{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,8]],"date-time":"2026-09-08T20:31:56Z","timestamp":1788899516241,"version":"build-2803163510"},"reference-count":50,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2026,3,22]],"date-time":"2026-03-22T00:00:00Z","timestamp":1774137600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100006978","name":"University of California at Berkeley","doi-asserted-by":"crossref","id":[{"id":"10.13039\/100006978","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Vaccines"],"abstract":"<jats:p>Background: Oral gene delivery vectors, such as those derived from attenuated Salmonella strains, have shown great promise in oral vaccine development against various human diseases. Human cytomegalovirus (CMV) is a herpesvirus capable of affecting the global population and establishing lifelong infection. Generation of an anti-CMV vaccine is a major public health priority. Methods: This study reports the development of a novel weakened Salmonella strain, S713, and the effects of this strain as an oral vaccine candidate against murine cytomegalovirus (MCMV) infection in mice. Results: The weakened Salmonella strain S713 was attenuated in killing mice in vivo by &gt;500,000 fold compared to a clinical strain, following intragastric instillation in animals. Mice intragastrically immunized with S713 that produced MCMV M24 protein exhibited elevated anti-MCMV mucosal IgA and serum IgG titers and enhanced anti-MCMV T cell responses. Moreover, immunization with the generated vaccine in MCMV-challenged mice not only suppressed viral replication in lungs, spleens, livers, and salivary glands but also increased animal survival. Conclusions: These findings demonstrate strong and effective anti-MCMV immune responses induced by the generated M24-expressing vaccine. Furthermore, our results reveal the promising capability of weakened strain S713 expressing different CMV proteins to act as oral vaccines against CMV infections and diseases.<\/jats:p>","DOI":"10.3390\/vaccines14030279","type":"journal-article","created":{"date-parts":[[2026,3,23]],"date-time":"2026-03-23T09:48:42Z","timestamp":1774259322000},"page":"279","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["An Oral Vaccine Derived from Attenuated Salmonella Producing Murine Cytomegalovirus M24 Protein Induces Successful Antiviral Immune Responses in Mice"],"prefix":"10.3390","volume":"14","author":[{"given":"Yujun","family":"Liu","sequence":"first","affiliation":[{"name":"School of Public Health, University of California, Berkeley, CA 94720, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hao","family":"Gong","sequence":"additional","affiliation":[{"name":"School of Public Health, University of California, Berkeley, CA 94720, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jiaming","family":"Zhu","sequence":"additional","affiliation":[{"name":"School of Public Health, University of California, Berkeley, CA 94720, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fenyong","family":"Liu","sequence":"additional","affiliation":[{"name":"School of Public Health, University of California, Berkeley, CA 94720, USA"},{"name":"Program in Comparative Biochemistry, University of California, Berkeley, CA 94720, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,3,22]]},"reference":[{"key":"ref_1","first-page":"e42","article-title":"Congenital Cytomegalovirus Infection: Update on Screening, Diagnosis and Treatment: Scientific Impact Paper No. 56","volume":"132","author":"Khalil","year":"2024","journal-title":"BJOG"},{"key":"ref_2","first-page":"389","article-title":"Cytomegalovirus","volume":"Volume 1","author":"Knipe","year":"2021","journal-title":"Fields Virology: DNA Viruses"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"e2120736","DOI":"10.1001\/jamanetworkopen.2021.20736","article-title":"Congenital Cytomegalovirus Infection Burden and Epidemiologic Risk Factors in Countries with Universal Screening: A Systematic Review and Meta-analysis","volume":"4","author":"Ssentongo","year":"2021","journal-title":"JAMA Netw. Open"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1366","DOI":"10.1056\/NEJM200105033441804","article-title":"Intrauterine transmission of cytomegalovirus to infants of women with preconceptional immunity","volume":"344","author":"Boppana","year":"2001","journal-title":"N. Engl. J. Med."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"S113","DOI":"10.1093\/infdis\/jiz447","article-title":"The Status of Vaccine Development Against the Human Cytomegalovirus","volume":"221","author":"Plotkin","year":"2020","journal-title":"J. Infect. Dis."