Immunization with Brucella abortus S19Δper Conferred Protection in Water Buffaloes against Virulent Challenge with B. abortus Strain S544.

Pallab Chaudhuri,Gurpreet Kaur,Syed Atif Ali,Praveen Malik,Shiv Varan Singh,Mani Saminathan,Sandeep K Singh,Ashwini K Singh,Tapas K Goswami,Jonathan Lalsiamthara,Raj K Singh

doi:10.3390/vaccines9121423

Pallab Chaudhuri, Gurpreet Kaur + Show 9 more

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https://doi.org/10.3390/vaccines9121423

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Abstract

Vaccination of cattle and buffaloes with Brucella abortus strain 19 has been the mainstay for control of bovine brucellosis. However, vaccination with S19 suffers major drawbacks in terms of its safety and interference with serodiagnosis of clinical infection. Brucella abortus S19∆per, a perosamine synthetase wbkB gene deletion mutant, overcomes the drawbacks of the S19 vaccine strain. The present study aimed to evaluate the potential of Brucella abortus S19Δper vaccine candidate in the natural host, buffaloes. Safety of S19∆per, for animals use, was assessed in guinea pigs. Protective efficacy of vaccine was assessed in buffaloes by immunizing with normal dose (4 × 1010 colony forming units (CFU)/animal) and reduced dose (2 × 109 CFU/animal) of S19Δper and challenged with virulent strain of B. abortus S544 on 300 days post immunization. Bacterial persistency of S19∆per was assessed in buffalo calves after 42 days of inoculation. Different serological, biochemical and pathological studies were performed to evaluate the S19∆per vaccine. The S19Δper immunized animals showed significantly low levels of anti-lipopolysaccharides (LPS) antibodies. All the immunized animals were protected against challenge infection with B. abortus S544. Sera from the majority of S19Δper immunized buffalo calves showed moderate to weak agglutination to RBPT antigen and thereby, could apparently be differentiated from S19 vaccinated and clinically-infected animals. The S19Δper was more sensitive to buffalo serum complement mediated lysis than its parent strain, S19. Animals culled at 6-weeks-post vaccination showed no gross lesions in organs and there was comparatively lower burden of infection in the lymph nodes of S19Δper immunized animals. With attributes of higher safety, strong protective efficacy and potential of differentiating infected from vaccinated animals (DIVA), S19Δper would be a prospective alternate to conventional S19 vaccines for control of bovine brucellosis as proven in buffaloes.

Highlights

Brucellosis is a major zoonotic disease caused by the Brucella species, which remains an uncontrolled problem in different developing countries, including India
Following the guidelines of IP for safety study, a group of six guinea pigs were injected with S19∆per
S19∆per vaccine candidate was proven safe for animal use

Summary

Introduction

Brucellosis is a major zoonotic disease caused by the Brucella species, which remains an uncontrolled problem in different developing countries, including India. Serological examination and culling of infected animals play pivotal roles in successful control and eradication of brucellosis [8]. In developing countries, the elimination of infected animals is not practicable due to economic burden and cultural belief restricting cow slaughter and leading to high prevalence of brucellosis in these countries. Vaccination of animals, thereby, continues to be the keystone of controlling animal brucellosis in these areas. S19 and Rev. vaccines have been successfully used worldwide, major drawbacks of these strains are presence of residual virulence and interference in serodiagnosis of the disease and inability of differentiating infected from vaccinated animals (DIVA)

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