Limits...
Human immune responses to infective stage larval-specific chitinase of filarial parasite, Onchocerca volvulus, Ov-CHI-1.

Wu Y, Egerton G, McCarthy JS, Nutman TB, Bianco AE - Filaria J (2003)

Bottom Line: Our results show a positive correlation between N- and C-termini of Ov-CHI-1 in their ability to provoke humoral and cellular immune responses in the human.Peripheral blood mononuclear cell (PBMC) proliferative responses to Ov-CHI-1 when assayed, were found to be significantly higher in the individuals from endemic areas and there was a statistically elevated response to Ov-CHI-1 in the infected individuals when compared to putative immune individuals.CONCLUSION: Ov-CHI-1 is an antigen that we have found strongly induces both humoral and cellular immune responses in humans.

View Article: PubMed Central - HTML - PubMed

Affiliation: Liverpool School of Tropical Medicine, Pembroke Place, L3 5QA, Liverpool UK. ywu@liv.ac.uk

ABSTRACT
BACKGROUND: Ov-CHI-1 is a chitinase specifically expressed in the infective stage larvae of the human filarial parasite Onchocerca volvulus. Evidence has show that it could be a vaccine candidate, however, there is no data available regarding the immunological status of people naturally exposed to infective stage larvae and thus provoked by this antigen. METHOD: We analysed the Ov-CHI-1-specific immune response present in four endemic foci of human onchocerciasis (Ecuador, Nigeria, Togo and Cameroon) by enzyme-linked immunosorbent assays and T-cell proliferation assays. RESULTS: In these foci of infection, antibodies to Ov-CHI-1 were found to be present in only 22% of individuals from Ecuador, but were detected in 42-62% of infected individuals in the three foci from West Africa (Nigeria, Togo and Cameroon). There was found to be no relationship between antibody level and age, gender, or infection intensity as indicated by microfilarial density and numbers of skin nodules. The isotype response to Ov-CHI-1 was dominated by the presence of IgG3, IgG1 was present to a lesser extent. Our results show a positive correlation between N- and C-termini of Ov-CHI-1 in their ability to provoke humoral and cellular immune responses in the human. Peripheral blood mononuclear cell (PBMC) proliferative responses to Ov-CHI-1 when assayed, were found to be significantly higher in the individuals from endemic areas and there was a statistically elevated response to Ov-CHI-1 in the infected individuals when compared to putative immune individuals. CONCLUSION: Ov-CHI-1 is an antigen that we have found strongly induces both humoral and cellular immune responses in humans.

No MeSH data available.


Related in: MedlinePlus

ELISA analysis of the IgG response to recombinant Ov-CHI-1 5' or 3' antigen in human onchocerciasis. Figure 4A: Comparison of the response in the sera of infected (INF) and putatively immune (PI) individuals. Figure 4B: The relationship of response to 5' antigen and 3' antigen for individual sera. The line of liner regression is shown for data sets in which there is a statistically significant correlation between responses to the two antigens (determined by Spearman's Rank Correlation Coefficient).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC153484&req=5

Figure 4: ELISA analysis of the IgG response to recombinant Ov-CHI-1 5' or 3' antigen in human onchocerciasis. Figure 4A: Comparison of the response in the sera of infected (INF) and putatively immune (PI) individuals. Figure 4B: The relationship of response to 5' antigen and 3' antigen for individual sera. The line of liner regression is shown for data sets in which there is a statistically significant correlation between responses to the two antigens (determined by Spearman's Rank Correlation Coefficient).

Mentions: Studies of bacterial and yeast chitinase [32,33] indicate that the primary chitinase gene structure possesses four domains. A signal peptide; conserved catalytic domain present at the n-terminus; a serine/threonine-rich region located towards the C-terminal and a region which is considerably degenerated amongst filarial chitinases which adjoins the extreme C-terminal chitin binding domain. The location of our 5' and 3' Ov-CHI-1 protein is shown in Figure 3. Published mapping of the MF1 epitope of the microfilarial chitinase of B. malayi, a chitinase which shares 72% homology with Ov-CHI-1 at the amino acid level, has identified the most reactive region against monoclonal antibody MF1 to be located at the carboxy terminus of the gene [19]. The reactive region of the B. malayi microfilarial chitinase has a high PEST (proline, glutamic acid, serine, threonine) score in the serine/threonine-rich region that was suggested to be the calcium-binding region responsible for activating MF1 in B. malayi microfilariae, [34] although this epitope may not be shared with Ov-CHI-1. We measured the serological activity of patient sera against 5' and 3' chitinase separately, to ascertain where the epitopes recognised by human immune system against 5' and 3' chitinase are localized. This was done to ascertain the location of the epitopes recognised by human sera and to demonstrate which of these epitopes contributed to protection from infection as measured by microfilarial counts and nodule numbers present. To this end, we analysed the IgG level against 5' or 3' antigen separately, dividing them into PI and INF groups, as shown in Figure 4A. There was no difference found in levels of the IgG to 5' protein between PI and INF individuals, whilst IgG against the 3' Ov-CHI-1 was found to be significantly increased in the PI individuals compared to the INF individuals (P < 0.05). Panels of sera were also analysed by ELISA against the recombinant 5' and 3' proteins in parallel (Figure 4B). Levels of antibody to one antigen were plotted against levels to the other for all individual serum samples. Interestingly, a significant, positive correlation was observed in the sera tested, (Spearman Rank Correlation coefficient r = 0.5389, P < 0.001). This result indicates that individuals responded equally to 5' and 3' chitinase and the C-terminal and N-terminal proteins are closely related in terms of provoking humoral immune response.


