Mohamed Abdo Rizk

An epidemiological survey of bovine Babesia and Theileria parasites in cattle, buffaloes, and sheep in Egypt

Cattle, buffaloes, and sheep are the main sources of meat and milk in Egypt, but their productivity is thought to be greatly reduced by hemoprotozoan parasitic diseases. In this study, we analyzed the infection rates of Babesia bovis, Babesia bigemina, Theileria annulata, and Theileria orientalis, using parasite-specific PCR assays in blood-DNA samples sourced from cattle (n=439), buffaloes (n=50), and sheep (n=105) reared in Menoufia, Behera, Giza, and Sohag provinces of Egypt. In cattle, the positive rates of B. bovis, B. bigemina, T. annulata, and T. orientalis were 3.18%, 7.97%, 9.56%, and 0.68%, respectively. On the other hand, B. bovis and T. orientalis were the only parasites detected in buffaloes and each of these parasites was only found in two individual DNA samples (both 2%), while one (0.95%) and two (1.90%) of the sheep samples were positive for B. bovis and B. bigemina, respectively. Sequence analysis showed that the B. bovis Rhoptry Associated Protein-1 and the B. bigemina Apical Membrane Antigen-1 genes were highly conserved among the samples, with 99.3-100% and 95.3-100% sequence identity values, respectively. In contrast, the Egyptian T. annulata merozoite surface antigen-1 gene sequences were relatively diverse (87.8-100% identity values), dispersing themselves across several clades in the phylogenetic tree containing sequences from other countries. Additionally, the T. orientalis Major Piroplasm Surface Protein (MPSP) gene sequences were classified as types 1 and 2. This is the first report of T. orientalis in Egypt, and of type 2 MPSP in buffaloes. Detection of MPSP type 2, which is considered a relatively virulent genotype, suggests that T. orientalis infection may have veterinary and economic significance in Egypt. In conclusion, the present study, which analyzed multiple species of Babesia and Theileria parasites in different livestock animals, may shed an additional light on the epidemiology of hemoprotozoan parasites in Egypt.

Titrimetric determination of some N-substituted phenothiazine derivatives

An indirect titrimetric method is described for the determination of some N-substituted phenothiazine derivatives. The method involves the use of 1,3-dibromo-5,5-dimethylhydantoin or N-bromosuccinimide as the titrant. A known excess of either reagent is added and, after a specified time, the residual reagent is determined iodimetrically. The proposed method was applied to the analysis of pharmaceutical preparations containing the drugs, and the results obtained compared favourably with those obtained by pharmacopoeial methods.

Optimization of a Fluorescence-Based Assay for Large-Scale Drug Screening against Babesia and Theileria Parasites

A rapid and accurate assay for evaluating antibabesial drugs on a large scale is required for the discovery of novel chemotherapeutic agents against Babesia parasites. In the current study, we evaluated the usefulness of a fluorescence-based assay for determining the efficacies of antibabesial compounds against bovine and equine hemoparasites in in vitro cultures. Three different hematocrits (HCTs; 2.5%, 5%, and 10%) were used without daily replacement of the medium. The results of a high-throughput screening assay revealed that the best HCT was 2.5% for bovine Babesia parasites and 5% for equine Babesia and Theileria parasites. The IC50 values of diminazene aceturate obtained by fluorescence and microscopy did not differ significantly. Likewise, the IC50 values of luteolin, pyronaridine tetraphosphate, nimbolide, gedunin, and enoxacin did not differ between the two methods. In conclusion, our fluorescence-based assay uses low HCT and does not require daily replacement of culture medium, making it highly suitable for in vitro large-scale drug screening against Babesia and Theileria parasites that infect cattle and horses.

