Assessing Environmental Risks during the Drug Development Process for Parasitic Vector-Borne Diseases: A Critical Reflection

Parasitic vector-borne diseases (VBDs) represent nearly 20% of the global burden of infectious diseases. Moreover, the spread of VBDs is enhanced by global travel, urbanization, and climate change. Treatment of VBDs faces challenges due to limitations of existing drugs, as the potential for side effects in nontarget species raises significant environmental concerns. Consequently, considering environmental risks early in drug development processes is critically important. Here, we examine the environmental risk assessment process for veterinary medicinal products in the European Union and identify major gaps in the ecotoxicity data of these drugs. By highlighting the scarcity of ecotoxicological data for commonly used antiparasitic drugs, we stress the urgent need for considering the One Health concept. We advocate for employing predictive tools and nonanimal methodologies such as New Approach Methodologies at early stages of antiparasitic drug research and development. Furthermore, adopting progressive approaches to mitigate ecological risks requires the integration of nonstandard tests that account for real-world complexities and use environmentally relevant exposure scenarios. Such a strategy is vital for a sustainable drug development process as it adheres to the principles of One Health, ultimately contributing to a healthier and more sustainable world.

Design and synthesis of imidazo[1,2-a]pyridine-chalcone conjugates as antikinetoplastid agents

A library of imidazo[1,2-a]pyridine-appended chalcones were synthesized and characterized using 1 H NMR, 13 C NMR and HRMS. The synthesized analogues were screened for their antikinetoplastid activity against Trypanosoma cruzi, Trypanosoma brucei brucei, Trypanosoma brucei rhodesiense and Leishmania infantum. The analogues were also tested for their cytotoxicity activity against human lung fibroblasts and primary mouse macrophages. Among all screened derivatives, 7f was found to be the most active against T. cruzi and T. b. brucei exhibiting IC50 values of 8.5 and 1.35 μM, respectively. Against T. b. rhodesiense, 7e was found to be the most active with an IC50 value of 1.13 μM. All synthesized active analogues were found to be non-cytotoxic against MRC-5 and PMM with selectivity indices of up to more than 50.

2-Aroyl quinazolinone: Synthesis and in vitro anti-parasitic activity

Trypanosomes and Leishmania are parasitic protozoans that affect millions of people globally. Herein we report the synthesis of 2-aroyl quinazolinones and their antiprotozoal efficacy against Trypanosoma brucei, Trypanosoma brucei rhodesiense, Trypanosoma cruzi, and Leishmania infantum. These compounds were counter-screened against a human cell line for cytotoxicity. Thirteen of the twenty target compounds in this study inhibited the growth of these parasites, with compounds KJ1, and KJ10 exhibiting IC50 values of 4.7 μM (T. b. brucei) and 1.1 μM (T. b. rhodesiense), respectively.

Cloning and Characterization of Trypanosoma congolense and T. vivax Nucleoside Transporters Reveal the Potential of P1-Type Carriers for the Discovery of Broad-Spectrum Nucleoside-Based Therapeutics against Animal African Trypanosomiasis

African Animal Trypanosomiasis (AAT), caused predominantly by Trypanosoma brucei brucei, T. vivax and T. congolense, is a fatal livestock disease throughout Sub-Saharan Africa. Treatment options are very limited and threatened by resistance. Tubercidin (7-deazaadenosine) analogs have shown activity against individual parasites but viable chemotherapy must be active against all three species. Divergence in sensitivity to nucleoside antimetabolites could be caused by differences in nucleoside transporters. Having previously characterized the T. brucei nucleoside carriers, we here report the functional expression and characterization of the main adenosine transporters of T. vivax (TvxNT3) and T. congolense (TcoAT1/NT10), in a Leishmania mexicana cell line ('SUPKO') lacking adenosine uptake. Both carriers were similar to the T. brucei P1-type transporters and bind adenosine mostly through interactions with N3, N7 and 3'-OH. Expression of TvxNT3 and TcoAT1 sensitized SUPKO cells to various 7-substituted tubercidins and other nucleoside analogs although tubercidin itself is a poor substrate for P1-type transporters. Individual nucleoside EC₅₀s were similar for T. b. brucei, T. congolense, T. evansi and T. equiperdum but correlated less well with T. vivax. However, multiple nucleosides including 7-halogentubercidines displayed pEC50>7 for all species and, based on transporter and anti-parasite SAR analyses, we conclude that nucleoside chemotherapy for AAT is viable.

