Browsing by Author "Vikas Kumar Somani"

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Cross-serotype protection against group A Streptococcal infections induced by immunization with SPy_2191
(Nature Research, 2020) Pooja Sanduja; Manish Gupta; Vikas Kumar Somani; Vikas Yadav; Meenakshi Dua; Emanuel Hanski; Abhinay Sharma; Rakesh Bhatnagar; Atul Kumar Johri
Group A Streptococcus (GAS) infection causes a range of diseases, but vaccine development is hampered by the high number of serotypes. Here, using reverse vaccinology the authors identify SPy_2191 as a cross-protective vaccine candidate. From 18 initially identified surface proteins, only SPy_2191 is conserved, surface-exposed and inhibits both GAS adhesion and invasion. SPy_2191 immunization in mice generates bactericidal antibodies resulting in opsonophagocytic killing of prevalent and invasive GAS serotypes of different geographical regions, including M1 and M49 (India), M3.1 (Israel), M1 (UK) and M1 (USA). Resident splenocytes show higher interferon-γ and tumor necrosis factor-α secretion upon antigen re-stimulation, suggesting activation of cell-mediated immunity. SPy_2191 immunization significantly reduces streptococcal load in the organs and confers ~76-92% protection upon challenge with invasive GAS serotypes. Further, it significantly suppresses GAS pharyngeal colonization in mice mucosal infection model. Our findings suggest that SPy_2191 can act as a universal vaccine candidate against GAS infections. © 2020, The Author(s).
Development of a novel multiepitope chimeric vaccine against anthrax
(Springer Verlag, 2019) Somya Aggarwal; Vikas Kumar Somani; Sonal Gupta; Rajni Garg; Rakesh Bhatnagar
Abstract: Bacillus anthracis (BA), the etiological agent of anthrax, secretes protective antigen (PA), lethal factor (LF), and edema factor (EF) as major virulence mediators. Amongst these, PA-based vaccines are most effective for providing immunity against BA, but their low shelf life limits their usage. Previous studies showed that B-cell epitopes, ID II and ID III present in PA domain IV possess higher toxin neutralization activity and elicit higher antibody titer than ID I. Moreover, N-terminal region of both LF and EF harbors PA-binding sites which share 100% identity with each other. Here, in this study, we have developed an epitope-based chimeric vaccine (ID–LFn) comprising ID II–ID III region of PA and N-terminal region of LF. We have also evaluated its protective efficacy as well as stability and found it to be more stable than PA-based vaccine. Binding reactivities of ID–LFn with anti-PA/LF/EF antibodies were determined by ELISA. The stability of chimeric vaccine was assessed using circular dichroism spectroscopy. ID–LFn response was characterized by toxin neutralization, lymphocyte proliferation isotyping and cytokine profiling. The protective efficacy was analyzed by challenging ID–LFn-immunized mice with B. anthracis (pXO1 + and pXO2 + ). ID–LFn was found to be significantly stable as compared to PA. Anti-ID–LFn antibodies recognized PA, LF as well as EF. The T-cell response and the protective efficacy of ID–LFn were found to be almost similar to PA. ID–LFn exhibits equal protective efficacy in mice and possesses more stability as compared to PA along with the capability of recognizing PA, LF and EF at the same time. Thus, it can be considered as an improved vaccine against anthrax with better shelf life. Graphical abstract: [Figure not available: see fulltext.] ID-LFn, a novel multiepitope chimeric anthrax vaccine: ID-LFn comprises of immunodominant epitopes of domain 4 of PA and N-terminal homologous stretch of LF and EF. The administration of this protein as a vaccine provides protection against anthrax. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.
Editorial: Understanding the impact of microbes on tumor progression and prevention: unveiling new avenues for cancer therapy
(Frontiers Media SA, 2025) Vikas Kumar Somani; Somya Aggarwal; Rajni Garg; Yoshiko Takeuchi; Samer Singh
[No abstract available]
Simultaneous immunization with omp25 and l7/l12 provides protection against brucellosis in mice
(MDPI AG, 2020) Sonal Gupta; Surender Mohan; Vikas Kumar Somani; Somya Aggarwal; Rakesh Bhatnagar
Currently used Brucella vaccines, Brucella abortus strain 19 and RB51, comprises of live attenuated Brucella strains and prevent infection in animals. However, these vaccines pose potential risks to recipient animals such as attenuation reversal and virulence in susceptible hosts on administration. In this context, recombinant subunit vaccines emerge as a safe and competent alternative in combating the disease. In this study, we formulated a divalent recombinant vaccine consisting of Omp25 and L7/L12 of B. abortus and evaluated vaccine potential individually as well as in combination. Sera obtained from divalent vaccine (Omp25+L7/L12) immunized mice group exhibited enhanced IgG titers against both components and indicated specificity upon immunoblotting reiterating its authenticity. Further, the IgG1/IgG2a ratio obtained against each antigen predicted a predominant Th2 immune response in the Omp25+L7/L12 immunized mice group. Upon infection with virulent B. abortus 544, Omp25+L7/L12 infected mice exhibited superior Log10 protection compared to individual vaccines. Consequently, this study recommends that simultaneous immunization of Omp25 and L7/L12 as a divalent vaccine complements and triggers a Th2 mediated immune response in mice competent of providing protection against brucellosis. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.