Sujata Jayaraman

Trends and advances in the diagnosis and control of paratuberculosis in domestic livestock.

ABSTRACT Paratuberculosis (pTB) is a chronic granulomatous enteritis caused by Mycobacterium avium subsp. paratuberculosis (MAP) in a wide variety of domestic and wild animals. Control of pTB is difficult due to the lack of sensitive, efficacious and cost-effective diagnostics and marker vaccines. Microscopy, culture, and PCR have been used for the screening of MAP infection in animals for quite a long time. Besides, giving variable sensitivity and specificity, these tests have not been considered ideal for large-scale screening of domestic livestock. Serological tests like ELISA easily detects anti-MAP antibodies. However, it cannot differentiate between the vaccinated and infected animals. Nanotechnology-based diagnostic tests are underway to improve the sensitivity and specificity. Newer generation diagnostic tests based on recombinant MAP secretory proteins would open new paradigm for the differentiation between infected and vaccinated animals and for early detection of the infection. Due to higher seroreactivity of secretory proteins vis-à-vis cellular proteins, the secretory proteins may be used as marker vaccine, which may aid in the control of pTB infection in animals. Secretory proteins can be potentially used to develop future diagnostics, surveillance and monitoring of the disease progression in animals and the marker vaccine for the control and eradication of pTB.

Comparative Evaluation of Different Test Combinations for Diagnosis of Mycobacterium avium Subspecies paratuberculosis Infecting Dairy Herds in India

A total of 355 cows were sampled (serum, n = 315; faeces, n = 355; milk, n = 209) from dairy farms located in the Punjab state of India. Faeces and serum/milk samples were screened by acid fast staining and “indigenous ELISA,” respectively. IS900 PCR was used to screen faeces and milk samples. Bio-load of MAP in dairy cows was 36.9, 15.6, 16.3, and 14.4%, using microscopy, serum ELISA, milk ELISA and milk PCR, respectively. Estimated kappa values between different test combinations: serum and milk ELISA, faecal microscopy and faecal PCR, milk ELISA and milk PCR, faecal PCR and serum ELISA were 0.325, 0.241, 0.682, and 0.677, respectively. Estimation of the relative sensitivity and specificity of different tests in the present study indicated that “serum ELISA” and “milk ELISA” were good screening tests, add “milk PCR” was “confirmatory test” for MAP infection. Combination of milk ELISA with milk PCR may be adopted as a model strategy for screening and diagnosis of JD in lactating/dairy cattle herds in Indian conditions.

Evalution of “indirect fluorescent antibody test‟ as potential screening test for Mycobacterium avium subspecies paratuberculosis using milk of lactating domestic livestock

In the present study, Indirect Fluorescent antibody test (iFAT) has been used as the “screening test” for the detection of MAP bacilli in the milk samples of lactating domestic livestock. A total of 372 milk samples from lactating animals were screened by iFAT and results were compared with microscopy of milk samples and milk ELISA test. Comparative analysis of the results of three tests showed that iFAT had fairly good sensitivity (84.7%) and specificity (90.4%), with respect to ZN staining (microscopy) with kappa value of 0.735 and „good‟ strength of agreement. Similar comparison with milk ELISA test revealed, sensitivity (73.3%) and specificity of (72.6%) with kappa value of 0.443 and strength of agreement was moderate. Lower or higher difference in sensitivity and specificity of iFAT with respect to ZN staining and milk ELISA may be due to the difference in detection „target‟ of the test i.e., antigen or antibody. It was concluded that iFAT was a reliable and sensitive diagnostic test for the detection of MAP in milk and can also be used for the „mass screening‟ of the milk samples. Shoor Vir Singh 1,* , Bjorn John Stephen 1,2 , Manju Singh 1,2 , Saurabh Gupta 1,3 , Kundan Kumar Chaubey 1,3 , Sahzad 1 , Sujata Jayaraman 2 , Tarun Kumar Sachan 1 , Gajendra Kumar Aseri 2 , Manali Dutta 2 , Jagdip Singh Sohal 2 , Kuldeep Dhama 4 , Shivalingappa Yamanappa Mukartal 5 and Doddamane Rathnamma 5