Search

Staphylococcus aureus is the leading cause of skin and soft tissue infections (SSTIs) in the U.S. as well as more serious invasive diseases, including bacteremia, sepsis, endocarditis, surgical site infections, osteomyelitis, and pneumonia. These infections are exacerbated by the emergence of antibiotic-resistant clinical isolates such as methicillin-resistant S. aureus (MRSA), highlighting the need for alternatives to antibiotics to treat bacterial infections. We have previously developed a multi-component toxoid vaccine (IBT-V02) in a liquid formulation with efficacy against multiple strains of Staphylococcus aureus prevalent in the industrialized world. However, liquid vaccine formulations are not compatible with the paucity of cold chain storage infrastructure in many low-to-middle income countries (LMICs). Furthermore, whether our IBT-V02 vaccine formulations are protective against S. aureus isolates from LMICs is unknown. To overcome these limitations, we developed lyophilized and spray freeze-dried formulations of IBT-V02 vaccine and demonstrated that both formulations had comparable biophysical attributes as the liquid formulation, including similar levels of toxin neutralizing antibodies and protective efficacy against MRSA infections in murine and rabbit models. To enhance the relevancy of our findings, we then performed a multi-dimensional screen of 83 S. aureus clinical isolates from LMICs (e.g., Democratic Republic of Congo, Palestine, and Cambodia) to rationally down-select strains to test in our in vivo models based on broad expression of IBT-V02 targets (i.e., pore-forming toxins and superantigens). IBT-V02 polyclonal antisera effectively neutralized toxins produced by the S. aureus clinical isolates from LMICs. Notably, the lyophilized IBT-V02 formulation exhibited significant in vivo efficacy in various preclinical infection models against the S. aureus clinical isolates from LMICs, which was comparable to our liquid formulation. Collectively, our findings suggested that lyophilization is an effective alternative to liquid vaccine formulations of our IBT-V02 vaccine against S. aureus infections, which has important implications for protection from S. aureus isolates from LMICs., Competing Interests: Authors IM, AV, RO, MM, SS, TK, RA, HK and MJ were employed by company Integrated Biotherapeutics Inc. Author MK was employed by company Engineered Biopharmaceuticals. Author NA has received previous grant support from Pfizer and Boehringer Ingelheim and has been a paid consultant for Janssen Pharmaceuticals. MJ and RA have stocks in Razi Holdings, Inc. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Wang, Mukherjee, Venkatasubramaniam, Dikeman, Orlando, Zhang, Ortines, Mednikov, Sherchand, Kanipakala, Le, Shukla, Ketner, Adhikari, Karauzum, Aman and Archer.)

Staphylococcus aureus has been acquiring multiple drug resistance and has evolved into superbugs such as Methicillin/Vancomycin-resistant S. aureus (MRSA/VRSA) and, consequently, is a major cause of nosocomial and community infections associated with high morbidity and mortality for which no FDA-approved vaccines or biotherapeutics are available. Previous efforts targeting the surface-associated antigens have failed in clinical testing. Here, we generated hyperimmune products from sera in rabbits against six major S. aureus toxins targeted by an experimental vaccine (IBT-V02) and demonstrated significant efficacy for an anti-virulence passive immunization strategy. Extensive in vitro binding and neutralizing titers were analyzed against six extracellular toxins from individual animal sera. All IBT-V02 immunized animals elicited the maximum immune response upon the first boost dose against all pore-forming vaccine components, while for superantigen (SAgs) components of the vaccine, second and third doses of a boost were needed to reach a plateau in binding and toxin neutralizing titers. Importantly, both anti-staphylococcus hyperimmune products consisting of full-length IgG (IBT-V02-IgG) purified from the pooled sera and de-speciated F(ab') 2 (IBT-V02-F(ab')2) retained the binding and neutralizing titers against IBT-V02 target toxins. F(ab') 2 also exhibited cross-neutralization titers against three leukotoxins (HlgAB, HlgCB, and LukED) and four SAgs (SEC1, SED, SEK, and SEQ) which were not part of IBT-V02. F(ab') 2 also neutralized toxins in bacterial culture supernatant from major clinical strains of S. aureus . In vivo efficacy data generated in bacteremia and pneumonia models using USA300 S. aureus strain demonstrated dose-dependent protection by F(ab') 2 . These efficacy data confirmed the staphylococcal toxins as viable targets and support the further development effort of hyperimmune products as a potential adjunctive therapy for emergency uses against life-threatening S. aureus infections., Competing Interests: RA and MA have stocks in Integrated Biotherapeutics Inc. RO, ThK, TuK, SS, GL, AC, MA, and RA are the currently employed by IBT. IM and MM were IBT employees when the study was conducted. Similarly, CN is currently employed by Emergent, and XH was employed by Emergent when the data was generated. Both have stock options in Emergent BioSolutions., (Copyright © 2022 Han, Ortines, Mukherjee, Kanipakala, Kort, Sherchand, Liao, Mednikov, Chenine, Aman, Nykiforuk and Adhikari.)

Staphylococcus aureus causes a wide range of diseases from skin infections to life threatening invasive diseases such as bacteremia, endocarditis, pneumonia, surgical site infections, and osteomyelitis. Skin infections such as furuncles, carbuncles, folliculitis, erysipelas, and cellulitis constitute a large majority of infections caused by S. aureus (SA). These infections cause significant morbidity, healthcare costs, and represent a breeding ground for antimicrobial resistance. Furthermore, skin infection with SA is a major risk factor for invasive disease. Here we describe the pre-clinical efficacy of a multicomponent toxoid vaccine (IBT-V02) for prevention of S. aureus acute skin infections and recurrence. IBT-V02 targets six SA toxins including the pore-forming toxins alpha hemolysin (Hla), Panton-Valentine leukocidin (PVL), leukocidin AB (LukAB), and the superantigens toxic shock syndrome toxin-1 and staphylococcal enterotoxins A and B. Immunization of mice and rabbits with IBT-V02 generated antibodies with strong neutralizing activity against toxins included in the vaccine, as well as cross-neutralizing activity against multiple related toxins, and protected against skin infections by several clinically relevant SA strains of USA100, USA300, and USA1000 clones. Efficacy of the vaccine was also shown in non-naïve mice pre-exposed to S. aureus . Furthermore, vaccination with IBT-V02 not only protected mice from a primary infection but also demonstrated lasting efficacy against a secondary infection, while prior challenge with the bacteria alone was unable to protect against recurrence. Serum transfer studies in a primary infection model showed that antibodies are primarily responsible for the protective response., Competing Interests: MA and HK have stocks and RA and FH have stock options in Integrated Biotherapeutics Inc. JL serves on the Scientific Advisory Board of Integrated BioTherapeutics. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Karauzum, Venkatasubramaniam, Adhikari, Kort, Holtsberg, Mukherjee, Mednikov, Ortines, Nguyen, Doan, Diep, Lee and Aman.)