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Schleiss, M.R., Crooks, C.M., Karthigeyan, K.P., Kruc, R.M., Otero, C.E., Wang, H.S., Permar, S.R., Plotkin, S.A., and Gautam, R. (2024). Proceedings of the Conference \u201cCMV Vaccine Development-How Close Are We?\u201d (27\u201328 September 2023). Vaccines, 12.","DOI":"10.3390\/vaccines12111231"},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Bruce, K., Ma, J., Lawler, C., Xie, W., Stevenson, P.G., and Farrell, H.E. (2022). Recent Advancements in Understanding Primary Cytomegalovirus Infection in a Mouse Model. Viruses, 14.","DOI":"10.3390\/v14091934"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"S60","DOI":"10.1093\/infdis\/jiz484","article-title":"Animal Models of Congenital Cytomegalovirus Transmission: Implications for Vaccine Development","volume":"221","author":"Roark","year":"2020","journal-title":"J. Infect. Dis."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Krauter, S., Buscher, N., Brauchle, E., Ortega Iannazzo, S., Penner, I., Kramer, N., Gogesch, P., Thomas, S., Kreutz, M., and Dejung, M. (2022). An Attenuated Strain of Human Cytomegalovirus for the Establishment of a Subviral Particle Vaccine. Vaccines, 10.","DOI":"10.3390\/vaccines10081326"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"e0126421","DOI":"10.1128\/JVI.01264-21","article-title":"A Live Olfactory Mouse Cytomegalovirus Vaccine, Attenuated for Systemic Spread, Protects against Superinfection","volume":"95","author":"Farrell","year":"2021","journal-title":"J. Virol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"104","DOI":"10.1186\/1743-422X-11-104","article-title":"Comparison of multiple DNA vaccines for protection against cytomegalovirus infection in BALB\/c mice","volume":"11","author":"Huang","year":"2014","journal-title":"Virol. J."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"3696","DOI":"10.1128\/JVI.74.8.3696-3708.2000","article-title":"Suppression of murine cytomegalovirus (MCMV) replication with a DNA vaccine encoding MCMV M84 (a homolog of human cytomegalovirus pp65)","volume":"74","author":"Morello","year":"2000","journal-title":"J. Virol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"159","DOI":"10.1128\/JVI.79.1.159-175.2005","article-title":"Systemic priming-boosting immunization with a trivalent plasmid DNA and inactivated murine cytomegalovirus (MCMV) vaccine provides long-term protection against viral replication following systemic or mucosal MCMV challenge","volume":"79","author":"Morello","year":"2005","journal-title":"J. Virol."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Wang, H., Huang, C., Dong, J., Yao, Y., Xie, Z., Liu, X., Zhang, W., Fang, F., and Chen, Z. (2015). Complete protection of mice against lethal murine cytomegalovirus challenge by immunization with DNA vaccines encoding envelope glycoprotein complex III antigens gH, gL and gO. PLoS ONE, 10.","DOI":"10.1371\/journal.pone.0119964"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Gong, H., Liu, Y., Yan, B., and Liu, F. (2025). Antiviral Immune Responses Against Murine Cytomegalovirus Induced by an Oral Salmonella-Based Vaccine Expressing Viral M33 Protein. Microorganisms, 13.","DOI":"10.3390\/microorganisms13071510"},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Liu, Y., Gong, H., Zhu, J., and Liu, F. (2025). Effective Immune Protection of Mice from Murine Cytomegalovirus Infection by Oral Salmonella-Based Vaccine Expressing Viral M78 Antigen. Vaccines, 13.","DOI":"10.3390\/vaccines13020137"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Liu, Y., Gong, H., Zhu, J., and Liu, F. (2025). Oral Vaccination with Attenuated Salmonella Expressing Viral M25 Protein Effectively Protects Mice Against Murine Cytomegalovirus Infection. Pathogens, 14.","DOI":"10.3390\/pathogens14040314"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"8249","DOI":"10.1128\/JVI.77.15.8249-8255.2003","article-title":"Vaccination of mice with bacteria carrying a cloned herpesvirus genome reconstituted in vivo","volume":"77","author":"Brune","year":"2003","journal-title":"J. Virol."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"e668","DOI":"10.1093\/infdis\/jiae114","article-title":"Safety and Immunogenicity of a Messenger RNA-Based Cytomegalovirus Vaccine in Healthy Adults: Results From a Phase 1 Randomized Clinical Trial","volume":"230","author":"Fierro","year":"2024","journal-title":"J. Infect. Dis."