{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,13]],"date-time":"2026-09-13T15:00:16Z","timestamp":1789311616382,"version":"build-2803163510"},"reference-count":23,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2025,6,25]],"date-time":"2025-06-25T00:00:00Z","timestamp":1750809600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Intervet Inc."}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Vaccines"],"abstract":"<jats:p>Background\/Objectives: This study describes multiple trials demonstrating the safety and efficacy of a tri-valent vaccine against diseases caused by Porcine Circovirus Types 2a and 2d (PCV2a, PCV2d), Mycoplasma hyopneumoniae, and Lawsonia intracellularis. Methods: For each of the PCV2a and PCV2d onset of immunity (OOIs) and duration of immunity (DOI) studies, 25 pigs were vaccinated with a tri-valent vaccine and 25 with placebo. After dual challenge with PCV2a and porcine reproductive and respiratory virus (PRRSV) (OOI) or single challenge with PCV2d (OOI and DOI), respectively, viremia and lymphoid depletion data were collected. For each of the M. hyopneumoniae OOI and DOI studies, 35 to 70 pigs were vaccinated with the tri-valent vaccine and 35 to 70 with placebo. After M. hyopneumoniae challenge, the lungs were scored for disease. For the L. intracellularis OOI study, 40 to 50 pigs were vaccinated with the tri-valent and 40 to 50 with placebo. After L. intracellularis challenge, the intestines were scored for disease. All pigs were vaccinated at approximately 3 weeks of age, and all placebo vaccines were product matched. Results: Vaccinating pigs with a tri-valent vaccine reduced viremia and lymphoid depletion due to PCV2a and PCV2d, reduced lung lesions due to M. hyopneumoniae and reduced ileum and colonization scores due to L. intracellularis. Conclusions: The trials reported here demonstrated the safety and efficacy of the first ready-to-use PCV2, M. hyopneumoniae, and L. intracellularis vaccine for pigs.<\/jats:p>","DOI":"10.3390\/vaccines13070681","type":"journal-article","created":{"date-parts":[[2025,6,26]],"date-time":"2025-06-26T06:55:13Z","timestamp":1750920913000},"page":"681","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Efficacy and Safety of a Tri-Valent Ready-to-Use Porcine Circovirus Type 2a, Mycoplasma hyopneumoniae and Lawsonia intracellularis Vaccine in Weaned Pigs"],"prefix":"10.3390","volume":"13","author":[{"given":"Michelle","family":"Allen","sequence":"first","affiliation":[{"name":"Intervet Inc. (d\/b\/a Merck Animal Health), De Soto, KS 66018, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0005-5657-9810","authenticated-orcid":false,"given":"Frank","family":"Roerink","sequence":"additional","affiliation":[{"name":"Intervet Inc. (d\/b\/a Merck Animal Health), De Soto, KS 66018, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Abigail","family":"Crowley","sequence":"additional","affiliation":[{"name":"Intervet Inc. (d\/b\/a Merck Animal Health), De Soto, KS 66018, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Susan","family":"Knetter","sequence":"additional","affiliation":[{"name":"Intervet Inc. (d\/b\/a Merck Animal Health), De Soto, KS 66018, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chandra","family":"Morgan","sequence":"additional","affiliation":[{"name":"Intervet Inc. (d\/b\/a Merck Animal Health), De Soto, KS 66018, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Huiling","family":"Wei","sequence":"additional","affiliation":[{"name":"Intervet Inc. (d\/b\/a Merck Animal Health), De Soto, KS 66018, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0001-6555-1191","authenticated-orcid":false,"given":"Ruud","family":"Segers","sequence":"additional","affiliation":[{"name":"Intervet International B.V., 5831 AN Boxmeer, The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,6,25]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"399","DOI":"10.1128\/CVI.00768-13","article-title":"Comparison of four commercial one-dose Porcine Circovirus Type 2 (PCV2) vaccines administered to pigs challenged with PCV2 and porcine reproductive and respiratory syndrome virus at 17 weeks postvaccination to control porcine respiratory disease complex under Korean field conditions","volume":"21","author":"Park","year":"2014","journal-title":"Clin. Vaccine Immunol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"43","DOI":"10.1016\/j.trivac.2015.04.002","article-title":"Efficacy and safety of a combined Porcine Circovirus and Mycoplasma hyopneumoniae vaccine in finishing pigs","volume":"4","author":"Witvliet","year":"2014","journal-title":"Trials Vaccinol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"186","DOI":"10.1136\/vr.l211","article-title":"Ongoing challenges posed by the infection dynamics of porcine circovirus 2","volume":"184","year":"2019","journal-title":"Vet. Rec."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"321","DOI":"10.54846\/jshap\/897","article-title":"Elimination of Mycoplasma hyopneumoniae from breed-to-wean- farms: A review of current protocols with emphasis on herd closure and medication","volume":"23","author":"Holst","year":"2015","journal-title":"J. Swine Health Prod."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"221","DOI":"10.1016\/j.tvjl.2008.02.020","article-title":"Current perspectives on the diagnosis and epidemiology of Mycoplasma hyopneumoniae infection","volume":"181","author":"Sibila","year":"2009","journal-title":"Vet. J."