Nucleosomal histone proteins of L. donovani: a combination of recombinant H2A, H2B, H3 and H4 proteins were highly immunogenic and offered optimum prophylactic efficacy against Leishmania challenge in hamsters
Authors: Rati Tandon
Amogh A Sahasrabuddhe
Rajendra K Baharia
Anuradha Dube
Shyam Sundar
Journal: PLoS ONE (2014)
Discipline: Multidisciplinary
Keywords: cloning; expression; recombinant proteins; immunogenicity; Leishmania donovani

Abstract:  The present study includes cloning and expression of recombinant Leishmania donovani histone proteins (rLdH2B, rLdH3, rLdH2A and rLdH4), assessment of their immunogenicity in Leishmania infected cured patients/endemic contacts as well as in cured hamsters and finally evaluation of their prophylactic efficacy in hamsters against L. donovani challenge. All recombinant proteins were expressed and purified from the heterologous bacterial host system. Leishmania infected cured patients/endemic contacts as well as cured hamsters exhibited significantly higher proliferative responses to individual recombinant histones and their pooled combination (rLdH2B+rLdH3+rLdH2A+rLdH4) than those of L.donovani infected hosts. The L.donovani soluble antigens (SLD) stimulated PBMCs of cured/exposed and Leishmania patients to produce a mixed Thl/Th2-type cytokine profile, whereas rLdH2B, rLdH3, rLdH2A, rLdH4 and pooled combination (rLdH2-4) stimulated the production of Th1 cytokines IFN-γ, IL-12 and TNF-α but not Th2 cytokines IL-4 or IL-10. The immunogenicity of these histone proteins along with their combination was also checked in cured hamsters where they stimulated higher lymphoproliferation and Nitric oxide production in lymphocytes of cured hamsters than that of infected controls. Moreover, significantly increased IgG2 response, an indicative of cell mediated immunity, was observed in cured hamsters against these individual proteins and their combination as compared to infected hamsters. Further, it was demonstrated that rLdH2B, rLdH3, rLdH2A and rLdH4 and pooled combination were able to provide considerable protection for hamsters against L. donovani challenge. The efficacy was supported by the increased inducible Nitric Oxide Synthase (iNOS) mRNA transcripts and Th1-type cytokines--IFN-γ, IL-12 and TNF-α and down-regulation of IL-4, IL-10 and TGF-β. Hence, it is inferred that pooled rLdH2-4 elicits Thl-type of immune responses exclusively and confer considerable protection against experimental Visceral Leishmaniasis. 

Retracted: No

PubPeer comments:
null, 
 This anomaly in Figure 1 has been communicated by the journal PlosOne in the year 2014-15 for the clarification and asked for crude images. We had responded with all the original and crude images of the Figure 1 for publishing it as an erratum. The Journal replied that it will be reviewed by the review committee and if necessary will contact the academic editor who handled the manuscript. Following this, the journal did not raise any further query, but at the same time the journal did not take any action on its part. We have recently requested again to the Journal for publishing figure 1 as an erratum. Nevertheless, it may be observed that this anomaly has not affected the conclusion of the study. However, we regret the inadvertent oversight of the figure 1 during the processing of the publication. Given below is the original crude image of the figure 1 we shared with journal for erratum. ![file] ![file] By Dr Anuradha Dube (corresponding author) , 
 May 20, 2021 Correction found here: https: journals.plos.org plosone article?id=10.1371 journal.pone.0252177 From the Correction Notice:  After publication of this article [1], concerns were raised about Fig 1: Panels a, b, and d appear to present the same image. Panels k and l appear to present the same image. There appear to be discontinuities suggestive of image splicing in panels c (after M lane), f (after lanes labelled M, 3), i (after lanes labelled 1, 2), j, k, l (for j-l, discontinuities are before and after the lane labelled 1). The M Lane appears similar in panels j, k, l. The authors noted that the whole panel duplications resulted from errors in figure preparation. With this notice, the authors provide an updated version of Fig 1 and its legend. In the updated figure, panels b, c, d, k and l have been replaced with the correct images from the original experiments. Raw image data supporting the updated figure are in S1 File. Panels f-h have been replaced with photos of the original full-sized gels. Comparing the new versus original versions of panels f-h one can see where lanes were spliced out of panels f, g, h when the original published figure was prepared. The authors apologize for not having noted the splice lines on the original figure or in the accompanying legend. They did not provide clarifications in regard to the other image splicing concerns or the similarities in marker lanes between panels j and k, l. As noted in the article [1], this study involved minor participants. Parents provided informed consent for these participants. The individual-level data underlying other results reported in this article are no longer available. ,