Immunization with non-replicating E. coli minicells delivering both protein antigen and DNA protects mice from lethal challenge with lymphocytic choriomeningitis virus

Abstract

In the midst of new investigations into the mechanisms of both delivery and protection of new vaccines and vaccine carriers, it has become clear that immunization with delivery mechanisms that do not involve living, replicating organisms are vastly preferred. In this report, non-replicating bacterial minicells simultaneously co-delivering the nucleoprotein (NP) of lymphocytic choriomeningitis virus (LCMV) and the corresponding DNA vaccine were tested for the ability to generate protective cellular immune responses in mice. It was found that good protection (89%) was achieved after intramuscular administration, moderate protection (31%) was achieved after intranasal administration, and less protection (7%) was achieved following gastric immunization. These results provide a solid foundation on which to pursue the use of bacterial minicells as a non-replicating vaccine delivery platform.

A highly optimized DNA vaccine confers complete protective immunity against high-dose lethal lymphocytic choriomeningitis virus challenge

“…At least eight weeks following the last immunization or infection, mice were challenged with a 20XLD 50 dose of LCMV Armstrong by the i.c. route, a dose at which protection in the LCMV model has been commonly assessed [21, 37, 40, 42, 45]. Figure 4 displays the data from the challenge study and survival statistics are shown for each group of mice.…”

“…For lethal challenge studies, mice were challenged i.c. with 20XLD 50 of LCMV Armstrong as previously described [21, 37, 40, 42, 45] in 30 μl of virus diluent (PBS with 20% FBS and 1X Anti-Anti (Invitrogen, Carlsbad, CA)). Mice were observed daily for 16 days, a time point known to be adequate in the LCMV i.c.…”

“…The former group consists of recombinant viral (vaccina virus expressing full-length, truncated, or poly-epitopes from NP and/or GP [18–22]; adenoviral vectors encoding NP proteins and epitopes [23, 24]; influenza [25] and Mengo [26] viruses expressing an NP epitope) or bacterial vectors ( L. monocytogenes expressing full-length NP [27]; recombinant strains of S. typhimurium expressing an NP epitope [28, 29] or a full-length Lassa NP [22]. Non-infectious vaccines have consisted of genetically detoxified CyaA toxoid proteins from B. pertussis containing an NP epitope [30, 31], recombinant Bluetongue virus (BTV) tubules containing a single NP epitope [32], hybrid recombinant parvovirus-like particles (VLP) vaccines expressing an NP epitope [33–35], listeriolysin O-containing liposomes with truncated NP [36], bacterial minicells derived from a non-pathogenic E. coli K-12 strain capable of the simultaneous delivery of both recombinant NP protein and the corresponding NP-encoding DNA vaccine [37], and various DNA vaccines expressing NP or GP [38–44] including one that was adjuvanted by encapsulation into liposomes [45]. …”

Nanosized Minicells Generated by Lactic Acid Bacteria for Drug Delivery

“…Minicells keep the rigid cell wall structure of 20 kinds of lipopolysaccharide like their parental bacteria [119]. The pathogen strains could produce minicells applied to vaccine but not complete safe for patient compared to lactic acid bacteria strains [120]. Therefore, minicells generated by lactic acid bacteria that are probiotic strain should be more interesting than others.…”

“…The polysaccharides associated with the bacterial cell walls and the extracellular polysaccharides of lactic acid bacteria are either neutral or acidic [120,121]. There are abundance polysaccharides at the outer surface of the cell wall and extracellular.…”