{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T01:30:02Z","timestamp":1760146202146,"version":"build-2065373602"},"reference-count":23,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2024,10,15]],"date-time":"2024-10-15T00:00:00Z","timestamp":1728950400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"New England Center of Excellence in Vector-borne Disease","award":["CDC U01CK000661"],"award-info":[{"award-number":["CDC U01CK000661"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Microorganisms"],"abstract":"<jats:p>Borrelia burgdorferi\u2019s inosine-5\u2032-monophosphate dehydrogenase (IMPDH, GuaB encoded by the guaB gene) is a potential therapeutic target. GuaB is necessary for B. burgdorferi replication in mammalian hosts but not in standard laboratory culture conditions. Therefore, we cannot test novel GuaB inhibitors against B. burgdorferi without utilizing mammalian infection models. This study aimed to evaluate modifications to a standard growth medium that may mimic mammalian conditions and induce the requirement of GuaB usage for replication. The effects of two GuaB inhibitors (mycophenolic acid, 6-chloropurine riboside at 125 \u03bcM and 250 \u03bcM) were assessed against B. burgdorferi (guaB+) grown in standard Barbour\u2013Stoenner\u2013Kelly-II (BSK-II) medium (6% rabbit serum) and BSK-II modified to 60% concentration rabbit serum (BSK-II\/60% serum). BSK-II directly supplemented with adenine, hypoxanthine, and nicotinamide (75 \u03bcM each, BSK-II\/AHN) was also considered as a comparison group. In standard BSK-II, neither mycophenolic acid nor 6-chloropurine riboside affected B. burgdorferi growth. Based on an ANOVA, a dose-dependent increase in drug effects was observed in the modified growth conditions (F = 4.471, p = 0.001). Considering higher drug concentrations at exponential growth, mycophenolic acid at 250 \u03bcM reduced spirochete replication by 48% in BSK-II\/60% serum and by 50% in BSK-II\/AHN (p &lt; 0.001 each). 6-chloropurine riboside was more effective in both mediums than mycophenolic acid, reducing replication by 64% in BSK-II\/60% serum and 65% in BSK-II\/AHN (p &lt; 0.001 each). These results demonstrate that modifying BSK-II medium with physiologically relevant levels of mammalian serum supports replication and induces the effects of GuaB inhibitors. This represents the first use of GuaB inhibitors against Borrelia burgdorferi, building on tests against purified B. burgdorferi GuaB. The strong effects of 6-chloropurine riboside indicate that B. burgdorferi can salvage and phosphorylate these purine derivative analogs. Therefore, this type of molecule may be considered for future drug development. Optimization of this culture system will allow for better assessment of novel Borrelia-specific GuaB inhibitor molecules for Lyme disease interventions. The use of GuaB inhibitors as broadcast sprays or feed baits should also be evaluated to reduce spirochete load in competent reservoir hosts.<\/jats:p>","DOI":"10.3390\/microorganisms12102064","type":"journal-article","created":{"date-parts":[[2024,10,15]],"date-time":"2024-10-15T08:09:08Z","timestamp":1728979748000},"page":"2064","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Effects of Inosine-5\u2032-monophosphate Dehydrogenase (IMPDH\/GuaB) Inhibitors on Borrelia burgdorferi Growth in Standard and Modified Culture Conditions"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8226-811X","authenticated-orcid":false,"given":"Eric L.","family":"Siegel","sequence":"first","affiliation":[{"name":"Laboratory of Medical Zoology, Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA"},{"name":"New England Center of Excellence in Vector-Borne Disease, Amherst, MA 01003, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Connor","family":"Rich","sequence":"additional","affiliation":[{"name":"Laboratory of Medical Zoology, Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA"},{"name":"New England Center of Excellence in Vector-Borne Disease, Amherst, MA 01003, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sanchana","family":"Saravanan","sequence":"additional","affiliation":[{"name":"Laboratory of Medical