NEW MICROBIOLOGICA, 31, 423-427, 2008 Heparin binding haemagglutin as potential diagnostic marker of Mycobacterium bovis Paola Molicotti 1 , Alessandra Bua 1 , Silvia Ortu 1 , Maura C. Ladu 2 , Giovanni Delogu 3 , Antonio Mura 4 , Leonardo A. Sechi 1 , Giovanni Fadda 3 , Stefania Zanetti 1 1 Department of Biomedical Sciences University of Sassari University of Sassari, Italy; 2 Istituto Zooprofilattico Sperimentale della Sardegna, Oristano; 3 Institute of Microbiology, Catholic University, Rome, Italy; 4 A.S.L. n. 2 of Olbia, Italy In this study, we characterized the humoral responses in cattle of Sardinia. The animals were divided into three groups: 1) 28 cattle infected with Mycobacterium bovis; 2) 48 cattle from herds in which foci of infection was notified; 3) 50 cattle from herds that were TB-free. Levels of IgG antibody were measured against the following antigens of M. tuberculosis: Heparin-Binding-Haemagglutin (HBHA), Ag85B, PPE44, and PE_PGRS33 to investigate their potential to diagnose TB in animals. Our results indi- cated that HBHA is a potential candidate for the development of a serological assay for rapid diagnosis of cattle in- fected with M. bovis. KEY WORDS: HBHA, Mycobacterium bovis, Humoral response, Bovine tuberculosis SUMMARY Received February 01, 2007 Accepted March 04, 2008 Corresponding author Alessandra Bua Department of Biomedical Sciences University of Sassari University of Sassari Viale San Pietro 43/b 07100 Sassari, Italy E-mail: ale.b76@email.it Bovine tuberculosis (TB) is a serious infectious disease caused by Mycobacterium bovis, a mem- ber of the Mycobacterium tuberculosis (MTB) complex (O’Reilly et al., 1995). The immune re- sponse to bovine TB is predominantly cell-medi- ated, however when the bacterial burden is high, the host mounts a significant humoral response to M. bovis antigens (O’Reilly et al., 1995, Hewinson et al., 1996). Several attempts have been made to develop simple, low-cost serologi- cal assays that can identify those animals with advanced infection that are nonetheless skin-test negative. The earliest assays of this type, based on the use of M. bovis Purified Protein Derivative (PPD) and phosphatide antigens (Harboe et al., 1995), lacked specificity, and subsequent efforts were thus aimed at identifying antigens expressed exclusively by M. bovis or at least by a limited number of mycobacterial species. Several anti- gens have proved to be specific for M. bovis, but assays based on their detection have displayed low sensitivity (Hanna et al., 1989, Hewinson et al., 1996, Lilenbaum et al., 2001; Harboe et al., 1990, Lightbody et al., 1998). Recently, our group demonstrated that the Heparin Binding Haemagglutin (HBHA) (Zanetti et al., 2005), expressed by M. tuberculosis and M. bovis (Menozzi et al., 1996), is a specific and sen- sitive marker that can discriminate between pa- tients with active TB and those vaccinated with BCG who were PPD positive. The aim of this work was to investigate whether an antibody- based test could be useful to diagnose TB in an- imals. Since the immune response to TB is vari-