United States Department of Agriculture, Animal Disease Research Unit, Agricultural Research Service, Pullman, Washington, United States of America.
Department of Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, Washington, United States of America.
PLoS One. 2023 Mar 30;18(3):e0282356. doi: 10.1371/journal.pone.0282356. eCollection 2023.
Chronic wasting disease (CWD) continues to spread in wild and farmed cervid populations. Early antemortem CWD testing of farmed cervids is of considerable interest to producers and regulatory agencies as a tool to combat this spread. The tissues accessible for antemortem sampling are limited and include biopsy of the tonsil and recto-anal mucosa-associated lymphoid tissue (RAMALT). The sensitivity to detect CWD by immunohistochemistry (IHC)-the regulatory gold standard-using biopsy samples of RAMALT from naturally infected white-tailed deer (WTD) has been determined by several studies. However, similar information is lacking for tonsil biopsy. In this study, two-bite tonsil biopsies from 79 naturally infected farmed WTD were used to determine the diagnostic sensitivity of tonsil IHC compared to the official CWD status based on results from the medial retropharyngeal lymph nodes and obex. IHC detection of CWD by tonsil biopsy was compared to the result and follicle metrics from the contralateral whole tonsil. The sensitivity of two-bite tonsil biopsy for detecting CWD by IHC was 72% overall. When the stage of infection was considered, the sensitivity was 92% for deer in late preclinical infection but only 55% for early preclinical infection. For deer with early preclinical infection, the sensitivity for deer homozygous for the prion protein gene (PRNP) coding for glycine at codon 96 (GG) was 66% but only 30% when heterozygous for the serine substitution (GS). The results indicate that the sensitivity of two-bite tonsil biopsy in WTD, and consequently its potential utility as an antemortem diagnostic, is limited during early infection, especially in WTD heterozygous for the serine substitution at PRNP codon 96.
慢性消耗病（CWD）继续在野生和养殖鹿群中传播。早期对养殖鹿进行 CWD 检测引起了生产者和监管机构的极大兴趣，将其作为控制疾病传播的一种手段。可用于生前采样的组织有限，包括扁桃体和直肠-肛门黏膜相关淋巴组织（RAMALT）活检。使用来自自然感染白尾鹿（WTD）的 RAMALT 活检样本通过免疫组织化学（IHC）检测 CWD 的敏感性（IHC 是监管的金标准）已被多项研究确定。然而，扁桃体活检的类似信息却缺乏。在这项研究中，使用来自 79 只自然感染的养殖 WTD 的两咬扁桃体活检来确定与基于中咽后淋巴结和枕骨凹的官方 CWD 状态相比，扁桃体 IHC 的诊断敏感性。与对侧整个扁桃体的滤泡指标和结果相比，通过扁桃体活检检测 CWD 的 IHC 检测结果。通过 IHC 检测两咬扁桃体活检检测 CWD 的总敏感性为 72%。当考虑感染阶段时，晚期临床前感染的鹿的敏感性为 92%，但早期临床前感染的鹿仅为 55%。对于早期临床前感染的鹿，对于 PRNP 基因（编码甘氨酸密码子 96 的 PRNP）编码为甘氨酸的纯合子（GG）的鹿的敏感性为 66%，而对于丝氨酸取代（GS）的杂合子的敏感性仅为 30%。结果表明，在感染早期，WTD 的两咬扁桃体活检的敏感性及其作为生前诊断的潜在用途有限，特别是在 PRNP 密码子 96 处携带丝氨酸取代的 WTD 中。
