Pathogenic E. coli cause urinary tract, soft tissue and central nervous system infections, sepsis, etc. Lytic bacteriophages can be used to combat such infections. We investigated six lytic E. coli bacteriophages isolated from wastewater. Transmission electron microscopy and whole genome sequencing showed that the isolated bacteriophages are tailed phages of the Caudoviricetes class. One-step growth curves revealed that their latent period of reproduction is 20–30 min, and the average value of the burst size is 117–155. During co-cultivation with various E. coli strains, the phages completely suppressed bacterial host culture growth within the first 4 h at MOIs 10⁻⁷ to 10⁻³. The host range lysed by each bacteriophage varied from six to two bacterial strains out of nine used in the study. The cocktail formed from the isolated bacteriophages possessed the ability to completely suppress the growth of all the E. coli strains used in the study within 6 h and maintain its lytic activity for 8 months of storage. All the isolated bacteriophages may be useful in fighting pathogenic E. coli strains and in the development of phage cocktails with a long storage period and high efficiency in the treatment of bacterial infections.

Colibacillosis in chickens can cause the death of young stock, decrease weight gain and lead to significant economic losses. Currently, antibiotic therapy is the main method of treatment of infected animals, but unchecked use of antibiotics has led to widespread antibiotic resistance among microorganisms. Therefore, it is necessary to develop alternative methods of treating bacterial infections that are fully consistent with the One Health concept and introduce them into practice. Phage therapy meets the specified requirements perfectly. This study describes the isolation and characterization of the lytic jumbo phage vB_EcoM_Lh1B and evaluates its potential use in controlling antibiotic-resistant E. coli infection in poultry. The complete phage genome is 240,200 bp long. Open reading frame (ORF) prediction shows that the phage genome does not contain genes encoding antibiotic resistance and lysogeny factors. Based on phylogenetic and electron microscopic analysis, vB_EcoM_Lh1B belongs to the group of myoviruses of the Seoulvirus genus of the Caudoviricetes class. The bacteriophage has good resistance to a wide range of pH and temperatures and has the ability to suppress 19 out of 30 studied pathogenic E. coli strains. The biological and lytic properties of the isolated vB_EcoM_Lh1B phage make it a promising target of further study as a therapeutic agent against E. coli infections in poultry.

The global burden of COVID-19 continues to rise, and despite significant progress in vaccine development, there remains a critical need for effective treatments for the severe inflammation and acute lung injury associated with SARS-CoV-2 infection. In this study, we explored the antiviral properties of a plant-derived complex consisting of flavonol and hydroxyorganic acid compounds. Our research focused on the ability of the flavonol and hydroxyorganic acid complex to suppress the activity of several key proteins involved in the replication and maturation of SARS-CoV-2. These proteins include ACE2 protein, HRV 3C Protease, and Mpro (Main Protease). It was shown that the plant-based complex effectively inhibited the activity of these viral proteins. In addition to its effects on viral proteins, the flavonol and hydroxyorganic acid complex were shown to suppress viral replication in Vero E6 cells. At a dose of 22 μg/mL, the drug demonstrated maximum antiviral activity, significantly reducing the replication of SARS-CoV-2 in vitro. In preliminary studies, the complex showed both prophylactic and therapeutic potential, suggesting that it may be useful for preventing infection, as well as reducing the severity of disease once an individual has been infected with SARS-CoV-2. Based on the compelling results of this study, we propose the flavonol and hydroxyorganic acid complex as a potential therapeutic compound for SARS-CoV-2. Its ability to inhibit key viral proteins, suppress viral replication and exhibit protective and therapeutic effects positions it as a valuable candidate for further research and clinical evaluation. As the global fight against SARS-CoV-2 continues, plant-based therapies like this complex could complement existing treatments and provide new options for managing and treating the disease.

