Institute of Health Sciences, Federal University of Bahia, Salvador, Bahia, Brazil.
Institute of Health Sciences, Federal University of Bahia, Salvador, Bahia, Brazil; Animal Sciences College, University of the Llanos, Villavicencio, Meta, Colombia.
Vaccine. 2020 Jun 19;38(30):4762-4772. doi: 10.1016/j.vaccine.2020.04.072. Epub 2020 May 23.
Toxocariasis, a natural helminth infection of dogs and cats caused by Toxocara canis and T. cati, respectively, that are transmitted to mammals, including humans. Infection control is based currently on periodic antihelmintic treatment and there is a need for the development of vaccines to prevent this infection.
Eight potential vaccine candidate T. canis recombinant proteins were identified by in silico (rTcGPRs, rTcCad, rTcVcan, rTcCyst) and larval proteomics (rTES26, rTES32, rMUC-3 and rCTL-4) analyses. Immunogenicity and protection against infectious challenge for seven of these antigens were determined in a murine model of toxocariasis. C57BL/6 female mice were immunized with each of or combinations of recombinant antigens prior to challenge with 500 T. canis embryonated eggs. Levels of specific antibodies (IgG, IgG1, IgG2a and IgE) in sera and cytokines (IL-5, INF-ɣ and IL-10) produced by antigens-stimulated splenocytes, were measured. Presence of specific antibodies to the molecules was measured in sera of T. canis-seropositive dogs and humans.
All seven molecules were immunogenic in immunized mice; all stimulated significantly elevated levels of specific IgG, IgG1 or IgG2a and six were associated with elevated levels of specific IgE; all induced elevated production of IFN- ɣ and IL-10 by splenocytes, but only the in silico-identified membrane-associated recombinants (rTcCad, rTcVcan, and rTcCyst) induced significantly increased IL-5 production. Vaccination with two of the latter (rTcCad and rTcVcan) reduced larval loads in the T. canis challenged mice by 54.3% and 53.9% (P < 0.0001), respectively, compared to unimmunized controls. All seven recombinants were recognized by T. canis-seropositive dog and human sera.
The identification of vaccine targets by in silico analysis was an effective strategy to identify immunogenic T. canis proteins capable of reducing larval burdens following challenge with the parasite. Two recombinant proteins, rTcCad and rTcVcan, were identified as promising vaccine candidates for canine toxocariasis.
旋毛虫病是一种由犬弓首蛔虫和猫弓首蛔虫引起的天然寄生虫感染，分别通过犬和猫传播给哺乳动物，包括人类。目前，感染控制基于定期驱虫治疗，需要开发疫苗来预防这种感染。
通过计算机分析（rTcGPRs、rTcCad、rTcVcan、rTcCyst）和幼虫蛋白质组学（rTES26、rTES32、rMUC-3 和 rCTL-4）分析，鉴定了 8 种潜在的犬旋毛形线虫重组蛋白候选疫苗。在犬旋毛虫病的小鼠模型中，确定了其中 7 种抗原的免疫原性和对感染性挑战的保护作用。雌性 C57BL/6 小鼠在接受 500 个犬弓首蛔虫胚胎卵感染前，用每种重组抗原或其组合进行免疫。测量血清中特异性抗体（IgG、IgG1、IgG2a 和 IgE）的水平和抗原刺激脾细胞产生的细胞因子（IL-5、INF-γ和 IL-10）。测量犬旋毛虫血清阳性犬和人类血清中针对这些分子的特异性抗体。
在免疫小鼠中，所有 7 种分子均具有免疫原性；所有分子均显著刺激特异性 IgG、IgG1 或 IgG2a 的产生水平，其中 6 种与特异性 IgE 的产生水平升高有关；所有分子均诱导脾细胞产生升高水平的 IFN-γ和 IL-10，但只有计算机分析鉴定的膜相关重组体（rTcCad、rTcVcan 和 rTcCyst）显著诱导 IL-5 产生增加。用其中两种（rTcCad 和 rTcVcan）疫苗接种可使感染犬旋毛虫的小鼠幼虫负荷分别降低 54.3%和 53.9%（P<0.0001），与未免疫对照组相比。所有 7 种重组蛋白均被犬旋毛虫血清阳性的犬和人类血清识别。
通过计算机分析鉴定疫苗靶点是一种有效的策略，可以识别出能够在寄生虫感染后降低幼虫负荷的免疫原性犬旋毛虫蛋白。两种重组蛋白 rTcCad 和 rTcVcan 被确定为犬旋毛虫病有前途的疫苗候选物。