Human immune responses to infective stage larval-specific chitinase of filarial parasite, Onchocerca volvulus, Ov-CHI-1.

Wu Y, Egerton G, McCarthy JS, Nutman TB, Bianco AE - Filaria J (2003)

ELISA analysis of the IgG response to recombinant Ov-CHI-1 5' or 3' antigen in human onchocerciasis. Figure 4A: Comparison of the response in the sera of infected (INF) and putatively immune (PI) individuals. Figure 4B: The relationship of response to 5' antigen and 3' antigen for individual sera. The line of liner regression is shown for data sets in which there is a statistically significant correlation between responses to the two antigens (determined by Spearman's Rank Correlation Coefficient).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC153484&req=5

Figure 4: ELISA analysis of the IgG response to recombinant Ov-CHI-1 5' or 3' antigen in human onchocerciasis. Figure 4A: Comparison of the response in the sera of infected (INF) and putatively immune (PI) individuals. Figure 4B: The relationship of response to 5' antigen and 3' antigen for individual sera. The line of liner regression is shown for data sets in which there is a statistically significant correlation between responses to the two antigens (determined by Spearman's Rank Correlation Coefficient).
Mentions: Studies of bacterial and yeast chitinase [32,33] indicate that the primary chitinase gene structure possesses four domains. A signal peptide; conserved catalytic domain present at the n-terminus; a serine/threonine-rich region located towards the C-terminal and a region which is considerably degenerated amongst filarial chitinases which adjoins the extreme C-terminal chitin binding domain. The location of our 5' and 3' Ov-CHI-1 protein is shown in Figure 3. Published mapping of the MF1 epitope of the microfilarial chitinase of B. malayi, a chitinase which shares 72% homology with Ov-CHI-1 at the amino acid level, has identified the most reactive region against monoclonal antibody MF1 to be located at the carboxy terminus of the gene [19]. The reactive region of the B. malayi microfilarial chitinase has a high PEST (proline, glutamic acid, serine, threonine) score in the serine/threonine-rich region that was suggested to be the calcium-binding region responsible for activating MF1 in B. malayi microfilariae, [34] although this epitope may not be shared with Ov-CHI-1. We measured the serological activity of patient sera against 5' and 3' chitinase separately, to ascertain where the epitopes recognised by human immune system against 5' and 3' chitinase are localized. This was done to ascertain the location of the epitopes recognised by human sera and to demonstrate which of these epitopes contributed to protection from infection as measured by microfilarial counts and nodule numbers present. To this end, we analysed the IgG level against 5' or 3' antigen separately, dividing them into PI and INF groups, as shown in Figure 4A. There was no difference found in levels of the IgG to 5' protein between PI and INF individuals, whilst IgG against the 3' Ov-CHI-1 was found to be significantly increased in the PI individuals compared to the INF individuals (P < 0.05). Panels of sera were also analysed by ELISA against the recombinant 5' and 3' proteins in parallel (Figure 4B). Levels of antibody to one antigen were plotted against levels to the other for all individual serum samples. Interestingly, a significant, positive correlation was observed in the sera tested, (Spearman Rank Correlation coefficient r = 0.5389, P < 0.001). This result indicates that individuals responded equally to 5' and 3' chitinase and the C-terminal and N-terminal proteins are closely related in terms of provoking humoral immune response.

Bottom Line: Our results show a positive correlation between N- and C-termini of Ov-CHI-1 in their ability to provoke humoral and cellular immune responses in the human.Peripheral blood mononuclear cell (PBMC) proliferative responses to Ov-CHI-1 when assayed, were found to be significantly higher in the individuals from endemic areas and there was a statistically elevated response to Ov-CHI-1 in the infected individuals when compared to putative immune individuals.CONCLUSION: Ov-CHI-1 is an antigen that we have found strongly induces both humoral and cellular immune responses in humans.

View Article: PubMed Central - HTML - PubMed

Affiliation: Liverpool School of Tropical Medicine, Pembroke Place, L3 5QA, Liverpool UK. ywu@liv.ac.uk

ABSTRACT
BACKGROUND: Ov-CHI-1 is a chitinase specifically expressed in the infective stage larvae of the human filarial parasite Onchocerca volvulus. Evidence has show that it could be a vaccine candidate, however, there is no data available regarding the immunological status of people naturally exposed to infective stage larvae and thus provoked by this antigen. METHOD: We analysed the Ov-CHI-1-specific immune response present in four endemic foci of human onchocerciasis (Ecuador, Nigeria, Togo and Cameroon) by enzyme-linked immunosorbent assays and T-cell proliferation assays. RESULTS: In these foci of infection, antibodies to Ov-CHI-1 were found to be present in only 22% of individuals from Ecuador, but were detected in 42-62% of infected individuals in the three foci from West Africa (Nigeria, Togo and Cameroon). There was found to be no relationship between antibody level and age, gender, or infection intensity as indicated by microfilarial density and numbers of skin nodules. The isotype response to Ov-CHI-1 was dominated by the presence of IgG3, IgG1 was present to a lesser extent. Our results show a positive correlation between N- and C-termini of Ov-CHI-1 in their ability to provoke humoral and cellular immune responses in the human. Peripheral blood mononuclear cell (PBMC) proliferative responses to Ov-CHI-1 when assayed, were found to be significantly higher in the individuals from endemic areas and there was a statistically elevated response to Ov-CHI-1 in the infected individuals when compared to putative immune individuals. CONCLUSION: Ov-CHI-1 is an antigen that we have found strongly induces both humoral and cellular immune responses in humans.

No MeSH data available.


Related in: MedlinePlus