Enhanced protective efficacy of nonpathogenic recombinant leishmania tarentolae expressing cysteine proteinases combined with a sand fly salivary antigen
Authors: Yasaman Taslimi
Elham Gholami
Barbara Papadopoulou
Shaden Kamhawi
Tahereh Taheri
Sima Rafati
Claudio Meneses
Negar Seyed
Jesus G Valenzuela
Fatemeh Torkashvand
Fatemeh Doustdari
Farnaz Zahedifard
Journal: PLoS Neglected Tropical Diseases (2014)
Discipline: IMMUNOLOGY
Keywords: vaccination approaches; leishmaniasis; live attenuated vaccines; Leishmania; lizard protozoan parasite
Affiliations: Molecular Immunology and Vaccine Research Laboratory, Pasteur Institute of Iran, Tehran, Iran., Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran., Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institute of Health, Rockville, Maryland, United States of America., Research Centre in Infectious Disease, CHUL Research Centre (CHU de Québec Research Centre) and Department of Microbiology, Infectious Disease and Immunology, Laval University, Quebec, Canada.

Abstract:  Background: Novel vaccination approaches are needed to prevent leishmaniasis. Live attenuated vaccines are the gold standard for protection against intracellular pathogens such as Leishmania and there have been new developments in this field. The nonpathogenic to humans lizard protozoan parasite, Leishmania (L) tarentolae, has been used effectively as a vaccine platform against visceral leishmaniasis in experimental animal models. Correspondingly, pre-exposure to sand fly saliva or immunization with a salivary protein has been shown to protect mice against cutaneous leishmaniasis. Methodology/principal findings: Here, we tested the efficacy of a novel combination of established protective parasite antigens expressed by L. tarentolae together with a sand fly salivary antigen as a vaccine strategy against L. major infection. The immunogenicity and protective efficacy of different DNA/Live and Live/Live prime-boost vaccination modalities with live recombinant L. tarentolae stably expressing cysteine proteinases (type I and II, CPA/CPB) and PpSP15, an immunogenic salivary protein from Phlebotomus papatasi, a natural vector of L. major, were tested both in susceptible BALB/c and resistant C57BL/6 mice. Both humoral and cellular immune responses were assessed before challenge and at 3 and 10 weeks after Leishmania infection. In both strains of mice, the strongest protective effect was observed when priming with PpSP15 DNA and boosting with PpSP15 DNA and live recombinant L. tarentolae stably expressing cysteine proteinase genes. Conclusion/significance: The present study is the first to use a combination of recombinant L. tarentolae with a sand fly salivary antigen (PpSP15) and represents a novel promising vaccination approach against leishmaniasis. 

Retracted: No

PubPeer comments:
 Figure 4C shows photos of mouse footpads infected with fluorescent L. major.. G1-G6 represent 6 different mouse groups receiving different types of Leishmania vaccines or controls. Four photos representing footpads of Group 3 (G3) mice (L. tarentolae live + DNA vaccination, L. major challenge) look remarkably similar to footpads of Group 5 (G5) mice (VR1020-SP15 DNA vaccination, L. major challenge). Highlighted with boxes of the same color. Of note, the intensities of the green color is higher in some photos in the G5 column than in the G3 column, suggesting that these are not simple duplications. Could the authors please check? ![file] , 
 #1 We checked the photographs of G3 and G5 in Fig 4C. There were too many pictures and we have made mistake for G3. The modified version for Fig 4C is attached and only four photos are now changed for G3. The other groups especially G5 is correct.![file] , 
 February 2021, Expression of Concern: https: journals.plos.org plosntds article?id=10.1371 journal.pntd.0009123 From the notice:  Following publication of this article [1], concerns were raised about duplication of image panels in Fig 4C. Due to an error in assembly of the originally published Fig 4C, image panels in Group G3 rows 2, 3, 4 and 6 are incorrect, showing images from the same samples as Group G5 rows 1, 2, 3, and 5, respectively. A revised Fig 4 is provided using the correct Group G3 images and a replacement Group G5 row 2 panel, all from the original experiment.  n addition, concerns were raised that in the originally published figure, the images in Group G3, row 3 (G3M3), and Group G5, row 2 (G5M2), are highly similar, but the two images differ in fluorescence intensity of the marked heel region on the right-hand side of the image panel. Upon editorial follow-up, the authors provided two different versions of underlying image files for the G5M2 sample (A and B versions, S1 File), which differ in fluorescence intensity of the heel region on the right-hand side of the image. The authors commented that differing fluorescence may be explained by the application of normalization procedures to reduce background autofluorescence (please see S2 File for a description of image acquisition and analysis methodology); image analysis parameters were adjusted using a normal mouse footpad as reference, and this normalization was applied to all images in the experiment. The dimmer u201cBu201d version of the G5M2 image is reported by the authors to be a pre-normalization image saved erroneously, while the brighter u201cAu201d version is considered consistent with the image after normalization is applied. Neither of the two underlying images are identical to the image used in the G5M2 panel of the originally published Fig 4C, and it has not been possible to reproduce the identical image because the original instrument is unavailable and the precise settings used are not known. In the revised Fig 4, the G5M2 panel has been replaced using the G5M2 u201cAu201d underlying image. Review of the underlying data was carried out in consultation with an independent expert who advised that to fully clarify this issue we would require the original .BIP files captured at the time of image analysis. However, the raw .BIP files and the full information about parameter settings used at the time of the original analysis are not available. In the absence of the raw data, it has not been possible to fully clarify the reason(s) underlying the differences between the images of the G5M2 footpad, and we have been unable to verify how the images reported in the figure align with the original experimental output. The authors stated that all intensity data used for the chart and statistical analysis in Fig 4D are derived from the raw quantitative data output of the imaging instrument and are unaffected by any adjustments to images in Fig 4C. The available quantitative data (S3 File) and processed image files (TIFFs, S4 File) for Fig 4 are provided here as Supporting Information. Individual-level data underlying the chart in Fig 4A are unavailable. All other underlying data for the article are available from the corresponding author upon request. In light of the concerns about the reporting of image data in Fig 4C, which could not be fully clarified because the raw image data are not available, the PLOS Publication Ethics Editors issue this Expression of Concern. ,