Schistosoma mansoni: penetration apparatus and epidermis of the miracidium

Free swimming miracidia of Schistosoma mansoni were studied with the electron microscope for the purpose of describing the penetration apparatus and the epidermis. The penetration apparatus was composed of 3 unicellular glands which contain membrane-bound vesicles containing macromolecular diglycols. Each gland contained a nucleus, rough endoplasmic reticulum, Golgi complexes, numerous mitochondria, and glycogen stores. Each gland cell opened to the exterior through the apical papilla.The surface of the miracidium, with the exception of the apical papilla, was covered with ciliated epidermal cells containing numerous mitochondria, membranous bodies, and glycogen. No nuclei were detected within these epidermal cells. Intercellular ridges connecting with subepidermal cytons interrupted the epidermal cells at numerous points. The ridges were joined to the epidermal cells by septate desmosomes. Beneath the epidermal cells were found circular and longitudinal muscle bundles.Sensory structures of various types were associated with the outer covering. These consisted of (1) numerous “knob-like” cytoplasmic projections associated with epidermal cells, (2) bulbous, lamelloid structures with external cytoplasmic projections, and (3) ciliated nerve endings with posterior epidermal tiers and ciliated nerve pits associated with apical papilla.     

Synthesis and evaluation of in vitro antioxidant capacities of some benzimidazole derivatives

New, except 1d, melatonin analogue benzimidazole derivatives were synthesized and characterized in the present study. The potential role of melatonin as an antioxidant by scavenging and detoxifying ROS raised the possibility that compounds that are analogous to melatonin can also be used for their antioxidant properties. Therefore the antioxidant effects of the newly synthesized compounds were investigated in vitro by means of their inhibitory effect on hydrogen peroxide-induced erythrocyte membrane lipid peroxidation (EMLP) and on various erythrocyte antioxidant enzymes viz. superoxide dismutase (SOD), catalase (CAT) and glucose-6-phosphate dehydrogenase (G6PD). The synthesized benzimidazole derivatives showed remarkable antioxidant activity in vitro in the H₂O₂-induced EMLP system. Furthermore their effects on various antioxidant enzymes are discussed and evaluated from the perspective of structure- activity relationships.     

Local host ant specificity of Phengaris (Maculinea) teleius butterfly,an obligatory social parasite of Myrmica ants

1. Phengaris butterflies are obligatory social parasites of Myrmica ants. Early research suggested that there is a different Myrmica host species for each of the five European Phengaris social parasites, but more recent studies have shown that this was an oversimplification. 2. The pattern of host ant specificity within a Phengaris teleius metapopulation from southern Poland is reported. A combination of studying the frequency distribution of Phengaris occurrence and morphometrics on adult butterflies were used to test whether use of different host species is reflected in larval development. 3. Phengaris teleius larvae were found to survive in colonies of four Myrmica species: M. scabrinodis, M. rubra, M. ruginodis, and M. rugulosa. Myrmica scabrinodis was the most abundant species under the host plant but the percentage of infested nests was similar to other host ant species at two sites and lower in comparison to nests of M. rubra and M. ruginodis at the other two sites. Morphometric measurements of adult butterflies reared by wild colonies of M. scabrinodis and M. ruginodis showed that wing size and number of wing spots were slightly greater for adults eclosing from nests of M. ruginodis. 4. Our results suggest that P. teleius in the populations studied is less specialised than previously suggested. The results are consistent with the hypothesis that P. teleius is expected to be the least specific of the European Phengaris species, as it has the largest and best defended fourth‐instar caterpillars and, as a predatory species, it spends less time in the central larval chambers of the host colonies. The fact that individuals reared by M. ruginodis had wider hind wings may suggest that P. teleius had better access to resources in M. ruginodis than in M. scabrinodis colonies.     

Disease-associated glycosylated molecular variants of human C-reactive protein activate complement-mediated hemolysis of erythrocytes in tuberculosis and Indian visceral leishmaniasis

Human C-reactive protein (CRP), as a mediator of innate immunity, removed damaged cells by activating the classical complement pathway. Previous studies have successfully demonstrated that CRPs are differentially induced as glycosylated molecular variants in certain pathological conditions. Affinity-purified CRPs from two most prevalent diseases in India viz. tuberculosis (TB) and visceral leishmaniasis (VL) have differential glycosylation in their sugar composition and linkages. As anemia is a common manifestation in TB and VL, we assessed the contributory role of glycosylated CRPs to influence hemolysis via CRP-complement-pathway as compared to healthy control subjects. Accordingly, the specific binding of glycosylated CRPs with erythrocytes was established by flow-cytometry and ELISA. Significantly, deglycosylated CRPs showed a 7–8-fold reduced binding with erythrocytes confirming the role of glycosylated moieties. Scatchard analysis revealed striking differences in the apparent binding constants (10⁴–10⁵ M⁻¹) and number of binding sites (10⁶–10⁷sites/erythrocyte) for CRP on patients’ erythrocytes as compared to normal. Western blotting along with immunoprecipitation analysis revealed the presence of distinct molecular determinants on TB and VL erythrocytes specific to disease-associated CRP. Increased fragility, hydrophobicity and decreased rigidity of diseased-erythrocytes upon binding with glycosylated CRP suggested membrane damage. Finally, the erythrocyte-CRP binding was shown to activate the CRP-complement-cascade causing hemolysis, even at physiological concentration of CRP (10 μg/ml). Thus, it may be postulated that CRP have a protective role towards the clearance of damaged-erythrocytes in these two diseases.     

