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O4-3 Use of brucellin skin test to identify water buffaloes (Bubalus bubalis) vaccinated with the live attenuated vaccine B. abortus strain RB51
2022, 4 - Immunology
2022

O4-3 Use of brucellin skin test to identify water buffaloes (Bubalus bubalis) vaccinated with the live attenuated vaccine B. abortus strain RB51

4 - Immunology
Published 2023-02-10
Fabrizio De Massis
WOAH and National Reference Laboratory for Brucellosis, Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise “G. Caporale”, Teramo, Italy
Flavio Sacchini
WOAH and National Reference Laboratory for Brucellosis, Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise “G. Caporale”, Teramo, Italy
Nicola D'Alterio
WOAH and National Reference Laboratory for Brucellosis, Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise “G. Caporale”, Teramo, Italy
Nicola Ferri
WOAH and National Reference Laboratory for Brucellosis, Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise “G. Caporale”, Teramo, Italy
Emanuela Rossi
WOAH and National Reference Laboratory for Brucellosis, Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise “G. Caporale”, Teramo, Italy
Giovanni Befacchia
WOAH and National Reference Laboratory for Brucellosis, Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise “G. Caporale”, Teramo, Italy
Manuela Tittarelli
WOAH and National Reference Laboratory for Brucellosis, Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise “G. Caporale”, Teramo, Italy

Keywords

Brucellosis
Water buffalo
immune response
Brucellin skin test

Categories

Abstract

The use of the live attenuated Brucella abortus RB51 vaccine in water buffaloes was exceptionally authorised in Italy in 2007 as an additional measure to reduce the impact of Brucellosis in some endemic areas. Vaccination was restricted to prepubescent animals only, to avoid the known risks of excretion with milk or abortion when administered to adult females. To survey non-authorised vaccinations, a diagnostic protocol was developed combining RB51 complement fixation (RB51-CFT) and brucellin skin tests (BST). The aim of the study has been to assess performances (Se and Sp) of BST when applied to a known population of buffaloes vaccinated with RB51, and controls. Data from two different RB51 vaccine trials were combined, and included 49 vaccinated animals and 9 controls. Both trials considered two separate injections of a triple dose of RB51 vaccine to young animals, but age and timing of vaccination and timing of booster dose differed slightly. BST was performed using commercial brucellergene OCB. In the first (long term) trial, BST was performed 3 months after delivery, i.e. 23-25 months after booster vaccination. In the second trial, BST was executed 18 months after the booster dose. Different cut-off for skin thickness increase were considered to evaluate BST performance. In both trials most vaccinated animals showed a BST positive reaction, that was more evident at 72hrs compared to 48hrs, this independently of the vaccination protocol applied. BST showed best value of Se (83,7%, 70,9-91,4 C.I.) and Sp (100%, 71,7-100 C.I.) when considering a skin thickness increase of 1,5 mm as cut-off. As expected, some vaccinated animals (8/49, 16,3%) tested negative to BST. Taken together, both study results indicate that BST, when applied at herd level, is a suitable test to identify RB51 vaccinated animals for long time after vaccination. Conversely, due to the low sensitivity, application of BST on individual animals is questionable.

References

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World organization for Animal Health (OIE) (2019). Brucellosis (Brucella abortus, B. melitensis and B. suis) (infection with B. abortus, B. melitensis and B. suis ), Chapter 3.1.4. [Version adopted in May 2016]. In Manual of Diagnostic Tests and Vaccines for Terrestrial Animals, OIE, Paris.