Facultad de Medicina Veterinaria y Zootecnia, Benemérita Universidad Autónoma de Puebla, Tecamachalco, Puebla, Mexico.
Unidad Académica de Medicina Veterinaria y Zootecnia, Universidad Autónoma de Guerrero, Ciudad Altamirano, Guerrero, Mexico.
Vet Parasitol. 2021 Jan;289:109340. doi: 10.1016/j.vetpar.2020.109340. Epub 2020 Dec 18.
Fasciolosis is a foodborne zoonotic disease that affects grazing animals and causes substantial economic losses worldwide. Excretory/secretory (E/S) products and cathepsin L mimotopes from Fasciola hepatica were used to immunise experimentally infected sheep against liver flukes. The level of protection was measured in terms of fluke burden, morphometric measurements and faecal egg counts, as well as the humoral and cellular immune responses elicited. Five groups of 5 sheep each were immunised with 1 × 10 phage particles of cathepsin L1 (group 1: SGTFLFS), cathepsin L1 (group 2: WHVPRTWWVLPP) and immunodominant E/S product (group 3) mimotopes with Quil A adjuvant, and wild-type M13KE phage (group 4) at the beginning and as a booster two weeks later. The control group received phosphate-buff ;ered saline. All groups were challenged with 300 metacercariae at week four and slaughtered 18 weeks later. The mean fluke burdens after challenge were reduced by 52.39 % and 67.17 % in sheep vaccinated with E/S products (group 3) and cathepsin L1 (group 1: SGTFLFS), respectively; no eff ;ect was observed in animals inoculated with cathepsin L1 (group 2: WHVPRTWWVLPP). Animals vaccinated showed a significant reduction in fluke length and width, wet weights and egg output Sheep immunised with phage-displayed mimotopes induced the development of specific IgG1 and IgG2, indicating a mixed Th1/Th2 immune response. Measurement of cytokine levels revealed higher levels of IFN-γ as well as lower production of IL-4 in sheep vaccinated with the mimotope peptide of F. hepatica. Fluke-specific production of IFN-γ in immunised animals was significantly correlated with fluke burden (P < 0.01). As helminth infection progressed, increased levels of IL-4 were evident in the wild-type M13KE phage (group 4) and the control groups (group 5), accompanied by a downregulation of IFN-γ production. Vaccinated animals with cathepsin L1 (group 1: SGTFLFS) showed that amino acids located in the middle (SG) of the linear sequence and C-terminal end (TFLFS) were associated with significant protection.
片形吸虫病是一种食源性病原体，可感染放牧动物，给全世界造成了巨大的经济损失。我们曾使用来自肝片形吸虫的排泄/分泌（E/S）产物和组织蛋白酶 L 模拟肽对实验感染的绵羊进行免疫，以预防肝片形吸虫感染。我们通过检测吸虫负荷、形态测量和粪便虫卵计数，以及体液和细胞免疫应答来衡量保护水平。每组 5 只绵羊，每组用 1×10 噬菌体颗粒的组织蛋白酶 L1（组 1：SGTFLFS）、组织蛋白酶 L1（组 2：WHVPRTWWVLPP）和免疫显性 E/S 产物（组 3）模拟肽与 Quil A 佐剂进行免疫，第 4 组用野生型 M13KE 噬菌体免疫，第 5 组（对照组）注射磷酸盐缓冲液。所有组在第 4 周用 300 尾囊蚴进行攻虫，18 周后宰杀。攻虫后，E/S 产物（组 3）和组织蛋白酶 L1（组 1：SGTFLFS）免疫的绵羊平均吸虫负荷分别降低 52.39%和 67.17%；而用组织蛋白酶 L1（组 2：WHVPRTWWVLPP）免疫的绵羊没有效果。接种疫苗的绵羊的吸虫长度和宽度、湿重和产卵量均显著降低。用噬菌体展示模拟肽免疫的绵羊诱导产生了特异性 IgG1 和 IgG2，表明存在混合的 Th1/Th2 免疫应答。细胞因子水平的测定表明，用 F. hepatica 模拟肽免疫的绵羊 IFN-γ 水平较高，IL-4 水平较低。免疫动物中与吸虫负荷显著相关的是 IFN-γ 的特异性产生（P<0.01）。随着寄生虫感染的进展，野生型 M13KE 噬菌体（组 4）和对照组（组 5）的 IL-4 水平升高，同时 IFN-γ 产生下调。用组织蛋白酶 L1（组 1：SGTFLFS）免疫的绵羊表明，线性序列中间（SG）和 C 末端（TFLFS）的氨基酸与显著保护有关。
