A step forward for an attenuated blood-stage malaria vaccine

A single dose of genetically-attenuated malaria blood-stage parasites protects against two Plasmodium species infections

Genetically-growth-attenuated blood-stage parasites were generated inPlasmodium falciparumby targeted deletion of NT1 (Nucleoside Transporter-1) gene, and Pfnt1(-) parasites only grew after providing the culture with supra-physiological concentrations of purines. Genetically-attenuatedP. yoeliint1(-)parasites induced sterile-protection against homologous blood-stage infectious challenge after immunization with single subpatent doses, which remained subpatent even in immune-compromised mice. Here, we showed that immunizations with frozen-stocks of equally-mixedP. bergheiandP. yoelii nt1(-)parasites in single subcutaneous doses, which did not lead to patent blood-stage infection, conferred sterile protection against intravenous infectious blood-stage challenge with wild-type parasites ofP. bergheiANKA andP. yoelii17X-NL strains. This data highlights the possibility that a single subcutaneous sub-patent dose of two species of genetically-growth-attenuated parasites, which can protect humans against twoPlasmodiumspp. infections, could be developed in cultures provided with supra-physiological concentrations of purines, and shipped to endemic areas as frozen-stock doses.

Polymeric Nanoparticle Based Diagnosis and Nanomedicine for Treatment and Development of Vaccines for Cerebral Malaria: A Review on Recent Advancement

Cerebral malaria occurs due to Plasmodium falciparum infection, which causes 228 million infections and 450,000 deaths worldwide every year. African people are mostly affected with nearly 91% cases, of which 86% are pregnant women and infants. India and Brazil are the other two countries severely suffering from malaria endemicity. Commonly used drugs have severe side effects, and unfortunately no suitable vaccine is available in the market today. In this line, this review is focused on polymeric nanomaterials and nanocapsules that can be used for the development of effective diagnostic strategies, nanomedicines, and vaccines in the management of cerebral malaria. Further, this review will help scientists and medical professionals by updating the status on the development stages of polymeric nanoparticle based diagnostics, nanomedicines, and vaccines and strategies to eradicate cerebral malaria. In addition to this, the predominant focus of this review is antimalarial agents based on polymer nanomedicines that are currently in the preclinical and clinical trial stages, and potential developments are suggested as well. This review further will have an important social and commercial impact worldwide for the development of polymeric nanomedicines and strategies for the treatment of cerebral malaria.

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

BACKGROUND

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.

METHODS

Systems for rapid amplification of cDNA ends (3'-RACE) and genome walking methods were used for sequence determination of apn-1 gene from Anopheles stephensi and distinct bioinformatics software were used for structural analysis. AsAPN-1 was expressed in Spodoptera frugiperda (Sf9) insect cell line using the baculovirus expression system. Recombinant AsAPN-1 was purified under the hybrid condition and its biological activity was assayed.

RESULTS

Asapn-1 gene and its coded protein from An. stephensi were characterized for the first time in this study. Subsequently, the structural features and immunological properties of its coded protein were evaluated by in silico approaches. Enzymatic activity of the recombinant AsAPN-1, which was expressed in Sf9 insect cell line, was equal to 6 unit/μl.

CONCLUSIONS

Results of this study revealed that AsAPN-1 is very similar to its counterpart in An. gambiae. In silico evaluation and fundamental data which are necessary for its evaluation as a VIMT-based vaccine in the next steps were acquired in this study and those could be useful for research groups that study on malaria vaccine for countries that An. stephensi is the main malaria vector there.