斯虫单克隆抗体制备的研究

应用淋巴细胞杂交瘤技术制备杂交瘤细胞株 ,经间接萤光抗体法筛选和克隆 ,获得了 5株能稳定分泌吉氏巴贝斯虫特异性抗体的杂交瘤细胞株 ,分别命名为C3B5、M8B7、E9C5、G6 D8、H2 A7。经过鉴定 ,这 5株杂交瘤细胞分泌的单克隆抗体亚类及相对分子质量分别为IgG2b,1 8× 1 0 4 ;IgG2a,1 8× 1 0 4 ;IgG1 ,1 8× 1 0 4 ;IgM ,3 2× 1 0 4 ;IgM ,1 8× 1 0 4 。腹水效价为 1∶1 0 4 ～ 1∶1 0 5。其中E9C5杂交瘤细胞株分泌的单克隆抗体是一种保护性抗体 ,经对实验感染吉氏巴贝斯虫小鼠体内虫体的杀虫试验证明具有较强的杀灭作用。     

The therapeutic efficacy of two antibabesial strategies against Babesia gibsoni

Various combination strategies for treating Babesia gibsoni have been described. However, relapses after administering some combinations of antibabesial drugs and the presence of drug-resistant B. gibsoni still pose significant challenges to veterinarians. To compare the efficacy of a combination of clindamycin, diminazene, and imidocarb (CDI) to that of a combination of atovaquone and azithromycin (AA) for the treatment of B. gibsoni and to correlate drug efficacy with B. gibsoni mutations, 30 client-owned dogs with natural B. gibsoni infections were collected in the study. 17 dogs were treated with AA, and 13 dogs were treated with CDI combination. Hematological parameters were recorded on the day that the dogs were presented for treatment and during treatment. To detect the parasitic DNA, the B. gibsoni 18S rRNA gene was amplified, and to analyze the mutations, the cytochrome b (CYTb) gene was sequenced. The therapy duration for all of the dogs that recovered was 23.3±7.8 days in the AA group and 41.7±12.4 days in the CDI group. Nine of the 17 dogs in the AA group and 11 of the 13 dogs in the CDI group completely recovered. Seven dogs in the AA group and 2 dogs in the CDI group relapsed after treatment. The M121I mutation in the B. gibsoni CYTb gene was detected in all of the samples that were collected from AA-relapsed and AA-nonremission dogs. The dogs in the CDI group exhibited higher recovery rates and lower relapse rates during treatment for B. gibsoni infection. In addition, the detected M121I mutation was associated with AA treatment. The CDI combination is a promising alternative treatment strategy for B. gibsoni.     

Efficacy of atovaquone against Babesia gibsoni in vivo and in vitro

The therapeutic efficacy of atovaquone against Babesia gibsoni was examined in three dogs experimentally infected with B. gibsoni isolated from naturally infected dogs in Aomori Prefecture, Japan. Once parasitemia reached 10%, atovaquone was administered orally (30 mg/kg twice daily for 7 days). Within 2 days of atovaquone treatment, the parasite disappeared from blood smears without any clinical side effects. Anemia and thrombocytopenia were significantly improved in all the dogs. However, a polymerase chain reaction assay revealed that a B. gibsoni marker gene was intermittently present in peripheral blood after atovaquone therapy, indicating that the organism had not been eliminated, and parasites reappeared in blood smears 33 days after the last treatment. To investigate the change in sensitivity against atovaquone, an in vitro sensitivity test was performed using peripheral blood obtained from an untreated dog that was infected with the original parasite isolate, and from two of the experimentally infected and atovaquone-treated animals (blood was collected at the time of the post-treatment recurrence of the B. gibsoni infection). Atovaquone was added to the culture medium to final concentrations of 0.1, 1, 10, 100, and 1000 nM. For the untreated parasites, complete growth inhibition occurred at 1000 nM of atovaquone, whereas the recurrent parasites were inhibited by only 39.52 +/- 8.34% and 31.31 +/- 8.14% at this concentration after 48 h of incubation. Thus, the recurring parasites were less sensitive to atovaquone than the untreated originally isolated parasites.     

Effects of Central Kalimantan plant extracts on intraerythrocytic Babesia gibsoni in culture

The inhibitory effects of 45 plant extracts selected from Central Kalimantan, Indonesia on Babesia gibsoni in vitro and their acute toxicity to mice were evaluated. Of these plant extracts studied, Arcangelisia flava, Curcuma zedoaria, Garcinia benthamiana, Lansium domesticum and Peronema canescens were found to have appreciable antibabesial activity with IC50 values from 5.3 to 49.3 microg/ml without acute toxicity in mice at the intraperitoneal dose of 0.7 g/kg of body weight.     

