Title : Studies on the gene expression profile of the immune regulatory genes in peripheral blood mononuclear cells of Cattle naturally infected with bovine tuberculosis.
Bovine tuberculosis (bTB) is a chronic infectious disease caused primarily by infection with M. bovis, which belongs to the Mycobacterium tuberculosis complex. The initial host response against bTB infections is mainly regulated by the Th1 response, which is characterized by the production of IFN-γ. With the progression of disease, Mycobacterium can survive in the host through the evasion of the host’s immune response by manipulating it. Whole blood based assays, particularly interferon gamma (IFN-γ) release assays (IGRAs), are used for the diagnosis of bTB. The aim of the current study was to evaluate a panel of immuneregulatory genes for their potential use as the diagnostic biomarkers of M. bovis infection in cattle. In the present study a total number of 168 cattle were screened by comparative intradermal tuberculin test and molecular confirmation of bTB was done using IS6100 PCR. The haematological analysis of (n=25) bTB positive and (n=25) bTB negative cattle was performed. PBMCs from (n=25) naturally infected cattle and (n=25) healthy cattle was cultured and stimulated with Bovine PPD used as the stimulating antigen in vitro. PBMCs were harvested after 16hrs stimulation with the stimulating antigen. Seven target genes (MCP-1, MMP-9, CCR5, iNOS, IFNγ, TNFα and IL-23A) and one reference gene (GAPDH) was studied by the SYBR green RT-PCR assay. Cattle positive for bTB has reduced total lymphocytes count along with increased TLC and granulocytes. All the target genes were significantly upregulated (p<0.05) in bTB positive cattle as compared to the healthy cattle. Findings suggest that (MCP-1, MMP-9, CCR5, iNOS, IFNγ, TNFα and IL-23A) can be consider as the potential diagnostic biomarkers of bTB infection in cattle.