Surface antigens ofLitomosoides cariniimicrofilariae: agglutinating antibodies react with sheath components of 40 and 120 kiloDalton molecular mass

Abstract

This study was conducted to identify surface antigens of the microfilarial sheath of Litomosoides carinii which are accessible to antibodies. Rabbit antisera were raised against the soluble and insoluble fractions of purified sheaths by extracting them with a buffer containing 2-mercaptoethanol and sodium dodecylsulphate. These sera and rabbit hyperimmune sera directed against homogenates of total microfilariae, mature (i.e. microfilariae liberating) female parasites and excretory-secretory products of adult females were able to agglutinate live and formaldehyde-fixed microfilariae. When the antisera directed against sheath constituents were administered to patently infected Mastomys coucha, the microfilaraemia of these animals was rapidly reduced and remained low for a period of 2-3 weeks. Antibodies specifically binding to the microfilarial surface were immunoaffinity-purified on formaldehyde-fixed microfilariae. The antibodies react with sheath antigens of 40 and 120 kDa molecular mass which are produced by the epithelium of the distal uterus of the mature female, secreted and attached to the surface of the sheaths. A 120 kDa antigen recognized by anti-sheath surface antibodies was also detected in the excretory-secretory products of in vitro-cultured immature female L. carinii from day 30 post-infection onwards. In the excretory-secretory products of mature adult female parasites recovered on day 130 post-infection, this 120 kDa molecule was absent. However, material reacting with the antibody was detected in the stacking gel of SDS-polyacrylamide gels. This finding may indicate that the basic units forming the 120 kDa antigen of immature adults or microfilarial sheath surface antigens occur in a highly polymerized form in the excretory-secretory products of mature female parasites.

Cloning and Expression Analysis of Two Mucin-like Genes Encoding Microfilarial Sheath Surface Proteins of the Parasitic Nematodes Brugia and Litomosoides

“…where the vagina and distal uterus contain elongated microfilariae) but not from extracts of the remaining portions of the uterus. In cross-sections of the parasites, antibody binding was selectively localized to the uterine epithelium of corresponding segments (6). Further support to a strictly localized expression of shp3 and shp3a is demonstrated in the present paper by the selective binding of DMAE-reactive antibodies to the sheath of elongated (mature) microfilariae and its failure to react with any younger developmental stage.…”

“…Thus, it seems to play an important role in the immune evasion strategy of the larvae, which at least temporarily guarantees their survival in the host. In our previous studies we identified and isolated two abundant sheath surface proteins of the L. sigmodontis microfilarial sheath (40 and 120 kDa), determined their amino acid compositions, and obtained partial polypeptide sequences from proteolytic fragments (3,6,15). This sequence information was used in this study to amplify the corresponding cDNAs followed by the isolation of both Litomosoides genes, Ls-shp3a and Lsshp3, and the orthologous genes from the lymphatic filariae B. malayi and B. pahangi.…”

“…The cotton rat filaria Litomosoides sigmodontis represents a suitable model organism for the lymphatics dwelling filarial parasites because of, in principle, a corresponding structure and genesis of the sheath (5). Previous studies with this parasite had identified two sheath proteins: Ls-Shp3a and Ls-Shp3 (40 and 120 kDa on SDS-PAGE) that appeared to represent the major sheath surface components of L. sigmodontis (6). As a particular property they turned out to be highly modified by dimethylaminoethanol (DMAE), 1 a new and unusual modification constituent (7).…”

Immunological Analysis of Agglutination in Dirofilaria immitis Microfilariae.

“…Agglutination of microfilariae is known in the parasitism of many different filarial species including D. immitis [8,10], Loa loa [6,7], Litomosoides carinii [9], Wuchereria bancrofti [5,11] and Brugia pahangi [10]. This phenomenon is utilized for a diagnostic examination of a host suspected of filarial infection [8,10].…”

DoesLitomosoides sigmodontissynthesize dimethylethanolamine from choline?

“…Specifically, this molecule was secreted into culture medium by juvenile but not fully mature female worms (Harnett et al 1986). Subsequently called Juv-120 (Hintz et al 1998), the molecule was also found to be present on the surface of the microfilaria sheath having been attached in the terminal part of the uterus following synthesis by maternal cells (Schares et al 1994). Further work indicated that Juv-p120 was also secreted by L. sigmodontis in vivo (Hintz et al 1998).…”