Epithelial STAT6 O-GlcNAcylation drives a concerted anti-helminth alarmin response dependent on tuft cell hyperplasia and Gasdermin C

The epithelium is an integral component of mucosal barrier and host immunity. Following helminth infection, the intestinal epithelial cells secrete "alarmin" cytokines, such as interleukin-25 (IL-25) and IL-33, to initiate the type 2 immune responses for helminth expulsion and tolerance. However, it is unknown how helminth infection and the resulting cytokine milieu drive epithelial remodeling and orchestrate alarmin secretion. Here, we report that epithelial O-linked N-Acetylglucosamine (O-GlcNAc) protein modification was induced upon helminth infections. By modifying and activating the transcription factor STAT6, O-GlcNAc transferase promoted the transcription of lineage-defining Pou2f3 in tuft cell differentiation and IL-25 production. Meanwhile, STAT6 O-GlcNAcylation activated the expression of Gsdmc family genes. The membrane pore formed by GSDMC facilitated the unconventional secretion of IL-33. GSDMC-mediated IL-33 secretion was indispensable for effective anti-helminth immunity and contributed to induced intestinal inflammation. Protein O-GlcNAcylation can be harnessed for future treatment of type 2 inflammation-associated human diseases.

Effect of heterogeneous mixing and vaccination on the dynamics of anthelmintic resistance: a nested model

Anthelmintic resistance is a major threat to current measures for helminth control in humans and animals. The introduction of anthelmintic vaccines, as a complement to or replacement for drug treatments, has been advocated as a preventive measure. Here, a computer-based simulation, tracking the dynamics of hosts, parasites and parasite-genes, shows that, depending on the degree of host-population mixing, the frequency of totally recessive autosomes associated with anthelmintic resistance can follow either a fast dynamical regime with a low equilibrium point or a slow dynamical regime with a high equilibrium point. For fully dominant autosomes, only one regime is predicted. The effectiveness of anthelminthic vaccines against resistance is shown to be strongly influenced by the underlying dynamics of resistant autosomes. Vaccines targeting adult parasites, by decreasing helminth fecundity or lifespan, are predicted to be more effective than vaccines targeting parasite larvae, by decreasing host susceptibility to infection, in reducing the spread of resistance. These results may inform new strategies to prevent, monitor and control the spread of anthelmintic resistance, including the development of viable anthelmintic vaccines.

Synergistic action of praziquantel and host specific immune response against Schistosoma mansoni at different phases of infection

The interaction between specific immune response to Schistosoma mansoni and praziquantel (PZQ) was studied in mice. In mice harboring concomitant immunity, 6-day-old parasites treated with PZQ were more effectively removed than 24 h treated parasites despite both had a significant worm burden reduction when compared with respective treated controls. These results show that PZQ can be effective at the skin and lung stages of parasite's development mainly acting with a established specific immune response, and particularly at the lung phase.

Porcine antibody responses to taenia solium antigens rGp50 and sTs18var1

Cysticercosis, a disease caused by the larval form of Taenia solium, is diagnosed by detection of specific antibodies or by imaging techniques. Our preferred immunologic assay for cysticercosis is the enzyme-linked immunoelectrodifusion transfer blot, or immunoblot, using the lentil lectin bound antigens from larval cysts. Antibody reactivity with any one of seven glycoproteins is diagnostic for cysticercosis. To develop a simple antibody detection assay for field use, we have synthesized an 8-kD diagnostic antigen, sTs18var1 (a secreted protein with a mature size of 67 amino acids), and expressed a 50-kD membrane protein antigen, rGp50. We used these two diagnostic proteins in a quantitative Falcon assay screening test-enzyme-linked immunosorbent assay (FAST-ELISA) to measure the antibody responses in Peruvian pigs with cysticercosis. Three study designs were used. First, we followed the kinetics of antibody responses against these two diagnostic proteins in pigs with cysticercosis that were treated with oxfendazole. Second, we measured antibody response in naive experimentally infected pigs. Third, we followed the maternal antibodies against rGp50 and sTs18var1 in piglets born from sows with cysticercosis. These studies showed that antibody responses against the two diagnostic proteins in the FAST-ELISA are quantitatively correlated with infection by viable cysts, with anti-sTs18var1 activity being most responsive to the status of infection.