Zoology, Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA"},{"name":"New England Center of Excellence in Vector-Borne Disease, Amherst, MA 01003, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Patrick","family":"Pearson","sequence":"additional","affiliation":[{"name":"Laboratory of Medical Zoology, Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA"},{"name":"New England Center of Excellence in Vector-Borne Disease, Amherst, MA 01003, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5240-9276","authenticated-orcid":false,"given":"Guang","family":"Xu","sequence":"additional","affiliation":[{"name":"Laboratory of Medical Zoology, Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA"},{"name":"New England Center of Excellence in Vector-Borne Disease, Amherst, MA 01003, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7175-6380","authenticated-orcid":false,"given":"Stephen M.","family":"Rich","sequence":"additional","affiliation":[{"name":"Laboratory of Medical Zoology, Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA"},{"name":"New England Center of Excellence in Vector-Borne Disease, Amherst, MA 01003, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2024,10,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"118","DOI":"10.15585\/mmwr.mm7306a1","article-title":"Surveillance for Lyme Disease After Implementation of a Revised Case Definition\u2014United States, 2022","volume":"73","author":"Kugeler","year":"2024","journal-title":"MMWR Morb. Mortal. Wkly. Rep."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"616","DOI":"10.3201\/eid2702.202731","article-title":"Estimating the Frequency of Lyme Disease Diagnoses, United States, 2010\u20132018","volume":"27","author":"Kugeler","year":"2021","journal-title":"Emerg. Infect. Dis."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"421","DOI":"10.7326\/0003-4819-136-6-200203190-00005","article-title":"Clinical Characteristics and Treatment Outcome of Early Lyme Disease in Patients with Microbiologically Confirmed Erythema Migrans","volume":"136","author":"Smith","year":"2002","journal-title":"Ann. Intern. Med."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"201","DOI":"10.1007\/s10096-018-3417-1","article-title":"Clinical Spectrum of Lyme Disease","volume":"38","author":"Welsh","year":"2019","journal-title":"Eur. J. Clin. Microbiol. Infect. Dis."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1105","DOI":"10.1016\/j.amjmed.2014.05.036","article-title":"Chronic Coinfections in Patients Diagnosed with Chronic Lyme Disease: A Systematic Review","volume":"127","author":"Lantos","year":"2014","journal-title":"Am. J. Med."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"2466","DOI":"10.1093\/nar\/gkv047","article-title":"Regulation of Mammalian Nucleotide Metabolism and Biosynthesis","volume":"43","author":"Lane","year":"2015","journal-title":"Nucleic Acids Res."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"580","DOI":"10.1038\/37551","article-title":"Genomic Sequence of a Lyme Disease Spirochaete, Borrelia Burgdorferi","volume":"390","author":"Fraser","year":"1997","journal-title":"Nature"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"3877","DOI":"10.1128\/IAI.00199-07","article-title":"Purine Salvage Pathways among Borrelia Species","volume":"75","author":"Pettersson","year":"2007","journal-title":"Infect Immun."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"589","DOI":"10.1080\/00325481.2019.1655258","article-title":"Perspective on Current and Emerging Drugs in the Treatment of Acute and Chronic Toxoplasmosis","volume":"131","author":"Lapinskas","year":"2019","journal-title":"Postgrad. Med."},{"key":"ref_10","first-page":"49","article-title":"Plasmodium Berghei Dihydrofolate Reductase. Isolation, Properties, and Inhibition by Antifolates","volume":"5","author":"Ferone","year":"1969","journal-title":"Mol. Pharmacol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"2903","DOI":"10.1021\/cr900021w","article-title":"IMP Dehydrogenase: Structure, Mechanism, and Inhibition","volume":"109","author":"Hedstrom","year":"2009","journal-title":"Chem. Rev."