吉氏巴贝斯虫mRNA的磁性分离及cDNA合成

从感染吉氏巴贝斯虫的摘脾犬的红细胞内提纯虫体,用异硫氰酸胍法提取虫体总RNA,再以Poly(A)~ mRNA磁性分离系统提取mRNA.最后以NotⅠPrimer-Adaptor为引物反转录出cDNA片段.琼脂糖凝胶电泳显示,所合成的cDNA分子量范围由100到6500bP,且绝大部分大于500bP.     

Clinical usefulness of antibodies against Babesia gibsoni detected by ELISA with recombinant P50

The clinical usefulness of antibodies against Babesia gibsoni detected by ELISA with recombinant P50 was examined in dogs in an area where B. gibsoni infection was endemic. Only 8 among 14 dogs with acute type B. gibsoni infection without a previous history of infection were positive. This high percentage of false-negative results is thought to be a weak point of ELISA as a diagnostic tool. However, 14 other anemic dogs with a confirmed history of B. gibsoni infection were all positive, thus confirming the higher sensitivity of ELISA in detecting a history of infection.     

犬吉氏巴贝斯虫的人工感染及治疗试验

为进一步证实犬吉氏巴贝斯虫（Ｂａｂｅｓｉａｇｉｂｓｏｎｉ）的致病作用,筛选较为理想的治疗药物,将１２只杂种狼犬均分为摘脾组与不摘脾组,进行了吉氏巴贝斯虫人工感染试验。人工感染犬临床症状与自然感染犬无明显差异,表现为体温升高、红细胞减少、Ｈｂ降低及虫血症等,摘脾组较不摘脾组虫血症和症状的出现早１～２ｄ。将此１２只人工感染犬及６７只自然感染犬随机分成４组,分别以贝尼尔（Ｂｅｒｅｎｉｌ）、阿卡普林（Ａ－ｃａｐｒｉｎｕｍ）、蒿甲醚（Ａｒｔｅｍｔｈｅｒｉｎ）和磷酸伯氨喹（Ｐｒｉｍａｑｕｉｎｅｐｈｏｓｐｈａｔｅ）４种药物进行治疗比较试验,结果以蒿甲醚疗效最好,用药后第２天虫体转阴率达７０％,第３天Ｈｂ由２８ｇ／Ｌ上升到６４ｇ／Ｌ,奏效迅速。     

Clindamycin in the treatment of Babesia gibsoni infections in dogs

This report examines the effectiveness of clindamycin for the treatment of babesiosis in dogs (n=10) experimentally infected with Babesia gibsoni (B. gibsoni). Clindamycin (25 mg/kg body weight, per os, q 12 hours for 14 days) gradually reduced parasitemia levels and induced morphological changes that indicated degeneration of parasites (e.g., segmentation; size reduction; localization in the cell limbic and/or torn state of the nucleus; and swelling, decrease, or disappearance of the cytoplasm) in the majority of dogs. Clindamycin treatment reduced the clinical symptoms characteristic of Babesia infection, including anemia, anorexia, and listlessness. Clindamycin might be useful as a medicine for treatment of B. gibsoni infection.     

大青叶板蓝根等5种清热类中药体外抗伪狂犬病病毒效果

中药具有抗病毒和免疫调节等作用,尤其是对病毒病和慢性疾病的预防和治疗具有独特的优势.部分中药可通过阻断病毒繁殖过程中的吸附、穿入、复制、成熟中的一个环节而直接杀灭病毒,而另一些中药可调节机体平衡,增强机体细胞及体液免疫功能,从而间接抑制病毒增殖;还有一些中药可诱发机体产生干扰素或IL-1等;而且由于中药多为天然药物,药性温和,不良反应少,使开发治疗猪伪狂犬病的中药制剂成为可能[1].     

The cause of the predilection of Babesia gibsoni for reticulocytes

This study was conducted to determine why Babesia gibsoni replicates well in reticulocytes. First, B. gibsoni was cultivated in resealed erythrocyte ghosts loaded with either erythrocyte or reticulocyte lysate, and in reticulocyte ghosts loaded with either erythrocyte or reticulocyte lysate. The parasites multiplied well in the erythrocyte or reticulocyte ghosts loaded with reticulocyte lysate compared to the other resealed cells loaded with erythrocyte lysate. Second, the parasites were cultivated in erythrocytes in culture medium supplemented with either erythrocyte or reticulocyte lysate. The parasites multiplied better in reticulocyte lysate-containing cultures than in erythrocyte lysate-containing cultures. Finally, the parasites were cultivated in erythrocytes in culture medium supplemented with glutamate, aspartate, asparagine, glycine, isoleucine, proline, taurine or GSH, which were present in higher concentrations in reticulocytes than in erythrocytes. Supplementation of the culture medium with glutamate and GSH resulted in enhancement of the multiplication of the parasites, while the other amino acids did not enhance the multiplication. These results indicated that the high levels of the multiplication of B. gibsoni in reticulocytes are partly due to the high concentrations of glutamate and GSH in reticulocytes.     

