Genetic diversity and immunogenicity of the merozoite surface protein 1 C-terminal 19-kDa fragment of Plasmodium ovale imported from Africa into China

Abstract Background Merozoite surface protein 1 (MSP1) plays an essential role in erythrocyte invasion by malaria parasites. The C-terminal 19-kDa region of MSP1 has long been considered one of the major candidate antigens for a malaria blood-stage vaccine against Plasmodium falciparum. However, there is limited information on the C-terminal 19-kDa region of Plasmodium ovale MSP1 (PoMSP119). This study aims to analyze the genetic diversity and immunogenicity of PoMSP119. Methods A total of 37 clinical Plasmodium ovale isolates including Plasmodium ovale curtisi and Plasmodium ovale wallikeri imported from Africa into China and collected during the period 2012–2016 were used. Genomic DNA was used to amplify P. ovale curtisi (poc) msp119 (pocmsp119) and P. ovale wallikeri (pow) msp119 (powmsp119) genes by polymerase chain reaction. The genetic diversity of pomsp119 was analyzed using the GeneDoc version 6 programs. Recombinant PoMSP119 (rPoMSP119)-glutathione S-transferase (GST) proteins were expressed in an Escherichia coli expression system and analyzed by western blot. Immune responses in BALB/c mice immunized with rPoMSP119-GST were determined using enzyme-linked immunosorbent assay. In addition, antigen-specific T cell responses were assessed by lymphocyte proliferation assays. A total of 49 serum samples from healthy individuals and individuals infected with P. ovale were used for the evaluation of natural immune responses by using protein microarrays. Results Sequences of pomsp119 were found to be thoroughly conserved in all the clinical isolates. rPoMSP119 proteins were efficiently expressed and purified as ~ 37-kDa proteins. High antibody responses in mice immunized with rPoMSP119-GST were observed. rPoMSP119-GST induced high avidity indexes, with an average of 92.57% and 85.32% for rPocMSP119 and rPowMSP119, respectively. Cross-reactivity between rPocMSP119 and rPowMSP119 was observed. Cellular immune responses to rPocMSP119 (69.51%) and rPowMSP119 (52.17%) induced in rPocMSP119- and rPowMSP119-immunized mice were found in the splenocyte proliferation assays. The sensitivity and specificity of rPoMSP119-GST proteins for the detection of natural immune responses in patients infected with P. ovale were 89.96% and 75%, respectively. Conclusions This study revealed highly conserved gene sequences of pomsp119. In addition, naturally acquired humoral immune responses against rPoMSP1 were observed in P. ovale infections, and high immunogenicity of rPoMSP119 in mice was also identified. These instructive findings should encourage further testing of PoMSP119 for rational vaccine design. Graphical abstract

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Genetic diversity and immunogenicity of the merozoite surface protein 1 C-terminal 19-kDa fragment (MSP119) of Plasmodium ovale imported from Africa to China

10.21203/rs.3.rs-845729/v1 ◽

2021 ◽

Author(s):

Qinwen Xu ◽

Sihong Liu ◽

Kokouvi Kassegne ◽

Bo Yang ◽

Jiachen Lu ◽

...

Keyword(s):

Genetic Diversity ◽

Immune Responses ◽

Expression System ◽

Surface Protein ◽

Merozoite Surface Protein ◽

High Avidity ◽

Natural Immunity ◽

Plasmodium Ovale ◽

Merozoite Surface Protein 1 ◽

Proliferation Assays

Abstract Background Merozoite surface protein 1 (MSP1) plays an essential role in erythrocyte invasion by malaria parasites. The C-terminal 19-kDa of MSP1 has long been considered as one of the major candidate antigens for malaria blood-stage vaccine in Plasmodium falciparum. However, there are limited information on the C-terminal 19-kDa region of Plasmodium ovale merozoite surface protein 1 (PoMSP119). This study, therefore, aims to analyse genetic diversity and immunogenicity of PoMSP119. Methods A total of 37 clinical P. ovale isolates including P. ovale curtisi (Poc) and P. ovale wallikeri (Pow) imported from Africa to China and collected between 2012 and 2016 were used. Genomic DNA were used to amplify pocmsp119 and powmsp119 genes by polymerase chain reaction (PCR). Genetic diversity of pomsp119 was analyzed using the MegAlign and GeneDoc v.6 programs. Recombinant PoMSP119-GST proteins were expressed in an Escherichia coli expression system and analyzed by Western blot. Immune responses in BALB/c mice immunized with rPoMSP119-GST were determined using enzyme-linked immunosorbent assays (ELISA). In addition, antigen-specific T-cell responses were performed by lymphocyte proliferation assays. A total of 49 serum samples from P. ovale infections and healthy people were used to evaluate natural immune responses through protein microarray assays. Results Sequences of pomsp119 were found thoroughly conserved in all clinical isolates. Recombinant PoMSP119 proteins were efficiently expressed and purified as ~ 37 kDa proteins. High antibody responses in immunized mice with rPoMSP119-GST were observed. The rPoMSP119-GST induced high avidity indexes with an average of 92.57% and 85.32% for Poc and Pow, respectively. Cross-reactivity between rPocMSP119 and rPowMSP119 was observed. Cellular immune responses to rPocMSP119 (69.51%) and rPowMSP119 (52.17%) induced in rPocMSP119- and rPowMSP119-immunized mice were found during splenocyte proliferation assays. The sensitivity and specificity of rPoMSP119-GST proteins for natural immune responses detection in patients infected with P. ovale were 89.96% and 75%, respectively. Conclusions This study revealed high conservation in sequences of pomsp119 and high immunogenicity of rPoMSP119. The rPoMSP119 proteins detected humoral immune responses in patients with P. ovale infection. Such informative results advance our understanding of natural immunity to P. ovale infection and contribute to the knowledge base for the development of a PoMSP119-based vaccine.

