Intramuscular vaccination of young calves with aSalmonellaDublin metabolic-drift mutant provides superior protection to oral delivery

Abstract

-In homologous and heterologous challenge trials using calves ≤ 6 weeks old, this comparative study investigated safety, in vivo behaviour and protective properties of oral and intramuscular vaccination with recently developed live attenuated Salmonella Dublin mutant N-RM25. Neither oral nor intramuscular vaccination produced unacceptable side effects. However, the vaccine strain was isolated for up to eight days from the faeces of orally vaccinated calves, but not intramuscularly vaccinated calves. Irrespective of the vaccination route, N-RM25 was isolated in low numbers (≤ 1 × 10 2 cfu/g) from the liver and spleen of calves euthanized at different time points post-vaccination. Vaccination by either route significantly reduced clinical signs and faecal shedding, prevented the development of systemic infection and protected calves from homologous lethal challenge conducted within 14 days post-immunisation. No challenge strain was isolated from major organs and the gut at 18 days post-challenge (except for a single mesenteric lymph node (MLN) specimen from the intramuscular group, but only following enrichment). Following heterologous challenge with a virulent Salmonella Typhimurium strain at 14 and 20 days post-immunisation, all vaccinated animals exhibited significantly fewer clinical signs and colonisation of the intestinal tract than non-vaccinated controls. When compared to oral vaccination, intramuscular vaccination significantly reduced the frequency of faecal shedding of S. Typhimurium (p = 0.0023) and markedly reduced colonisation of MLN. The findings indicate that intramuscular administration of N-RM25 was safer in terms of environmental contamination by the vaccine and provided better early onset protection in young calves following both homologous and heterologous challenge.Salmonella Dublin / metabolic-drift mutant / live attenuated vaccine / early onset protection / calf

A structured approach to control of Salmonella Dublin in 10 Danish dairy herds based on risk scoring and test-and-manage procedures

“…However, vaccination is mainly useful for reducing clinical signs and shedding of bacteria from affected animals. It does not entirely stop bacteria from spreading to the environment and between animals (Mizuno, McLennan, & Trott, 2008;Segall & Lindberg, 1993).…”

Vaccination for the Prevention of Neonatal Calf Diarrhea in Cow-Calf Operations: A Scoping Review

“…Salmonella enterica (abbreviated Salmonella from here on), a zoonotic agent, is divided into serogroups based on the O antigen and named by capital letters A, B, C, etc ( Peek & Divers, 2018 ). Salmonella are further subdivided into serovars of which Salmonella typhimurium , and Salmonella dublin are most commonly isolated from clinical cases in cattle ( Mizuno et al., 2008 ). Salmonella dublin is the host adapted serotype in cattle that can result in calf diarrhea and pneumonia outbreaks as well as subclinically infected carriers ( Habing et al., 2011 ).…”