Protection studies of an excretory–secretory protein HcABHD against Haemonchus contortus infection

Unlike the successful immunization of native H. contortus antigens that contributed to the realization of the first commercial vaccine Barbervax, not many studies revealed the encouraging protective efficacies of recombinant H. contortus antigens in laboratory trials or under field conditions. In our preliminary study, H. contortus α/β-hydrolase domain protein (HcABHD) was demonstrated to be an immunomodulatory excretory–secretory (ES) protein that interacts with goat T cells. We herein evaluated the protective capacities of two HcABHD preparations, recombinant HcABHD (rHcABHD) antigen and anti-rHcABHD IgG, against H. contortus challenge via active and passive immunization trials, respectively. Parasitological parameter, antibody responses, hematological pathology and cytokine profiling in unchallenged and challenged goats were monitored and determined throughout both trials. Subcutaneous administration of rHcABHD with Freund adjuvants elicited protective immune responses in challenged goats, diminishing cumulative fecal egg counts (FEC) and total worm burden by 54.0% and 74.2%, respectively, whereas passive immunization with anti-rHcABHD IgG conferred substantial protection to challenged goats by generating a 51.5% reduction of cumulative FEC and a 73.8% reduction of total worm burden. Additionally, comparable changes of mucosal IgA levels, circulating IgG levels, hemoglobin levels, and serum interleukin (IL)-4 and IL-17A levels were observed in rHcABHD protein/anti-rHcABHD IgG immunized goats in both trials. Taken together, the recombinant version of HcABHD might have further application under field conditions in protecting goats against H. contortus infection, and the integrated immunological pipeline of ES antigen identification, screening and characterization may provide new clues for further development of recombinant subunit vaccines to control H. contortus.

Praziquantel - chitosan nanoformulation against murine Schistosoma mansoni infection

The aim of the present work was to design praziquantel (PZQ) loaded chitosan nanoparticles (PZQ-Cs) to improve the oral bioavailability and overcome the drawbacks of conventional PZQ therapy. The synthesized chitosan nanoparticles (CsNPs) were physico-chemically characterized by TEM and dynamic light scattering (DLS) with the calculation of the encapsulation efficiency (EE). PZQ was loaded into CsNPs in three different doses; reduced dose (250 mg/kg), high dose (500 mg/kg) and fully effective dose (1000 mg/ kg). Infected treated groups received either oral PZQ-Cs or oral PZQ alone 42 days post-infection and were sacrificed 2 weeks post-treatment. The current study revealed that PZQ-Cs induced a significant anti-schistosomal effect, compared to the infected non-treated control. However, on comparison with conventional PZQ treatment at the corresponding doses, oral PZQ-Cs showed a lower anti-schistosomal potential as reflected by the total worm burden, tissue ova count and oogram pattern. PZQ-Cs was significantly effective in attenuating the oxidative insult associated with S. mansoni infection, compared to the infected non-treated and PZQ treated groups. Genotoxicity assessment proved the safety of CsNPs, as they did not induce a significant DNA fragmentation in non-infected mice treated with blank CsNPs. The present work highlights CsNPs as safe, effective anti-inflammatory and antioxidant agents that could find a clinical use in the treatment of schistosomiasis induced oxidative stress and hepatic dysfunction. Further studies are recommended, however, to investigate how PZQ-Cs could be further modified to increase its anti-schistosomal potential.

Therapeutic efficacy of a newly synthesized benzimidazole compound BTP-OH against murine schistosomiasis mansoni

Because of the increasingly emerging praziquantel resistance, there is a crucial need to develop new anti-schistosomal agents. This work was conducted to assess the therapeutic efficacy of a new benzimidazole compound (BTP-OH) in mice experimentally infected with Schistosoma mansoni. A total of 40 Swiss albino female mice were divided into an infected untreated group and three infected treated groups (using praziquantel and BTP-OH). The compound activity was evaluated through parasitological, histopathological and scanning electron microscopy studies. Praziquantel and BTP-OH at both doses significantly reduced male (75%, 42.67% and 61.08%, respectively), female (71.45%, 48.94% and 68.13%, respectively) and total worm burden (75.21%, 42.42% and 62.28%, respectively), as well as tissue egg load in the liver (71.22%, 42.12% and 66.04%, respectively). In oogram, praziquantel significantly increased the percentage of dead eggs (65.89%), while BTP-OH significantly reduced the percentage of immature eggs (30.43% and 19.64%). BTP-OH significantly diminished granuloma count (33.87% and 44.77%) and diameter (39.23% and 49.40%), and caused ultrastructural changes in the tegument of adult schistosomes. This study provides evidence for the schistosomicidal efficacy of BTP-OH. However, future studies are needed to elucidate the full mechanisms of action and effects of BTP-OH on other human schistosomes.

