Journal of Animal Research: v.9 n.6, p. 919-925. December 2019 DOI: 10.30954/2277-940X.06.2019.21 How to cite this article: Bassessar, V., Shrivastava, A.B. and Swamy, M. (2019). Histopathological and molecular investigation of natural cases of bovine tuberculosis infection in cattle. J. Anim. Res., 9(6): 919-925. Histopathological and Molecular Investigation of Natural Cases of Bovine Tuberculosis Infection in Cattle Varun Bassessar 1* , A.B. Shrivastava 2 and Madhu Swamy 1 1 Department of Veterinary Pathology, College of Veterinary Scince & A.H., NDVSU, Jabalpur, M.P., INDIA 2 Centre for Wildlife Forensic and Health, NDVSU, Jabalpur, M.P., INDIA * Corresponding author: V Bassessar; E-Mail: varun.vets@gmail.com Received: 16 Oct., 2019 Revised: 10 Nov., 2019 Accepted: 18 Nov., 2019 ABSTRACT Bovine tuberculosis (bTB), a chronic infection in cattle caused by Mycobacterium tuberculosis/bovis, that impacts productivity and represents a major public health threat. Although the considerable economic costs and zoonotic risk consequences associated with the disease, accurate estimates of bTB prevalence are lacking in many countries, including India. Therefore, in the current study for collection of tubercular lesions the postmortem examination of 100 cattle was conducted. All major viscera and regional lymph nodes were examined and incised. Histopathology was performed in the cases where gross lesions were suggestive of tuberculosis. PCR was performed on the tissue and faecal samples by using IS6110 insertion sequence, Mycobacterium tuberculosis/bovis complex PCR kit. In 12 animals, nodular lesions with casseating mass suggestive of tuberculosis were observed in the lung tissue. All the 12 lung impression smear and only fve faecal smear showed acid fast bacilli stained by Ziehl-Neelsen staining. Histologic features comprised a classic granuloma as a characteristic lesion of tuberculosis composed of a central caseous necrosis with mantle of macrophages, lymphocytes, plasma cells, epithelioid macrophages and Langhan’s giant cells and were observed in all 12 cases. All the tissue samples and 11 faecal samples were positive for the Mycobacterium tuberculosis complex using IS6110 sequence. 8 tissue samples and 4 faecal samples were positive by using Mycobacterium tuberculosis/bovis complex PCR kit. It can be concluded that there was good agreement between histopathology, acid fast staining and PCR. It can also be concluded that faecal samples which are easier to collect should be preferred for diagnosis of TB by PCR in cattle. Keywords: Bovine tuberculosis, Histopathology, Faecal PCR, Tissue PCR, IS6110 insertion sequence, Mycobacterium tuberculosis/bovis complex PCR kit Bovine tuberculosis (BTB) caused by Mycobacterium bovis is a chronic, infectious and progressive disease of cattle, other domesticated animals and certain free or captive wildlife species. It is characterized by the formation of non-vascular granulomas known as tubercles which occur most frequently in lungs, lymph nodes, liver, intestine, and kidney (Varshney et al., 2017). The bovine TB is a signifcant veterinary disease that can spread to humans via ingestion of contaminated milk and contact with infected animals. Bovine tuberculosis is still a major problem in developing countries for wildlife, public health, food safety, and the economy of livestock industries. Animals infected with bTB loose 10-25% of their productive effciency in terms of milk production, weight gain, infertility and condemnation of meat (Miller et al., 2002). Eradication of BTB is not easy in developing countries due to slam interaction between human and animal and lack of effective control measures. The disease in wildlife still poses a risk to livestock, tourism economy, and wildlife conservation even BTB has been mostly eradicated in the livestock industry of some developed countries through culling of infected animals and milk pasteurization (Mishra et al., 2005). Both offcially bovine TB-free (OTF) and non-OTF countries reported