Genetic diversity and naturally acquired immune responses to plasmodium vivax thrombospondin-related adhesive protein (pvtrap) in patients from area of an unstable malaria transmission of iran

Saeed Nazeri,1,* Sedigheh zakeri,2 Akram abouie mehrizi,3 Navid dinparast djadid,4

1. pasteur institute, Biotechnology Research Center, malaria and vector research department
2. pasteur institute, Biotechnology Research Center, malaria and vector research department
3. pasteur institute, Biotechnology Research Center, malaria and vector research department
4. pasteur institute, Biotechnology Research Center, malaria and vector research department

Abstract

Introduction

The thrombospondin-related adhesion protein is one of the major sporozoite antigens that plays an important role in the invasion of hepatocytes by sporozoites. to design a broadly protective vaccine for elimination of plasmodium vivax, it is critical to have adequate information on genetic diversity and the natural immune responses to a particular antigen in diverse populations with different genetic background.

Methods

For this purposes, 50 iranian pvtrap genes were sequenced and then the most prevalent haplotype of pvtrap gene was expressed in escherichia coli rosetta (de3) and applied as an antigen in elisa. the igg and it’s subclasses antibodies to pvtrap, as well as the association between anti-pvtrap antibody responses with host age were evaluated in patients from malaria-endemic areas of iran (n = 116).

Results

The nucleotide sequence analysis of pvtrap gene in comparison with the sal-1 sequence showed 12 amino acid substitutions, resulting in 10 haplotypes, that all of them were detected in ectodomain of pvtrap. moreover, the results revealed that only 42.24% of patients infected with p. vivax had positive anti-pvtrap igg. furthermore, the positive responses of antibody responses to pvtrap revealed no significant correlation with age (p > 0.05). moreover, the dominant subclasses to rpvtrap in iranian patients who were infected with p. vivax, was igg1 and igg3 and had high to intermediate avidity against rpvtrap antigen.

Conclusion

In conclusion, the present study has shown that genetic diversity in the pvtrap exhibits low-level diversity and individuals exposed to vivax malaria in iran are able to produce antibodies to the trap antigen at all ages in response to p. vivax infections that could help to understand the interactions between the host and p. vivax parasite in developing and testing a trap-based vaccine.

Keywords

Plasmodium vivax, genetic diversity, naturally acquired immune responses, trap