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1340","DOI":"10.1016\/j.vaccine.2019.01.029","article-title":"Multi-antigenic recombinant subunit vaccine against Lawsonia intracellularis: The etiological agent of porcine proliferative enteropathy","volume":"37","author":"Montesina","year":"2019","journal-title":"Vaccine"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1500","DOI":"10.1016\/j.vaccine.2017.12.049","article-title":"A novel inactivated vaccine against Lawsonia intracellularis induces rapid induction of humoral immunity, reduction of bacterial shedding and provides robust gut barrier function","volume":"36","author":"Roerink","year":"2018","journal-title":"Vaccine"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"264","DOI":"10.1016\/j.tvjl.2009.05.010","article-title":"Porcine proliferative enteropathy: An important disease with questions remaining to be solved","volume":"184","author":"Jacobson","year":"2010","journal-title":"Vet. J."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"830","DOI":"10.1128\/CVI.00455-08","article-title":"Effect of a porcine circovirus type 2 (PCV2) vaccination of the dam on PCV2 replication in utero","volume":"16","author":"Madson","year":"2009","journal-title":"Clin. Vaccine Immunol."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"420","DOI":"10.1177\/104063870201400512","article-title":"A comparative study of an indirect fluorescent antibody test and an immunoperoxidase monolayer assay for the diagnosis of porcine proliferative enteropathy","volume":"14","author":"Guedes","year":"2002","journal-title":"J. Vet. Diagn. Investig."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"217","DOI":"10.1016\/j.jviromet.2008.02.002","article-title":"Development and validation of a duplex real-time PCR assay for the simultaneous detection and quantification of porcine circovirus type 2 and an internal control on porcine semen samples","volume":"149","author":"Pal","year":"2008","journal-title":"J. Virol. Methods"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"598","DOI":"10.1177\/104063871002200416","article-title":"Development of a polymerase chain reaction assay for quantification of Lawsonia intracellularis","volume":"22","author":"Wattanaphansak","year":"2010","journal-title":"J. Vet. Diagn. Investig."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1284","DOI":"10.1111\/tbed.13467","article-title":"Genetic diversity and prevalence of porcine circovirus type 3 (PCV3) and type 2 (PCV2) in the Midwest of the USA during 2016\u20132018","volume":"67","author":"Wang","year":"2020","journal-title":"Transbound Emerg. Dis."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"529","DOI":"10.1016\/j.vaccine.2020.12.013","article-title":"Evaluation of novel recombinant porcine circovirus type 2d (PCV2d) vaccine in pigs naturally infected with PCV2d","volume":"39","author":"Kim","year":"2021","journal-title":"Vaccine"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"72","DOI":"10.1016\/j.vetmic.2016.11.009","article-title":"PCV2d-2 is the predominant type of PCV2 DNA in pig samples collected in the U.S. during 2014\u20132016","volume":"197","author":"Xiao","year":"2016","journal-title":"Vet. Microbiol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"17","DOI":"10.1186\/s40813-015-0012-z","article-title":"Porcine circovirus 2 immunology and viral evolution","volume":"1","author":"Kekarainen","year":"2015","journal-title":"Porc. Health Manag."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"297","DOI":"10.1016\/j.vetmic.2007.09.008","article-title":"Control of Mycoplasma hyopneumoniae infections in pigs","volume":"126","author":"Maes","year":"2008","journal-title":"Vet. Microbiol."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.tvjl.2015.10.030","article-title":"Porcine respiratory disease complex: Interaction of vaccination and porcine circovirus type 2, porcine reproductive and respiratory syndrome virus, and Mycoplasma hyopneumoniae","volume":"212","author":"Chae","year":"2016","journal-title":"Vet. J."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"44","DOI":"10.1186\/1751-0147-55-44","article-title":"Individual risk factors for Mycoplasma hyopneumoniae infections in suckling pigs at the age of weaning","volume":"55","author":"Nathues","year":"2015","journal-title":"Acta Vet. Scand."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"83","DOI":"10.1016\/j.vetmic.2015.01.006","article-title":"Porcine circovirus type 2 (PCV2) enteric disease: An independent condition or part of the systemic disease?","volume":"176","author":"Baro","year":"2015","journal-title":"Vet. Microbiol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"109959","DOI":"10.1016\/j.vetimm.2019.109959","article-title":"Immune response and protection against Lawsonia intracellularis infections in pigs","volume":"219","author":"Obradovic","year":"2020","journal-title":"Vet. Immunol. Immunopathol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"462","DOI":"10.1093\/jas\/skx074","article-title":"Impact of Mycoplasma hyopneumoniae and Lawsonia intracellularis on the performance of pigs divergently selected for feed efficiency","volume":"96","author":"Helm","year":"2018","journal-title":"J. Anim. Sci."},{"key":"ref_23","first-page":"3196","article-title":"Metabolic adaptation of pigs to a Mycoplasma hyopneumoniae and Lawsonia intracellularis dual challenge","volume":"96","author":"Helm","year":"2018","journal-title":"J. Anim. Sci."}],"container-title":["Vaccines"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-393X\/13\/7\/681\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T17:58:20Z","timestamp":1760032700000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-393X\/13\/7\/681"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,6,25]]},"references-count":23,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2025,7]]}},"alternative-id":["vaccines13070681"],"URL":"https:\/\/doi.org\/10.3390\/vaccines13070681","relation":{},"ISSN":["2076-393X"],"issn-type":[{"value":"2076-393X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,6,25]]}}}