Evaluation and Differential Diagnosis of a Genetic Marked Brucella Vaccine A19ΔvirB12 for Cattle.

Jianghua Yang,Mengzhi Liu,Sun He,Xiaohu Han,Chuanyu He,Hailong Zhao,Lisong Ren,Dongling Wu,Fangyuan Du,Zeliang Chen,Huan Zhang,Baoshan Liu

doi:10.3389/fimmu.2021.679560

Abstract

Brucella abortus is an important zoonotic pathogen that causes severe economic loss to husbandry and poses a threat to human health. The B. abortus A19 live vaccine has been extensively used to prevent bovine brucellosis in China. However, it is difficult to distinguish the serological response induced by A19 from that induced by natural infection. In this study, a novel genetically marked vaccine, A19ΔvirB12, was generated and evaluated. The results indicated that A19ΔvirB12 was able to provide effective protection against B. abortus 2308 (S2308) challenge in mice. Furthermore, the safety and protective efficacy of A19ΔvirB12 have been confirmed in natural host cattle. Additionally, the VirB12 protein allowed for serological differentiation between the S2308 challenge/natural infection and A19ΔvirB12 vaccination. However, previous studies have found that the accuracy of the serological detection based on VirB12 needs to be improved. Therefore, we attempted to identify potential supplementary antigens with differential diagnostic functions by combining label-free quantitative proteomics and protein chip technology. Twenty-six proteins identified only in S2308 were screened; among them, five proteins were considered as potential supplementary antigens. Thus, the accuracy of the differential diagnosis between A19ΔvirB12 immunization and field infection may be improved through multi-antigen detection. In addition, we explored the possible attenuation factors of Brucella vaccine strain. Nine virulence factors were downregulated in A19ΔvirB12. The downregulation pathways of A19ΔvirB12 were significantly enriched in quorum sensing, ATP-binding cassette transporter, and metabolism. Several proteins related to cell division were significantly downregulated, while some proteins involved in transcription were upregulated in S2308. In conclusion, our results contribute to the control and eradication of brucellosis and provide insights into the mechanisms underlying the attenuation of A19ΔvirB12.

Highlights

Brucellosis is an important reemerging zoonosis that causes tremendous economic losses in animal husbandry and presents a significant risk to public health
Mice inoculated with live attenuated Brucella vaccine strains were maintained under biosafety level-2 (BSL-2) containment and those inoculated with S2308 were maintained under BSL-3 containment
In order to determine the protection efficiency of A19DvirB12, the mice were vaccinated i.p. with A19DvirB12 or A19, and the phosphate-buffered saline (PBS)-inoculated group served as the control (Figure 1C)

Summary

Introduction

Brucellosis is an important reemerging zoonosis that causes tremendous economic losses in animal husbandry and presents a significant risk to public health. In the absence of an effective vaccine protecting humans from Brucella infection, the research and development of animal vaccines will be beneficial to both animals and humans [4, 5]. The antibody response induced by the O-side chain of the A19 vaccine interferes with serological diagnosis, which hardly distinguishes between vaccinated and infected animals [6]. This shortcoming of traditional vaccines impairs efforts to control and eradicate infectious diseases. It is well known that the use of gene-deleted vaccines, such as gE-null marker strains, has led to great progress in the eradication of Pseudorabies virus in some areas [9]

Methods

Results

Discussion

Conclusion