The impact of cinnarizine and griseofulvin on juvenile and adult stages of Schistosoma mansoni

Schistosomiasis affects millions globally. There is no vaccine, and treatment depends entirely on praziquantel (PZQ). Field isolates exhibit reduced susceptibility to PZQ, and resistance has been experimentally induced, suggesting that reliance on a single treatment is particularly dangerous. The present study investigated the value of cinnarizine and griseofulvin against Schistosoma mansoni through their in vitro effects on adult worms and oviposition as well as in vivo evaluation in early and late infection, compared to PZQ, in a preliminary experimental model. In vitro, both cinnarizine and griseofulvin showed uncoupling, sluggish worm movement and complete absence of ova at 100 μg/ml. In early infection, cinnarizine showed a significant reduction in the number of porto-mesenteric couples compared to the griseofulvin and control groups, a finding similar to PZQ. Remarkably, cinnarizine significantly exceeded PZQ and griseofulvin in reducing the total worm burden. In late infection, cinnarizine and griseofulvin showed results similar to PZQ by significantly reducing the numbers of hepatic and porto-mesenteric couples and total worm burden compared to controls. Cinnarizine performed better than griseofulvin by reducing hepatic and intestinal ovum counts, and it led to complete disappearance of the first two immature stages. The current work suggests the possibility of using cinnarizine and griseofulvin, mainly in late S. mansoni infection, especially cinnarizine, which showed similar results to PZQ and surpassed it in early infection. Further studies are required to elucidate their exact mechanisms of action and particularly their synergistic effect with PZQ.

Immunization with adult Schistosoma mansoni tegument, treated with sub-curative praziquantel, partially protects mice against the infection

The tegument of schistosomes is a source of many potential anti-Schistosoma vaccine molecules. This work aimed to assess the protective effects of the adult Schistosoma mansoni tegument treated (TT) with sub-curative praziquantel (PZQ), whether in vivo (in vivo TT) or in vitro (in vitro TT), in murine schistosomiasis. In vitro TT and in vivo TT showed great similarity, and they differed from untreated tegument antigen (Teg) in terms of quantity and quality of protein bands on SDS–PAGE. Two immunization trials were performed, each with 50 mice, divided randomly into five groups of 10 mice each: (1) uninfected control mice (UC), (2) infected mice given phosphate buffer saline + adjuvant (PBS + adjuvant), (3) infected, Teg vaccinated, (4) infected, in vivo TT vaccinated, and (5) infected, in vitro TT vaccinated. All the immunizations with antigens induced mixed Th1/Th2 immune responses, as indicated by significantly high (P < 0.001) specific IgG2a and IgG1 levels, with Th1 predominating, as shown by a diminished IgG1/IgG2a ratio, as well as a high serum concentration of IFN-γ, an absence of IL-4 and increased IL-10. In vitro TT gave the most pronounced response. With respect to reduction of total worm burden, relative to PBS + adjuvant mice, in vitro TT achieved the highest significant (P < 0.001) results, followed by in vivo TT and Teg (51.8–57.04%, 44.6–50.2% and 35.2–39.3%, respectively). In scanning electron microscopy studies, all the tested antigens caused tegumental changes in adult worms, with the worst occurring with in vitro TT, such as retracted ventral sucker, an effect on the gynaecophoric canal, and changes to tubercles. In conclusion, in vitro TT, which is cheap to prepare, could be a potential vaccine against S. mansoni.

