Data_Sheet_1_Management of Suspected Cases of Feline Immunodeficiency Virus Infection in Eurasian Lynx (Lynx lynx) During an International Translocation Program.docx

The Eurasian lynx (Lynx lynx) population in Switzerland serves as a source for reintroductions in neighboring countries. In 2016–2017, three lynx from the same geographical area were found seropositive for feline immunodeficiency virus (FIV) in the framework of an international translocation program. This novel finding raised questions about the virus origin and pathogenicity to lynx, the emerging character of the infection, and the interpretation of serological results in other lynx caught for translocation. Archived serum samples from 84 lynx captured in 2001–2016 were retrospectively tested for FIV antibodies by Western blot. All archived samples were FIV-negative. The three seropositive lynx were monitored in quarantine enclosures prior to euthanasia and necropsy. They showed disease signs, pathological findings, and occurrence of co-infections reminding of those described in FIV-infected domestic cats. All attempts to isolate and characterize the virus failed but serological data and spatiotemporal proximity of the cases suggested emergence of a lentivirus with antigenic and pathogenic similarities to FIV in the Swiss lynx population. A decision scheme was developed to minimize potential health risks posed by FIV infection, both in the recipient and source lynx populations, considering conservation goals, animal welfare, and the limited action range resulting from local human conflicts. Development and implementation of a cautious decision scheme was particularly challenging because FIV pathogenic potential in lynx was unclear, negative FIV serological results obtained within the first weeks after infection are unpredictable, and neither euthanasia nor repatriation of multiple lynx was acceptable options. The proposed scheme distinguished between three scenarios: release at the capture site, translocation, or euthanasia. Until April 2021, none of the 40 lynx newly captured in Switzerland tested FIV-seropositive. Altogether, seropositivity to FIV was documented in none of 124 lynx tested at their first capture, but three of them seroconverted in 2016–2017. Diagnosis of FIV infection in the three seropositive lynx remains uncertain, but clinical observations and pathological findings confirmed that euthanasia was appropriate. Our experiences underline the necessity to include FIV in pathogen screenings of free-ranging European wild felids, the importance of lynx health monitoring, and the usefulness of health protocols in wildlife translocation.

瑞士境内的欧亚猞猁（Lynx lynx）种群，是周边国家开展猞猁再引入工作的种源来源。2016-2017年，在一项国际移置保护计划框架下，从同一地理区域捕获的3只猞猁被检出猫免疫缺陷病毒（feline immunodeficiency virus, FIV）血清学阳性。这一新发现引发了诸多疑问：该病毒的起源、对猞猁的致病性、该感染的新发特征，以及对其他用于移置的捕获猞猁的血清学结果的解读。
研究人员对2001-2016年间捕获的84份存档血清样本，采用免疫印迹（Western blot）法开展了FIV抗体回顾性检测，结果所有存档样本均呈FIV阴性。
这3只血清学阳性的猞猁在安乐死与剖检前，被安置于隔离检疫笼舍中进行监测。它们表现出与FIV感染家猫类似的疾病症状、病理特征及合并感染情况。所有分离并鉴定该病毒的尝试均告失败，但血清学数据与病例的时空关联性提示，瑞士猞猁种群中出现了一种与FIV具有抗原性和致病性相似的慢病毒（lentivirus）。
研究团队制定了一套决策方案，以尽可能降低FIV感染对接收种群与源种群的潜在健康风险，同时兼顾保护目标、动物福利，以及当地人类冲突导致的有限行动空间。该谨慎决策方案的制定与实施颇具挑战，原因在于：猞猁体内FIV的致病潜力尚不明确，感染初期数周内获得的FIV血清学阴性结果难以预判，且安乐死或遣返多只猞猁均非可接受的处置选项。
该方案区分了三种情形：就地放归、移置，或安乐死。截至2021年4月，瑞士新捕获的40只猞猁均未检出FIV血清学阳性。综上，在124只首次捕获时接受检测的猞猁中，未发现FIV血清阳性个体，但其中3只在2016-2017年间出现了血清转换。
这3只血清学阳性猞猁的FIV感染诊断仍未明确，但临床观察与病理结果证实，安乐死是恰当的处置方式。本研究的经验凸显了将FIV纳入野生欧洲猫科动物病原体筛查的必要性、猞猁健康监测的重要性，以及野生动物移置过程中健康规程的实用价值。