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To investigate the role of Toll like receptor (TLR) in the activation of dendritic cells (DC) during early Plasmodium yoelii infection of the lethal strain 17XL (P.y 17XL), susceptible BALB/c and resistant DBA/2 mice were infected by i.p.injection of the P.y l7XL-parasitized erythrocytes, and the parasitemia of individua1 mice was monitored by the microscopic examination of blood smear stained with Giemsa.Mice from norma1 and infected groups were sacrificed on 0,3 and 5 days post-infection to collect their spleen cells.And the expressions of TLR-9 and TLR-4 on the cell surface of DCs in spenonocytes of these two strains of mice were assayed by applying flow cytometry to quantitatively analyze the percentages of CD11c+TLR9+ DCs and CD11c+TLR4+ DCs. It was found that the population of CD11c+DCs expressing TLR9 was significantly increased on day 3 and peaked on 5 p.i. in BALB/c (P<0.01) and DBA/2 mice(P<0.01). However, there was no statistical significance between these two strains of mice. Meanwhile, there was no change on the population of CD11c+ DCs expressing TLR4 in BALB/c and DBA/2 mice. These results indicate that TLR9 may contribute to the DC activation during early stages of P.y17XL infection.
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Objective To investigate the development and dynamic changes of host immune response in DBA/2 mice infected with Plasmodium yoelii 17XL. Methods Female DBA/2 mice were infected by intraperitoneal ( i. p. ) injection of 106 P. yoelii 17XL parasitized erythrocytes ( PRBC). Levels of IL-12, IFN-γ, IL-4, IL-10 and P. yoelii 17XL-specific antibody in sera were measured by ELISA. Concentrations of NO in cell supernatants were measured by the Griess reaction. Parasitemia,percentage of mononuclear-macrophages of individual mice were monitored daily, and phagocytosis of mononuclear macrophages was also observed. Results Primary parasitemia in vein blood was developed on day 3 postinfection, which peaked with a level of 46. 9% on day 9. Most mice cleared the infection and survived by day 20 postinfection. From day 6 to day 16, the phagocytosis of PRBC by rodent macrophages was observed on the blood smear. Infected mice had a continuously increased level of IL-12 in serum from day 1 postinfection. Accordingly, high level of IFN-γ was also detected in sera from day 1 postinfection,which peaked on day 6. Infected mice produced higher level of IL-4 and IL-10 in serum on day 6 postinfection, which peaked on day 9 and day 15 postinfection respectively. In addition, splenocytes from infected mice produced significantly higher level of NO on day 6 and 20 postinfection. Level of P. yoelii 17XL-specific IgG was determined in the sera of infected mice with a steadily increased trend after infection, which peaked on day 70 postinfection. Conclusions Effective polarizing of Thl cells is significant in inhibition of parasitemia and eventual clearance of the Plasmodium parasites. Activated mononuclear-macrophages play a key role in inhibiting parasitemia in the early phase of infection with P. yoelii 17XL.
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Objective :To investigate the effects of ethanol precipitate(ET-Pre) and RNA of Grifola frondosa on non-specific immunity in mouse.Methods:The common biological methods were used to examine the levels of cytokines and immunocyte activity. Results: The killing activity of the NK cells, the phagocytosis function of macrophages and the levels of TNF?/IL-1 in the animals treated with ET-Pre and RNA respectively were significantly higher than those in the control.The RNA was stronger than ET-Pre in increasing killing activity of NK cells and phagocytosis function of macrophages. Conclusion:Both ET-Pre and RNA extracts of Grifola frondosa may promote immunoactivity nonspecifi-cally and inhibit tumor cells indirectly.
