An antigenic profile of adult
Paramphistomum cervi was revealed by sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE) and immunoblotting using sera from cattle naturally infected ...with
P. cervi,
Fasciola gigantica and strongylids. SDS–PAGE of whole worm extracts exhibited 26 distinct protein bands. Immunoblotting analysis of these proteins showed five major antigenic bands which were recognized by serum of individual cattle naturally infected with
P. cervi. These antigenic proteins had molecular weights ranging from 23 to 116
kDa. One antigenic protein with a molecular weight of 52
kDa exhibited a consistent reaction with sera from all infected cattle. It’s diagnostic sensitivity, specificity and accuracy using this test were 100%, 98% and 98.9%, respectively. The positive and negative predictive values were 97.6% and 100%, respectively. This finding suggests that the 52
kDa protein may be a diagnostic antigen for paramphistomosis.
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► The infection by the malaria parasite is initiated in host hepatocyte. ► The intracellular calcium increased during sporozoite transformation. ► Modulators of calcium signaling ...accelerated the sporozoite-rounding process. ► Calcium signal regulates the morphological development of sporozoite to EEF. ► We proposed a role for calcium as a transducer in the parasitic life cycle.
The infection by the malaria parasite of its mammalian host is initiated by the asexual reproduction of the parasite within the host hepatocyte. Before the reproduction, the elongated sporozoites undergo a depolarizing morphogenesis to the spherical exo-erythrocytic form (EEF). This change can be induced in vitro by shifting the environmental conditions, in the absence of host hepatocytes. Using rodent malaria parasites expressing a FRET-based calcium sensor, YC3.60, we observed that the intracellular calcium increased at the center of the bulbous structure during sporozoite transformation. Modulators of intracellular calcium signaling (A23187 and W-7) accelerated the sporozoite-rounding process. These data suggest that calcium signaling regulates the morphological development of the malaria parasite sporozoite to the EEF, and support a fundamental role for calcium as a universal transducer of external stimuli in the parasitic life cycle.
LAWRENCE, R. A., GRAY, C. A., OSBORNE, J., and MAIZELS, R. M. 1996.Nippostrongylus brasiliensis:Cytokine responses and nematode expulsion in normal and IL-4-deficient mice.Experimental ...Parasitology84,65–73. Infection with the nematode,Nippostrongylus brasiliensis,results in a Th2-dominated immune response. We describe the dynamics of this response in both local and systemic environments. Th2-type responses were evident first in the mesenteric lymph node, with parasite antigen-specific proliferation and IL-4/IL-5 release peaking at Days 7–9 postinfection, shortly before expulsion of the adult worms from the gut. IFN-γ responses were not observed in the mesenteric lymph node. Responses in the spleen generally followed those in the mesenteric lymph nodes by 2–3 days and showed a greater degree of Th1-type cytokine production.N. brasiliensiswas shown to be a powerful inducer of IL-4 responses with as few as six infectiveN. brasiliensislarvae eliciting IL-4 production in the mesenteric lymph node, but only high doses of larvae (600) elicited IL-4 secretion in the spleen. Similar levels of IL-4 production by lymph node cells stimulated with Con A or parasite antigen postinfection indicated the extent of polyclonal Th2 stimulation by this parasite. Infection of IL-4-deficient mice showed that despite the absence of IL-4-dependent Th2 responses, these mice were able to curtail egg production and expel adultN. brasiliensisin a time frame similar to that of fully immunocompetent animals. These results emphasize the magnitude of the Th2 response toN. brasiliensisand also show that IL-4 is not a prerequisite for the development of immunity toN. brasiliensis.
Lawrie, C. H., Randolph, S. E., and Nuttall, P. A. 1999. Ixodes ticks: Serum species sensitivity of anti-complement activity. Experimental Parasitology93, 207–214. Ixodid ticks feed for extended ...periods of up to 2 weeks or more. To complete engorgement, they must overcome their host's innate immune mechanisms of which the complement system is a major component. Using in vitro assays, salivary gland extracts of the ixodid ticks, Ixodes ricinus, I. hexagonus, and I. uriae, were shown to inhibit activity of the alternative pathway of complement. The ability of the different Ixodes species to inhibit complement activity varied with the animal species used as a complement serum source. Serum species sensitivity correlates to the reported host range of the tick species tested.
Complementary experiments were performed to indicate the presence or absence of sialic acids in axenically cultured Panagrellus redivivus and Caenorhabditis elegans. Competitive displacement ...experiments with radiolabeled Limax flavus agglutinin demonstrated the presence of sialic acid in nematodes grown in medium which contained liver extract as a growth factor but the absence of sialic acid when heme was substituted for liver extract. This finding suggested that sialic acid present in the liver medium was responsible for conflicting results of other studies. Transmission electron microscopy of thin sections from nematodes labeled with an LFA-ferritin conjugate revealed no label to the surface area of the cephalic chemosensilla. Fluorometric analysis with a modification of the thiobarbituric acid assay was negative for sialic acid. Analyses by gas chromatography-mass spectrometry, sensitive to the high picomole range, were also negative for sialic acid. Taken together the results provide evidence for the absence of sialic acid in P. redivivus and C. elegans using the most sensitive and diagnostic technique currently available.
Lammel, E. M., Barbieri, M. A., Wilkowsky, S. E., Bertini, F., and Isola, E. L. D. 1996.Trypanosoma cruzi:Involvement of intracellular calcium in multiplication and differentiation.Experimental ...Parasitology83,240–249. The possible role of intracellular Ca2+level onTrypanosoma cruzidifferentiation was explored. The addition to epimastigotes of aTriatoma infestansintestinal homogenate, which that triggers off the differentiation to the infective metacyclic form, induced a sudden rise in Ca2+ifrom the basal value, 94 ± 28 to 584 ± 43 nmole/liter. This increase was not affected by the presence of EGTA in the medium. Trypsin-treated intestinal homogenate did not alter the Ca2+iof epimastigotes. Calmodulin inhibitors (Calmidazolium, Trifluoperazine, and Chlorpromazine) blocked differentiation. Although the calcium ionophore ionomycin increased Ca2+ito 342 ± 29 nmole/liter, it was unable to induce differentiation by itself. BAY K8644 and Methoxyverapamil (agonist and antagonist of Ca2+channels, respectively) were unable to affect Ca2+iby themselves, or when added to stimulated parasites, and did not exert a stimulatory or inhibitory effect on morphogenesis. BAPTA/AM, a Ca2+chelator, partially blocked the rise in Ca2+iand morphogenesis; this effect was reversed by ionomycin. The requirement of intracellular Ca2+on epimastigote multiplication was also evaluated. The addition of EGTA to the culture medium led to a decrease in epimastigote multiplication till it practically ceased in the sixth passage. When such parasites were transferred to LIT they partially recovered the growth rate. Parasites from passages III, IV, and V in the Ca2+-depleted medium maintained their basal Ca2+i, but when treated with the intestinal homogenate, the rise in Ca2+iwas abrogated. Accordingly, the differentiation percentages of such parasites dropped significantly compared with controls.
This study analysed the suramin sensitivity of 29 stocks of Trypanosoma evansi isolated from Egypt, Sudan, and Indonesia and compared the results with the isoenzyme banding patterns of 20 soluble ...enzymes in these stocks of T. evansi. The results showed that the type VII banding pattern of malic enzyme was found only in T. evansi stocks which were highly resistant to suramin.
