R. Quinn

The effect of temperature and antimetabolites on antibody binding to the outer surface of second stage Toxocara canis larvae

In vitro maintained second stage Toxocara canis larvae do not bind antiserum raised to their excretions and secretions (ES) at 37 degrees C as detected by indirect fluorescence. However, when these larvae were incubated at 2 degrees C under the same conditions intense fluorescence on the whole outer surface was observed. This fluorescence remained as long as the larvae were maintained at 2 degrees C. When these larvae were reincubated at 37 degrees C a gradual loss of fluorescence along their outer surfaces occurred. This loss was complete after 3 h. Larvae which were preincubated in antimetabolites at 37 degrees C exhibited intense fluorescence on their outer surfaces as did those incubated at 2 degrees C with antimetabolites. It is concluded that antigens present in ES occur along the whole length of the larval outer surface and turn over at 37 degrees C. This turnover occurs along the whole outer surface and is metabolically dependent. Should this occur in vivo it could afford the parasite with a mechanism for evasion of the immune response.

Studies on the incidence of Toxocara and Toxascaris spp. ova in the environment. 1. A comparison of flotation procedures for recovering Toxocara spp. ova from soil

Seven different flotation fluids were assessed for their efficiency in recovering Toxocara canis ova from artificially seeded soil samples. Using the most efficient (a saturated solution of magnesium sulphate plus 5% potassium iodide) 25 g amounts of 234 environmental soil samples were examined for the presence of Toxocara spp. and Toxascaris ova. Twenty-six samples (11.1%) yielded ova of one or other species. There was no discernible pattern of distribution of positives with relation to the source of the samples. The maximum number of ova recovered in any one sample was 19. All the ova recovered from the environment were considered viable and potentially infective.

Preservation of fossil biopolymeric structures: Conclusive immunological evidence

Abstract Immunological assays are highly favoured for their ability to readily discriminate subtle structural differences in complex biopolymers, such as proteins and polysaccharides. Immunological reactions previously reported with extracts from biominerals at least 70 Myr old have fuelled hopes that such biopolymeric structures can survive the process of fossilization. We have raised antibodies against biopolymers from a range of Recent brachiopod shells to reconstruct a fine-grained pattern of phylogenetic relationships. Using the same antibodies, the phylogenetic affinities of fossil relatives were tested. Immunological reaction patterns for Plio-Pleistocene shells were essentially identical to the patterns of modern shells (although the breadth of reactivity was narrowed) and entirely consistent with current systematic interpretations. Older samples (>4–21 Myr) were immunologically reactive, but failed to satisfy the criterion of systematic specificity. Our results provide an unequivocal demonstration that original macromolecular structures capable of yielding systematic information are preserved and accessible for immunological analysis for at least two million years. Non-specific reactions observed with the older material may relate in part to formation of mineral-induced diagenetic determinants (MIDDs).

Sero‐taxonomy of skeletal macromolecules in living Terebratulid brachiopods

Antibodies prepared against macromolecules isolated from the shells of three living brachiopod genera have proved to be of considerable taxonomic significance, in that the pattern of cross‐reactivity of all three antisera consistently points to a new interpretation for the evolution of the largest extant brachiopod order, the Terebratulida. This new molecular evidence actually complements rather than contradicts the existing morphology‐based taxonomy, since detailed systematic investigation of the taxa in question has already demonstrated subtle but significant morphological differences in the major taxonomic characters which appear to reflect this new interpretation. As fragments of skeletal macromolecules, including antigenic determinants, are known to survive for many millions of years within the protected micro‐environments provided by enclosing biominerals, these results suggest that such molecular fossils could well provide important insights on at least the high‐level taxonomic relationships of fos...

A monoclonal antibody specific for the A antigen of Brucella spp.

Two murine monoclonal antibodies of the IgG3 class have been isolated after immunization with Brucella abortus. An indirect immunofluorescence test was used to screen hybridoma supernatants and subsequently to determine the cross-reactivity of the monoclonal antibodies with other bacteria. One monoclonal antibody reacted with all the smooth Brucella biotypes tried and with Yersinia enterocolitica serogroup 0:9, though not with rough Br. ovis or with strains of Escherichia, Proteus, Salmonella, Pseudomonas, Francisella and Bordetella. The other monoclonal antibody displayed a high degree of specificity for brucellae carrying the A lipopolysaccharide-protein surface antigen. The implications for the diagnosis of brucellosis are discussed.

Intracrystalline Molecules from Brachiopod Shells

Shells are composed of both organic and inorganic constituents. It is believed that the organic compounds have important functions at several stages during the formation of biominerals. In brachiopod shells the disposition of inorganic biominerals and their enclosing organic sheaths have been thoroughly investigated using both scanning and transmission electron microscopy but little is known about the biochemistry of the intracrystalline molecules i.e. those enclosed within the inorganic portion. Such information is crucial for an understanding of biominerals if, as has been suggested, these compounds (i) induce crystal nucleation by providing a surface for precipitation, (ii) form compartments that determine the shape and volume of the biocrystal and (iii) determine the pattern of growth in the mineral phase in what is termed ‘matrix mediated nuneralisation’ [1].

A paper radioimmunosorbent test (PRIST) for the detection of larva-specific antibodies to Toxocara canis in human sera.

A paper radioimmunosorbent test (PRIST) was shown to be sensitive and reproducible when used with excretory/secretory antigen of Toxocara canis second stage larvae. Whatman No. 50 filter paper (5 mm discs) gave the most consistent and clear results with antigen at a concentration of 100 micrograms/ml, and could be stored for up to 3 weeks in vacuo at -70 degrees C. Antigen coated discs were incubated with test sera at 1:10 dilution for 3 h at room temperature (21 degrees C), reacted with [125I]anti-human IgG for 1 h and counts determined in a gamma counter. Sera from patients with fascioliasis, taeniasis, schistosomiasis, oxyuriasis, trichinellosis and ancyclostomiasis gave counts similar to cord serum controls. Sera from patients with ascariasis gave counts of up to twice as great as controls, but sera from patients with toxicariasis produced counts of 7,000-13,000, a 4-6-fold increase.