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Lutzomyia longipalpis saliva or salivary protein LJM19 protects against Leishmania braziliensis and the saliva of its vector, Lutzomyia intermedia.

Tavares NM, Silva RA, Costa DJ, Pitombo MA, Fukutani KF, Miranda JC, Valenzuela JG, Barral A, de Oliveira CI, Barral-Netto M, Brodskyn C - PLoS Negl Trop Dis (2011)

Bottom Line: Animals immunized with Lu. longipalpis saliva exhibited smaller lesion sizes as well as reduced disease burdens both at lesion site and in the draining lymph nodes.These alterations were associated with a significant decrease in the expression levels of IL-10 and TGF-β.These findings point out an important role of immune response against saliva components, suggesting the possibility to develop a vaccine using a single component of Lu. longipalpis saliva to generate protection against different species of Leishmania, even those transmitted by a different vector.

View Article: PubMed Central - PubMed

Affiliation: Centro de Pesquisa Gonçalo Moniz, FIOCRUZ, Salvador, Bahia, Brazil.

ABSTRACT

Background: Leishmania transmission occurs in the presence of insect saliva. Immunity to Phlebotomus papatasi or Lutzomyia longipalpis saliva or salivary components confers protection against an infection by Leishmania in the presence of the homologous saliva. However, immunization with Lutzomyia intermedia saliva did not protect mice against Leishmania braziliensis plus Lu. intermedia saliva. In the present study, we have studied whether the immunization with Lu. longipalpis saliva or a DNA plasmid coding for LJM19 salivary protein would be protective against L. braziliensis infection in the presence of Lu. intermedia saliva, the natural vector for L. braziliensis.

Methodology/principal findings: Immunization with Lu. longipalpis saliva or with LJM19 DNA plasmid induced a Delayed-Type Hypersensitivity (DTH) response against Lu. longipalpis as well as against a Lu. intermedia saliva challenge. Immunized and unimmunized control hamsters were then intradermally infected in the ears with L. braziliensis in the presence of Lu. longipalpis or Lu. intermedia saliva. Animals immunized with Lu. longipalpis saliva exhibited smaller lesion sizes as well as reduced disease burdens both at lesion site and in the draining lymph nodes. These alterations were associated with a significant decrease in the expression levels of IL-10 and TGF-β. Animals immunized with LJM19 DNA plasmid presented similar findings in protection and immune response and additionally increased IFN-γ expression.

Conclusions/significance: Immunization with Lu. longipalpis saliva or with a DNA plasmid coding LJM19 salivary protein induced protection in hamsters challenged with L. braziliensis plus Lu. intermedia saliva. These findings point out an important role of immune response against saliva components, suggesting the possibility to develop a vaccine using a single component of Lu. longipalpis saliva to generate protection against different species of Leishmania, even those transmitted by a different vector.

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Ear thickness and parasite load in Lu. longipalpis SGS immunized hamsters following infection with L. braziliensis.Hamsters were inoculated three times in the right ear dermis with Lu. longipalpis SGS (closed symbols) or with saline (open symbols) and were infected in the left ear with 105 L. braziliensis stationary promastigotes in the presence of Lu. intermedia SGS (squares; 7 hamsters per group total) or Lu. longipalpis SGS (circles, 8 hamsters per group total). The course of lesion development was monitored weekly (A). The points represent the means and the vertical bars represent standard errors of the means. The areas contained under the curves (AUC) obtained in A for each group was compared (B). The parasite number in the ear (C, D) or draining lymph node (E, F) was evaluated by Limiting Dilution Assay (LDA), estimated by ELIDA in 3, 5 and 8 weeks after the infection. Each bar represents the mean and the vertical bars represent standard errors of the means. The disease burden of the ear (C) or draining lymph node (E) show reduced parasite load in immunized hamsters evaluated by Mann-Whitney non-parametric t test. The areas contained under the curves (AUC) obtained in C and E for each group was compared (D, F) and the experiments were repeated five times. *p<0.05; **p<0.01.
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pntd-0001169-g002: Ear thickness and parasite load in Lu. longipalpis SGS immunized hamsters following infection with L. braziliensis.Hamsters were inoculated three times in the right ear dermis with Lu. longipalpis SGS (closed symbols) or with saline (open symbols) and were infected in the left ear with 105 L. braziliensis stationary promastigotes in the presence of Lu. intermedia SGS (squares; 7 hamsters per group total) or Lu. longipalpis SGS (circles, 8 hamsters per group total). The course of lesion development was monitored weekly (A). The points represent the means and the vertical bars represent standard errors of the means. The areas contained under the curves (AUC) obtained in A for each group was compared (B). The parasite number in the ear (C, D) or draining lymph node (E, F) was evaluated by Limiting Dilution Assay (LDA), estimated by ELIDA in 3, 5 and 8 weeks after the infection. Each bar represents the mean and the vertical bars represent standard errors of the means. The disease burden of the ear (C) or draining lymph node (E) show reduced parasite load in immunized hamsters evaluated by Mann-Whitney non-parametric t test. The areas contained under the curves (AUC) obtained in C and E for each group was compared (D, F) and the experiments were repeated five times. *p<0.05; **p<0.01.

