Transcriptomic analysis of Ascaris suum larvae during their hepatopulmonary migration

Common roundworms are important intestinal nematodes of man (Ascaris lumbricoides) and pig (Ascaris suum). During the first stages of the infection, the larvae of these parasites undergo a hepatopulmonary migration. This migration is likely to require tightly regulated transcriptional changes in the parasite. We explored this aspect in Ascaris suum by characterizing the transcription profiles of infective L3s from eggs, liver- and lung-L3s and intestinal L4s by next generation sequencing approach. When the most abundant transcripts per life stage were investigated, results showed that in the egg-L3s, transcripts associated with the regulation of translation and transcription, mainly ribosomal proteins, were most abundant. From the liver-L3s onwards, high transcription levels were seen for cuticle collagens, indicating the growth of the larvae during their migration. Interestingly, the type of highly expressed cuticle collagens in the intestinal L4s differed with those present in the liver- and lung-L3s. Apart from collagens, potentially important molecules for host-parasite interaction like C-type lectin-4 and Mucin-5 were in the top 5 of most abundant transcripts in the lung-L3. Unfortunately, a great number of transcripts that are specific for certain larval stages did not show any homology to other proteins within the NCBI database, suggesting that many biologically interesting molecules from this parasite are still to be investigated

Comparison of Kato-Katz thick smear, Mini-FLOTAC, and Flukefinder for the detection and quantification of Fasciola hepatica eggs in artificially spiked human stool

We compared the diagnostic performance of the standard method (Kato-Katz) with two recently developed methods (Mini-FLOTAC and Flukefinder) for the detection and quantification of Fasciola hepatica eggs in human stool. Uninfected human stool samples were artificially spiked with F. hepatica eggs to reach final concentrations of 14, 28, 41, or 96 eggs per gram of stool (epg). Only Flukefinder showed 100% sensitivity in all but the samples with the lowest concentration of eggs (14 epg), in which it had a sensitivity of 60%. Each of the methods underestimated the true fecal egg counts (FECs), Flukefinder resulting in the most biased egg counts (egg counts 0.18 times lower than the expected FECs). Only the Flukefinder resulted in more precise results (coefficient of variance < 30%) from FECs of 96 epg onward. The outcome of this study indicates that the Flukefinder is a useful alternative diagnostic method for human fascioliasis in stool

A phosphorylcholine-containing glycolipid-like antigen present on the surface of infective stage larvae of Ascaris spp. is a major antibody target in infected pigs and humans

BACKGROUND: The pig parasite Ascaris suum plays and important role in veterinary medicine and represents a suitable model for A. lumbricoides, which infects over 800 million people. In pigs, continued exposure to Ascaris induces immunity at the level of the gut, protecting the host against migrating larvae. The objective of this study was to identify and characterize parasite antigens targeted by this local immune response that may be crucial for parasite invasion and establishment and to evaluate their protective and diagnostic potential. METHODOLOGY/PRINCIPAL FINDINGS: Pigs were immunized by trickle infection for 30 weeks, challenged with 2,000 eggs at week 32 and euthanized two weeks after challenge. At necropsy, there was a 100% reduction in worms recovered from the intestine and a 97.2% reduction in liver white spots in comparison with challenged non-immune control animals. Antibodies purified from the intestinal mucus or from the supernatant of cultured antibody secreting cells from mesenteric lymph nodes of immune pigs were used to probe L3 extracts to identify antibody targets. This resulted in the recognition of a 12kDa antigen (As12) that is actively shed from infective Ascaris L3. As12 was characterized as a phosphorylcholine-containing glycolipid-like antigen that is highly resistant to different enzymatic and chemical treatments. Vaccinating pigs with an As12 fraction did not induce protective immunity to challenge infection. However, serological analysis using sera or plasma from experimentally infected pigs or naturally infected humans demonstrated that the As12 ELISA was able to detect long-term exposure to Ascaris with a high diagnostic sensitivity (98.4% and 92%, respectively) and specificity (95.5% and 90.0%) in pigs and humans, respectively. CONCLUSIONS/SIGNIFICANCE: These findings show the presence of a highly stage specific, glycolipid-like component (As12) that is actively secreted by infectious Ascaris larvae and which acts as a major antibody target in infected humans and pigs

Study on the relationship between seroprevalence of Ascaris suum in fatteners, farm management factors and production parameters

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