ANALYSIS OF CHICKEN TLR4, CD28, MIF, MD-2, AND LITAF GENES IN Salmonella enteritidis RESOURCE POPULATION IN POULTRY

¹ Institut für Nutztierwissenschaften, Statistische Tiergenetik, ETH Zentrum UNS D8, Universitätsstrasse 65, CH-8092 Zürich, Switzerland

² Iowa State University, Department of Animal Science, 2255 Kildee Hall, Ames, Iowa 50011-3150 USA

Salmonella enteritidis (SE), a food borne pathogen, is one of the most common serotypes of Salmonella in USA. Responses to pathogenic SE colonization or to SE vaccination were measured in a response resource population. Outbred broiler sires and three diverse, highly inbred dam lines produced 508 F1 progeny that were evaluated as young chicks for either bacterial load isolated from spleen or cecum content after pathogenic SE inoculation, or circulating antibody level after SE vaccination. Five candidate genes were considered based on their function as possible candidate genes affecting response to SE: Toll-like receptor 4 (TLR4), T-cell specific surface protein (CD28), Macrophage migration inhibitory factor (MIF), MD-2, and Lipid-induced TNF-á factor (LITAF). Gene fragments were sequenced from the founder lines of the resource population to identify genomic sequence variation. The LITAF and MIF genes were monomorphic for analyzed sequence. Single nucleotide polymorphisms (SNPs) were identified in three genes, TLR4, CD 28 and MD-2. These SNPs were used to test for association with SE. Linear mixed models were used for statistical analyses. Association analyses revealed effects of TLR4 for spleen count (P < 0.14). Varied and moderate association effects were also revealed for CD28 for spleen (P < 0.13), cecum (P < 0.003) SE bacterial load, and SE vaccine antibody response (P < 0.05). Study of MD-2 showed an association level of (P < 0.04) and (P < 0.10) on spleen and cecum SE bacterial load respectively. This is the first reported study on the association of SNPs in TLR4, CD28, and MD-2, using chicken response to SE. The use of these genes in marker assisted selection may result in substantial improvements to enhance disease resistance. (Key words: candidate gene, inbred line, Salmonella enteritidis, single nucleotide polymorphism)