{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,31]],"date-time":"2026-07-31T22:25:14Z","timestamp":1785536714855,"version":"3.56.0"},"reference-count":30,"publisher":"Wiley","issue":"6","license":[{"start":{"date-parts":[[2019,4,5]],"date-time":"2019-04-05T00:00:00Z","timestamp":1554422400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Zoetis, Inc."}],"content-domain":{"domain":["beva.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Equine Veterinary Journal"],"published-print":{"date-parts":[[2019,11]]},"abstract":"<jats:title>Summary<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>\n                      Potomac horse fever (\n                      <jats:styled-content style=\"fixed-case\">PHF<\/jats:styled-content>\n                      ) is a potentially fatal enterocolitis of horses caused by\n                      <jats:italic>Neorickettsia risticii<\/jats:italic>\n                      . The disease was originally recognised almost 40\u00a0years ago in the state of Maryland in the\n                      <jats:styled-content style=\"fixed-case\">US<\/jats:styled-content>\n                      . It is now known to occur in many areas of North America, as well as having been described in South America and Europe. Monocomponent\n                      <jats:styled-content style=\"fixed-case\">PHF<\/jats:styled-content>\n                      vaccines are available, but clinical protection with vaccination has been reported to be inconsistent.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Objectives<\/jats:title>\n                    <jats:p>\n                      This study was designed to assess the immunogenicity of a commercially available Potomac Horse Fever (\n                      <jats:styled-content style=\"fixed-case\">PHF<\/jats:styled-content>\n                      ) vaccine when administered as either a monovalent\n                      <jats:styled-content style=\"fixed-case\">PHF<\/jats:styled-content>\n                      vaccine simultaneously co\u2010administered with a separate monovalent Rabies vaccine or as a multivalent\n                      <jats:styled-content style=\"fixed-case\">PHF<\/jats:styled-content>\n                      \/Rabies vaccine in horses.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Study design<\/jats:title>\n                    <jats:p>Randomised parallel group trial.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      Ninety\u2010one client or University owned horses participated in this open\u2010label randomised study, with 45 horses receiving the monovalent vaccines at separate sites and 46 receiving the multivalent vaccine at a single site. Serum\n                      <jats:styled-content style=\"fixed-case\">PHF IFA<\/jats:styled-content>\n                      titres were determined twice prior to vaccination and at 1, 2 and 3\u00a0months after vaccination.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Both vaccination protocols exhibited poor immunogenicity, with only one\u2010third of all the animals demonstrating seroconversion, defined as an increase in titre of greater than 400 over baseline, at any time point after vaccination. The monovalent\n                      <jats:styled-content style=\"fixed-case\">PHF<\/jats:styled-content>\n                      vaccine exhibited significantly greater immunogenicity in terms of the number of horses exhibiting seroconversion, as compared to the multivalent vaccine, at one (20 vs. 11, P\u00a0=\u00a00.03) and two (18 vs. 9, p\u00a0=\u00a00.02) months post vaccination. The monovalent\n                      <jats:styled-content style=\"fixed-case\">PHF<\/jats:styled-content>\n                      vaccine also exhibited significantly greater immunogenicity in terms of the median (interquartile range)\n                      <jats:styled-content style=\"fixed-case\">IFA<\/jats:styled-content>\n                      titres, as compared to the multivalent vaccine, at one (800 [200\u20131600] vs. 400 [200\u2013800], P\u00a0=\u00a00.009) and 2\u00a0months (400 [200\u20131600] vs. 400 [100\u2013800], P\u00a0=\u00a00.02) post vaccination. There was no significant difference between groups at 3\u00a0months in either seroconversion rate or median\n                      <jats:styled-content style=\"fixed-case\">IFA<\/jats:styled-content>\n                      titers.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Main limitations<\/jats:title>\n                    <jats:p>\n                      This study did not assess the actual protective effects of\n                      <jats:styled-content style=\"fixed-case\">PHF<\/jats:styled-content>\n                      vaccination but rather used the serologic response to vaccination as a surrogate biomarker of immunity.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>\n                      The multivalent\n                      <jats:styled-content style=\"fixed-case\">PHF<\/jats:styled-content>\n                      \/Rabies vaccine exhibited lower immunogenicity as compared to the monovalent\n                      <jats:styled-content style=\"fixed-case\">PHF<\/jats:styled-content>\n                      vaccine co\u2010administered with a separate Rabies vaccine.\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.1111\/evj.13096","type":"journal-article","created":{"date-parts":[[2019,3,12]],"date-time":"2019-03-12T02:46:18Z","timestamp":1552358778000},"page":"774-778","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Immunogenicity of Potomac horse fever vaccine when simultaneously co\u2010administered with rabies vaccine in a multivalent vaccine or as two monovalent vaccines at separate sites"],"prefix":"10.1111","volume":"51","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8230-2237","authenticated-orcid":false,"given":"H. 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