{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T01:42:55Z","timestamp":1760060575353,"version":"build-2065373602"},"reference-count":44,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2025,9,4]],"date-time":"2025-09-04T00:00:00Z","timestamp":1756944000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Slovakian Research and Development Agency","award":["APVV-23-0325","VEGA 2\/0011\/25","09I03-03-V04-00556"],"award-info":[{"award-number":["APVV-23-0325","VEGA 2\/0011\/25","09I03-03-V04-00556"]}]},{"name":"Scientific Grant Agency of the Ministry of Education and Slovakian Academy of Sciences","award":["APVV-23-0325","VEGA 2\/0011\/25","09I03-03-V04-00556"],"award-info":[{"award-number":["APVV-23-0325","VEGA 2\/0011\/25","09I03-03-V04-00556"]}]},{"name":"Recovery and Resilience Plan of the Slovak Republic","award":["APVV-23-0325","VEGA 2\/0011\/25","09I03-03-V04-00556"],"award-info":[{"award-number":["APVV-23-0325","VEGA 2\/0011\/25","09I03-03-V04-00556"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Pathogens"],"abstract":"<jats:p>Nanoparticles have emerged as innovative tools for combating bacterial infections, offering a potential solution to antibiotic resistance and the limitations of conventional antimicrobials. Nanoparticles exhibit antibacterial activity through multiple mechanisms, including oxidative stress induction, metal ion release, direct membrane damage, disruption of DNA and proteins, and indirect immune system enhancement. Rickettsia helvetica, R. monacensis, R. slovaca, and R. conorii subsp. raoultii are tick-borne pathogens transmitted by Ixodes ricinus, Dermacentor reticulatus, and D. marginatus ticks across Europe causing spotted fever rickettsiosis. While rickettsioses are successfully treated with antibiotics, resistance of rickettsiae to antimicrobial therapy has been reported. Here, we evaluated the anti-rickettsial activity of silver (AgNPs), selenium (SeNPs), and chitosan (CSNPs) nanoparticles against R. conorii subsp. caspia, a tick-borne bacterial pathogen, in African green monkey kidney cell line (Vero). At their highest non-cytotoxic concentrations, CSNPs exhibited the strongest inhibitory effect (87%). SeNPs also significantly reduced bacterial load (76%), although their efficacy was constrained by cytotoxicity at higher doses. In contrast, AgNPs did not show significant activity under the tested conditions. The differences observed among nanoparticles reflect both the antimicrobial properties and host cell tolerance limits. These findings highlight CSNPs and SeNPs as promising candidates for further development of nanoparticle-based strategies to combat intracellular, tick-borne pathogens.<\/jats:p>","DOI":"10.3390\/pathogens14090885","type":"journal-article","created":{"date-parts":[[2025,9,4]],"date-time":"2025-09-04T09:18:57Z","timestamp":1756977537000},"page":"885","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Anti-Rickettsial Activity of Chitosan, Selenium, and Silver Nanoparticles: Efficacy in Vero Cells"],"prefix":"10.3390","volume":"14","author":[{"given":"Yevheniy-Yuliy","family":"Peresh","sequence":"first","affiliation":[{"name":"Institute of Virology, Biomedical Research Center, Slovak Academy of Sciences, D\u00fabravsk\u00e1 cesta 9, 845 05 Bratislava, Slovakia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2589-9035","authenticated-orcid":false,"given":"Zdenko","family":"\u0160pitalsk\u00fd","sequence":"additional","affiliation":[{"name":"Institute of Polymer, Slovak Academy of Sciences, D\u00fabravsk\u00e1 cesta 9, 845 41 Bratislava, Slovakia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mohamed","family":"Shaalan","sequence":"additional","affiliation":[{"name":"Institute of Polymer, Slovak Academy of Sciences, D\u00fabravsk\u00e1 cesta 9, 845 41 Bratislava, Slovakia"},{"name":"Department of Pathology, Faculty of Veterinary Medicine, Cairo University, Giza 12211, Egypt"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6138-7136","authenticated-orcid":false,"given":"Eva","family":"\u0160pitalsk\u00e1","sequence":"additional","affiliation":[{"name":"Institute of Virology, Biomedical Research Center, Slovak Academy of Sciences, D\u00fabravsk\u00e1 cesta 9, 845 05 Bratislava, Slovakia"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,9,4]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"102","DOI":"10.1111\/j.1574-6968.2009.01510.x","article-title":"Life cycle of Rickettsia slovaca in L929 cell line studied by quantitative real-time PCR and transmission electron microscopy","volume":"293","year":"2009","journal-title":"FEMS Microbiol. 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