ISSN:0141-9838    

DOI:10.1046/j.1365-3024.1996.d01-77.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

During the course of chronic malaria infection antigenic variants of a parasite antigen are expressed and exposed on the surface of infected erythrocyte membranes. There also exists a number of apparently invariant single gene copy blood‐stage antigens, exposed or non‐exposed, which have been shown to afford immunity under experimental conditions. To determine why the host, presented with invariant ‘protective’ antigens, is unable to control infections effectively, immunity to a representative single gene copy antigen, the merozoite surface protein 1 (MSP1) was investigated inPlasmodium chabaudi chabaudiAS, a murine model of chronic malaria. Immunization with monoclonal antibody affinity purified native MSP1 resulted in enhanced control of parasitaemia on challenge, irrespective of the parasite inoculum size; challenge with a single parasite, however, suggested that expansion of resistant parasite subpopulations was not occurring. Challenge of mice immunized with recombinant fusion proteins encoding N‐ or C‐terminal regions of theP.c. chabaudiAS MSP1 produced inconsistent effects, often parasitaemias were indistingishable from controls despite significant anti‐MSP1 antibody responses. The not unlikely contamination of MSP1 native preparations with erythrocyte (E) components was considered. Immunization with a mixture of the MSP1 C‐terminus recombinant polypeptide and a Triton X‐100 solubilized lysate of normal E resulted in enhanced control of parasitaemia, however, no effect was seen after administration of either component on its own. Co‐immunization of E with the N‐terminus polypeptide reversed the inhibition seen, on this occasion with

ISSN:0141-9838    

DOI:10.1046/j.1365-3024.1996.d01-82.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

This paper summarizes the first conclusions arising from an analysis of parasite diversity in blood samples collected during longitudinal surveys conducted in Senegal. Parasite typing was carried out using a PCR‐based molecular analysis of allelic polymorphism. The parasite populations circulating in the village of Dielmo during periods of intense transmission (when the inoculation rate was 0.5–1 infective bite/night) are characterized by a considerable allelic diversity of the MSP‐1, MSP‐2 and TRAP loci. A large proportion of blood samples contained several MSP‐1 or MSP‐2 alleles. In asymptomatic carriers, the complexity of the infections (number of alleles and genetic diversity of these alleles) was age‐dependent. In children, the trend was for a reduced complexity during clinical episodes. Molecular typing showed that successive clinical episodes experienced by children were caused by genetically distinct parasites. Longitudinal analysis of asymptomatic carriers indicated that in the absence of transmission, the same parasite types were carried for long periods, while rapidly changing profiles were observed during intense transmission season. The consequences of these findings on our understanding of acquired anti‐parasite immunity in humans living in endemi

ISSN:0141-9838    

DOI:10.1046/j.1365-3024.1996.d01-79.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

Antibody responses to solubleSchistosoma haematobiumegg (SEA) and worm (SWA) antigens in a rural Zimbabwean study population were examined by ELISA. One hundred and sixteenS. haematobiuminfected and 124 non‐infected individuals representing individuals greater than five years old, were included. Non‐endemic control sera were obtained from a schistosomiasis non‐endemic part of Zimbabwe and from Norwegian blood donors. A possible association between IgE antibody responses and resistance toS. haematobiuminfection was indicated by a negative correlation between IgE anti‐SEA levels and intensity ofS. haematobiuminfection, and by a positive correlation between IgE responses to SEA and SWA and age. Similarly, an association between IgA and anti‐SWA and resistance toS. haematobiumwas suggested by a negative correlation to intensity of infection and a positive correlation with age. A probably association between IgM and IgG4 with susceptibility toS. haematobiuminfection was described; intensity ofS. haematobiuminfection correlated positively with IgG, IgG4 and IgM responses to SEA and with IgG4 and IgM responses to SWA, also age correlated negatively with IgG4 and IgM responses to SEA and with IgG4 responses to SWA. These findings support the concept of IgG4 and IgM as blocking antibodies. Significant positive correlations between antibody responses to SEA and SWA suggests cross‐reactivity between eggs and adult worms. In addition, the recognition by IgE and IgG4 of the same schistosomulum antigens in immunoblotting suggests competition for the sa

ISSN:0141-9838    

DOI:10.1046/j.1365-3024.1996.d01-78.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

C57BL/6 mice which were treated with recombinant mouse interleukin‐6 (rmIL‐6), 75 ng in 0.2 ml saline, i.p., 24 h before inoculation withPlasmodium chabaudi chabaudiand on days one, two and three could not control the primary acute parasitaemia but were able to suppress secondary parasitaemia significantly, peak of 3% and to reduce parasitaemia to subpatent levels within three weeks. Control C57BL/6 mice, which received saline injections only, developed two identical peaks of parasitaemia of at least 21% each, typical of a primaryP. chabaudi chabaudiinfection and cleared parasitaemia by day 28 post‐inoculation. Serum levels of IL‐6 measured in the first week by enzyme‐linked immunosorbent assay were significantly higher (two‐fold) in recipients compared to control mice. Anti‐plasmodial IgG1, 2a and 2b titres were four to 16 times higher in rmIL‐6 recipients than in the control mice. Reduction of parasitaemia to subpatency during the secondary phase ofP. chabaudi chabaudiinfection in C57BL/6 mice is primarily antibody‐mediated and rmIL‐6 accelerates this process by boosting the levels of the required specific anti‐plasmodial I

ISSN:0141-9838    

DOI:10.1046/j.1365-3024.1996.d01-80.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

This paper describes the evaluation of the protective antibody response of sheep to vaccination againstTaenia ovisinfection with a defined recombinant antigen (45W). Sera from 181 vaccinated sheep, collected prior to experimental challenge withT.ovis, were assessed for 45W specific IgA, IgG, IgG1, IgG2and IgM levels and these results correlated with protection data. There were significant relationships (P < 0.001) between IgG, IgG1and IgG2titres and protection. Serum IgA levels did not correlate with protection and there were no significant levels of 45W specific IgM detected. Killing of several other taeniid cestodes has been shown to be complement mediated and the findings in this study are consistent with the involvement of this immune mechanism in 45W vaccinated sheep. A comparison of the adjuvants used in this study (saponin and oil in water) demonstrated that whereas both adjuvants stimulated the production of similar levels of 45W specific IgG1, the IgG2response was significantly higher in sheep vaccinated with oil adjuv

ISSN:0141-9838    

DOI:10.1046/j.1365-3024.1996.d01-81.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

It has been reported that some breeds of cattle such as the N'Dama mount a more effective antibody response to the variable surface glycoprotein coat of trypanosomes and that this may contribute to their ability to control the infection. Thus we have investigated antibody responses to surface exposed epitopes of the variable surface glycoprotein inTrypanosoma congolense‐infected N'Dama (trypanotolerant) and Boran (susceptible) cattle. Similar titres and isotypes were found in both N'Damas and Borans indicating that trypanotolerance is not associated with superior antibody‐mediated destruction of trypanosomes. However, significant differences in antibody responses to cryptic VSG epitopes and non‐trypanosome antigens were identified. Trypanosusceptible Boran cattle had low IgG1responses to cryptic epitopes but high IgM responses to non‐trypanosome antigens such as β‐galactosidase. In contrast the N'Dama cattle had significantly higher IgG1responses to cryptic VSG epitopes and negligible responses to β‐galactosidase. These results indicate differences in the induction of anti‐trypanosome immune responses between trypanotolerant and susceptible cattle infected w

ISSN:0141-9838    

DOI:10.1046/j.1365-3024.1996.d01-76.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY