Ighm^tm1Fbb

A single loxP site remained in place of a genomic fragment encompassing Igh-6 exons mu1 through mu4 and a portion of the intergenic region between Igh-6 and Igh-5 after the incorporation and subsequent excision of a floxed neo-HSV cassette. The intergenic region contained regulatory cis-elements of the Igh-5 locus. IgM (Igh-6) was undetected by flow cytometric analysis whereas levels of soluble IgD (Igh-5) were increased relative to wild-type. (J:57600)