Reactivity of anti-tegument monoclonal antibodies with target epitopes in different worm tissues and developmental stages ofSchistosoma mansoni

Abstract

Sixteen monoclonal antibodies (MABs) were selected for their reactivity with adult schistosome tegument. The distribution of target epitopes in different tissues of the adult and in various developmental stages was investigated by indirect immunofluorescence. The distinct patterns of reactivity of the MABs permitted their classification into 9 groups. The distribution of epitopes in larvae, particularly 3 h schistosomula, generally mirrored that in adults. A change in distribution of epitopes coincided with transformation from cercaria to schistosomulum providing a marker for this process. Two MABs reacted with surface membranes of intact cercariae, and 5 with the surfaces of intact 3 h schistosomula. The target epitopes of these 5 MABs were present in the tegument of adults, but not accessible externally. These observations suggest masking of antigens, not shedding, in the course of development. Indeed, no MAB reacted with intact lung or liver worms unless they were damaged. Three MABs reacted with membranes of the tegument and most other tissues, implying properties in common. Evidence for shared functions between epithelia was provided by the reactivity of 2 MABs with the tegument and protonephridia. Eight MABs bound both to the tegument and its cell bodies. Since the latter contains the machinery for protein synthesis, it is difficult to explain why 5 MABs bound to the tegument alone. Little cross-reactivity was found with the tissues of the tapeworm Hymenolepis, rather more with the closely related Schistosoma japonicum. It was concluded that tegument antigens are to a degree tissue specific but definitely not stage specific.

Schistosoma mansoni: immunolocalization of two different fucose-containing carbohydrate epitopes

“…Several studies have been conducted to localize antigenic epitopes in adult worms (Deelder et al 1985;de Water, Fransen & Deelder, 1986;Yi et al 1986;Koster, 1987;Gregoire et al 1987;Koster & Strand, 1989;Riengrojpitak et al 1989;Linder, Thors & Lundin, 1991). Only a-carbohydrate mAbs 1.G1 (Gregoire et al 1987) and 2C1 (Koster & Strand, 1989) reacted with the structures recognized by mAb 128C3/3, e.g.…”

The schistosome in the mammalian host: understanding the mechanisms of adaptation

“…14, 18, 19, 22 and 24 kDa antigens). Monoclonal antibodies made against the tegumental antigens showed some cross-reactivity with other tissues, such as the protonephridial (excretory) system (Riengrojpitak et al 1989), indicating excretory antigens may be released from both the surface membrane and the latter system. This possibility must be examined further by molecular techniques, for example, by whole mount in situ hybridization.…”

Schistosoma mansoni host-exposed surface antigens characterized by sera and recombinant antibodies from schistosomiasis-resistant rats

“…Proposed strategies include minimizing protein exposure at the surface, antigen masking with host antigens, epitope concealment by poorly immunogenic carbohydrates, poor immunogenicity of exposed antigens, induction of blocking antibodies, secretion of a variety of immune modulators and rapid tegument turnover. The inability to identify anti-tegument monoclonal antibodies (mAbs) that recognize epitopes exposed on living juvenile or adult worms (Riengrojpitak et al, 1989) has limited studies on immune evasion and highlighted the effectiveness of the parasites’ immune evasion capability. The unique heptalaminate outer tegumental membrane itself may be an adaptation of blood-dwelling trematodes that resists host immune effectors such as complement and antibody-dependent cell-mediated cytotoxicity (ADCC) (Threadgold, 1984; Capron et al, 1987: Skelly, 2004).…”