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"e12816","DOI":"10.1111\/pim.12816","article-title":"Interactions between Borrelia burgdorferi and Its Hosts across the Enzootic Cycle","volume":"43","author":"Helble","year":"2021","journal-title":"Parasite Immunol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"6231","DOI":"10.1128\/JB.00450-09","article-title":"GuaA and GuaB Are Essential for Borrelia burgdorferi Survival in the Tick-Mouse Infection Cycle","volume":"191","author":"Jewett","year":"2009","journal-title":"J. Bacteriol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"791","DOI":"10.1007\/BF00971517","article-title":"Hypoxanthine Transport through the Blood-Brain Barrier","volume":"12","author":"Spector","year":"1987","journal-title":"Neurochem. Res."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1517","DOI":"10.1111\/j.1365-2958.2009.06740.x","article-title":"Borrelia burgdorferi Bb0426 Encodes a 2\u2032-deoxyribosyltransferase That Plays a Central Role in Purine Salvage","volume":"72","author":"Lawrence","year":"2009","journal-title":"Mol. Microbiol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"4533","DOI":"10.1021\/bi992645l","article-title":"Crystal Structure at 2.4 \u00c5 Resolution of Borrelia burgdorferi Inosine 5\u2032-Monophosphate Dehydrogenase: Evidence of a Substrate-Induced Hinged-Lid Motion by Loop 6","volume":"39","author":"McMillan","year":"2000","journal-title":"Biochemistry"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"21977","DOI":"10.1074\/jbc.272.35.21977","article-title":"Expression, Purification, and Characterization of Inosine 5\u2032-Monophosphate Dehydrogenase from Borrelia Burgdorferi","volume":"272","author":"Zhou","year":"1997","journal-title":"J. Biol. Chem."},{"key":"ref_18","first-page":"521","article-title":"Isolation and Cultivation of Lyme Disease Spirochetes","volume":"57","author":"Barbour","year":"1984","journal-title":"Yale J. Biol. Med."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Lynch, A., Pearson, P., Savinov, S.N., Li, A.Y., and Rich, S.M. (2023). Lactate Dehydrogenase Inhibitors Suppress Borrelia Burgdorferi Growth In Vitro. Pathogens, 12.","DOI":"10.3390\/pathogens12070962"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1307","DOI":"10.1007\/BF00964000","article-title":"Determination of Ribonucleosides, Deoxyribonucleosides, and Purine and Pyrimidine Bases in Adult Rabbit Cerebrospinal Fluid and Plasma","volume":"8","author":"Eells","year":"1983","journal-title":"Neurochem. Res."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1310","DOI":"10.1016\/j.ttbdis.2018.05.014","article-title":"Integrated Control of Juvenile Ixodes Scapularis Parasitizing Peromyscus Leucopus in Residential Settings in Connecticut, United States","volume":"9","author":"Williams","year":"2018","journal-title":"Ticks Tick-Borne Dis."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Dunn, J.M., Krause, P.J., Davis, S., Vannier, E.G., Fitzpatrick, M.C., Rollend, L., Belperron, A.A., States, S.L., Stacey, A., and Bockenstedt, L.K. (2014). Borrelia burgdorferi Promotes the Establishment of Babesia microti in the Northeastern United States. PLoS ONE, 9.","DOI":"10.1371\/journal.pone.0115494"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"522","DOI":"10.1645\/13-278.1","article-title":"Mycophenolic acid, mycophenolate mofetil, mizoribine, ribavirin, and 7-nitroindole inhibit propagation of Babesia parasites by targeting inosine 5\u2032-monophosphate dehydrogenase","volume":"100","author":"Cao","year":"2014","journal-title":"J. Parasitol."}],"container-title":["Microorganisms"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-2607\/12\/10\/2064\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T16:13:43Z","timestamp":1760112823000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-2607\/12\/10\/2064"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,10,15]]},"references-count":23,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2024,10]]}},"alternative-id":["microorganisms12102064"],"URL":"https:\/\/doi.org\/10.3390\/microorganisms12102064","relation":{},"ISSN":["2076-2607"],"issn-type":[{"type":"electronic","value":"2076-2607"}],"subject":[],"published":{"date-parts":[[2024,10,15]]}}}