High-resolution Genetic and Physical Map of theLgn1Interval in C57BL/6J ImplicatesNaip2orNaip5inLegionella pneumophilaPathogenesis

Prior genetic and physical mapping has shown that the Naip gene cluster on mouse chromosome 13D1-D3 contains a gene, Lgn1 , that is responsible for determining the permissivity of ex vivo macrophages to Legionella pneumophila replication. We have identified differences in the structure of the Naip array among commonly used inbred mouse strains, although these gross structural differences do not correlate with differences in L. pneumophila permissiveness. A physical map of the region employing clones of the C57BL/6J haplotype confirms that there are fewer copies of Naip in this strain than are in the physical map of the 129 haplotype. We have also refined the genetic location of Lgn1 , leaving only Naip2 and Naip5 as candidates for Lgn1 . Our genetic map suggests the presence of two hotspots of recombination within the Naip array, indicating that the 3′ portion of Naip may be involved in the genomic instability at this locus. [The sequence data described in this paper have been submitted to the GenBank data library under accession nos. AF240489 – AF240530 .]