Host Immune Response to Mosquito-Transmitted Chikungunya Virus Differs from That Elicited by Needle Inoculated Virus

Background

Mosquito-borne diseases are a worldwide public health threat. Mosquitoes transmit viruses or parasites during feeding, along with salivary proteins that modulate host responses to facilitate both blood feeding and pathogen transmission. Understanding these earliest events in mosquito transmission of arboviruses by mosquitoes is essential for development and assessment of rational vaccine and treatment strategies. In this report, we compared host immune responses to chikungunya virus (CHIKV) transmission by (1) mosquito bite, or (2) by needle inoculation.

Methods and Findings

Differential cytokine expression was measured using quantitative real-time RT-PCR, at sites of uninfected mosquito bites, CHIKV-infected mosquito bites, and needle-inoculated CHIKV. Both uninfected and CHIKV infected mosquitoes polarized host cytokine response to a T_H2 profile. Compared to uninfected mosquito bites, expression of IL-4 induced by CHIKV-infected mosquitoes were 150 fold and 527.1 fold higher at 3 hours post feeding (hpf) and 6 hpf, respectively. A significant suppression of T_H1 cytokines and TLR-3 was also observed. These significant differences may result from variation in the composition of uninfected and CHIKV-infected mosquito saliva. Needle injected CHIKV induced a robust interferon-γ, no detectable IL-4, and a significant up-regulation of TLR-3.

Conclusions

This report describes the first analysis of cutaneous cytokines in mice bitten by CHIKV–infected mosquitoes. Our data demonstrate contrasting immune activation in the response to CHIKV infection by mosquito bite or needle inoculation. The significant role of mosquito saliva in these earliest events of CHIKV transmission and infection are highlighted.     

Acquisition and expression of resistance by Bos indicus and Bos indicus X Bos taurus calves to Amblyomma americanum infestation

Purebred and crossbred Bos indicus calves were infested 1, 2, or 3 times with 10 female and 5 male Amblyomma americanum. Resistance was acquired by both the purebred and the crossbred calves after 1 infestation and resulted in statistically significant decreases in the percentages of females that engorged, the mean weights of engorged females, and the mean weights of egg masses. Comparisons between breeds of the percent of female ticks that engorged during the first and second infestations indicate that purebred B. indicus expressed a stronger acquired resistance to A. americanum more readily than did crossbred animals. However, calves of both genetic compositions displayed similar levels of resistance during a third exposure. All tick-exposed and control animals were skin tested with salivary gland extracts of A. americanum, A. cajennense and Dermacentor andersoni. Control, uninfested calves, did not display significant cutaneous reactivity to these extracts. All calves that had been infested had immediate, 30-min, 5-hr and delayed, 24-hr, skin reactions to Amblyomma species antigens. Reactions to D. andersoni salivary antigens in tests of both purebred and crossbred calves with acquired resistance to A. americanum suggest that Amblyomma species salivary gland antigens might have cross reactive moieties with a salivary extract prepared from D. andersoni. Peripheral blood lymphocyte in vitro responsiveness to Amblyomma species antigens was detected in purebred calves after a first, second, and third infestation, indicating the presence of cells of the immune system capable of recognizing and undergoing blast transformation in response to tick salivary components.(ABSTRACT TRUNCATED AT 250 WORDS)     

Dot-ELISA assessment of guinea pig antibody responses to repeated Dermacentor andersoni infestations

Acquired resistance to ixodid tick infestation is expressed by cattle and laboratory animals. Humoral factors appear to be involved in host acquired resistance to tick bite; however, specific immune responses have yet to be fully characterized. This study examined tick resistance expressed by Hartley guinea pigs upon repeated infestation with Dermacentor andersoni, and describes longitudinal development of antigen specific immunoglobulin over approximately 180 days. Guinea pigs were infested either 4 times with D. andersoni adults, or twice with nymphs. Both infestation groups, adults and nymphs, demonstrated a significant level of resistance to re-infestation, following initial exposure. Dot enzyme-linked immunosorbent assay (Dot-ELISA) was employed to detect antibody reactive with D. andersoni salivary gland antigens (SGA). Animals infested with adults had antibody that increased at a relatively constant rate until the fourth infestation, which was differentiated by a sharp increase in titer, that was maintained for approximately 2 wk. Guinea pigs that received nymph infestations had SGA-specific antibody; however, titers were lower than those in the adult infestation group. Antibody levels continued to increase approximately 80 days beyond the final (second) infestation for this group. A direct correlation between resistance and antibody titer was not evident, since resistance was relatively stable after the second infestation in both infestation groups, and tick-specific immunoglobulin levels continually increased.     

Tick genomics: the Ixodes genome project and beyond

Ticks and mites (subphylum Chelicerata; subclass Acari) include important pests of animals and plants worldwide. The Ixodes scapularis (black-legged tick) genome sequencing project marks the beginning of the genomics era for the field of acarology. This project is the first to sequence the genome of a blood-feeding tick vector of human disease and a member of the subphylum Chelicerata. Genome projects for other species of Acari are forthcoming and their genome sequences will likely feature significantly in the future of tick research. Parasitologists interested in advancing the field of tick genomics research will be faced with specific challenges. The development of genetic tools and resources, and the size and repetitive nature of tick genomes are important considerations. Innovative approaches may be required to sequence, assemble, annotate and analyse tick genomes. Overcoming these challenges will enable scientists to investigate the genes and genome organisation of this important group of arthropods and may ultimately lead to new solutions for control of ticks and tick-borne diseases.