Pusterla Nicola, Vannucci Fabio A, Mapes Samantha M, Nogradi Nora, Collier Jessica R, Hill Jackie A, Difrancesco Melissa, White Alexandria M, Akana Nina K, Simonek Greg, Gebhart Connie J
Department of Veterinary Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA.
Am J Vet Res. 2012 May;73(5):741-6. doi: 10.2460/ajvr.73.5.741.
To determine the efficacy of an avirulent Lawsonia intracellularis vaccine in preventing proliferative enteropathy in weanling foals.
12 healthy weanling foals.
Foals were randomly assigned to a vaccinated, nonvaccinated, or control group. Vaccinated foals received an avirulent porcine L intracellularis frozen-thawed vaccine intrarectally 60 and 30 days prior to experimental challenge. On day 1, vaccinated and nonvaccinated foals were challenged via nasogastric intubation with a virulent heterologous isolate of L intracellularis. Control foals were not challenged. Clinical observation and ultrasonographic evaluation of the small intestine were performed, and body weight, serum concentration of total solids, fecal excretion of L intracellularis, and seroconversion were measured for each foal until day 56. Diseased foals were treated with antimicrobials and supportive care.
None of the 4 vaccinated foals developed clinical disease following challenge with virulent L intracellularis. Three of 4 nonvaccinated foals developed moderate to severe clinical signs compatible with proliferative enteropathy, hypoproteinemia, and thickened small intestinal loops. Vaccinated foals had significantly less fecal shedding of L intracellularis than nonvaccinated foals. Serologic responses between vaccinated and nonvaccinated foals after challenge were similar. Control foals remained clinically unaffected with no evidence of fecal shedding and seroconversion.
Intrarectal administration of a commercial avirulent porcine vaccine against L intracellularis resulted in complete protection against proliferative enteropathy in the foals in this study and may also reduce environmental contamination with the organism on endemic farms.
确定无毒力胞内劳森菌疫苗预防断奶幼驹增生性肠炎的效果。
12匹健康断奶幼驹。
将幼驹随机分为接种疫苗组、未接种疫苗组或对照组。接种疫苗的幼驹在实验性攻毒前60天和30天经直肠接种无毒力猪源胞内劳森菌冻融疫苗。在第1天，对接种疫苗和未接种疫苗的幼驹经鼻胃管接种毒力较强的胞内劳森菌异源分离株。对照幼驹不进行攻毒。对幼驹进行临床观察和小肠超声检查，并测量每匹幼驹直至第56天的体重、血清总固体浓度、胞内劳森菌粪便排泄量和血清转化情况。患病幼驹接受抗菌药物治疗和支持性护理。
4匹接种疫苗的幼驹在接种毒力较强的胞内劳森菌后均未出现临床疾病。4匹未接种疫苗的幼驹中有3匹出现了与增生性肠炎、低蛋白血症和小肠肠袢增厚相符的中度至重度临床症状。接种疫苗的幼驹胞内劳森菌粪便排出量明显低于未接种疫苗的幼驹。攻毒后接种疫苗和未接种疫苗的幼驹血清学反应相似。对照幼驹临床上未受影响，没有粪便排出和血清转化的证据。
在本研究中，经直肠接种市售无毒力猪源胞内劳森菌疫苗可使幼驹完全预防增生性肠炎，还可能减少地方病流行农场中该菌对环境的污染。