In vitro and in vivo effects of hesperidin treatment on adult worms of Schistosoma mansoni

Hesperidin has been reported to exert a wide range of pharmacological effects, including antifungal, antiviral, antioxidant, anti-inflammatory and anticarcinogenic activities. Herein, the schistosomicidal activity of this compound was evaluated in vitro and in vivo. Using an in vitro assay, a concentration of 200 μg/ml of hesperidin resulted in the mortality of 100% adult worms of Schistosoma (S.) mansoni within 72 h and a partial tegumental alteration in 10% of worms. However, after 144 h incubation, 50 and 100 μg/ml concentrations showed 0% and 10% mortality in adult worms, respectively, without any changes to the tegument. Sublethal doses did not influence egg output nor the development of eggs deposited by pairs of adult worms. In an in vivo study, mice infected with S. mansoni and treated with 600 mg hesperidin/kg body weight showed a respective reduction of 50, 45.2, 50 and 47.5% of males, females, worm pairs and total worm burden. In addition, a respective reduction, based on the number of eggs/g tissue, of 41.5, 63.7 and 58.6% was observed in the liver, intestine and liver/intestinal tissue combined. Furthermore, S. mansoni-specific IgG level significantly increased with hesperidin treatment, whereas IgA and IgE levels were not significantly changed. IgM levels decreased in response to cercarial antigen preparation but were not altered in response to soluble worm or soluble egg antigen. As in hesperidin-treated mice, praziquantel-treated mice showed a similar pattern of specific antibody response to S. mansoni antigens. The present study represents the first report on the effects of the schistosomicidal activity of hesperidin.

In VivoActivity of Aryl Ozonides against Schistosoma Species

ABSTRACTWe evaluated thein vivoantischistosomal activities of 11 structurally diverse synthetic peroxides. Of all compounds tested, ozonide (1,2,4-trioxolane) OZ418 had the highest activity against adultSchistosoma mansoni, with total and female worm burden reductions of 80 and 90% (P< 0.05), respectively. Furthermore, treatment ofS. haematobium-infected mice with OZ418 reduced the total worm burden by 86%. In conclusion, OZ418 is a promising antischistosomal lead compound.

Effects of Haemonchus contortus infection on sodium status of sheep

Eight five-month-old male lambs received a diet with marginal levels of sodium (0.5 g Na/kg DM); four lambs were given a single dose of infective Haemonchus contortus larvae (4,600 L3/ head) and four were kept uninfected. The lambs were slaughtered 30 days after the infection. Sodium concentration was determined in the abomasal fluid at the slaughter. The balance between intake and faecal excretion of sodium was evaluated. Saliva was collected at days zero, 20 and 30 to determine the Na:K ratio. The mean total worm burden retrieved was 1390. The infection increased abomasal sodium concentration (p< 0.001) and reduced faecal sodium excretion (p<0.02), but there was not a significant relationship between worm burden and abomasal (p >0.082) or faecal sodium excretion (p>0.5). The higher the abomasum sodium concentration, the lower the faecal sodium excretion (p < 0.001). Apparent digestibility of sodium was similar between infected and uninfected. At the end of the experiment a slight decrease in the salivary Na:K ratio was observed, in animals of both groups, caused mostly by diet rather than the parasitism. It was concluded that although H. contortus infection increased the loss of sodium into the abomasum there was a greater compensatory intestinal absorption to prevent a significant change in the sodium status of sheep.

Effects of continuous intake of condensed tannins on parasitised sheep

Parasitised sheep consuming forages high in condensed tannins (CT) show lower faecal egg counts (FEC) and total worm burden (TWB) compared to those consuming CT free forages (Niezen et al., 1998). This may be due to an indirect effect of CT, through an increase in protein availability; extra protein could improve the host’s ability to mount an effective response towards gastrointestinal parasites, during the expression of the immunity (Coop and Kyriazakis, 1999). However, CT have been also shown to have a direct anthelmintic effect on adult Trichostrongylus colubriformis (intestinal nematode), when they were administered for a short period (Athanasiadou et al., 2000). The objectives of this experiment were i) to elucidate the effects of a continuous intake of CT during the development of a T.colubriformis infection and ii) to test whether these effects are dose dependent.