Salivary antigen SP32 is the immunodominant target of the antibody response to Phlebotomus papatasi bites in humans
Authors: Maha Abdeladhim
Mélika Ben Ahmed
Hechmi Louzir
Fabiano Oliveira
Chaouki Ben Abdessalem
Soumaya Marzouki
Beya Ferjani
Jesus G Valenzuela
Dana Gilmore
Journal: PLoS neglected tropical diseases (2012)
Discipline: IMMUNOLOGY
Keywords: Zoonotic cutaneous leishmaniasis; Phlebotomus papatasi; saliva; immunodominant protein; recombinant protein
Affiliations: Laboratory of Transmission, Control and Immunobiology of Infection, LR11IPT02, Institut Pasteur de Tunis, Tunis, Tunisie.

Abstract:  Background: Zoonotic cutaneous leishmaniasis (ZCL) due to Leishmania major is highly prevalent in Tunisia and is transmitted by a hematophagous vector Phlebotomus papatasi (P. papatasi). While probing for a blood meal, the sand fly injects saliva into the host's skin, which contains a variety of compounds that are highly immunogenic. We recently showed that the presence of anti-saliva antibodies was associated with an enhanced risk for leishmaniasis and identified the immunodominant salivary protein of Phlebotomus papatasi as a protein of approximately 30 kDa. Methodology/principal findings: We cloned and expressed in mammalian cells two salivary proteins PpSP30 and PpSP32 with predicted molecular weights close to 30 kDa from the Tunisian strain of P. papatasi. The two recombinant salivary proteins were purified by two-step HPLC (High-Performance Liquid Chromatography) and tested if these proteins correspond to the immunodominant antigen of 30 kDa previously shown to be recognized by human sera from endemic areas for ZCL and exposed naturally to P. papatasi bites. While recombinant PpSP30 (rPpSP30) was poorly recognized by human sera from endemic areas for ZCL, rPpSP32 was strongly recognized by the tested sera. The binding of human IgG antibodies to native PpSP32 was inhibited by the addition of rPpSP32. Consistently, experiments in mice showed that PpSP32 induced the highest levels of antibodies compared to other P. papatasi salivary molecules while PpSP30 did not induce any detectable levels of antibodies. Conclusions: Our findings demonstrate that PpSP32 is the immunodominant target of the antibody response to P. papatasi saliva. They also indicate that the recombinant form of PpSP32 is similar to the native one and represents a good candidate for large scale testing of human exposure to P. papatasi bites and perhaps for assessing the risk of contracting the disease. 

Retracted: No

PubPeer comments:
 Figure 7A. The S+ and S- panels appear to be unexpectedly similar. Image exposure made darker to bring out details. Could the authors please check? ![file] , 
 Dear Elisabeth We deeply apologize for this oversight, it was definitely unintentionally and probably it happened while we were preparing the figure 7 and we did not notice this. Here is the original figure showing the lack of reactivity of the positive and negative sera against rPpSP30. We are very grateful for letting us know of this mistake and for your interest to our work to make it better. Please find attached the original gels and the new figure 7 Regards ![file] ![file] , 
 Dear Dr. Marzouki, thank you so much for showing the original figure. Much appreciated. Can you give us an update, please? Did you contact the journal for a correction? ,