The intrinsic peritrophic matrix protein peritrophin-95 from larvae of Lucilia cuprina is synthesised in the cardia and regurgitated or excreted as ahighly immunogenic protein

The intrinsic peritrophic matrix glycoprotein, peritrophin-95, from the mid gut of larvae of Lucilia cuprina can only be solubilized from the matrix us ing strong denaturants. This suggests that the protein has a structural rol e in the matrix. Consistent with this is the finding that immune-gold and i mmune-fluorescence localizations of the protein showed a uniform distributi on within the peritrophic matrix. RT-PCR demonstrated that expression of pe ritrophin-95 mRNA was restricted to the larval cardia, a small organ locate d in the anterior midgut from which the type 2 peritrophic matrix originate s. Immune-blots and ELISAs demonstrated that the sera from sheep infested n aturally or artificially with these larvae recognised peritrophin-95. This indicates that peritrophin-95 stimulates the ovine immune system during lar val infestation even though the protein is firmly attached to the peritroph ic matrix in the larval midgut and seemingly "concealed" from the ovine imm une surveillance system. Analyses of larval regurgitated or excreted materi al by immune-blots, immune-affinity purification and amino-terminal sequenc ing demonstrated the presence of soluble monomeric peritrophin-95. These re sults indicate that peritrophin-95, a candidate vaccine antigen for use in sheep is not a "concealed" antigen as previously thought. The presence of s oluble peritrophin-95 in the regurgitated/excreted material from larvae sug gests that this protein may be involved in a maturation phase of peritrophi c matrix production, a by-product of which is the excretion or regurgitatio n of soluble peritrophin-95. (C) 2000 Elsevier Science Ltd. All rights rese rved.