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Immunogenicity analysis of conserved fragments in Plasmodium ovale species merozoite surface protein 4

10.21203/rs.2.21524/v2 ◽

2020 ◽

Author(s):

Uwase Juliette ◽

Ruilin Chu ◽

Kokouvi Kassegne ◽

Yao Lei ◽

Feihu Shen ◽

...

Keyword(s):

Immune Responses ◽

Plasmodium Species ◽

Surface Protein ◽

Merozoite Surface Protein ◽

Effective Vaccine ◽

Plasmodium Ovale ◽

Tropical Regions ◽

Cellular Immune Responses ◽

Cellular Immune ◽

Proliferation Assays

Abstract Background: There is an urgent need for an effective vaccine to control and eradicate malaria, one of the most serious global infectious diseases. Plasmodium merozoite surface protein 4 (MSP4) has been listed as a blood-stage subunit vaccine candidate for malaria. Plasmodium ovale species (spp.) infection is also a source of malaria burden in tropical regions where it is sometimes mixed with other Plasmodium species. However, little is known about P. ovale spp. MSP4. Methods: The msp4 gene was amplified through polymerase chain reaction using genomic DNA extracted from blood samples of 46 patients infected with P. ovale spp. and amplified products were sequenced. Open reading frames predicted as immunogenic peptides consisting of 119 and 97 amino acids of P. ovale curtisi MSP4 (PocMSP4) and P. ovale wallikeri MSP4 (PowMSP4), respectively, were selected for protein expression. Recombinant proteins (rPoMSP4) were expressed in Escherichia coli, purified, analyzed, and immunized in BALB/c mice. The specificity of anti-MSP4-immunoglubulin (Ig) G antibodies was evaluated by Western blot and enzyme-linked immunosorbent assays, and cellular immune responses were analyzed via lymphocyte proliferation assays. Results: Full peptide sequences of PocMSP4 and PowMSP4 were completely conserved in all clinical isolates, except in the epidermal growth factor-like domain at the carboxyl terminus where only one mutation was observed in one P. ovale wallikeri isolate. Furthermore, we successfully expressed the truncated pocmsp4 and powmsp4 and purified as ~32 kDa proteins. Our results showed that PocMSP4 and PowMSP4 induced high antibody responses with end-point titers ranging from 1:10,000 to 1:2,560,000 in all immunized mouse groups and with high IgG avidity to PocMSP4 (80.5%) and PowMSP4 (92.3%). Furthermore, rPocMSP4 and rPowMSP4 cross-reacted with anti-PowMSP4-specific or anti-PocMSP4-specific antibodies. Additionally, anti-PoMSP4 IgG antibodies showed broad immuno-specificity in reacting against rPoMSP1 and rPoAMA1. Lastly, PocMSP4- and PowMSP4-immunized mice induced cellular immune responses with PocMSP4 (36%) and PowMSP4 cells (15.8%) as observed through splenocyte proliferation assays. Conclusion: Our study suggested conservation in PoMSP4 protein sequences and high immunogenicity was observed in rPoMSP4. Furthermore, PocMSP4- and PowMSP4-immunized mice induced cellular immune responses, suggesting that both humoral and cellular immune responses play crucial roles in the protection against any antigen.

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Immunogenicity analysis of conserved fragments in Plasmodium ovale merozoite surface protein 4

10.21203/rs.2.21524/v1 ◽

2020 ◽

Author(s):

Uwase Juliette ◽

Ruilin Chu ◽

Kokouvi Kassegne ◽

Yao Lei ◽

Feihu Shen ◽

...

