Preliminary Investigation Towards a Safety Tool for Swine Brucellosis Diagnosis by a Proteomic Approach Within the One-Health Framework

Brucellosis is a zoonosis that affects domestic and wild animals, causing reproductive disorders and significant economic losses in livestock. <i>Brucella melitensis</i>, <i>B. abortus</i>, and <i>B. suis</i> are the main agents of brucellosis in livestock and humans, thereby their control and eradication are crucial. Serological tests based on identification of antibodies against <i>Brucella</i> smooth lipopolysaccharides (sLPS) in the serum of infected animals are traditionally used. This approach shows two main limits: (i) tests can give false positives due to the similarity of <i>Brucella</i> sLPS with the LPS of other Gram-negative bacteria; (ii) antigen production represents a possible risk of zoonoses. In this work, a proteomic approach, starting from <i>B. melitensis</i> Brucellergene, was employed to identify possible <i>Brucella</i> antigenic proteins useful for a more specific and safe serological diagnosis. Four proteins binding to the infected swine serum were identified: (i) "probable sugar-binding periplasmic protein <i>B. abortus</i> str 2308A"; (ii) "peptide ABC transporter substrate-binding protein <i>B. melitensis</i>"; (iii) "GntR family transcriptional regulator <i>B. melitensis</i>"; (iv) "conserved hypothetical protein <i>B. melitensis</i> M28". These proteins could be promising specific antigens for serological investigations in swine. In the near future, these antigenic proteins could be synthesized in vitro and used to produce a safer and more specific diagnostic kit.