Mentions: The onset of lesion development in naive hosts was at two weeks post-infection and lesions progressed until 12 weeks (data not shown), confirming the high susceptibility of hamsters to Leishmania infection [9], [16], [17]. After this period, the animals were euthanized due to the lesions severity. Disease burden was calculated by weekly measure of ear thickness and by comparison of the area under the resulting curves, as explained in statistical analysis section in Material and Methods. Immunization with Lu. longipalpis SGS resulted in significantly (p = 0.011) smaller ear thickness following challenge with parasites plus Lu. intermedia SGS as compared to the control group (Fig. 2A–B). The mean of ear thickness ranged between 0.5 mm and 1.0 mm in immunized hamsters during the infection compared with the range of 1.0 mm to 2.0 mm in the control group (Fig. 2A). Parasite load in the ear (from 1.4×108 in unimmunized group to 1.1×107 in immunized group, p = 0.029) and in the lymph node (from 4.6×108 to 9.0×105, p = 0.001) was also significantly reduced in this group (Fig. 2C–F). No significant differences in ear thickness were observed in the group challenged with parasites plus Lu. longipalpis SGS (Fig 2A–B). However, there was a significant reduction in ear (from 1.7×108 to 2×107, p = 0.036) and lymph node (from 8×107 to 4.6×106, p = 0.009) parasite load in this group (Fig. 2C–F).


Lutzomyia longipalpis saliva or salivary protein LJM19 protects against Leishmania braziliensis and the saliva of its vector, Lutzomyia intermedia.

Tavares NM, Silva RA, Costa DJ, Pitombo MA, Fukutani KF, Miranda JC, Valenzuela JG, Barral A, de Oliveira CI, Barral-Netto M, Brodskyn C - PLoS Negl Trop Dis (2011)

Ear thickness and parasite load in Lu. longipalpis SGS immunized hamsters following infection with L. braziliensis.Hamsters were inoculated three times in the right ear dermis with Lu. longipalpis SGS (closed symbols) or with saline (open symbols) and were infected in the left ear with 105 L. braziliensis stationary promastigotes in the presence of Lu. intermedia SGS (squares; 7 hamsters per group total) or Lu. longipalpis SGS (circles, 8 hamsters per group total). The course of lesion development was monitored weekly (A). The points represent the means and the vertical bars represent standard errors of the means. The areas contained under the curves (AUC) obtained in A for each group was compared (B). The parasite number in the ear (C, D) or draining lymph node (E, F) was evaluated by Limiting Dilution Assay (LDA), estimated by ELIDA in 3, 5 and 8 weeks after the infection. Each bar represents the mean and the vertical bars represent standard errors of the means. The disease burden of the ear (C) or draining lymph node (E) show reduced parasite load in immunized hamsters evaluated by Mann-Whitney non-parametric t test. The areas contained under the curves (AUC) obtained in C and E for each group was compared (D, F) and the experiments were repeated five times. *p<0.05; **p<0.01.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3104964&req=5