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Objective:To study the activity of APC in early phase infection by detection of the differentiation of Th0 cells from TG mice Methods:Detection of IFN ? and IL 4 by cytokine ELISA Identification of the phenotype of T cells from culture wells by FACS Results:Infected APC induced the T cells of TG mice to differentiate into Th1 cells, uninfected APC induced it into Th2 cells IL 4 and IL 12 influenced the effect of APC on the differentiation of T cells Conclusion:Infection and added cytokines influenced the presenting function of APC
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Objective:To clarify the mechanism of crisis serum' mediated gametocyte infectivity to the mosquito vector Methods:Observing the effects of mouse serum , which was obtained 5 days after P yoelii infection (D5 serum) on gametocyte infectivity by IFA and mosquito live feeds, and the production of IFN ??TNF ??IL 4 and NO - 2 in the hosts in vivo and in vitro by ELISA and Griess reaction And to investigate the ability of malaria parasitized red blood cell extract (PRBC extract) to induce NO Results:The development of the gametocytes from mice 5 days postinfection into ookinetes were completely inhibited D5 serum was not immediate to inhibit gametocyte development, which was injected intravenously into the mice 3 days after P yoelii infection But 4 h later after injection D5 serum stimulated the increasing IFN ? and NO production and inhibited gametocyte infectivity Moreover, PRBC extract showed the ability to induce NO Conclusion:Infected host serum blocks transmission of P yoelii via a nitric oxide dependent mechanism
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Objective To observe the effect of nitric oxide (NO) on exflagellation of malaria parasite. Methods The level of parasitemia and gametocytemia in DBA/2 mice infected with Plasmodium yoelii 17XL was measured by scanning Giemsa-stained blood smears, and the NO level in culture supernatant of splenocytes was checked using Griess reaction. The mice were injected with different doses of NO donor (NOC5) on day 4 post-infection, and control mice were injected with NOC5 precursor. On day 6 post-infection, mice were injected with NOS inhibitor (L-NMMA), and control mice were injected with D-NMMA and PBS, respectively. Blood samples were collected from tail vein of mice before injection, 30 and 60 min after being injected with NOC5 and NOC5 precursor, 4 and 8 h after being injected with L-NMMA, D-NMMA, and PBS respectively. Exflagellation number of gametocytes in blood culture was counted under microscope. Results The NO level in culture supernatant of splenocytes from mice on day 4 and 6 post-infection was 16.5 mmol/L and 30.4 mmol/L, and exflagellation number was 11.33 and 0.66, respectively. The number of exflagellation in parasitized erythrocytes, obtained from mice on day 4 post-infection, was 5.33 and 2.66, respectively, 30 and 60 min after injection of 1 mg NO donor (NOC5), significantly lower than that of the control (P
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Objective To investigate the genetic diversity of Plasmodium vivax transmission_blocking vaccine candidate antigen (TBV) Pvs25, with P.vivax isolates from Hubei and Zhejiang Provinces, and to compare the genetic polymorphism of Pvs25 with that from Bangladesh. MethodsThe parasite DNA used for the genetic polymorphism assay was obtained from dried filter paper blood spots. The genes were PCR amplified and the products were purified and sequenced directly. Results 45 complete new sequences were analyzed. Only 3 nucleotide changes were found that would result in amino acid substitutions in Pvs25 in comparison with the sequence from P.vivax Sal_I strain. The measurement of nucleotide diversity (?) was remarkably similar for the two populations, indicating that DNA sequences and deduced amino acid sequences were highly homologous among the geographically dispersed isolates or isolates from the same geographical region.Conclusion The results suggest that Pvs25 has limited antigenic polymorphism, especially compared with candidate antigens expressed by hepatic and erythrocytic stage, which may support the development and application of Pvs25_based transmission_blocking vaccine in China.
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Objective:To investigate the expression of antigens in Plasmodium yoelii sexual stage and transmission blocking effects of monoclonal antibodies(McAbs).Methods:Observing the effects of anti Pys25 McAb4 and anti Pys21 McAb10 on developmental course of parasites in mosquitoes by direct mosquito feeds on passively immunized P.yoelii infected mice and the expression of Pys21 and Pys25 from gametocytes to ookinetes in indicated culture times by IFA and Western blotting.Results:The transmission blocking activity of the anti Pys25 McAb4 was complete and more potent than that of the anti Pys21 McAb10.Both Pys25 and Pys21 were presented in whole developmental course from gametocytes to ookinetes.Furthermore,the expression of Pys25 appeared to be earlier than that of Pys21 on zygote surfact.Conclusion:Pys25 and Pys21 are target antigens of transmission blocking immunity and that anti Pys25 McAb4 has more significantly transmission blocking activity is related with the early stage expression of Pys25 on zygote surface.