Laboratório de Imunopatologia, Núcleo de Pesquisas em Ciências Biológicas, Universidade Federal de Ouro Preto, Ouro Preto, Minas Gerais, Brazil.
PLoS One. 2012;7(11):e49780. doi: 10.1371/journal.pone.0049780. Epub 2012 Nov 26.
In the last decade, the search for new vaccines against canine visceral leishmaniasis has intensified. However, the pattern related to immune protection during long periods after experimental infection in vaccine trials is still not fully understood. Herein, we investigated the immunogenicity and parasitological levels after intradermal challenge with Leishmania infantum plus salivary gland extract in dogs immunized with a vaccine composed of L. braziliensis antigens plus saponin as an adjuvant (LBSap vaccine). The LBSap vaccine elicited higher levels of total anti-Leishmania IgG as well as both IgG1 and IgG2. Furthermore, dogs vaccinated had increased levels of lymphocytes, particularly circulating B cells (CD21(+)) and both CD4(+) and CD8(+) T lymphocytes. LBSap also elicited an intense in vitro cell proliferation associated with higher levels of CD4(+) T lymphocytes specific for vaccine soluble antigen and soluble lysate of L. infantum antigen even 885 days after experimental challenge. Furthermore, LBSap vaccinated dogs presented high IFN-γ and low IL-10 and TGF-β1 expression in spleen with significant reduction of parasite load in this tissue. Overall, our results validate the potential of LBSap vaccine to protect against L. infantum experimental infection and strongly support further evaluation of efficiency of LBSap against CVL in natural infection conditions.
在过去的十年中，人们对针对犬内脏利什曼病的新型疫苗的研究日益深入。然而，在疫苗试验中，针对实验感染后长时间内的免疫保护模式仍不完全清楚。在此，我们研究了用利什曼原虫加唾液腺提取物经皮攻击感染后，用含有巴西利什曼原虫抗原加皂苷佐剂的疫苗（LBSap 疫苗）免疫的犬的免疫原性和寄生虫学水平。LBSap 疫苗可引起更高水平的总抗利什曼原虫 IgG 以及 IgG1 和 IgG2。此外，接种疫苗的犬增加了淋巴细胞水平，特别是循环 B 细胞（CD21(+)）以及 CD4(+)和 CD8(+)T 淋巴细胞。LBSap 还引发了强烈的体外细胞增殖，与针对疫苗可溶性抗原和利什曼原虫可溶性裂解物的 CD4(+)T 淋巴细胞特异性相关，甚至在实验挑战后 885 天也有高水平。此外，接种 LBSap 的犬脾脏中 IFN-γ表达水平较高，IL-10 和 TGF-β1 表达水平较低，该组织中的寄生虫载量也显著减少。总体而言，我们的结果验证了 LBSap 疫苗预防犬内脏利什曼病实验感染的潜力，并强烈支持进一步评估 LBSap 疫苗在自然感染条件下对犬内脏利什曼病的疗效。
