Differential display analysis of gene expression during the induction of mucosal immunity

One approach to understanding the physiologically relevant events during th e induction of an immune response is to identify genes that are expressed w hen the immune system first encounters antigen. Such an investigation requi res a naive but fully functional immune system, and the fetal lamb provides these conditions during the last trimester of gestation. 'Intestinal segme nts,' containing a jejunal Peyer's patch, were surgically prepared in fetal lambs (>120 days gestation) and individual 'intestinal segments' were inje cted with either culture medium or infectious bovine rotavirus. Peyer's pat ch tissue was collected 18 h postinfection. Histology and virus culture con firmed that bovine rotavirus had infected the mucosal epithelium. RNA was e xtracted from jejunal Peyer's patch tissue and mRNA differential display wa s used to identify genes expressed following rotavirus infection. Ten cDNAs were identified by differential display and these cDNAs were isolated, clo ned, and sequenced. One of the cDNAs sequenced, displayed homology to the g one encoding the sperm surface protein Sp17. Differential expression of thi s gene in antigen-exposed jejunal Peyer's patches was confirmed by Northern blot and RT-PCR. The complete sequence for sheep Sp17 mRNA was obtained fr om a lambda cDNA library, prepared from the jejunal Peyer's patch of a youn g lamb, Sp17 expression was detected by RT-PCR in a variety of mucosa-assoc iated lymphoid tissues but not in primary or other secondary lymphoid tissu es, Thus, the fetal lamb model may be appropriate for identifying genes rel evant to mucosal immunity.