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vaccine

NOT Open Access | Effect of immune regulatory pathways after immunization with GMZ2 malaria vaccine candidate in healthy lifelong malaria-exposed adults

May 13, 2020 - 13:57 -- NOT Open Access
Author(s): 
Nouatin O, Ateba Ngoa U, Adegnika AA, et al.
Reference: 
Vaccine. 2020 May 5. pii: S0264-410X(20)30540-5

Despite appreciable immunogenicity in malaria-naive populations, many candidate malaria vaccines are considerably less immunogenic in malaria-exposed populations. This could reflect induction of immune regulatory mechanisms involving Human Leukocyte Antigen G (HLA-G), regulatory T (Treg), and regulatory B (Breg) cells. Here, we addressed the question whether there is correlation between these immune regulatory pathways and both plasmablast frequencies and vaccine-specific IgG concentrations.

A novel vaccine target for malaria

May 13, 2020 - 13:46 -- Open Access
Author(s): 
Wrighton KH
Reference: 
Nat Rev Microbiol. 2020 May 6

Malaria is a leading cause of death in children; however, developing an effective vaccine has been challenging. Raj et al. now show that Plasmodium falciparum glutamic-acid-rich protein (PfGARP), an 80 kDa antigen expressed on the surface of erythrocytes infected by P. falciparum, is a malaria vaccine candidate for specifically targeting the blood stage of P. falciparum.

The RH5-CyRPA-Ripr Complex as a Malaria Vaccine Target

May 5, 2020 - 13:09 -- Open Access
Author(s): 
Ragotte RJ, Higgins MK, Draper SJ
Reference: 
Trends Parasitol. 2020 Apr 28. pii: S1471-4922(20)30099-4

Despite ongoing efforts, a highly effective vaccine against Plasmodium falciparum remains elusive. Vaccines targeting the pre-erythrocytic stages of the P. falciparum life cycle are the most advanced to date, affording moderate levels of efficacy in field trials.

Not Open Access | WHO's malaria vaccine study represents a "serious breach of international ethical standards"

March 3, 2020 - 12:35 -- NOT Open Access
Author(s): 
Doshi P
Reference: 
BMJ. 2020 Feb 26;368:m734

Experts are troubled by the apparent lack of informed consent in a large, cluster randomised study of the malaria vaccine. Peter Doshi reports

Evaluation of Plasmodium vivax HAP2 as a transmission-blocking vaccine candidate

March 2, 2020 - 15:04 -- Open Access
Author(s): 
Qiu Y, Zhao Y, Liu F, Ye B, Zhao Z, Thongpoon S, Roobsoong W, Sattabongkot J, Cui L, Fan Q, Cao Y
Reference: 
Vaccine. 2020 Feb 21. pii: S0264-410X(20)30184-5

Transmission-blocking vaccine (TBV) is a promising strategy to interfere with the transmission of malaria. To date, only limited TBV candidate antigens have been identified for Plasmodium vivax. HAP2 is a gamete membrane fusion protein, with homology to the class II viral fusion proteins. Herein we reported the characterization of the PvHAP2 for its potential as a TBV candidate for P. vivax.

Identification, molecular characterization and expression of aminopeptidase N-1 (APN-1) from Anopheles stephensi in SF9 cell line as a candidate molecule for developing a vaccine that interrupt malaria transmission

February 24, 2020 - 14:27 -- Open Access
Author(s): 
Javad Dadgar Pakdel, Sedigheh Zakeri, Abbasali Raz and Navid Dinparast Djadid
Reference: 
Malaria Journal 2020 19:79, 19 February 2020

According to the World Health Organization reports, billions of people around the world are at risk for malaria disease and it is important to consider the preventive strategies for protecting the people that are living in high risk areas. One of the main reasons of disease survival is diversity of vectors and parasites in different malaria regions that have their specific features, behaviour and biology. Therefore, specific regional strategies are necessary for successful control of malaria. One of the tools that needs to be developed for elimination and prevention of reintroduction of malaria is a vaccine that interrupt malaria transmission (VIMTs). VIMT is a broad concept that should be adjusted to the biological characteristics of the disease in each region. One type of VIMT is a vector-based vaccine that affects the sexual stage of Plasmodium life cycle. According to recent studies, the aminopeptidase N-1 of Anopheles gambiae (AgAPN-1) is as a potent vector-based VIMT with considerable inhibition activity against the sexual stage of Plasmodium parasite.

Optimization of a Plasmodium falciparum circumsporozoite protein repeat vaccine using the tobacco mosaic virus platform

February 17, 2020 - 15:01 -- Open Access
Author(s): 
Langowski MD, Khan FA, Dutta S, et al.
Reference: 
Proc Natl Acad Sci U S A. 2020 Feb 11;117(6):3114-3122

Plasmodium falciparum vaccine RTS,S/AS01 is based on the major NPNA repeat and the C-terminal region of the circumsporozoite protein (CSP). RTS,S-induced NPNA-specific antibody titer and avidity have been associated with high-level protection in naïve subjects, but efficacy and longevity in target populations is relatively low. In an effort to improve upon RTS,S, a minimal repeat-only, epitope-focused, protective, malaria vaccine was designed. Repeat antigen copy number and flexibility was optimized using the tobacco mosaic virus (TMV) display platform.

A C-terminal Pfs48/45 malaria transmission-blocking vaccine candidate produced in the baculovirus expression system

January 27, 2020 - 13:26 -- Open Access
Author(s): 
Lee SM, Hickey JM, Miura K, Joshi SB, Volkin DB, King CR, Plieskatt JL
Reference: 
Sci Rep. 2020 Jan 15; 10(1):395

The Plasmodium falciparum gametocyte surface protein, Pfs48/45, is a potential target for malaria transmission-blocking vaccines. However, due to its size and complexity, expression of the full-length protein has been difficult, leading to focus on the C-terminal six cysteine domain (6C) with the use of fusion proteins to facilitate expression and folding. In this study, we utilized the baculovirus system to evaluate the expression of three Pfs48/45 proteins including the full-length protein, the 6C domain fragment and the 6C domain mutant to prevent glycosylation. Expression of the recombinant Pfs48/45 proteins was conducted in super Sf9 cells combined with the use of tunicamycin to prevent N-glycosylation.

NOT Open Access | Population genetic structure analysis of thrombospondin-related adhesive protein (TRAP) as a vaccine candidate antigen in worldwide Plasmodium falciparum isolates

January 27, 2020 - 13:24 -- NOT Open Access
Author(s): 
Mehrizi AA, Zadeh AJ, Zakeri S, Djadid ND
Reference: 
Infection, Genetics and Evolution, 16 January 2020, 104197

Antigenic diversity is a major concern in malaria vaccine development that requires to be considered in developing a malaria vaccine. Plasmodium falciparum thrombospondin-related adhesive protein (PfTRAP) is a leading malaria vaccine candidate antigen. In the current study, we investigated the level of genetic diversity and natural selection of pftrap sequences in P. falciparum isolates from Iran (n = 47). The gene diversity of Iranian pftrap sequences was also compared to available global pftrap sequences deposited in the GenBank or PlasmoDB databases (n = 220).

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