Immunological responses of naturally infected dogs to Type I and II recombinant cysteine proteinases of Leishmania infantum

Purpose: Evaluation of humoral and cellular immune responses of naturally infected dogs against type I (rCPB) (Recombinant cycsteine proteinase B), and II (rCPA) (Recombinant cycsteine proteinase A) recombinant cysteine proteinases and C-terminal extension (CTE) of Leishmania infantum (L. infantum). Materials and Methods: In this study, fourteen infected dogs (۷ with symptoms, ۷ asymptomatics) from an endemic area and three uninfected dogs from a nonendemic region were selected and their humoral and cellular responses against type I and II recombinant cysteine proteinases, C-terminal extension (CTE) and F/T of Leishmania infantum were evaluated using the ELISA and lymphocyte proliferation assay, respectively. The level of specific IgG isotypes (IgG۱ and IgG۲) and lymphocyte proliferative response against rCPA, rCPB, CTE and Freezed/Thawed lysate (F/T) of L. infantum were examined. Results and Discussion: The results showed that in both of the symptomatic and asymptomatic dogs there is a high lymphoproliferative response to F/T antigens and moderate responses were observed when rCPs (Recombinant cycsteine proteinase) (rCPA and rCPB) and CTE were used. The level of antibody (total IgG, IgG۱ and IgG۲) recognition toward rCPA was low in the both groups of the dogs. In contrast, the CTE stimulates similarly as the CPB both of the humoral and cellular responses of all the infected animals and the level of total IgG and IgG۲ isotypes against these antigens compared to the IgG۱ was higher in the asymptomatic dogs. Since, the CTE is the terminal fragment of the CPB, it seems that the immunogenicity of the CPB is dependent on the CTE. Conclusion: The results of our investigation indicates that the CPB and CTE stimulate both humoral and cellular immune responses of L. infantum infected dogs, wherase the CPA is a weaker immunogen.

کلیدواژه ها:

Cysteine proteinases of L. infantum ، C-terminal extension (CTE) ، Canine visceral leishmaniasis ، Cellular and humoral responses ، لیشمانیا اینفانتوم ، سیستئین پروتئیناز ، بخش انتهای کربوکسی (CTE) ، لیشمانیوز احشایی ، ایمنی هومورال و سلولی