Evolutionary Insights into the Microneme-Secreted, Chitinase-Containing High-Molecular-Weight Protein Complexes Involved in Plasmodium Invasion of the Mosquito Midgut.

While general mechanisms by which Plasmodium ookinetes invade the mosquito midgut have been studied, details regarding the interface of the ookinete, specifically its barriers to invasion, such as the proteolytic milieu, the chitin-containing, protein cross-linked peritrophic matrix, and the midgut epithelium, remain to be understood. Here, we review our knowledge of Plasmodium chitinases and the mechanisms by which they mediate ookinetes crossing the peritrophic matrix. The integration of new genomic insights into previous findings advances our understanding of Plasmodium evolution. Recently obtained Plasmodium species genomic data enable identification of the conserved residues in the experimentally demonstrated hetero-multimeric, high-molecular-weight complex comprised of a short chitinase covalently linked to binding partners, von Willebrand factor A domain-related protein (WARP) and secreted ookinete adhesive protein (SOAP). Artificial intelligence-based high-resolution structural modeling using the DeepMind AlphaFold algorithm yielded highly informative three-dimensional structures and insights into how short chitinases, WARP, and SOAP may interact at the atomic level to form the ookinete-secreted peritrophic matrix invasion complex. Elucidating the significance of the divergence of ookinete-secreted micronemal proteins among Plasmodium species may lead to a better understanding of the ookinete invasion machinery and the coevolution of Plasmodium-mosquito interactions.

REVIEW OF DNA VACCINE APPROACHES AGAINST THE PARASITE TOXOPLASMA GONDII.

Toxoplasma gondii is an apicomplexan parasite that affects both humans and livestock. Transmitted to humans through ingestion, it is the second-leading cause of foodborne illness-related death. Currently, there exists no approved vaccine for humans or most livestock against the parasite. DNA vaccines, a type of subunit vaccine which uses segments of the pathogen's DNA to generate immunity, have shown varying degrees of experimental efficacy against infection caused by the parasite. This review compiles DNA vaccine efforts against Toxoplasma gondii, segmenting the analysis by parasite antigen, as well as a review of concomitant adjuvant usage. No single antigenic group was consistently more effective within in vivo trials relative to others.

Genetic Diversity of Microneme Protein 2 and Surface Antigen 1 of Eimeria tenella.

Avian coccidiosis is a disease caused by members of the genus Eimeria. Huge economic losses incurred by the global poultry industry due to coccidiosis have increased the need for cost-effective and easily available recombinant vaccines. Microneme protein 2 (MIC2) and surface antigen 1 (SAG1) of E. tenella have been recognised as potential vaccine candidates. However, the genetic diversity of the antigens in field isolates, which affects vaccine efficacy, has yet to be largely investigated. Here, we analysed genetic diversity and natural selection of etmic2 and etsag1 in Korean E. tenella isolates. Both genes exhibited low levels of genetic diversity in Korean isolates. However, the two genes showed different patterns of nucleotide diversity and amino acid polymorphism involving the E. tenella isolates obtained from different countries including China and India. These results underscore the need to investigate the genetic diversity of the vaccine candidate antigens and warrant monitoring of genetic heterogeneity and evolutionary aspects of the genes in larger numbers of E. tenella field isolates from different geographical areas to design effective coccidial vaccines.