Antibabesial activity of protoberberine alkaloids and 20-hydroxyecdysone from Arcangelisia flava against Babesia gibsoni in culture

Bioassay-guided fractionation of the boiled extract from the stems of Arcangelisia flava led to the isolation of palmatine (1), berberine (2), jatrorrhizine (3), dihydroberberine (4) and 20-hydroxyecdysone (5). The chemical structures of these compounds were elucidated on the basis of their chemical and spectral evidence. The isolated compounds were evaluated for their growth inhibiting effects on Babesia gibsoni in culture for a week. Compounds (1-4) showed significant inhibitions at concentrations from 100 to 1.0 microg/ml, while compound 5 at a concentration of 100 microg/ml, only.     

吉氏巴贝斯虫cDNA探针的制备及杂交试验

本实验将－６．６ｋｂ的吉氏巴贝斯虫ｃＤＮＡ片段以光照活化法标记光敏生物素，制备成光敏生物素探针。与吉氏巴贝斯虫基因组ＤＮＡ、伊氏锥虫基因组ＤＮＡ、犬白细胞ＤＮＡ的斑点杂交试验表明，该探针可与０．００１ｎｇ以上量的吉氏巴贝斯虫ＤＮＡ杂交，而不与任何浓度的伊氏锥虫ＤＮＡ和犬ＤＮＡ杂交，具有很高的敏感性和特异性。     

犬吉氏巴贝斯虫BgTRAP的原核表达及抗原表位分析

为表达犬吉氏巴贝斯虫Bg TRAP蛋白及鉴定其抗原表位,本研究将犬吉氏巴贝斯虫Bg TRAP编码基因的密码子进行优化和高效表达,并利用生物学软件分析预测,结果显示,Bg TRAP中存在10个潜在的线性抗原表位,通过原核表达系统对其预测表位的多肽进行表达,以筛选的阳性血清样品为检测抗体进行ELISA检测,结果表明其中3个多肽能够与抗体特异性结合,其多肽序列分别为126DYVIAVEDTTHFGE139、672AYILAGFA GLLLIT685和497SDELGDEMGLTTNE510。本研究对Bg TRAP蛋白抗原表位的鉴定,为进一步开发基于Bg TRAP的犬吉氏巴贝斯虫诊断抗原及Bg TRAP的免疫学特性研究奠定了基础。     

中国犬吉氏巴贝斯虫srRNA的序列测定及其在PCR诊断上的应用

用特异引物ＢＧ－１和ＢＧ－２从南京株吉氏巴贝斯虫ｃＤＮＡ文库中克隆出ｓｓｒＲＮＡ序列，测定了该序列的核苷酸组成。通过基因库同源性查询表明，该序列与美洲株吉氏巴贝斯虫ｓｓｒＲＮＡ具有８７％的同源性。本实验通过优化ＢＧ－１和ＢＧ－２引物对ｓｓｒＲＮＡ基因的扩增反应条件，建立了对吉氏巴贝斯虫的特异、敏感的诊断方法。该方法可广泛用于其他血液原虫的ＰＣＲ诊断     

一例犬吉氏巴贝斯虫感染引起的免疫介导溶血性贫血的诊治

犬免疫介导溶血性贫血是一种与自身红细胞抗体有关的溶血性贫血,发病原因可分为原发性和继发性,论文主要介绍了一例由吉氏巴贝斯虫感染后继发的犬自身免疫溶血性贫血的诊断、治疗和预后。     

Molecular cloning and phylogenetic analysis of Babesia gibsoni heat shock protein 70

The Babesia gibsoni heat shock protein 70 gene (BGHsp70) was cloned by polymerase chain reaction (PCR) and sequenced. The length of the gene was 1938 bp and the predicted polypeptide was 646 amino acids long with a calculated molecular weight of 70,627. The amino acid sequences of BGHsp70 from 17 isolates were identical, though there were six types of polymorphisms among the corresponding nucleotide sequences. There was no intron in the BGHsp70 gene. Phylogenetic analysis of the amino acid sequence of Hsp70 showed that B. gibsoni was most closely related to B. bovis and lies within a phylogenetic cluster with Theileria. These results suggest that Hsp70 was well conserved among intraerythrocytic protozoa.