Phiri I K, Phiri A M, Harrison L J S
Department of Clinical Studies, School of Veterinary Medicine, University of Zambia, P.O. Box 32379, Lusaka, Zambia.
Vet Parasitol. 2006 Nov 5;141(3-4):234-42. doi: 10.1016/j.vetpar.2006.05.019. Epub 2006 Jun 23.
This study investigated the immunoglobulin isotype responses of sheep and cattle chronically infected with Fasciola hepatica and Fasciola gigantica to adult F. hepatica excretory/secretory products (Fh-ES) or F. gigantica excretory/secretory products (Fg-ES), respectively. An antibody enzyme-linked immunosorbent assay (Ab-ELISA) was used to determine serum antibody (total Ig, IgG(1), IgM, IgG(2) and IgA) responses. At necropsy, the mean number of flukes recovered was lower in cattle than in sheep. All F. hepatica and F. gigantica infected sheep and cattle showed an increased total Ig levels from 3 to 4 weeks post-infection (wpi). Among isotypes IgG(1) was most dominant while IgM was the earliest (2 wpi) to be detected in both sheep and cattle infected with both F. hepatica and F. gigantica animals. IgG(2) response was early (2 wpi) in sheep infected by F. hepatica but there was no response in sheep infected with F. gigantica. There was a late and strong IgG(2) response in cattle infected with both flukes. The IgA isotype showed an early and a clear biphasic response in sheep with F. hepatica but was less pronounced in F. gigantica infected sheep. While IgA response to Fh-ES was noticed 5 wpi in F. hepatica infected cattle, it appeared much later (21 wpi) in those infected with F. gigantica. The dominance of IgG(1) isotype in infected sheep and cattle suggest an associated Th2 response. This early response to adult Fasciola spp. ES antigen suggests an early exposure to the antigen presumably through the cross-reacting ES products of juvenile flukes. There is clearly difference in IgG(2) isotype response in cattle (resistant) compared to sheep (susceptible). The late IgG(2) response in cattle may suggest late Th1 involvement in bovine cellular responses to adult Fh-ES/Fg-ES.
本研究调查了长期感染肝片吸虫和巨片吸虫的绵羊和牛，分别针对肝片吸虫成虫排泄/分泌产物（Fh-ES）或巨片吸虫排泄/分泌产物（Fg-ES）的免疫球蛋白同种型反应。采用抗体酶联免疫吸附测定（Ab-ELISA）来确定血清抗体（总Ig、IgG(1)、IgM、IgG(2)和IgA）反应。尸检时，回收的吸虫平均数量牛比绵羊少。所有感染肝片吸虫和巨片吸虫的绵羊和牛在感染后3至4周（wpi）时总Ig水平均升高。在同种型中，IgG(1)最为主要，而在感染肝片吸虫和巨片吸虫的绵羊和牛中，IgM是最早（2 wpi）被检测到的。感染肝片吸虫的绵羊中IgG(2)反应较早（2 wpi），但感染巨片吸虫的绵羊没有反应。感染两种吸虫的牛中IgG(2)反应较晚且强烈。IgA同种型在感染肝片吸虫的绵羊中呈现早期且明显的双相反应，但在感染巨片吸虫的绵羊中不太明显。虽然感染肝片吸虫的牛在5 wpi时注意到对Fh-ES的IgA反应，但在感染巨片吸虫的牛中出现得要晚得多（21 wpi）。感染绵羊和牛中IgG(1)同种型占主导表明存在相关的Th2反应。对成虫片形吸虫属ES抗原的这种早期反应表明可能通过幼虫吸虫的交叉反应性ES产物早期接触到了该抗原。与绵羊（易感）相比，牛（抗性）在IgG(2)同种型反应上存在明显差异。牛中较晚的IgG(2)反应可能表明Th1较晚参与了牛对成虫Fh-ES/Fg-ES的细胞反应。