Antibody isotype responses to Schistosoma japonicum antigens in subjects from a schistosomiasis area with repeated praziquantel chemotherapy compared with a new endemic zone in Hunan Province, P.R. China

To demonstrate the dynamics of specific antibody isotypes against schistosome adult worm (AWA) and soluble egg (SEA) antigens, we evaluated (in 1999-2000) 112 subjects infected with Schistosoma japonicum from 2 regions of Hunan Province, China. Fifty-eight subjects were from Area A, a well-known endemic area with repeated chemotherapy. Area B (n = 54) is a new endemic focus in another part of the same province. Serum samples were collected prior to praziquantel (PZQ) chemotherapy, and at 2 and 12 months post-treatment. IgM, IgA, IgG, IgG2, IgG4 and IgE antibodies to AWA and SEA were measured by quantitative enzyme-linked immunosorbent assay (ELISA). Pre-treatment antibody isotype levels from Area A, except IgA against AWA and SEA, were significantly higher than those from Area B. In response to chemotherapy, most antibody isotype levels fell or remained stable. However, in Area A there was a significant increase in the IgA, IgE and IgG4 responses to AWA 2 months after PZQ--which fell to approach pre-treatment levels by 12 months. A similar response was seen in Area B with IgE and IgG4 to AWA. Levels of all AWA-specific IgE and IgG4 were significantly higher in subjects from Area A compared with Area B at all time-points. AWA-IgE levels demonstrated significant linear correlations with age and number of previous PZQ treatments in Area A only. All SEA-specific isotypes in both areas fell significantly in response to treatment--except IgE, which remained stable in both area. All SEA-specific isotype levels (except IgA) were significantly higher from Area A at baseline. This significant difference was maintained through 12-months follow-up for IgE, IgG2 and IgG4 only. This study suggests that multiple episodes of schistosome infection may be required to generate antibody isotype levels that have been associated with resistance to re-infection in other studies. Further, a surrogate marker of successful chemotherapy (AWA-IgG4) performed less effectively in patients with previous treatment courses.

Effects of previous suppressive anthelmintic treatments on subsequent nematode infection in fattening cattle in Argentina

The effect of previous suppressive anthelmintic treatments after weaning on parasitological parameters and weight gain of cattle was studied in the Pampeana region of Argentina. The study was carried out at two grazing fattening periods: April 1995/July 1996 and April 1997/July 1998. During both periods, 60 weaned calves that grazed contaminated pastures, were divided into three groups during the first part of the periods: GY1 group was treated every 2 weeks with doramectin while GY2 and GY3 groups remained untreated. During the second part of the periods, from October onwards GY1 and GY2 remained untreated and GY3 was treated every 2 weeks. In this second period two new groups of 20 weaning young calves were added: TG (treated every 2 weeks) and UG (untreated). Egg counts (EPG), larval cultures, pasture larval counts, serum pepsinogen (Pep) and live weight gain (LWG) were recorded monthly. Ostertagia, Cooperia, Trichostrongylus and Haemonchus were the predominant genera. Despite low levels of previous infection during the first part of the period, slight differences of EPG between GY1 (P<0.09) or UG (P<0.05) and GY2 were detected in the second part of the fattening period in 1995/1996. In 1997/1998 moderate infection levels during the first part of the period were observed. During the second part of this period, GY1 and UG showed higher (P<0.001) EPG than GY2, and only GY3 and TG had (P<0.05) lower Pep levels. Also, during the second part of 1997/1998, LWG responses of GY3 were higher (P<0.001) than those of GY1 and GY2. Live weight gain of GY2 exceeded GY1 by 10.7kg (P<0.006). Higher EPG and lower LWG of GY1 suggest that suppressive treatments negatively affected the level of resistance to infection of yearlings, but these effects were influenced by previous levels of nematode infection. The lack of differences between yearling (GY1) and calves (UG) groups suggest that, under the conditions of this study, there was no evidence that resistance to infection and the related parameters are influenced by the age.

