Premium
Equine leptospirosis: Experimental challenge of Leptospira interrogans serovar Bratislava fails to establish infection in naïve horses
Author(s) -
Zilch Tiago J.,
Lee JenJie,
Saleem Muhammad Zain,
Zhang Hui,
Cortese Victor,
Voris Nathan,
McDonough Sean P.,
Divers Thomas J.,
Chang YungFu
Publication year - 2021
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.1111/evj.13442
Subject(s) - leptospirosis , leptospira interrogans , serotype , leptospira , serology , direct agglutination test , urinalysis , horse , medicine , urine , veterinary medicine , biology , physiology , immunology , antibody , paleontology
Background Little information is available about experimental inoculation of leptospirosis in horses and the pathogenicity of Leptospira interrogans serovar Bratislava in this host. Objectives To determine the serological, clinical, pathological and haematological responses of horses to L. interrogans serovar Bratislava strain PigK151. Study design Randomised controlled in vivo experiment. Methods Ten seronegative female foals were divided into 2 groups, control (n = 4) and challenged (n = 6). The challenged group received 1 × 10 9 leptospires divided equally between topical ocular and intraperitoneal injections. Blood and urine samples were analysed. The temperature was recorded daily for the first 9 days, then weekly. Sera were tested by microscopic agglutination test (MAT). Automated complete blood count, differential and chemistry panel were performed. Histopathological analysis was performed on sections of liver, kidney, urinary bladder, uterine body and pineal gland. Sample culturing was performed from blood, urine, liver, kidney, reproductive tract and vitreous humour. Results No pyrexia was noted. PCR and culture were negative from all samples. Differences between groups were found in CBC, differential counts and serum biochemistry panel (or profile), suggesting that leptospiral challenge triggered an inflammatory response. No evidence of leptospirosis was found from histopathological analysis. All challenged foals developed a humoral response. The MAT allowed the confirmation of the infecting serovar at a later stage, but it also revealed cross‐reactive results that were further explained by genomic analysis. Main limitations This experimental challenge had two main limitations: (a) the results might have varied if another strain from the same serovar had been used and (b) the use of another route of infection and a higher bacterial dose might have achieved colonisation. Conclusions Based on these findings, it may suggest that L. interrogans serovar Bratislava is neither pathogenic nor host‐adapted serovar for horses, although these results might have varied if another strain from the same serovar had been used instead.