Facultad de Medicina Veterinaria y Zootecnia, Benemérita Universidad Autónoma de Puebla, Tecamachalco Puebla, Mexico.
Departamento de Parasitología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Av. Universidad 3000, Alcaldía Coyoacán, Ciudad de México C.P. 04510, Mexico.
Parasitol Int. 2021 Aug;83:102355. doi: 10.1016/j.parint.2021.102355. Epub 2021 Apr 16.
Fascioliasis is a worldwide emergent zoonotic disease that significantly constrains the productivity of livestock. In this study, fluke burdens, liver fluke size and biomass, faecal eggs counts, serum levels of hepatic enzymes and immune response were assessed in sheep vaccinated with peptide mimotopes of cathepsin L and infected with metacercariae. A total of 25 sheep were allocated randomly into five groups of five animals each, and experimental groups were immunised with 1 × 10 filamentous phage particles of cathepsin L1 (CL1) (TPWKDKQ), CL2 (YGSCFLR) and mixtures of CL1 + CL2 mimotopes, in combination with Quil A adjuvant, and wild-type M13KE phage in a two-vaccination scheme on weeks 0 and 4. The control group received phosphate-buffered saline. All groups were challenged with 300 metacercariae two weeks after the last immunisation and euthanised 16 weeks later. The CL1 vaccine was estimated to provide 57.58% protection compared with the control group; no effect was observed in animals immunised with CL2 and CL1 + CL2 (33.14% and 11.63%, respectively). However, animals receiving CL2 had a significant reduction in parasite egg output. Vaccinated animals showed a significant reduction in fluke length and width and wet weights. In the CL1 group, there was a significant reduction in the total biomass of parasites recovered. Egg development was divided into seven stages: dead, empty, unembryonated, cell division, eyespot, hatched and hatching. The highest percentage of developmental stages was detected for vaccinated sheep administered CL1 + CL2 with cell division, and the lowest percentage was observed in the hatching stage. Furthermore, a significant difference in all developmental stages was observed between vaccinated animals and the control group (P < 0.01). The levels of anti-phage total IgG in immune sera increased significantly at four weeks after immunisation and were always significantly higher for cathepsin L vaccine group than in the challenged control group. Total IgG was inversely and significantly correlated with worm burden in the CL1 group.
片形吸虫病是一种全球性的新兴人畜共患病，严重限制了家畜的生产力。在这项研究中，我们评估了用组织蛋白酶 L 的肽模拟物免疫并感染囊蚴的绵羊的吸虫负荷、肝吸虫大小和生物量、粪便卵计数、肝酶血清水平和免疫反应。总共将 25 只绵羊随机分配到五组，每组五只动物，实验组用 1×10 丝状噬菌体颗粒的组织蛋白酶 L1（CL1）（TPWKDKQ）、CL2（YGSCFLR）和 CL1+CL2 模拟物混合物、联合 Quil A 佐剂、以及野生型 M13KE 噬菌体，在 0 周和 4 周进行两次疫苗接种。对照组接受磷酸盐缓冲液。所有组在最后一次免疫后两周内用 300 个囊蚴进行攻毒，并在 16 周后安乐死。CL1 疫苗的估计保护率为 57.58%，与对照组相比；用 CL2 和 CL1+CL2 免疫的动物没有观察到效果（分别为 33.14%和 11.63%）。然而，用 CL2 免疫的动物寄生虫卵排出量显著减少。接种疫苗的动物的吸虫长度、宽度和湿重均显著降低。在 CL1 组，回收的寄生虫总生物量显著减少。卵的发育分为七个阶段：死亡、空、未胚胎化、细胞分裂、眼点、孵化和孵化。在接受 CL1+CL2 免疫的绵羊中，检测到的发育阶段百分比最高，在孵化阶段最低。此外，在所有发育阶段，接种疫苗的动物与对照组之间均存在显著差异（P<0.01）。免疫血清中的抗噬菌体总 IgG 在免疫后四周显著增加，并且在组织蛋白酶 L 疫苗组中总是显著高于攻毒对照组。CL1 组的总 IgG 与虫负荷呈负相关且显著相关。
