A new study shows a promising strategy for the development of a vaccine against Plasmodium vivax, the most prevalent malaria parasite outside sub-Saharan Africa. The research, led by Global Health Institute Barcelona (ISGlobal), ​​indicates the possibility of using small vesicles (or exosomes) secreted by immature red blood cells as a platform for vaccination against malaria. The results have been published in Scientific Reports.

Reticulocytes are immature red blood cells that during their maturation process eliminate cellular proteins through the secretion of small vesicles called exosomes, which are 100 times smaller than a red blood cell. Previously the team demonstrated with a mouse model of malaria that exosomes derived from reticulocytes contain parasite proteins, and that they could function as a vaccine when administered to other mice.

Thanks to a proteomic analysis, the new study identifies 360 new proteins present in the exosomes of human reticulocytes. “This broad list of proteins present in these human exosomes represents a valuable resource to better understand how the malaria parasite infects red blood cells,” says Carmen Fernandez-Becerra, one of the authors.

For example, some of the proteins identified allow the entry of Plasmodium vivax into the reticulocyte, “which explains in part the failure of in vitro cultures,” explains Miriam Diaz-Varela, first author of the study.

Cellular immunity

The work also found the presence of molecules called HLA-class I in exosomes of human reticulocytes (HuRex) obtained from umbilical cord blood. These proteins are responsible for unmasking fragments of the parasite so that the immune system destroys the infected cells.

To know whether reticulocyte exosomes are capable of inducing immunity against Plasmodium vivax, a functional assay showed that HuRex are captured by dendritic cells, key sentry cells that regulate the initiation of the immune response. “These results converge with other recent results on the subject and should boost the development of new preventive vaccines against malaria, based on cellular immunity,” the authors say.

The team points out that the results open the way to future studies on exosomes in infections to discover new antigens for vaccines, as well as to explore the potential of HuRex as a vaccine platform to generate cytotoxic T cells against vivax malaria.

 

Source: SINC