Brown M B, McLaughlin G S, Klein P A, Crenshaw B C, Schumacher I M, Brown D R, Jacobson E R
Department of Pathobiology and Division of Comparative Medicine, College of Veterinary Medicine, University of Florida, Gainesville, Florida 32611-0880, USA.
J Clin Microbiol. 1999 Jul;37(7):2262-9. doi: 10.1128/JCM.37.7.2262-2269.1999.
Upper respiratory tract disease (URTD) has been observed in a number of tortoise species, including the desert tortoise (Gopherus agassizii) and the gopher tortoise (Gopherus polyphemus). Clinical signs of URTD in gopher tortoises are similar to those in desert tortoises and include serous, mucoid, or purulent discharge from the nares, excessive tearing to purulent ocular discharge, conjunctivitis, and edema of the eyelids and ocular glands. The objectives of the present study were to determine if Mycoplasma agassizii was an etiologic agent of URTD in the gopher tortoise and to determine the clinical course of the experimental infection in a dose-response infection study. Tortoises were inoculated intranasally with 0.5 ml (0.25 ml/nostril) of either sterile SP4 broth (control group; n = 10) or 10(8) color-changing units (CCU) (total dose) of M. agassizii 723 (experimental infection group; n = 9). M. agassizii caused clinical signs compatible with those observed in tortoises with natural infections. Clinical signs of URTD were evident in seven of nine experimentally infected tortoises by 4 weeks postinfection (p.i.) and in eight of nine experimentally infected tortoises by 8 weeks p.i. In the dose-response experiments, tortoises were inoculated intranasally with a low (10(1) CCU; n = 6), medium (10(3) CCU; n = 6), or high (10(5) CCU; n = 5) dose of M. agassizii 723 or with sterile SP4 broth (n = 10). At all time points p.i. in both experiments, M. agassizii could be isolated from the nares of at least 50% of the tortoises. All of the experimentally infected tortoises seroconverted, and levels of antibody were statistically higher in infected animals than in control animals for all time points of >4 weeks p.i. (P < 0.0001). Control tortoises in both experiments did not show clinical signs, did not seroconvert, and did not have detectable M. agassizii by either culture or PCR at any point in the study. Histological lesions were compatible with those observed in tortoises with natural infections. The numbers of M. agassizii 723 did not influence the clinical expression of URTD or the antibody response, suggesting that the strain chosen for these studies was highly virulent. On the basis of the results of the transmission studies, we conclude that M. agassizii is an etiologic agent of URTD in the gopher tortoise.
上呼吸道疾病（URTD）已在多种陆龟物种中被观察到，包括沙漠陆龟（Gopherus agassizii）和穴小陆龟（Gopherus polyphemus）。穴小陆龟URTD的临床症状与沙漠陆龟相似，包括鼻孔浆液性、黏液性或脓性分泌物、从浆液性眼部分泌物到脓性眼部分泌物的过度流泪、结膜炎以及眼睑和眼腺水肿。本研究的目的是确定阿氏支原体是否为穴小陆龟URTD的病原体，并在剂量反应感染研究中确定实验性感染的临床病程。将陆龟经鼻接种0.5 ml（每鼻孔0.25 ml）无菌SP4肉汤（对照组；n = 10）或10⁸ 个颜色改变单位（CCU）（总剂量）的阿氏支原体723（实验感染组；n = 9）。阿氏支原体引起的临床症状与自然感染陆龟中观察到的症状相符。在感染后4周时，9只实验感染陆龟中有7只出现了URTD的临床症状，在感染后8周时，9只实验感染陆龟中有8只出现了URTD的临床症状。在剂量反应实验中，将陆龟经鼻接种低剂量（10¹ CCU；n = 6）、中剂量（10³ CCU；n = 6）或高剂量（10⁵ CCU；n = 5）的阿氏支原体723或无菌SP4肉汤（n = 10）。在两个实验的所有感染后时间点，至少50%的陆龟鼻孔中可分离出阿氏支原体。所有实验感染的陆龟都发生了血清转化，并且在感染后>4周的所有时间点，感染动物的抗体水平在统计学上均高于对照动物（P < 0.0001）。两个实验中的对照陆龟均未表现出临床症状，未发生血清转化，并且在研究的任何时间点通过培养或PCR均未检测到阿氏支原体。组织学病变与自然感染陆龟中观察到的病变相符。阿氏支原体723的数量并未影响URTD的临床表现或抗体反应，这表明为这些研究选择的菌株具有高度致病性。基于传播研究的结果，我们得出结论，阿氏支原体是穴小陆龟URTD的病原体。
