NE US Academic Publishers Advances in Animal and Veterinary Sciences June 2015 | Volume 3 | Issue 6 | Page 325 INTRODUCTION L isteriosis caused by pathogenic strains of Listeria monocytogenes and L.ivanovii, is a serious invasive dis- ease characterized by three forms namely; encephalitis, septicaemia and abortion in animals (Low and Donachie, 1997). Listeriosis leads to septicaemia, abortion, stillbirth, perinatal infections, meningitis, gastroenteritis and menin- goencephalitis, especially in immunocompromised indi- viduals (Barbudde et al., 2012). he occurrence of listeric infections in the Indian subcontinent has been extensively reviewed by many workers (Malik et al., 2002; Barbudde et al., 2012). In India, we have recorded outbreaks of lis- teriosis in animal populations (Kumar et al., 2007; Yadav and Roy. 2008; Kaur et al., 2010). Recently, a database of Listeria strains isolated in India from various sources, Indi- an Listeria Culture Database (ILCD) has been established ( Jangam et al., 2010, Barbuddhe et al., 2000; http://www. icargoa.res.in/ilcd). he database provides visualization of geographical source of the strain, its lineage, serotype, source of isolation (animal/human), year of isolation, phe- notypic and genotypic characteristics as well as antibiotic sensitivity patterns. Listeric infection in animals is usually acquired by consumption of spoiled silage, in which these bacteria multiply, resulting in herd outbreaks. hough the reliable diagnosis of listeriosis is made by isolation and identiication of the pathogen but it is time consuming (Rocourt et al., 1983). herefore, the diagnosis of patho- genic Listeria spp. and listeric infection can be made on the basis of virulence genes (Notermans et al., 1991b). Lis- Research Article Abstract | In the present investigation, a total of 880 clinical samples comprising blood (n=215), vaginal swabs (n=220), fecal swabs (n=220), placenta (n=10) and sera (n=215) from ewes with abortion or history of abortion as well as from apparently healthy ewes of organized and migratory locks were collected for screening listeric infection by isolation, serological and molecular diagnostic methods. 23 diferent isolates were recovered which comprised of 15 L. monocy- togenes, 2 L. ivanovii and 6 other listeriae. Among these, four haemolytic isolates (L. ivanovii-2 and L. monocytogenes-2) were found pathogenic based on hemolysis on sheep blood agar, CAMP test, PI-PLC activity, virulence-associated genes (prfA, plcA, actA, hlyA and iap) as well as by in vivo pathogenicity tests namely, chick embryo and mice inoc- ulation tests. Indirect plate ELISA revealed 41.96% seropositivity for antibodies against listeriolysin O in ewes with abortion or history of abortion and 26.21% in apparently healthy ewes, which after adsorption of sera with Streptolysin O (SLO) reduced to 18.75% and 9.70% in respective groups. On over all basis, out of 215 sheep sera, 74 (34.42%) sera showed positivity for ALLO, which was reduced to 31(14.42%) following adsorption with SLO, indicating the need for sera adsorption for removing the cross-reactivity. he study had signiicant implications in understanding the epidemiology of listeric infection in migratory locks. Keywords | Listeria spp, Migratory sheep, Abortion, LLO, ELISA SHIVARAMU KEELARA 1 *, SATYA VEER SINGH MALIK 2 , SHIVASHARANAPPA NAYAKVADI 3 , SAMIR DAS 2 , SUKHADEO BALIRAM BARBUDDHE 4 Isolation and Characterization of Listeria spp. from Organized and Migratory Sheep Flocks in India Editor | Kuldeep Dhama, Indian Veterinary Research Institute, Uttar Pradesh, India. Received | March 28, 2015; Revised | April 29, 2015; Accepted | April 30, 2015; Published | May 07, 2015 *Correspondence | Shivaramu Keelara, University of Maryland, College Park, USA; Email: shivakeelara@gmail.com Citation | Keelara S, Malik SSV, Nayakvadi S, Das S, Barbuddhe SB (2015). Isolation and characterization of Listeria spp. from organized and migratory sheep locks in India. Adv. Anim. Vet. Sci. 3(6): 325-331. DOI | http://dx.doi.org/10.14737/journal.aavs/2015/3.6.325.331 ISSN (Online) | 2307-8316; ISSN (Print) | 2309-3331 Copyright © 2015 Keelara et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 Department of Nutrition and Food Science, University of Maryland, College Park, MD 20742, USA; 2 Division of Veterinary Public Health, Indian Veterinary Research Institute, Izatnagar, 243122, India; 3 Animal Sciences Section, Central Coastal Agricultural Research Institute, Goa, 403402, India; 4 National Institute of Biotic Stresses Manage- ment, Raipur, Chhattisgarh, India.