Assembly, Biochemical Characterization, Immunogenicity, Adjuvanticity, and Efficacy of Shigella Artificial Invaplex

Abstract

The native Invaplex (Invaplex) vaccine and adjuvant is an ion exchange-purified product derived from the water extract of virulent species. The key component of Invaplex is a high-molecular-mass complex (HMMC) consisting of the lipopolysaccharide (LPS) and the invasin proteins IpaB and IpaC. To improve product purity and immunogenicity, artificial Invaplex (Invaplex) was developed using recombinant IpaB and IpaC proteins and purified LPS to assemble an HMMC consisting of all three components. Characterization of Invaplex by various methods demonstrated similar characteristics as the previously reported HMMC in Invaplex. The well-defined Invaplex vaccine consistently contained greater quantities of IpaB, IpaC, and LPS than Invaplex. Invaplex and Invaplex immunogenicities were compared in mouse and guinea pig dose escalation studies. In both models, immunization induced antibody responses specific for Invaplex and LPS while Invaplex induced markedly higher anti-IpaB and -IpaC serum IgG and IgA endpoint titers. In the murine model, homologous protection was achieved with 10-fold less Invaplex than Invaplex and mice receiving Invaplex lost significantly less weight than mice receiving the same amount of Invaplex. Moreover, mice immunized with Invaplex were protected from challenge with both homologous and heterologous serotypes. Guinea pigs receiving approximately 5-fold less Invaplex compared to cohorts immunized with Invaplex were protected from ocular challenge. Furthermore, adjuvanticity previously attributed to Invaplex was retained with Invaplex. The second-generation Invaplex vaccine, Invaplex, offers significant advantages over Invaplex in reproducibility, flexible yet defined composition, immunogenicity, and protective efficacy. species are bacteria that cause severe diarrheal disease worldwide, primarily in young children. Treatment of shigellosis includes oral fluids and antibiotics, but the high burden of disease, increasing prevalence of antibiotic resistance, and long-term health consequences clearly warrant the development of an effective vaccine. One vaccine under development is termed the invasin complex or Invaplex and is designed to drive an immune response to specific antigens of the bacteria in an effort to protect an individual from infection. The work presented here describes the production and evaluation of a new generation of Invaplex. The improved vaccine stimulates the production of antibodies in immunized mice and guinea pigs and protects these animals from infection. The next step in the product's development will be to test the safety and immune response induced in humans immunized with Invaplex.

A Novel Shigella Proteome Microarray Discriminates Targets of Human Antibody Reactivity following Oral Vaccination and Experimental Challenge

“…The top-10 antigen list (representative of the greatest mean antibody responses) was populated with proteins that constitute the Shigella T3SS, a needlelike structure that promotes invasion of the host cell by delivering effector proteins from the bacterium into the host cytoplasm ( 40 , 41 ). Of these, the microarray confirmed immunoreactivity to IpaB, -C, and -D, which have been included in several vaccine candidate approaches, including Invaplex (LPS plus IpaB, IpaC, and IpaD) ( 42 ); IpaB and IpaD delivered mucosally ( 43 ); IpaB and IpaD delivered parenterally with adjuvants ( 44 – 46 ); an IpaBD fusion ( 45 ); and IpaB, -C, and -D-containing outer membrane vesicles ( 47 ). Invaplex was shown to be immunogenic in humans ( 33 ), and the remaining candidates were shown to be protective in animals (reviewed in reference 8 ).…”

<p><em>Shigella</em>: Antibiotic-Resistance Mechanisms And New Horizons For Treatment</p>

“…At present, studies in humans and animals have shown that protection by vaccination is possible. Potential candidates for Shigella vaccines include glycoconjugate vaccines, such as recombinant glycoconjugate, synthetic glycoconjugate, O -polysaccharide covalently linked to immunogenic carrier proteins,177,178 virG-based live attenuated (WRSS1, WRSs3, WRSf3, WRSf2G12, WRSf2G15and WRSd1),179,180 recombinant outer-membrane proteins,181 live attenuated vaccines,182,183 invasion-plasmid antigens B, C, and D,184 DNA-based vaccines, Ty21a typhoid vaccine expressing Shigella LPS,185 recombinant probiotic–based candidates,186 and whole-cell-killed and Shigella trivalent inactivated whole-cell and heat-killed multiserotype Shigella ,187,188 as well as novel antigen candidates, such as triacylated S-LPS, subcellular complexes purified from virulent cultures (Invaplex),189 GMMA protein particles,190 and an OMV-NP vaccine (Table 3). 191…”

Classical and novel strategies to develop aShigellaglycoconjugate vaccine: from concept to efficacy in human

“…In contrast to purified high molecular weight capsular polysaccharides, which are well-established licensed vaccines for use in human, endotoxicity precludes the use of LPS as a parenterally administered immunogen. Instead, formulations whereby LPS toxicity is masked as in Invaplex, 29 reduced and even abolished as in GMMA 30 or encompassing LPS derivatives devoid of toxicity, especially in the form of protein conjugates, were investigated.…”