pntd-0001169-g002: Ear thickness and parasite load in Lu. longipalpis SGS immunized hamsters following infection with L. braziliensis.Hamsters were inoculated three times in the right ear dermis with Lu. longipalpis SGS (closed symbols) or with saline (open symbols) and were infected in the left ear with 105 L. braziliensis stationary promastigotes in the presence of Lu. intermedia SGS (squares; 7 hamsters per group total) or Lu. longipalpis SGS (circles, 8 hamsters per group total). The course of lesion development was monitored weekly (A). The points represent the means and the vertical bars represent standard errors of the means. The areas contained under the curves (AUC) obtained in A for each group was compared (B). The parasite number in the ear (C, D) or draining lymph node (E, F) was evaluated by Limiting Dilution Assay (LDA), estimated by ELIDA in 3, 5 and 8 weeks after the infection. Each bar represents the mean and the vertical bars represent standard errors of the means. The disease burden of the ear (C) or draining lymph node (E) show reduced parasite load in immunized hamsters evaluated by Mann-Whitney non-parametric t test. The areas contained under the curves (AUC) obtained in C and E for each group was compared (D, F) and the experiments were repeated five times. *p<0.05; **p<0.01.
Mentions: The onset of lesion development in naive hosts was at two weeks post-infection and lesions progressed until 12 weeks (data not shown), confirming the high susceptibility of hamsters to Leishmania infection [9], [16], [17]. After this period, the animals were euthanized due to the lesions severity. Disease burden was calculated by weekly measure of ear thickness and by comparison of the area under the resulting curves, as explained in statistical analysis section in Material and Methods. Immunization with Lu. longipalpis SGS resulted in significantly (p = 0.011) smaller ear thickness following challenge with parasites plus Lu. intermedia SGS as compared to the control group (Fig. 2A–B). The mean of ear thickness ranged between 0.5 mm and 1.0 mm in immunized hamsters during the infection compared with the range of 1.0 mm to 2.0 mm in the control group (Fig. 2A). Parasite load in the ear (from 1.4×108 in unimmunized group to 1.1×107 in immunized group, p = 0.029) and in the lymph node (from 4.6×108 to 9.0×105, p = 0.001) was also significantly reduced in this group (Fig. 2C–F). No significant differences in ear thickness were observed in the group challenged with parasites plus Lu. longipalpis SGS (Fig 2A–B). However, there was a significant reduction in ear (from 1.7×108 to 2×107, p = 0.036) and lymph node (from 8×107 to 4.6×106, p = 0.009) parasite load in this group (Fig. 2C–F).

Bottom Line: Animals immunized with Lu. longipalpis saliva exhibited smaller lesion sizes as well as reduced disease burdens both at lesion site and in the draining lymph nodes.These alterations were associated with a significant decrease in the expression levels of IL-10 and TGF-β.These findings point out an important role of immune response against saliva components, suggesting the possibility to develop a vaccine using a single component of Lu. longipalpis saliva to generate protection against different species of Leishmania, even those transmitted by a different vector.

View Article: PubMed Central - PubMed

Affiliation: Centro de Pesquisa Gonçalo Moniz, FIOCRUZ, Salvador, Bahia, Brazil.

ABSTRACT

Background: Leishmania transmission occurs in the presence of insect saliva. Immunity to Phlebotomus papatasi or Lutzomyia longipalpis saliva or salivary components confers protection against an infection by Leishmania in the presence of the homologous saliva. However, immunization with Lutzomyia intermedia saliva did not protect mice against Leishmania braziliensis plus Lu. intermedia saliva. In the present study, we have studied whether the immunization with Lu. longipalpis saliva or a DNA plasmid coding for LJM19 salivary protein would be protective against L. braziliensis infection in the presence of Lu. intermedia saliva, the natural vector for L. braziliensis.

Methodology/principal findings: Immunization with Lu. longipalpis saliva or with LJM19 DNA plasmid induced a Delayed-Type Hypersensitivity (DTH) response against Lu. longipalpis as well as against a Lu. intermedia saliva challenge. Immunized and unimmunized control hamsters were then intradermally infected in the ears with L. braziliensis in the presence of Lu. longipalpis or Lu. intermedia saliva. Animals immunized with Lu. longipalpis saliva exhibited smaller lesion sizes as well as reduced disease burdens both at lesion site and in the draining lymph nodes. These alterations were associated with a significant decrease in the expression levels of IL-10 and TGF-β. Animals immunized with LJM19 DNA plasmid presented similar findings in protection and immune response and additionally increased IFN-γ expression.

Conclusions/significance: Immunization with Lu. longipalpis saliva or with a DNA plasmid coding LJM19 salivary protein induced protection in hamsters challenged with L. braziliensis plus Lu. intermedia saliva. These findings point out an important role of immune response against saliva components, suggesting the possibility to develop a vaccine using a single component of Lu. longipalpis saliva to generate protection against different species of Leishmania, even those transmitted by a different vector.

Show MeSH
Related in: MedlinePlus