Keyword(s):

Immune Responses ◽

Surface Protein ◽

Merozoite Surface Protein ◽

Effective Vaccine ◽

Plasmodium Ovale ◽

Tropical Regions ◽

Malaria Burden ◽

Cellular Immune Responses ◽

Cellular Immune ◽

Proliferation Assays

Abstract Background: An effective vaccine to control and eradicate malaria, one of the most serious global infectious diseases, is an urgent need. Plasmodium merozoite surface protein 4 (MSP4) has been listed as a blood-stage subunit vaccine candidate for malaria. Plasmodium ovale infection is also a source of malaria burden in tropical regions where it is sometimes mixed with other Plasmodium species. However, little is known about P. ovale MSP4. Methods: The msp4 gene was amplified through polymerase chain reaction using genomic DNA extracted from blood samples of 46 patients infected with P. ovale and then sequenced. Open reading frames predicted as immunogenic peptides consisting of 119 and 97 amino acids of P. ovale curtisi MSP4 (PocMSP4) and P. ovale wallikeri MSP4 (PowMSP4), respectively, were selected for protein expression. Recombinant proteins (rPoMSP4) were expressed in Escherichia coli, purified, analyzed, and immunized in BALB/c mice. The specificity of anti-MSP4-immunoglubulin (Ig) G antibodies was evaluated by Western blot and enzyme-linked immunosorbent assays, and cellular immune responses were analyzed via lymphocyte proliferation assays.Results: Full peptide sequences of PocMSP4 and PowMSP4 were completely conserved in all clinical isolates, except in the epidermal growth factor-like domain at the carboxyl terminus where only one mutation was observed in one P. ovale wallikeri isolate. Furthermore, we successfully expressed the truncated pocmsp4 and powmsp4 and purified as ~32 kDa proteins. Our results showed that PocMSP4 and PowMSP4 induced high antibody responses with end-point titers ranging from 1:2,560,000 to 1:10,000 in all immunized mouse groups and with high IgG avidity to PocMSP4 (80.5%) and PowMSP4 (92.3%). Furthermore, rPocMSP4 and rPowMSP4 cross-reacted with anti-PowMSP4-specific or anti-PocMSP4-specific antibodies. Additionally, anti-PoMSP4 IgG antibodies showed broad immuno-specificity in reacting against rPoMSP1 and rPoAMA1. Lastly, PocMSP4- and PowMSP4-immunized mice induced cellular immune responses with PocMSP4 (36%) and PowMSP4 cells (15.8%) as observed through splenocyte proliferation assays. Conclusion: Our study suggested conservation in PoMSP4 protein sequences with high immunogenicity. Furthermore, PocMSP4- and PowMSP4-immunized mice induced cellular immune responses, suggesting that both humoral and cellular immune responses play crucial roles in the protection against any antigen.

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In Vivo Expression and Immunological Studies of the 42-Kilodalton Carboxyl-Terminal Processing Fragment of Plasmodium falciparum Merozoite Surface Protein 1 in the Baculovirus-Silkworm System

Infection and Immunity ◽

10.1128/iai.70.6.2772-2779.2002 ◽

2002 ◽

Vol 70 (6) ◽

pp. 2772-2779 ◽

Cited By ~ 15

Author(s):

Alan L. Y. Pang ◽

Caryn N. Hashimoto ◽

Leslie Q. Tam ◽

Z. Q. Meng ◽

George S. N. Hui ◽

...

Keyword(s):

Plasmodium Falciparum ◽

B Cell ◽

Expression System ◽

Surface Protein ◽

Merozoite Surface Protein ◽

Enzyme Linked Immunosorbent Assay ◽

Attractive Alternative ◽

B Cell Epitopes ◽

Merozoite Surface Protein 1 ◽

Carboxyl Terminal

ABSTRACT The 42-kDa carboxyl-terminal processing fragment of Plasmodium falciparum merozoite surface protein 1 (MSP-142) is an anti-erythrocytic stage malaria vaccine candidate. In this study, MSP-142 was expressed by using the Bombyx mori nuclear polyhedrosis virus-silkworm expression system, and the antigenicity and immmunogenicity of the recombinant protein, Bmp42, were evaluated. The average yield of Bmp42, as determined by a sandwich enzyme-linked immunosorbent assay (ELISA), was 379 μg/ml of infected silkworm hemolymph, which was >100-fold higher than the level attainable in cell culture medium. N-terminal amino acid sequencing revealed that Bmp42 was correctly processed in silkworm cells. Data from immunoblotting, as well as from the inhibition ELISA, suggested that the conformational B-cell epitopes of MSP-142 were recreated in Bmp42. Immunization of rabbits with Bmp42 in complete Freund's adjuvant generated high-titer antibody responses against the immunogen. Specificity analyses of the anti-Bmp42 antibodies using several recombinant MSP-119 proteins expressing variant and conserved B-cell epitopes suggested that the anti-Bmp42 antibodies recognized primarily conserved epitopes on MSP-119. Furthermore, the anti-Bmp42 antibodies were highly effective in inhibiting the in vitro growth of parasites carrying homologous or heterologous MSP-142. Our results demonstrated that the baculovirus-silkworm expression system could be employed to express biologically and immunologically active recombinant MSP-142 at elevated levels; thus, it is an attractive alternative for producing a protective MSP-142 vaccine for human use.

