A Cooperia punctata gene family encoding 14 kDa excretory–secretory antigens conserved for trichostrongyloid nematodes

Abstract

A polymorphic set of 14 kDa excretory-secretory (E-S) antigen-encoding cDNAs, with similarity to a previously characterized 15 kDa E-S antigen of Haemonchus contortus, was cloned from Cooperia punctata. Five cDNAs encoding predicted proteins of 70-80% identity were sequenced. Genomic analyses of individuals proved the existence of three 14 kDa E-S antigen-encoding genes, excluding that the differences reflected polymorphisms between individuals in a population. Southern blots indicated the presence of additional members of this gene family. Thus, despite the fact that heterologously expressed C. punctata 14 kDa E-S products are shown to be recognized by immune sera, potential pitfalls in the development of a recombinant vaccine are presented by this genetic diversity. Vaccine design could be further rationalized by knowledge of the function, and possible redundancy in function, of the E-S products which is presently lacking. The limitations encountered in assigning a function to the 14/15 kDa family of E-S proteins that is thus far unique to the trichostrongyloid nematodes are discussed.

Comprehensive Analysis of the Secreted Proteins of the Parasite Haemonchus contortus Reveals Extensive Sequence Variation and Differential Immune Recognition

“…N-linked oligosaccharides of H. contortus have different structures in comparison to the host (24) and have been shown to contribute to immune recognition (25). In combination with the presence of gene families, as has been demonstrated for an Hc15 homologue of the nematode Cooperia punctata (26), this has clear implications for vaccination trials.…”

“…A specific problem of helminth infections, which is also hard to address by this technique, is discrimination between variants of a protein derived from the same, but mutated, gene of different individuals and variants derived from expression of different members of a multigene family within an individual. Occurrence of the latter option has been demonstrated by RT-PCR experiments on members of protein families homologous to Hc15 and Hc24 in single C. punctata individuals (26,31), but current protein detection methods (even by specific monoclonals) preclude such experiments for single worms except for a few of the most abundant proteins.…”

In-Depth Proteomic and Glycomic Analysis of the Adult-Stage Cooperia oncophora Excretome/Secretome

“…The proteomic analysis also revealed a low molecular weight spot cluster mainly consisting of several variants of two low-molecular weight antigens, which have previously been employed in a diagnostic assay but whose true function(s) remain unclear. Apart from the homologues identified in the closely related parasite Cooperia punctata , so far this protein family has not been identified in any other nematode species. Why these proteins display such extensive diversity, as seen in their 2D-PAGE spot profile, remains unclear, although it has been hypothesized that this may create antigenic diversity and/or a set of redundant proteins, which may be eliminated through the host immune response without serious detrimental effects on parasite viability …”

“…Apart from the homologues identified in the closely related parasite Cooperia punctata , so far this protein family has not been identified in any other nematode species. Why these proteins display such extensive diversity, as seen in their 2D-PAGE spot profile, remains unclear, although it has been hypothesized that this may create antigenic diversity and/or a set of redundant proteins, which may be eliminated through the host immune response without serious detrimental effects on parasite viability …”

“…Why these proteins display such extensive diversity, as seen in their 2D-PAGE spot profile, remains unclear, although it has been hypothesized that this may create antigenic diversity and/or a set of redundant proteins, which may be eliminated through the host immune response without serious detrimental effects on parasite viability. 44 …”