Toward the Development of an Antidisease, Transmission‐Blocking Intranasal Vaccine for Group A Streptococcus

Abstract

Infection with group A streptococcus (GAS) may result in a number of clinical conditions, including the potentially life-threatening postinfectious sequelae of rheumatic fever and rheumatic heart disease. As part of the search for a vaccine to prevent GAS infection, a conformationally constrained and minimally conserved peptide, J14, from the M protein of GAS has been defined. In the present study, J14 was formulated with bacterial outer membrane proteins (proteosomes) and then intranasally administered to outbred mice without additional adjuvant. Such immunization led to high titers of J14-specific serum immunoglobulin (Ig) G and mucosal IgA. After upper respiratory tract GAS challenge, immunized mice demonstrated increased survival and reduced GAS colonization of the throat.

An efficient, chemically-defined semisynthetic lipid-adjuvanted nanoparticulate vaccine development system

“…17 Antibody titers were defined as the lowest dilution with an OD450 value greater than three standard deviations above the mean absorbance of control wells (sera from PBS immunized mice). ELISA data ( Figure 4) is expressed as mean antigen--specific IgG antibody titer.…”

“…A 'string--of--beads' (polytope) approach was used (1, Figure 2, A) to link seven strain--specific N--terminal M protein antigens, from GAS isolates prevalent in the Australian Aboriginal population of the Northern Territory, 18 to a conserved M protein conformational B cell epitope (J14i; bold sequence in J14), which is flanked by peptides designed to promote its native α--helical structure (J14: KQAEDKVKASREAKKQVEKALEQLEDKVK). 17 Several of these antigens, when administered as part of a synthetic LCP system, have been demonstrated to elicit long--lasting antibody mediated immunity in murine preclinical models. 21 A universal source of T cell help (PADRE 1024.03) 22 was also included to aid memory B cell production in genetically diverse populations (e.g.…”

JJo, a Recombinant Dimer of Conformationally Restricted Peptide Elicits Protective Response against Group A Streptococcus (GAS) Isolates from a GAS-Endemic Region

“…On day 50, C3HeJ mice were challenged intraperitoneally with a pre-determined minimal lethal dose, following previously described methods [16]. To enhance virulence for these experiments, GAS isolates were serially passaged several times in mice [17].…”

“…Bactericidal assays were performed as described previously [16], GAS isolates were cultured overnight in Todd-Hewitt broth at 37˚C. Fifty μl of the diluted culture (10 5 ) were mixed with 50 μl of serum (normal or immune serum from B10BR, Quackenbush and C3HeJ mice) and then the mixture was incubated for 3 hrs at 37˚C with end-over-end mixing with 400 μl of non-opsonic human blood which supports growths of GAS by > 32 times [17].…”

“…Earlier studies [16] showed that J14, a conformational restricted peptide antigen which is genetically restricted, offered protection against GAS infection when conjugated to diphtheria toxoid. However, J14 lost its immunogenicity when it was expressed with a fusion partner in a recombinant construct [10].…”