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Limited genetic diversity of N-terminal of merozoite surface protein-1 (MSP-1) in Plasmodium ovale curtisi and P. ovale wallikeri imported from Africa to China

Parasites & Vectors ◽

10.1186/s13071-018-3174-0 ◽

2018 ◽

Vol 11 (1) ◽

Cited By ~ 4

Author(s):

Ruilin Chu ◽

Xinxin Zhang ◽

Sui Xu ◽

Limei Chen ◽

Jianxia Tang ◽

...

Keyword(s):

Genetic Diversity ◽

Surface Protein ◽

Merozoite Surface Protein ◽

Plasmodium Ovale ◽

Plasmodium Ovale Curtisi ◽

Merozoite Surface Protein 1 ◽

Limited Genetic Diversity

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Immunogenicity analysis of conserved fragments in Plasmodium ovale species merozoite surface protein 4

10.21203/rs.2.21524/v3 ◽

2020 ◽

Author(s):

Juliette Uwase ◽

Ruilin Chu ◽

Kokouvi Kassegne ◽

Yao Lei ◽

Feihu Shen ◽

...

Keyword(s):

Immune Responses ◽

Plasmodium Species ◽

Surface Protein ◽

Merozoite Surface Protein ◽

Effective Vaccine ◽

Plasmodium Ovale ◽

Tropical Regions ◽

Cellular Immune Responses ◽

Cellular Immune ◽

Proliferation Assays

Abstract Background : There is an urgent need for an effective vaccine to control and eradicate malaria, one of the most serious global infectious diseases. Plasmodium merozoite surface protein 4 (MSP4) has been listed as a blood-stage subunit vaccine candidate for malaria. Plasmodium ovale species (spp.) infection is also a source of malaria burden in tropical regions where it is sometimes mixed with other Plasmodium species. However, little is known about P. ovale spp. MSP4. Methods : The msp4 gene was amplified through polymerase chain reaction using genomic DNA extracted from blood samples of 46 patients infected with P. ovale spp. and amplified products were sequenced. Open reading frames predicted as immunogenic peptides consisting of 119 and 97 amino acids of P. ovale curtisi MSP4 (PocMSP4) and P. ovale wallikeri MSP4 (PowMSP4), respectively, were selected for protein expression. Recombinant proteins (rPoMSP4) were expressed in Escherichia coli , purified, analyzed, and immunized in BALB/c mice. The specificity of anti-MSP4-immunoglubulin (Ig) G antibodies was evaluated by Western blot and enzyme-linked immunosorbent assays, and cellular immune responses were analyzed via lymphocyte proliferation assays. Results : Full peptide sequences of PocMSP4 and PowMSP4 were completely conserved in all clinical isolates, except in the epidermal growth factor-like domain at the carboxyl terminus where only one mutation was observed in one P. ovale wallikeri isolate. Furthermore, we successfully expressed the truncated pocmsp4 and powmsp4 and purified as ~32 kDa proteins. Our results showed that PocMSP4 and PowMSP4 induced high antibody responses with end-point titers ranging from 1:10,000 to 1:2,560,000 in all immunized mouse groups and with high IgG avidity to PocMSP4 (80.5%) and PowMSP4 (92.3%). Furthermore, rPocMSP4 and rPowMSP4 cross-reacted with anti-PowMSP4-specific or anti-PocMSP4-specific antibodies. Additionally, anti-PoMSP4 IgG antibodies showed broad immuno-specificity in reacting against rPoMSP1 and rPoAMA1. Lastly, PocMSP4- and PowMSP4-immunized mice induced cellular immune responses with PocMSP4 (36%) and PowMSP4 cells (15.8%) as observed through splenocyte proliferation assays. Conclusion : Our study suggested conservation in PoMSP4 protein sequences and high immunogenicity was observed in rPoMSP4. Furthermore, PocMSP4- and PowMSP4-immunized mice induced cellular immune responses, suggesting that both humoral and cellular immune responses play crucial roles in the protection against any antigen.

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