THE GENE CODING FOR THE MAJOR SHEATH PROTEIN OF LITOMOSOIDES-CARINII MICROFILARIAE, GP22, IS TRANSCRIBED IN OOCYTES AND EMBRYONIC-CELLS

The transcription and translation of the gene encoding gp22, a major c onstituent of the microfilarial sheath of the filarial parasite Litomo soides carinii were studied by in situ hybridisation and immunohistolo gy. Transcription of the gp22 gene is confined to oocytes and embryos in the reproductive organs of adult female worms. It starts in oocytes in the rhachis zone, is maximal in multicellular embryos and decrease s slowly as the microfilariae develop. Blood microfilariae lack the gp 22 transcript. The gp22 gene product is first detectable in parasites recovered on day 32 post infection. Expression of gp22 begins in multi cellular embryos in the uteri of mature female worms and can be detect ed in all further developed intrauterine stages. The gp22 gene product appears to be exported by the embryonic cells and becomes integrated into the sheath where it may contribute to the flexibility of the latt er structure.