title: Antibodies to S. aureus LukS-PV Attenuated Subunit Vaccine Neutralize a Broad Spectrum of Canonical and Non-Canonical Bicomponent Leukotoxin Pairs.
abstract: S. aureus vaccine development has proven particularly difficult. The conventional approach to achieve sterile immunity through opsonophagocytic killing has been largely unsuccessful. S. aureus is highly toxigenic and a great body of evidence suggests that a successful future vaccine for this organism should target extracellular toxins which are responsible for host tissue destruction and immunosuppression. Major staphylococcal toxins are alpha toxin (a single subunit hemolysin) along with a group of bicomponent pore-forming toxins (BCPFT), namely Panton-Valentine leukocidin (PVL), gamma hemolysins (HlgCB and AB), LukAB and LukED. In our previous report, an attenuated mutant of LukS-PV (PVL- S subunit) named as "LukS-mut9" elicited high immunogenic response as well as provided a significant protection in a mouse sepsis model. Recent discovery of PVL receptors shows that mice lack receptors for this toxin, thus the reported protection of mice with the PVL vaccine may relate to cross protective responses against other homologous toxins. This manuscript addresses this issue by demonstrating that polyclonal antibody generated by LukS-mut9 can neutralize other canonical and non-canonical leukotoxin pairs. In this report, we also demonstrated that several potent toxins can be created by non-canonical pairing of subunits. Out of 5 pairs of canonical and 8 pairs of non-canonical toxins tested, anti-LukS-mut9 polyclonal antibodies neutralized all except for LukAB. We also studied the potential hemolytic activities of canonical and noncanonical pairs among biocomponent toxins and discovered that a novel non-canonical pair consisting of HlgA and LukD is a highly toxic combination. This pair can lyse RBC from different species including human blood far better than alpha hemolysin. Moreover, to follow-up our last report, we explored the correlation between the levels of pre-existing antibodies to new sets of leukotoxins subunits and clinical outcomes in adult patients with S. aureus bacteremia. We found that there is an inversed correlation between the antibody titer to sepsis for leukotoxins LukS-mut9, LukF-PV, HlgC, LukE and LukAB, suggesting the risk of sepsis was significantly lower in the patients with higher antibody titer against those toxins.
authors.affiliation: Integrated Biotherapeutics Inc., Gaithersburg, Maryland, United States of America.
authors.forename: Rajan P
authors.initials: RP
authors.lastname: Adhikari
authors.affiliation: Integrated Biotherapeutics Inc., Gaithersburg, Maryland, United States of America.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kort
authors.affiliation: Integrated Biotherapeutics Inc., Gaithersburg, Maryland, United States of America.
authors.forename: Sergey
authors.initials: S
authors.lastname: Shulenin
authors.affiliation: Integrated Biotherapeutics Inc., Gaithersburg, Maryland, United States of America.
authors.forename: Tulasikumari
authors.initials: T
authors.lastname: Kanipakala
authors.affiliation: Integrated Biotherapeutics Inc., Gaithersburg, Maryland, United States of America.
authors.forename: Nader
authors.initials: N
authors.lastname: Ganjbaksh
authors.affiliation: Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, Maryland, United States of America; VA Maryland Health Care System, Baltimore, Maryland, United States of America.
authors.forename: Mary-Claire
authors.initials: MC
authors.lastname: Roghmann
authors.affiliation: Integrated Biotherapeutics Inc., Gaithersburg, Maryland, United States of America.
authors.forename: Frederick W
authors.initials: FW
authors.lastname: Holtsberg
authors.affiliation: Integrated Biotherapeutics Inc., Gaithersburg, Maryland, United States of America.
authors.forename: M Javad
authors.initials: MJ
authors.lastname: Aman
mesh_terms: D000328:Adult; D000818:Animals; D000906:Antibodies / Q000276:immunology; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology* / Q000633:toxicity; D001427:Bacterial Toxins / Q000235:genetics / Q000276:immunology / Q000633:toxicity; D003429:Cross Reactions; D003601:Cytotoxicity Tests, Immunologic; D005098:Exotoxins / Q000235:genetics / Q000276:immunology / Q000633:toxicity; D005260:Female; D006801:Humans; D007956:Leukocidins / Q000235:genetics / Q000276:immunology* / Q000633:toxicity; D008807:Mice, Inbred BALB C; D008813:Mice, Inbred ICR; D009500:Neutralization Tests; D011817:Rabbits; D013203:Staphylococcal Infections / Q000382:microbiology; D013209:Staphylococcal Vaccines / Q000276:immunology* / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000276:immunology* / Q000472:pathogenicity; D014613:Vaccines, Attenuated / Q000276:immunology
chemical_list: D000906:Antibodies; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D005098:Exotoxins; D007956:Leukocidins; C115218:LukD protein, Staphylococcus aureus; C078284:Panton-Valentine leukocidin; D013209:Staphylococcal Vaccines; D014613:Vaccines, Attenuated; C586430:leukocidin AB, Staphylococcus aureus; C108483:leukocidin S-component protein, Staphylococcus