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Lankina, A., Raposo, M., Hargreaves, A., Atkinson, C., Griffiths, P., and Reeves, M.B. (2025). Developing a Vaccine Against Human Cytomegalovirus: Identifying and Targeting HCMV\u2019s Immunological Achilles\u2019 Heel. Vaccines, 13.","DOI":"10.3390\/vaccines13050435"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"2118","DOI":"10.1038\/mt.2014.133","article-title":"A cationic nanoemulsion for the delivery of next-generation RNA vaccines","volume":"22","author":"Brito","year":"2014","journal-title":"Mol. Ther."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"328","DOI":"10.1128\/CMR.5.3.328","article-title":"Oral immunization using live attenuated Salmonella spp. as carriers of foreign antigens","volume":"5","author":"Cardenas","year":"1992","journal-title":"Clin. Microbiol. Rev."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"39","DOI":"10.4049\/jimmunol.1600608","article-title":"Salmonella Vaccines: Conduits for Protective Antigens","volume":"200","author":"Curtiss","year":"2018","journal-title":"J. Immunol."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"87","DOI":"10.1016\/j.ijmm.2007.08.006","article-title":"Rational design of Salmonella recombinant vaccines","volume":"298","author":"Cheminay","year":"2008","journal-title":"Int. J. Med. Microbiol."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"728","DOI":"10.1111\/j.1462-5822.2006.00706.x","article-title":"Manipulating cellular transport and immune responses: Dynamic interactions between intracellular Salmonella enterica and its host cells","volume":"8","author":"Abrahams","year":"2006","journal-title":"Cell Microbiol."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"571","DOI":"10.1046\/j.1365-2958.1998.00952.x","article-title":"A lethal role for lipid A in Salmonella infections","volume":"29","author":"Khan","year":"1998","journal-title":"Mol. Microbiol."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"19414","DOI":"10.1073\/pnas.1217554109","article-title":"Turning self-destructing Salmonella into a universal DNA vaccine delivery platform","volume":"109","author":"Kong","year":"2012","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"3222","DOI":"10.1073\/pnas.1014975108","article-title":"Oral delivery of RNase P ribozymes by Salmonella inhibits viral infection in mice","volume":"108","author":"Bai","year":"2011","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"238","DOI":"10.1038\/291238a0","article-title":"Aromatic-dependent Salmonella typhimurium are non-virulent and effective as live vaccines","volume":"291","author":"Hoiseth","year":"1981","journal-title":"Nature"},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Gong, H., Vu, G., Bai, Y., Chan, E., Wu, R., Yang, E., Liu, F., and Lu, S. (2011). A Salmonella small non-coding RNA facilitates bacterial invasion and intracellular replication by modulating the expression of virulence factors. PLoS Pathogens, 7.","DOI":"10.1371\/journal.ppat.1002120"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1315","DOI":"10.1099\/0022-1317-83-6-1315","article-title":"The products of human cytomegalovirus genes UL23, UL24, UL43 and US22 are tegument components","volume":"83","author":"Adair","year":"2002","journal-title":"J. Gen. Virol."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"14223","DOI":"10.1073\/pnas.2334032100","article-title":"Functional profiling of a human cytomegalovirus genome","volume":"100","author":"Dunn","year":"2003","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"529","DOI":"10.1089\/vim.2022.0041","article-title":"Human Cytomegalovirus UL24 and UL43 Cooperate to Modulate the Expression of Immunoregulatory UL16 Binding Protein 1","volume":"35","author":"Sleman","year":"2022","journal-title":"Viral Immunol."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"383","DOI":"10.1007\/s13337-022-00799-3","article-title":"Human cytomegalovirus UL24 and UL43 products participate in SAMHD1 subcellular localization","volume":"33","author":"Sleman","year":"2022","journal-title":"Virusdisease"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"673","DOI":"10.1084\/jem.20050882","article-title":"Broadly targeted human cytomegalovirus-specific CD4+ and CD8+ T cells dominate the memory compartments of exposed subjects","volume":"202","author":"Sylwester","year":"2005","journal-title":"J. Exp. Med."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"6891","DOI":"10.1128\/JVI.78.13.6891-6899.2004","article-title":"Murine cytomegalovirus with a transposon insertional mutation at open reading frame m155 is deficient in growth and virulence in mice","volume":"78","author":"Abenes","year":"2004","journal-title":"J. Virol."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"7056","DOI":"10.1128\/JVI.73.8.7056-7060.1999","article-title":"Systematic excision of vector sequences from the BAC-cloned herpesvirus genome during virus reconstitution","volume":"73","author":"Wagner","year":"1999","journal-title":"J. Virol."