Worm Breeder's Gazette 14(1): 86 (October 1, 1995)
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
Dept Biology, McGill University H3A 1B1 PQ Canada
Upstream of the unc-24 gene on IV is what appears to be a gene which could encode a protein with significant similarity to a protein from the parasitic nematode Onchocerca volvulus, the causative agent of onchocerciasis, or river-blindness. In this parasitic disease, blindness arises from damage to both the anterior and posterior segments of the eye. The etiology of the posterior segment disease has autoimmune qualities. That is, it appears as if the pathogen evades host responses in general by mimicking host antigens; this hyporesponsiveness can fail, and when it does a cross-reaction with a host antigen of the posterior segment of the eye appears to occur. There is an Onchocerca protein that is a strong candidate to contain an epitope implicated in this pathophysiology. Antibodies against this 22K protein, Ov39, cross-react with a 44K antigen located in human and bovine retinal pigment epithelial cells, and innoculation of Lewis rats with bacterially-produced parasite antigen efficiently induces eye damage, to cite just some of the data. This is the protein to which the proposed gene upstream of unc-24 bears similarity, and we suggest the name ora-1 for onchocerciasis-related antigen. 32P mutagenesis (or more accurately phosphate-decay mutagenesis) frequently produces small deletions, and indeed, the pdi allele of unc-24, e927, is a small deletion. We describe this here because it deletes ora-1. We have therefore renamed this allele qmDf1. However, qmDf1 homozygotes in the dissecting scope appear just like other unc-24 homozygotes. We have also identified a second C. elegans member of this family from Consortium sequence, found on cosmid F40E10, and for which we propose the name ora-2. Thus either ora-1 mutants have a subtle phenotype, or there is some redundancy between ora-1 and ora-2. Ov39 (no more similar to either ORA-1 or ORA-2) is expressed in the hypodermis and the somatic gonad in adult Onchocerca, and also in muscle cells in microfilariae (ie dauer equivalents). We would be interested in hearing from anybody who wants to pursue the further characterization of ora-1.