High immunogenecity and erythrocyte-binding activity in the tryptophan-rich domain (TRD) of the 74-kDa Plasmodium vivax alanine-tryptophan-rich antigen (PvATRAg74)

Mohammad Tauqeer Alam, Hema Bora, Neeru Singh, Yagya D. Sharma

Research output: Contribution to journalArticlepeer-review

Abstract

Plasmodium vivax is the most widespread species of human malaria parasite affecting 70-80 million people worldwide each year. In recent years, some potential vaccine candidate antigens from P. vivax have been identified including tryptophan-rich antigens PvTRAg and PvTARAg55. We report here the identification and partial characterization of a 74 kDa P. vivax alanine-tryptophan-rich antigen (PvATRAg74) which is expressed by all asexual blood stages of the parasite. This protein contains two major domains, i.e. alanine-rich domain (ARD) in N-terminal region and the tryptophan-rich domain (TRD) at C-terminus. PvATRAg74 also contains variable numbers of octa-peptide repeats in the ARD region. The C-terminal PvATRAg74 containing TRD was highly conserved among 32 P. vivax isolates while N-terminal ARD showed genetic polymorphisms. The 36 kDa TRD was expressed in E. coli and named here as His6-TRD. The purified recombinant His6-TRD showed binding with uninfected human erythrocytes. This antigen was also recognized by all 38 P. vivax patients' sera on ELISA thus showing a very high seropositivity rates. In vitro stimulation of lymphocytes with purified His6-TRD indicated that it induced T cell immune response in majority (94%, n = 16) of P. vivax exposed individuals. The stimulated T cells produced higher amount of IL-4 and IL-10 than IFN-γ, TNF-α, and IL-12 indicating a Th2 type of response bias. Unlike PvTARAg55, this antigen is more immunogenic in humans and possesses the erythrocyte-binding activity. Immunogenecity of PvATRAg74 is similar to PvTRAg whose erythrocyte-binding activity still remains unknown.

Original languageEnglish (US)
Pages (from-to)3787-3794
Number of pages8
JournalVaccine
Volume26
Issue number31
DOIs
StatePublished - Jul 23 2008
Externally publishedYes

Keywords

  • Plasmodium vivax
  • Tryptophan-rich antigen
  • Vaccine candidate

ASJC Scopus subject areas

  • Molecular Medicine
  • Immunology and Microbiology(all)
  • veterinary(all)
  • Public Health, Environmental and Occupational Health
  • Infectious Diseases

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