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"8833","DOI":"10.1128\/jvi.70.12.8833-8849.1996","article-title":"Analysis of the complete DNA sequence of murine cytomegalovirus","volume":"70","author":"Rawlinson","year":"1996","journal-title":"J. Virol."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"451","DOI":"10.1128\/IAI.70.2.451-461.2002","article-title":"The global regulator ArcA controls resistance to reactive nitrogen and oxygen intermediates in Salmonella enterica serovar Enteritidis","volume":"70","author":"Lu","year":"2002","journal-title":"Infect. Immun."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"6640","DOI":"10.1073\/pnas.120163297","article-title":"One-step inactivation of chromosomal genes in Escherichia coli K-12 using PCR products","volume":"97","author":"Datsenko","year":"2000","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"6832","DOI":"10.1128\/JVI.00609-11","article-title":"A reassortment-incompetent live attenuated influenza virus vaccine for protection against pandemic virus strains","volume":"85","author":"Hai","year":"2011","journal-title":"J. Virol."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"e0032022","DOI":"10.1128\/jvi.00320-22","article-title":"Reduction of Influenza A Virus Transmission in Mice by a Universal Intranasal Vaccine Candidate is Long-Lasting and Does Not Require Antibodies","volume":"96","author":"Price","year":"2022","journal-title":"J. Virol."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"2561","DOI":"10.1016\/j.vaccine.2011.01.060","article-title":"The virus-induced signaling adaptor molecule enhances DNA-raised immune protection against H5N1 influenza virus infection in mice","volume":"29","author":"Luo","year":"2011","journal-title":"Vaccine"},{"key":"ref_44","doi-asserted-by":"crossref","unstructured":"Galen, J.E., Wahid, R., and Buskirk, A.D. (2021). Strategies for Enhancement of Live-Attenuated Salmonella-Based Carrier Vaccine Immunogenicity. Vaccines, 9.","DOI":"10.3390\/vaccines9020162"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"1996","DOI":"10.1086\/315497","article-title":"Biodistribution and genetic stability of the novel antitumor agent VNP20009, a genetically modified strain of Salmonella typhimurium","volume":"181","author":"Clairmont","year":"2000","journal-title":"J. Infect. Dis."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"888","DOI":"10.1172\/JCI112899","article-title":"Safety, infectivity, immunogenicity, and in vivo stability of two attenuated auxotrophic mutant strains of Salmonella typhi, 541Ty and 543Ty, as live oral vaccines in humans","volume":"79","author":"Levine","year":"1987","journal-title":"J. Clin. Investig."},{"key":"ref_47","first-page":"E1","article-title":"Overview of the impact of Typhoid and Paratyphoid fever. Utility of Ty21a vaccine (Vivotif(R))","volume":"58","author":"Amicizia","year":"2017","journal-title":"J. Prev. Med. Hyg."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"6359","DOI":"10.1016\/j.vaccine.2017.09.066","article-title":"A brief review on the immunological scenario and recent developmental status of vaccines against enteric fever","volume":"35","author":"Howlader","year":"2017","journal-title":"Vaccine"},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"891","DOI":"10.1016\/0140-6736(90)92266-K","article-title":"Comparison of enteric-coated capsules and liquid formulation of Ty21a typhoid vaccine in randomised controlled field trial","volume":"336","author":"Levine","year":"1990","journal-title":"Lancet"},{"key":"ref_50","doi-asserted-by":"crossref","unstructured":"Buzila, E.R., Dorneanu, O.S., Trofin, F., Sima, C.M., and Iancu, L.S. (2025). Assessing Salmonella Typhi Pathogenicity and Prevention: The Crucial Role of Vaccination in Combating Typhoid Fever. Int. J. Mol. Sci., 26.","DOI":"10.3390\/ijms26093981"}],"container-title":["Vaccines"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-393X\/14\/3\/279\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,3,24]],"date-time":"2026-03-24T05:42:51Z","timestamp":1774330971000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-393X\/14\/3\/279"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,3,22]]},"references-count":50,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2026,3]]}},"alternative-id":["vaccines14030279"],"URL":"https:\/\/doi.org\/10.3390\/vaccines14030279","relation":{},"ISSN":["2076-393X"],"issn-type":[{"value":"2076-393X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,3,22]]}}}