Nucleoside analogues for the treatment of animal trypanosomiasis

Animal trypanosomiasis (AT) is a parasitic disease with high socio-economic impact. Given the limited therapeutic options and problems of toxicity and drug resistance, this study assessed redirecting our previously identified antitrypanosomal nucleosides for the treatment of AT. Promising hits were identified with excellent in vitro activity across all important animal trypanosome species. Compound 7, an inosine analogue, and our previously described lead compound, 3'-deoxytubercidin (8), showed broad spectrum anti-AT activity, metabolic stability in the target host species and absence of toxicity, but with variable efficacy ranging from limited activity to full cure in mouse models of Trypanosoma congolense and T. vivax infection. Several compounds show promise against T. evansi (surra) and T. equiperdum (dourine). Given the preferred target product profile for a broad-spectrum compound against AT, this study emphasizes the need to include T. vivax in the screening cascade given its divergent susceptibility profile and provides a basis for lead optimization towards such broad spectrum anti-AT compound.

Molecular survey of mcr1 and mcr2 plasmid mediated colistin resistance genes in Escherichia coli isolates of animal origin in Iran

Objectives

The emergence of colistin-resistant Enterobacteriaceae from human and animal sources is one of the major public health concerns as colistin is the last-resort antibiotic for treating infections caused by multidrug-resistant Gram-negative bacteria. We aimed to determine the prevalence of the prototype widespread colistin resistance genes (mcr-1 and mcr-2) among commensal and pathogenic Escherichia coli strains isolated from food-producing and companion animals in Iran.

Results

A total of 607 E. coli isolates which were previously collected from different animal sources between 2008 and 2016 used to uncover the possible presence of plasmid-mediated colistin resistance genes (mcr-1 and mcr-2) by PCR. Overall, our results could not confirm the presence of any mcr-1 or mcr-2 positive E. coli among the studied isolates. It is concluded that despite the important role of food-producing animals in transferring the antibiotic resistance, they were not the main source for carriage of mcr-1 and mcr-2 in Iran until 2016. This study suggests that the other mcr variants (mcr-3 to mcr-9) might be responsible for conferring colistin resistance in animal isolates in Iran. The possible linkage between pig farming industry and high level of mcr carriage in some countries needs to be clarified in future prospective studies.

Risk factors for recurrence of FMD outbreaks in Iran: a case-control study in a highly endemic area

BACKGROUND

Foot-and-mouth disease (FMD) is an acute viral disease of cloven-hoofed animals with high economic impact. FMD remains endemic in Iran particularly in the livestock-dense province of Khorasan Razavi in northeastern Iran where FMD outbreaks continuously occur. In this study, we aimed to quantify risk factors for the recurrence of FMD outbreaks in Iran by analyzing a time-series of FMD outbreak data from the province of Khorasan Razavi.

RESULTS

This study used FMD outbreak data collected from 2012 to 2014. Data were collected by local offices of the Iranian Animal Disease Department and the veterinarian of the veterinary council of the Khorasan Razavi province. An outbreak investigation questionnaire was delivered to 127 farms, including 46 case farms (FMD-infected) and 81 control farms (FMD-free). To quantify and compare the odds of exposure to a risk factor in FMD-infected farms versus FMD-free farms, logistic regression models were built using SPSS software version 16. Our results of multivariable logistic regression indicate that hygienic status of the farm (OR = 11.83; CI = 3.38-41.43), FMD vaccination status (OR = 0.06; CI = 0.01-0.68), transportation of livestock (OR = 0.40; CI = 0.163-0.981) and inhibition of livestock dealers' entry into the farm (OR = 0.36; CI = 0.12-1.09) were identified as important risk factors for farm-level FMD infection.

CONCLUSION

This study generated much needed evidence on a set of modifiable risk factors for the recurrence of FMD outbreaks in the high risk province of Khorasan Razavi. This information can be used to improve existing national FMD control program and suggest new guidelines to prevent FMD outbreaks in the country.