Аннотация Escherichia coli — комменсальный микроорганизм, способный приобретать определенные признаки вирулентности и вызывать широкий спектр заболеваний у домашних животных. На животноводческих фермах E. coli часто является причиной колибактериоза телят, что представляет собой серьезную проблему для их здоровья и благополучия, может привести к высокому уровню заболеваемости и смертности, и большим экономическим потерям. В частности, эта проблема может быть связана с неэффективностью лечения из-за наличия резистентности к противомикробным препаратам. Особенно это актуально для E. coli, которая обладает такими факторами вирулентности, как термостабильный токсин типа Ia (STa) и фимбрии K99. Недостаток информации об устойчивости к противомикробным препаратам у микрофлоры крупного рогатого скота в Казахстане побудил нас провести данное исследование, целью которого было оценить распространенность устойчивости к антибиотикам среди штаммов E. coli, выделенных из фекалий телят с клиническими признаками кишечной инфекции. В результате фенотипического тестирования чувствительности к антибиотикам полученных изолятов было выявлено, что общая распространенность антимикробной резистентности у изолятов E. coli была очень высокой для большинства из восьми протестированных классов противомикробных препаратов. Самый высокий уровень резистентности среди изолятов был обнаружен к аминогликозидам (87,3%), поликетидам (60%) и аминопенициллинам (57 %), за ними следовали сульфаниламиды (47%), амфениколы (43%) и фторхинолоны (33%). Самый низкий уровень резистентности наблюдался к колистину (3%).

The search for novel antiviral agents against Newcastle disease virus (NDV) remains a priority in industrial poultry farming due to the virus’s high contagiousness and associated economic losses, prompting evaluation of polyene macrolides as potential therapeutic candidates. We employed a comprehensive approach combining computational modeling (molecular docking and dynamics simulation) and laboratory experiments to investigate the antiviral potential of natamycin, nystatin, and filipin complex against three NDV strains. Molecular docking analysis indicated binding sites for macrolides within the hydrophobic regions of surface glycoproteins HN and F, with binding energies ranging from −6.5 to −10.5 kcal/mol, while 50 ns molecular dynamics simulation confirmed complex stability. Laboratory testing using fluorescence-based neuraminidase assays demonstrated dose-dependent inhibitory activity with IC₅₀ values of 0.0043 ± 0.0015 mg/mL for filipin complex, 0.0117 ± 0.0029 mg/mL for nystatin, and 0.0220 ± 0.0138 mg/mL for natamycin, with similar ranking observed for fusion inhibition (EC₅₀ values of 0.00053 ± 0.00039, 0.00545 ± 0.00560, and 0.01196 ± 0.00965 mg/mL, respectively). While filipin complex exhibited the highest antiviral activity, its significant cytotoxicity limits therapeutic application, whereas natamycin demonstrated a favorable safety profile consistent with its GRAS status. These findings indicate that natamycin exhibits a favorable safety-to-efficacy profile in vitro, warranting further in vivo investigation to clarify its mechanism of action and establish practical application protocols for NDV control in poultry.

The spread of antibiotic-resistant pathogenic Escherichia coli poses a serious threat to calf health on livestock farms. With the decline in antibiotic therapy effectiveness, alternative approaches such as phage therapy are urgently needed. This study aimed to isolate lytic E. coli bacteriophages, characterize their properties, and evaluate the synergistic effects of their combined use with veterinary antibiotics against colibacillosis pathogens in calves. As a result of the work, 4 bacteriophages were isolated from wastewater from various cities of Kazakhstan: vB_EcoS_ABO/4, vB_EcoM_PL/4, vB_Eco_CWW/26, vB_EcoM_ShWW/46. Morphological, biological, and genomic analyses showed that the phages belong to different genera of the Caudoviricetes class, possess high lytic activity, broad host range, environmental stability, and lack genes associated with lysogeny, antibiotic resistance, or virulence. Interaction studies with antibiotics revealed synergistic or additive effects in over 75% of cases. These findings highlight the strong potential of the isolated bacteriophages for independent or adjunctive use in the treatment and prevention of colibacillosis in calves. However, further in vivo studies are required to definitively confirm their therapeutic efficacy.