Evaluation of a Fluorescence-Based Method for Antibabesial Drug Screening

ABSTRACT In vitro evaluation of chemotherapeutic agents against Babesia and Theileria parasites has become routine, and the effectiveness of these chemicals is usually determined by comparing the parasitemia dynamics of untreated and treated parasites. Although microscopy is widely used to calculate parasitemia, several disadvantages are associated with this technique. The present study evaluated a fluorescence-based method using SYBR green I stain (SG I) to screen antibabesial agents in in vitro cultures of Babesia bovis. The linearity between relative fluorescence units (RFU) and parasitemia was found to be well correlated with a 0.9944 goodness-of-fit (r2) value. Subsequently, 50% inhibitory concentration (IC50) values were calculated for 3 antiprotozoan agents, diminazene aceturate, nimbolide, and gedunin, by this method. For diminazene aceturate and nimbolide, the IC50s determined by the fluorescence-based method (408 nM and 8.13 μM, respectively) and microscopy (400.3 nM and 9.4 μM, respectively) were in agreement. Furthermore, the IC50 of gedunin determined by the fluorescence-based method (19 μM) was similar to the recently described microscopy-based value (21.7 μM) for B. bovis. Additionally, the Z′ factor (0.80 to 0.90), signal-to-noise (S/N) ratio (44.15 to 87.64), coefficient of variation at the maximum signal (%CVmax) (0.50 to 2.85), and coefficient of variation at the minimum signal (%CVmin) (1.23 to 2.21) calculated for the fluorescence method using diminazene aceturate were comparable to those previously determined in malaria research for this assay. These findings suggest that the fluorescence-based method might be useful for antibabesial drug screening and may have potential to be developed into a high-throughput screening (HTS) assay.

Titrimetric determination of some thioxanthene derivatives

An indirect titrimetric method is described for the determination of several thioxanthene derivatives, namely, chlorprothixene, thiothixene and methixene hydrochloride. The method involves the use of 1,3-dibromo-5,5-dimethylhydantion, N-bromosuccinimide or N-bromophthalimide as the titrant. A known excess of one of these reagents is added and, after a specified time, the residual reagent is determined iodimetrically. The proposed method was applied to the analysis of pharmaceutical preparations containing these drugs and the results obtained, compared favourably with those obtained by the pharmacopoeial methods.

Spectrophotometric titration of phenothiazines using 2,3-dichloro-5,6-dicyano-1,4-benzoquinone

A specific Spectrophotometric titration method is described for the micro-determination of some phenothiazine derivatives in strong orthophosphoric acid medium using the π-acceptor 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as a mild oxidizing titrant. The wavelengths of maximum absorption of the formed phenothiazonium cation radicals are 500, 515, 530, 533 and 650 nm for trifluoperazine dihydrochloride, promethazine hydrochloride, prochlorperazine dimaleate, chlorpromazine hydrochloride and thiethylperazine dihydrochloride, respectively. Quantitative recoveries are reported for pure drugs and their dosage forms. The method is simple and specific for determining phenothiazine derivatives in presence of their induced degraded oxidation products.

Large-scale drug screening against Babesia divergens parasite using a fluorescence-based high-throughput screening assay

The validation of a fluorescence-based high-throughput screening (HTS) assay for determining the efficacies of large chemical libraries against Babesia divergens (bovine strain) in in vitro cultures was evaluated in this study. Hematocrits (HCTs) of 2.5%, 5%, and 10% were used for the in vitro culture at 1% parasitemia without daily replacement of the medium. Linearity and HTS assay results revealed that the best HCTs were 5% and 10%. The obtained IC50 values of diminazene aceturate, either by fluorescence-based HTS assay with and without daily replacement of medium or by fluorescence- and microscopy-based methods, did not differ significantly at 5% HCT. Actinonin and chloroquine diphosphate were the most effective drugs against the in vitro growth of B. divergens, followed by pyronaridine tetraphosphate- and luteolin-treated cultures. On contrary, tetracycline hydrochloride and (-)-epigallocatechin-3-gallate from green tea exhibited poor activity as compared with diminazene aceturate (positive control drug). The data indicated that 5% HCT without daily replacement of the culture medium mixed with bovine serum in vitro using a fluorescence-based HTS assay creates the best conditions for large-scale drug screening against B. divergens that infect cattle.