Detection of unwanted residues of ivermectin in bovine milk by dissociation-enhanced lanthanide fluoroimmunoassay

Avermectins are frequently used to control parasitic infestations in many animal species. Previous studies have shown the long-term persistence of unwanted residues of these drugs in animal tissues and fluids. An immunoassay screening test for the detection and quantification of ivermectin residues in bovine milk has been developed. After an extensive extraction procedure, milk samples were applied to a competitive dissociation-enhanced lanthanide fluoroimmunoassay using a monoclonal antibody against an ivermectin-transferrin conjugate. The monoclonal antibody, raised in Balb C mice, showed cross-reactivity with eprinomectin (92%), abamectin (82%) and doramectin (16%). The limit of detection of the assay (mean + 3 SD), calculated from the analysis of 17 known negative samples, was calculated as 4.6 ng/mL. Intra- and inter-assay RSDs were determined as 11.6% and 15.8%, respectively, using a negative bovine milk sample fortified with 25 ng/mL ivermectin. Six Friesian milking cows were treated with ivermectin, three with a pour-on formulation of the drug and three with an injectable solution at the manufacturer's recommended dose rate. An initial mean peak in ivermectin residue concentration was detected at day 4 (mean level = 47.5 ng/mL) and day 5 post-treatment (mean level = 26.4 ng/mL) with the injectable form and pour-on treatment, respectively. A second peak in residue concentration was observed using the DELFIA procedure 28 days post-treatment in both treatment groups (23.1 ng/mL injectable and 51.9 ng/mL pour-on). These second peaks were not confirmed by HPLC and must at this time be considered to be false-positive results. By day 35 after treatment the mean ivermectin residue concentration of both groups fell below the limit of detection of the assay.

Induction of protective immunity to Dictyocaulus viviparus in calves while under treatment with endectocides

Three groups of five parasite-naive calves were used. The treatments were: (a) Group 1 calves were weighed on Day 0 and injected with doramectin at 200 microg/kg. From Day 1 to 19 they were dosed orally with 2000 infective larvae of Dictyocaulus viviparus. On Day 28 they were again injected with doramectin, and infected with D. viviparus larvae from Days 33 to 41. They were then left untreated until Day 81 when they were infected with 20 infective larvae of D. viviparus per kg body weight. They were killed on Day 110 and lungworms were counted; (b) Group 2 calves were immunised with oral lungworm vaccine on Days 0 and 28, and infected and slaughtered as Group 1 on Days 81 and 110, respectively; (c) Group 3 calves acted as infection controls. Blood samples were taken at Days 0, 21, 49, 77 and 110 for antibody tests to D. viviparus. At autopsy there were no significant differences between the number of lungworms from Groups 1 and 2 (Means 17.4 and 31.3, respectively); Group 1 had significantly less value than Group 3 (Mean 228) (p < 0.05). Increased antibody titres to the larval sheath of the infective larvae were observed from Groups 1 and 2, showing that the larvae in Group 1 had penetrated the intestine before being killed by the circulating anthelmintic. This experiment shows that if calves are exposed to infective larvae while under systemic endectocide cover, an immune reaction is stimulated.

Anti-Dirofilaria immitis antibody levels before and after anthelmintic treatment of experimentally infected dogs

Antibody to Dirofilaria immitis was measured in 6 dogs before and after treatment with thiacetarsamide. Antibody to microfilarial surface antigens was ascertained with an indirect fluorescent antibody assay (IFA). Various patterns of the production, or presence, of antibody to microfilarial surface antigens were observed. There was no apparent relationship between IFA results and adulticide success. Antibody to adult worm antigen was measured with an enzyme-linked immunosorbent assay (ELISA). ELISA titers increased following infection and decreased transiently at the end of the prepatent period. A marked increase in ELISA titers was noted in all dogs subsequent to an initial thiacetarsamide treatment. In general, ELISA titers returned to low levels in dogs which were successfully treated; however, in dogs with persistent infections or infections which apparently necessitated 2 adulticide treatments ELISA titers remained at pre-treatment levels during the period of observation. Since ELISA titers appeared to decrease to pre-infection levels in successfully treated dogs, the assay should have utility in subsequent antibody determinations and may permit retrospective prediction of chemotherapeutic success.