Development of Safe, Effective and Immunogenic Vaccine Candidate for Diarrheagenic Escherichia coli Main Pathotypes in Mouse Model

Abstract

Background: Erythrocyte invasion byPlasmodium falciparum parasites is central to malaria pathogenesis. Thus, it is critical to understand this intricate biological process for the development of novel malaria intervention strategies. P. falciparum erythrocyte invasion is a complex, multistep process that is mediated by a number of redundant ligand-receptor interactions. Extensive research over three decades has aimed at identifying an essential parasite ligand that could be targeted across multiple parasite strains. In this regard, PfRH5 was identified as a critical ligand that binds with the erythrocyte receptor, Basigin and elicits potent cross-strain neutralizing antibodies. We have for the first time expressed fulllength recombinant PfRH5 in E. coli with a structural integrity that mimics the native parasite protein. Our recombinant PfRH5 protein is functional, binds with Basigin and elicits potent cross-strain transcending parasite neutralising antibodies that substantiates its claim as a leading vaccine candidate (IAI, 2014). In addition, PfRH5 lacks a transmembrane domain or GPI anchor and thus a major question has been that how PfRH5 is anchored on the merozoite surface during invasion such that it can engage with its receptor Basigin and mediate attachment. We have successfully solved this conundrum and identified an essential, novel, conserved GPI-anchored parasite molecule, CyRPA that tethers PfRH5 on the parasite surface as a multiprotein complex (PNAS 2015).Methods & Materials: We have produced different fragments of PfRH5/CyRPA recombinant proteins, functionally characterized their binding properties and measured the parasite neutralizing ability of their antibodies.Results: We demonstrate that PfRH5/CyRPA monoclonal and polyclonal antibodies potently block erythrocyte invasion synergistically in a strain-transcending manner by abrogating formation of the PfRH5/CyRPA essential complex. We have thus identified a new conserved mechanism overcoming the previous challenges of blood-stage vaccines (antigen diversity, redundancy, heterologous strain cross-reactivity) paving the way forward to develop new generation blood stage P. falciparum vaccines based on PfRH5 and CyRPA. Conclusion:Our previous discovery had elucidated the formation of a novel multi-protein PfRH5/CyRPA complex essential for erythrocyte invasionl, which we have validated in vitro as a new potent target for the development of novel blood-stage vaccines that could elicit protection alone or in combination with the advanced pre-erythrocytic RTS.S sub-unit vaccine.

Killed whole genome-reduced bacteria surface-expressed coronavirus fusion peptide vaccines protect against disease in a porcine model

“…Several KWCVs have been developed against pathogenic E. coli (reviewed in (6)). In one study, mice were immunized subcutaneously with five different pathogenic E. coli KWCVs (7) with no adverse effects noted. In another study, an oral genetically engineered enterotoxigenic E. coli (ETEC) vaccine overexpressing colonization factors was safe in mice (8).…”