Chemotherapeutic efficacies of a clofazimine and diminazene aceturate combination against piroplasm parasites and their AT-rich DNA-binding activity on Babesia bovis

Recently, we reported that clofazimine (CF) has an anti-piroplasm activity, but it could not completely eliminate parasites in the host. The currently available anti-piroplasm drug, diminazene aceturate (DA), has sometimes been reported to have toxic side effects. In the present study, we evaluated the combination treatment with CF and DA against piroplasms both in vitro and in vivo. Additionally, mRNA level and DNA amounts were analyzed in CF‒ and DA‒treated Babesia bovis by a qPCR. The CF–DA combination had additive effects on Babesia bovis, B. bigemina, and B. caballi and synergistic effects on Theileria equi. The CF–DA combination chemotherapies against B. microti in mice were more potent than their monotherapies. In the CF‒ and DA‒treated B. bovis, CF dose-dependently down-regulated mRNA level and DNA amounts of extranuclear genes (AT-rich featured), whereas DA down-regulated only DNA amounts of extranuclear genes, but those of nuclear genes were slightly down- or up-regulated by CF and DA. In conclusion, the CF–DA combination has a higher efficiency against piroplasms than CF or DA monotherapies. CF and DA might have an AT-rich DNA-binding activity. All results suggest that the CF–DA combination chemotherapy will be a better choice to treat piroplasmosis instead of DA monotherapy.

Animal level risk factors associated with Babesia and Theileria infections in cattle in Egypt

In present study, blood samples were collected randomly from 439 cows at three main regions of Egypt (northern, central and southern). Molecular diagnosis of Babesia and Theileria infections by PCR amplification of DNA (gene) fragments, then cloning and sequencing of the positive samples were conducted. A questionnaire was created to imply the assumed risk factors and logistic regression statistical analysis was carried out to appraise the potential factors on the animal level. The results revealed that 49 (11.16%) and 45 (10.25%) cattle were infected with Babesia and Theileria parasites, respectively. B. bigemina (7.97%) and T. annulata (9.56%) were the most prevalent parasites. For Babesia sp., final multivariate logistic regression analysis showed a significant association between the infection and irregular use of antiprotozoal drugs (P = 0.003; OR: 0.28; 95% CI: 0.12–0.65), management practice (P = 0.029; OR: 6.66; 95% CI: 1.21–36.59) and ecology area (P = 0.006; OR: 5.62; 95% CI: 1.63–19.31). However, for Theileria sp. infection, animal breed (P = 0.003; OR: 0.44; 95% CI:.45–1.00) and irregular use of antiprotozoal drugs (P<0.001; OR: 4.22; 95% CI: 2.62–5.60) were the potential risk factors. The results of the present study declare the prevalent bovine Babesia and Theileria sp. in Egypt based on molecular description. An impression on the potential risk factors associated with infections was obtained. Recognition of the potential risk factors associated with tick borne disease may be helpful to construct the best preventive measures.

Molecular characterization of the vitamin D receptor (VDR) gene in Holstein cows

Vitamin D plays a vital role in calcium homeostasis, growth, and immunoregulation. Because little is known about the vitamin D receptor (VDR) gene in cattle, the aim of the present investigation was to present the molecular characterization of exons 5 and 6 of the VDR gene in Holstein cows. DNA extraction, genomic sequencing, phylogenetic analysis, synteny mapping and single nucleotide gene polymorphism analysis of the VDR gene were performed to assess blood samples collected from 50 clinically healthy Holstein cows. The results revealed the presence of a 450-base pair (bp) nucleotide sequence that resembled exons 5 and 6 with intron 5 enclosed between these exons. Sequence alignment and phylogenetic analysis revealed a close relationship between the sequenced VDR region and that found in Hereford cattle. A close association between this region and the corresponding region in small ruminants was also documented. Moreover, a single nucleotide polymorphism (SNP) that caused the replacement of a glutamate with an arginine in the deduced amino acid sequence was detected at position 7 of exon 5. In conclusion, Holstein and Hereford cattle differ with respect to exon 5 of the VDR gene. Phylogenetic analysis of the VDR gene based on nucleotide sequence produced different results from prior analyses based on amino acid sequence.