106 Original article doi: 10.1016/S2222-1808(15)60994-X ©2016 by the Asian Pacific Journal of Tropical Disease. All rights reserved. Single nucleotide polymorphism and expression studies of the interferon gamma gene and its role against Haemonchus contortus in Garole and Sahabadi sheep Gautam Patra 1* , Ruma Jas 2 , Joydev Ghosh 2 , Sonjoy Kumar Borthakur 1 , Avisek Paul 3 1 Department of Veterinary Parasitology, College of Veterinary Sciences and Animal Husbandry, Selesih, Aizawl, Mizoram, India 2 Department of Veterinary Parasitology, West Bengal University of Animal and Fishery Sciences, K.B. Sarani, Kolkata, West Bengal, India 3 Division of Physiology, Indian Veterinary Research Institute, Izatnagar, Bareilly, Uttar Pradesh, India Asian Pac J Trop Dis 2016; 6(2): 106-112 Asian Pacific Journal of Tropical Disease journal homepage: www.elsevier.com/locate/apjtd *Corresponding author: Gautam Patra, Department of Veterinary Parsitology, College of Veterinary Sciences and Animal Husbandry, Selesih, Aizawl, Mizoram, India. Tel: +91 8582859415 E-mail: dr.gautampatra@yahoo.co.in All experimental procedures involving sheep were conducted in accordance to experimental protocol in live animals laid down by the West Bengal University of Animal and Fishery Sciences, Kolkata, India and approved by the Institutional Animal Ethic Committee under CPCSEA vide their approved number WBUAFS/ Vety/IAEC/ 26 Dtd. 8th September 2014. The journal implements double-blind peer review practiced by specially invited international editorial board members. Foudation Project: Supported by the Central Agricultural University, Imphal, Manipur, India (Grand No. D.15/CVSC/CAU/06/793 dated 21/07/2011). 1. Introduction Gastrointestinal nematode infection continues to be one of the major constraints of the animal production particularly in small ruminant livestock throughout the world[1,2]. Among gastrointestinal nematode infection, Haemonchus contortus (H. contortus) is of particular concern because it can cause severe economic loss in small ruminant farming due to anaemia, anorexia, depression, loss of condition and ultimate death. Anthelmintic resistance is the major constrain in controlling gastrointestinal nematodes. Even the recent introduction of a new class of anthelmintic, the amino acetyl nitrile derivatives, have shown resistance to nematodes of sheep and goats in less than two years of use[3-6]. It is, therefore, imperative to search for alternative control measures which would lead to less reliance on anthelmintics and at the same time reduce the cost of parasite control. Selecting animals with enhanced resistance to parasites would be a promising sustainable approach. The advantages of genetic selection include permanent genetic change which keeps working throughout the life and adds diversity to helminth management programs[7,8]. Genetic mechanism underscoring the variation of resistance can be related to the development of different profiles of Th1/Th2 cytokines[9,10]. Dysfunction in T cell differentiation and regulation contributed to breed susceptibility for nematodes has been currently hypothesized[11,12]. Because of its preeminent role in the immune response, interferon gamma (IFN-γ) is considered as a functional candidate antigen gene for resistance to gastrointestinal nematodes. Although the role of IFN-γ ARTICLE INFO ABSTRACT Objective: To evaluate the role of interferon gamma (IFN- γ) gene in Haemonchus contortus (H. contortus) resistant in Garole/Sahabadi breed of sheep. Methods: Five Garole sheep (Group I) consistently showing low egg per gram in faeces (≤ 150) and another five Garole sheep(Group II) which had high egg per gram (≥ 500) were challenged with third-stage (L3) H. contortus larvae with 500 larvae/kg body weight. Five Sahabadi sheep (Group III) which were known to be susceptible to H. contortus were also fed with the same dose. Blood was collected from each group at different date of infection, viz. 0 day, 7 days and 14 days of post infection. The ovine IFN-γ was partially isolated and sequenced including intron and exon regions from six Garole sheep and three Sahabadi sheep prior to infection. The level of messenger ribonucleic acid of IFN-γ was evaluated by means of real-time PCR at different days of post infection. Results: In addition to one single nucleotide polymorphism at exon 3 of IFN-γ gene in three resistant Garole sheep, the level of mRNA in two susceptible groups was found significantly higher (P ≤ 0.05) as compared to the resistant group in the present study. Conclusions: We could clearly identify a single cytokine gene which is differentially expressed between the resistant and the susceptible animals that could be a potential target for identifying the genetic marker of Haemonchus resistance. Finding of one single nucleotide polymorphism at exon 3 in three resistance Garole sheep might have novelty. Contents lists available at ScienceDirect Article history: Received 14 Dec 2015 Received in revised form 6 Jan 2016 Accepted 19 Jan 2016 Available online 21 Jan 2016 Keywords: Single nucleotide polymorphism mRNA expression IFN-γ gene H. contortus Garole/Sahabadi sheep